Ruma Pal · Avik Kumar Choudhury An Introduction to : Diversity and Ecology An Introduction to Phytoplanktons: Diversity and Ecology

Ruma Pal • Avik Kumar Choudhury

An Introduction to Phytoplanktons: Diversity and Ecology Ruma Pal Avik Kumar Choudhury Department of Botany University of Calcutta Kolkata , West Bengal , India

ISBN 978-81-322-1837-1 ISBN 978-81-322-1838-8 (eBook) DOI 10.1007/978-81-322-1838-8 Springer New Delhi Heidelberg New York Dordrecht London

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Springer is part of Springer Science+Business Media (www.springer.com) Pref ace

Phytoplankton community in water bodies support the base of the natural food chain depending on which the natural fauna including the fi sh popula- tions can survive. At the same time they produce almost 70 % of world’s atmospheric oxygen. On the other hand, excessive production in the water bodies causes extensive problems like fi sh poisoning and deterioration of water quality in drinking water management, swimming pools and other water-based recreations. Therefore, it is dire necessity to study the different factors controlling phytoplankton growth or in other words phytoplankton ecology. The microscopic phytoplanktonic genera are represented by different algal groups like , , Bacillariophyta, Euglenophyta, Prymnesiophyta, etc. Therefore, identifi cation of planktonic genera requires a good knowledge in algal . Algal taxonomy is nowadays based on different characters like ultrastructure of algal and fl agella, cellular biochemistry, molecular characterization, etc., rather than morphotaxonomy of early days. With the advent of different sophisticated instruments like TEM, SEM, AFM, HPLC, HPTLC, etc., change in algal taxonomy is a regular phenomenon. For this reason, an attempt has been taken to discuss the chrono- logical changes in algal taxonomy. Pigment composition is nowadays an important characteristic for classifying the algal kingdom, especially the marine phytoplanktons; therefore, we have attempted to discuss pigment composition of different groups of algae in detail. To correlate the phytoplankton productivity together with varied physico- chemical parameters, different statistical methods are to be employed for data analysis, based upon which different ecological models are proposed. To study the phytoplankton diversity and ecology, sampling is an important factor to get the actual results. Different methods of samplings have also been discussed here. Therefore, phytoplankton ecology is a complex science, as it includes the interactions between biogeochemical cycling and environ- mental parameters. This phenomenon can be explained by the simple question, ‘What lives where and why?’, as stated by the famous phytoplankton ecologist Reynolds. In general, there is scarcity of books on phytoplanktons related to diversity and ecology for students as well as researchers, which I experienced during my research work for the last 20 years on phytoplankton ecology. Therefore, presently for the benefi t of students and phytoplankton researchers, we have

v vi Preface tried to compile a general account of phytoplanktons, their physical and chemical environments, sampling methods and the statistical analysis together with similar case studies on phytoplankton ecology. The results of the case studies are the doctoral work of my student Dr. Avik Kumar Choudhury and research fi ndings of my other students, Sri Nirupam Barman, Sri Gour Gopal Satpati and Ms Anindita Singha Roy. I think this book will help the students of botany, zoology, microbiology and environmental biology together with the researchers.

Kolkata , India Ruma Pal 17 Sep 2013 Acknowledgement

The development of this book was made possible by the fi nancial support from University Grants Commission (UGC), Govt. of India, for two research projects on phytoplankton dynamics of Eastern Indian coast and other ecological niche. Dr. Avik Choudhury and Ms. Anindita Singha Roy worked as Project Fellows, and their research fi ndings are represented as Case Study in Chap. 5 . Financial support from Council of Scientifi c and Industrial Research (CSIR), Govt. of India, is also acknowledged for survey work at Indian Sunderbans area under NIMTLI program. Mr. Nirupam Barman and Sri Gour Gopal Satpati surveyed different parts of Sunderbans, and their work is also included in this book.

20 Jan 2014 Ruma Pal

vii

C o n t e n t s

1 A Brief Introduction to Phytoplanktons ...... 1 1.1 General ...... 1 1.2 Historical Perspective ...... 1 1.3 Algal Classifi cation ...... 2 1.3.1 Old Classical Taxonomy ...... 3 1.3.2 Modern System of Algal Classifi cation ...... 8 1.4 Classifi cation of Phytoplanktons ...... 15 1.4.1 On the Basis of Size Variations ...... 15 1.4.2 On the Basis of Habitat ...... 16 1.5 Algal Pigments ...... 18 1.6 Ecological Signifi cance ...... 23 1.6.1 Phytoplankton Bloom ...... 23 1.6.2 Cyanobacterial Bloom ...... 24 1.6.3 Dinofl agellate Bloom ...... 25 1.6.4 Algal Toxins ...... 27 1.7 Algae in Wetlands ...... 28 1.7.1 Role of Phytoplanktons in Wetlands ...... 29 1.7.2 Nutrient Status of Wetland Ecosystem ...... 29 1.7.3 Types of Wetlands ...... 30 1.8 Key to Identifi cation of Common Phytoplankton Genera...... 30 1.8.1 Division: Cyanobacteria ...... 30 1.8.2 Division: Chlorophyta ...... 31 1.8.3 Order: Volvocales ...... 32 1.8.4 Order: Chlorococcales ...... 32 1.8.5 Division: Bacillariophyta () ...... 33 References ...... 39 2 Physicochemical Environment of Aquatic Ecosystem ...... 43 2.1 Physical Factors ...... 43 2.1.1 Light and Temperature ...... 43 2.1.2 Turbulence ...... 45 2.2 Major Nutrients ...... 46 2.2.1 Redfi eld Ratio ...... 47 2.2.2 Carbon ...... 47 2.2.3 Nitrogen ...... 49 2.2.4 Phosphorus ...... 50

ix x Contents

2.2.5 Silicon ...... 51 2.2.6 Nutrient Uptake Model ...... 52 References ...... 52 3 Phytoplanktons and Primary Productivity ...... 55 References ...... 57 4 Community Pattern Analysis ...... 59 4.1 Phytoplankton Sampling ...... 59 4.1.1 Bottle Samplers ...... 59 4.1.2 Plankton Pumps ...... 60 4.1.3 Plankton Nets ...... 61 4.2 Biomass Estimation ...... 62 4.2.1 Cell Counts...... 63 4.2.2 Utermohl Sedimentation Method for Cell Counts ...... 63 4.2.3 Biovolume ...... 64 4.2.4 Chlorophyll and Photopigments ...... 65 4.3 Species Diversity Index ...... 68 4.3.1 Species Evenness ...... 69 4.3.2 Species Richness ...... 69 4.4 Multivariate Analysis ...... 70 4.4.1 Preparation of Data Sets ...... 70 4.4.2 Data Transformations ...... 70 4.4.3 Exploratory Analysis ...... 71 References ...... 73 5 Case Study ...... 75 5.1 Studies from Eastern Mediterranean Region: A Review ...... 75 5.2 Case Study I: Phytoplankton Diversity of East Calcutta Wetland: A Ramsar Site ...... 78 5.2.1 Study Area ...... 78 5.2.2 Results ...... 79 5.3 Case Study II: Phytoplankton Diversity of Indian Sunderbans ...... 88 5.3.1 List of Phytoplankton Genera Recorded from Sunderbans ...... 89 5.3.2 Taxonomic Account of a Few Phytoplankton Taxa Recorded from Sunderbans (Rest Are in Case Studies I and III) ...... 89 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast ...... 92 5.4.1 Study Area ...... 92 5.4.2 Nutrient and Phytoplankton Dynamics of Coastal West Bengal ...... 92 References ...... 158

Glossary ...... 163

Bibliography ...... 167 About the Author

Dr. Ruma Pal did her M.Sc. and Ph.D. from University of Calcutta. Presently, she is Associate Professor in Botany, Department of Botany, University of Calcutta, India. Prior to this assignment she had served in Presidency College, Calcutta and Nara Sigh, Dutt College Howrah. She has more than 30 years of research experience in Phycology. Her research interest is related to various fi elds of algal biotechnology, like, Phycoremediation, aquaculture, biofuel production, nanotechnology, etc. Algal diversity study, phytoplankton dynamics and ecological modelling are also the areas of her interest. She has already conducted more than 15 research projects in the fi eld of algal applica- tion and has published more than 50 papers in refereed journals.

xi xii About the Author

Dr. Avik Kumar Choudhury completed his postgraduation from Banaras Hindu University in Botany in 2004. Subsequently, he worked as a UGC Project Fellow at Department of Botany, University of Calcutta. He completed his doctoral work from the same institute and received his Ph.D. degree in 2011 under the guidance of Dr. R. Pal. He also worked as a DBT (Department of Biotechnology, Govt. of India) Postdoctoral Research Associate at Department of Biological Sciences, Indian Institute of Science Education and Research. Presently he is in West Bengal School service. A Brief Introduction to Phytoplanktons 1

1.1 General meaning ‘pool’ or ‘lake’ or ‘swamp’. The study of biological limnology originated in 1674 ‘Phytoplanktons’ are free-fl oating, photosynthetic, with the fi rst microscopic description of aquatic microorganisms, which move from one Spirogyra from Berkelse Lake, Netherlands, by place to another, either actively by their locomo- Leeuwenhoek. The first work on limnology tory organs (fl agella) or passively by water cur- was probably published in the USA by Louis rents. The name ‘phytoplankton’ came from the Agassiz (1850 ) entitled Lake Superior: Its Greek words ‘φυτόν’ (phyton), meaning ‘plant’, Physical Character, Vegetation and Animals . and ‘πλαγκτός’ (planktos), meaning ‘wanderer’ Professor Forel of the University of Lausanne, or ‘drifter’. The term ‘plankton’ was fi rst used by who is considered as the ‘father of limnology’, the German biologist Victor Hensen in 1887. published the fi rst textbook on limnology in According to Hensen, ‘plankton included all 1869 on the bottom fauna of Geneva Lake organic particles which fl oat freely and involun- entitled Introduction a letude de la faune pro- tarily in open water, independent of shores and fonde du Lac Leman and for the fi rst time he bottom (Ruttner 1940; Hutchinson 1957 )’. used the term ‘limnology’ in his book. Most of the phytoplanktons survive on the The study of lotic estuarine systems was initi- open surface waters of lakes, rivers and oceans. ated by J.R. Lorenz in the Elbe, Germany, in the The phytoplankton community is mainly repre- 1860s. At the same time, pollution research sented by algal representatives including both started in the Thames in England, and the prokaryotes and eukaryotic genera. Plankton realization of the problems of survival in populations are mostly represented by members brackish waters was initiated with the biological of Cyanobacteria, Chlorophyta, Dinophyta, approaches (Meyer and Möbius 1865–72 ). The Eugleno phyta, Haptophyta, Chrysophyta, importance of ecological concepts in limnology Cryptophyta and Bacillariophyta. Planktonic rep- was fi rst established by the English botanist resentative taxa are absent in other algal divisions Tansley which was later popularized by G.E. like Phaeophyta and Rhodophyta. Hutchinson and R.L. Lindenman in the latter’s paper entitled The Trophic Dynamic Aspect of Ecology (1942) . Professor Birge of the University 1.2 Historical Perspective of Wisconsin contributed to limnology in the USA through his study of the plankton of Lake It has been proposed that studies related to Mendota (1917). Other eminent scientists like plankton are included under ‘limnology’ where C.A. Kofoid, J.G. Needham and C. Juday also the name comes from the Greek word ‘limnos’ worked on different rivers and lakes. In the early

R. Pal and A.K. Choudhury, An Introduction to Phytoplanktons: Diversity and Ecology, 1 DOI 10.1007/978-81-322-1838-8_1, © Springer India 2014 2 1 A Brief Introduction to Phytoplanktons part of the twentieth century, Professor P.S. In early times, the classifi cation was mainly Welch wrote the fi rst American textbook on lim- based on the morphotaxonomy. But very nology. Similar books were also written like recently the situation is marked by the quest of Fundamentals of Limnology by Franz Ruttner a compromise between the conventional (artifi - (1940) and Professor G.E. Hutchinson published cial) system and the phylogenetic system the book entitled Treatise on Limnology (1957, together with the molecular genetics. The classi- 1967) which is considered as standard reference cal approaches using morphological characters work throughout the world. do not refl ect the phylogenetic relationships, In the nineteenth century, it was felt to publish e.g. molecular data revealed that among the the journals on limnology that would pull together green algae, the genera with spherical ball-type the increasing volume of limnological informa- thallus evolved independently in different tions that were developing every day. Thus, on lineages of algae. On the other hand, highly January 1, 1936, the Limnological Society of diverse morphotypes can belong to one and the America was established, which was later same phylogenetic lineage. (1948) named as the ‘American Society of In algal systematics nowadays, a polyphasic Limnology and Oceanography’ and used to pub- approach is widely suggested. Therefore, phylo- lish till date the most well- circulated and popular geneticists suggest the following criteria for journal titled Limnology and Oceanography . The proper identifi cation and phylogenetic place- year 1948 is also marked for the formation of the ment of any algal groups: ‘Freshwater Biological Association’ in Britain. 1. Conventional morphological and ecophy- This association maintains a continuous record of siological study of algae under fi eld physical, chemical and biological informations condition of 17 lakes in the Lake District of northwest 2. Isolation of unialgal culture for morphological, England. Similarly ‘Istituto Italiano di ontogenetic, biochemical and physiological Idrobiologia’ in Italy carried out intensive studies studies under laboratory conditions on northern Italian lakes, and the science of lim- 3. Ultrastructural studies of different cell organ- nology in Europe fl ourished. Similar other elles of algal cell, especially the chloroplast renowned institutes developed around this time ultrastructure in Europe, for example, at Plön, Germany; 4. Use of molecular markers (conserved sequences) Uppsala and Lund, Sweden; Copenhagen, for molecular phylogenetic analysis Denmark; and on Lake Constance, Germany. The most commonly used sequences are the 16S rRNA or the small subunit (SSU) of ribo- somal RNA (rRNA) for prokaryotic cells and 18S 1.3 Algal Classifi cation rRNA for eukaryotic cells. Besides some other markers are also used for phylogenetic analysis, Algae are considered as the most primitive e.g. rbcL and tufA gene. plants with well diversifi cations. They all have a Therefore, for convenience we can consider chlorophyll- bearing thalloid plant body and two phases of algal systematics. In the fi rst their reproductive structures are without sterile phase, starting from placement of algae in jackets. They have variations in morphology plant kingdom by Eichler (1886 ), followed by and cellular biochemistry together with repro- algal classifi cation by Fritsch (1935 ) and Smith ductive behaviour and life cycle patterns. On the (1950 ), up to Bold and Wynne’s (1985 ) system, basis of these characters, algologists classifi ed only morphological characters were consid- the entire algal kingdom into different divisions ered for taxonomic purpose. Therefore, these and classes from time to time. classifi cations can be considered under ‘old The systematics or classifi cation of algae classical taxonomy’. In another approach or in has been changing dramatically through ages. the second phase, other parameters including 1.3 Algal Classifi cation 3 ultrastructural, biochemical and molecular between algae and fungi was recognized as the characters are also considered – refl ecting the presence or absence of chlorophyll. evolution and phylogeny of and can be desig- This system of classifi cation is considered as nated as ‘modern system of classifi cation’. incorrect by most of the scientists now. Indeed, we think it is still needed to be taught to a bota- nist to understand the phylogenetic position of 1.3.1 Old Classical Taxonomy algae and other plant groups which also indicate the evolutionary tendency among different plant Eichler (1886 ) mentioned the phylogenetic groups in a broader sense. position of algae in relation to other plant In the old classical system of algal classifi ca- groups. He divided the entire plant kingdom tion, famous algologists like Smith, Fritsch, into two groups: Cryptogamia (spore-producing Prescott, Bold and Wynne and Chapman and plants) and Phanerogamia (seed plants). These Chapman have classifi ed the algal kingdom on two groups are again divided into three divi- the basis of variation in cell structure (prokary- sions and four classes. Algae are placed in Class otic and eukaryotic), fl agellar position, number I of division Thallophyta under Cryptogamia in and structure, pigment composition, reserve food close association with fungi. The only difference matters, mode of reproduction, etc.

Plant kingdom

A. Cryptogamae B. Phenerogamae (Spore producing plants) (Seed plant)

-Division I –Thallophyta (Lower plant with a thallus) Division I- Gymnospermae Division II- Angiospermae (Plants with naked seeds) (Plants with enclosed seeds)

Class I- Algae Class II- Fungi Class I- Monocotyledonae Class II- Dicotyledonae (Plants with 1 cotyledon) (Plants with 2 cotyledons)

-Division II: Bryophyta (Mosses and liverworts) -Division III. Pteridophyta (Vascular cryptogams)

Eichler’s system of classifi cation (1886)

Afterwords, Fritsch (1935 ) divided the algal VI. Dinophyceae kingdom into 11 classes: VII. Chloromonadineae Class VIII. Euglenineae I. IX. Phaeophyceae II. Xanthophyceae X. Rhodophyceae III. Chrysophyceae XI. Myxophyceae IV. Bacillariophyceae On the basis of the morphological characters, V. Cryptophyceae Fritsch distinguished clearly 11 classes of the 4 1 A Brief Introduction to Phytoplanktons algae. The termination ‘phyceae’ has been 3. Chrysophyceae – Members are with brown- adopted wherever the class includes forms with or orange-coloured chromatophores contain- an algal organization, while for fl agellates the old ing one or more accessory pigments. Starch designation is retained. Therefore, he designated is absent, but naked pyrenoid-like bodies are the different groups of algae as ‘classes’ – rather occasionally present. Fat and a compound than ‘divisions’. leucosin are found in the form of rounded The 11 classes were characterized as follows: whitish opaque lumps as the food storage. 1. Chlorophyceae (Isokontae) – Members with A large proportion of the members are fl ag- grass-green-coloured chromatophores and ellate and devoid of a special cell membrane. contain the same pigment compositions and The motile cells possess one or two (rarely approximately in the same proportions as in three) fl agella attached at the front end. The higher plants. Starch is the customary form of cells typically contained one or two parietal storage products of , often chromatophores. The most advanced habit is (especially in resting stages) accompanied by that of a branched fi lament. Sexual reproduc- oil, and pyrenoids commonly surrounded by tion is extremely rare and not yet quite a starch sheath are frequently present inside clearly established in any one case; the exist- the . Cells are surrounded by a ing records point only to isogamy. The class cell wall in which cellulose is the constitu- is widely distributed in freshwaters, but a ent. The motile cells are with equal whiplash few are marine. An example is Chromulina . type of fl agella (commonly two or four) 4. Bacillariophyceae (diatoms) – Unicellular which arise from the front end of swarmers. members with yellow or golden-brown In many members the cells contain only one chromatophores containing accessory brown or few chromatophores. The members of pigments. Pyrenoid-like bodies are often Chlorophyceae exhibit sexual reproduction present and the products of photosynthesis – ranging from isogamy to advanced oogamy. are fat and volutin. All the members are Most of the taxa are haploid with zygote rep- unicellular or colonial. A cell wall is always resenting the only diploid phase, but some present and is composed of mainly silica and exhibit a regular alternation of generation partly of pectic substances. The cell consists with similar haploid and diploid individuals. of two halves, each composed of two or more The class is more widely represented by pieces, and is commonly richly ornamented. freshwater members than in salt water, and One set of forms (Centrales) is radially and there is a marked terrestrial tendency. Examples the other (Pinales) bilaterally symmetrical. are Chlamydomonas and Spirogyra. The diatoms produce a special type of spore – 2. Xanthophyceae (Heterokontae) – The mem- the . The Pinales show a special bers are with yellow-green chromatophores type of sexual fusion between the protoplasts due to presence of xanthophylls as major of the ordinary individuals. The members of pigment. Starch is absent and storage product this class are probably diploid. Diatoms are is oil. The algal members have a cell wall very widely distributed in the sea and in all which is often rich in pectic compounds. The kinds of freshwaters, as well as in the soil motile cells possess two very unequal fl agella and in other terrestrial habitat. Examples are (or sometimes only one) arising from the and . front end. As a general rule the cells contain a 5. Cryptophyceae – The members are of fl agellate number of discoid chromatophores. Sexual organization and with oogamous type of repro- reproduction is always isogamous. The most duction. The cells are with usually two large advanced forms have a simple fi lamentous parietal chromatophores showing very diverse habit. All are probably haploid. The class is pigmentation. Pyrenoid-like bodies occur, but more widely distributed in freshwater than in appear often to be independent of the chromato- the sea. An example is Vaucheria . phores; the products of photosynthesis are 1.3 Algal Classifi cation 5

solid carbohydrates, in some cases starch, in photosynthesis is a polysaccharide, paramylum, others a compound akin to it. The motile which occurs in the form of solid grains of cells are pronouncedly dorsiventral, have diverse and often very distinctive shape. two slightly unequal fl agella and possess a Only fl agellate members are known and the very specialized and characteristic structure. majority is motile with the help of one or There is often a complex vacuolar system. two fl agella which arise from the base of a The class is relatively small and appears to canal-like invagination at the front end. be equally scantily represented in the sea and There is a complex vacuolar system and a freshwater. An example is Cryptomonas . large and prominent nucleus. Only few cases 6. Dinophyceae (Peridiniidae) – The majority of sexuality (isogamous) are known and of the members are motile unicells and many these are not quiet fully substantiated. The possess a very elaborate cellulose envelope bulk of the members of this class probably composed of a large number of often richly inhabits freshwaters. The class is highly sculptured plates; some are with a branched specialized and no really simple form is fi lament. The members usually have numer- known. An example is Euglena . ous discoid chromatophores which are dark 9. Phaeophyceae – The majority of cells are yellow, brown, etc., and contain a number of with brown chromatophores containing, special pigments. The products of photo- apart from the usual pigments, the yellow synthesis are starch and oil (fat). Many spe- fucoxanthin. Naked pyrenoid-like bodies cies are colourless saprophytes or exhibit occur in some of the lower forms. The assim- holozoic nutrition; one extensive series is ilatory products are sugar alcohols (mannitol) parasitic. The motile cells have two furrows, with only traces of sugars, as well as polysac- the transverse one harbouring the transverse charides (laminarin) and fats. Characteristic fl agellum which usually encircles the body fucosan vesicles are present which probably and the other longitudinal constituting the represent waste products. The motile repro- starting point for the longitudinal fl agellum ductive cells have two laterally attached fl a- which is directed backwards. Resting cysts gella, of which one is directed forwards and of characteristic form are often produced. the other backwards. These swarmers are Isogamous sexual reproduction is certainly always formed in special organs which are of rare occurrence and not yet clearly estab- either unilocular or septate with numerous lished. A class of mainly plankton organisms small compartments (plurilocular sporan- is more widely represented in the sea than in gia). Sexual reproduction is of wide occur- freshwaters. An example is Gymnodinium. rence and ranges from isogamy to oogamy of 7. Chloromonadineae – The members of this a primitive type, with liberation of the ovum class are motile fl agellates, with two almost prior to fertilization. The zygote exhibits no equal fl agella. Cells are with numerous dis- resting period. The life cycle is very diverse, coid chromatophores having a bright green with varied types of alternation of genera- tint and containing an excess of xantho- tions. An example is Laminaria . phylls. Pyrenoids are lacking and oil is the 10. Rhodophyceae – The majority attains to a assimilatory product. Although superfi cially considerable complexity of structure, though like Xanthophyceae the detailed structure of the simplest forms are fi lamentous. Cells the cells is altogether different (complex are with chromatophores containing, apart vacuolar apparatus, etc.). The class is only from the usual pigments, others like the recorded from freshwaters. An example is red phycoerythrin and blue phycocyanin. Gonyostomum (). Pyrenoid- like bodies are found in the lower 8. Euglenineae – Unicellular thallus with pure groups and the product of assimilation is a green chromatophores, each cell usually with solid polysaccharide similar to starch (fl orid- several pyrenoid-like bodies. The product of ean starch). Neither motile reproductive stages 6 1 A Brief Introduction to Phytoplanktons

nor fl agellate members are known. Evident The divisions were characterized by the fol- protoplasmic connections are the rule lowing basic characteristics: between the cells of the majority of forms. 1 . Chlorophyta – The grass-green algae with Most of the Rhodophyceae are marine. All the major pigments chlorophyll a and b exhibit sexual reproduction of an advanced together with carotenes and xanthophylls. oogamous type, the female organ having a Photosynthetic reserves are usually stored in long receptive neck and the antheridium the form of starch. It is always in association producing but a single motionless male cell. with pyrenoid. Motile stages have fl agella of As a result of fertilization, special spores equal length with a few exceptions. The zoo- (carpospores) are produced from bunches of spores and motile gametes have two or four threadlike structures that arise from the fl agella. Sexual reproduction is a phenomenon female organ after fertilization. The of wide occurrence within the group and in Rhodophyceae are either haploid or exhibit various orders it ranges all the way from isog- a regular alternation of similar haploid and amy to oogamy. This group also shows a wide diploid individuals, the latter bearing char- range in vegetative structures (Chlorella ). acteristic sporangia (tetrasporangia), each 2 . Euglenophyta – All the members are unicel- producing four spores. An example is lular and most of them are naked free- Polysiphonia. swimming cells with one, two or three fl agella. 11. Myxophyceae (Cyanophyceae) – Members Many of the genera have grass-green, discoid with a simple type of cell, containing at the band-shaped or stellate chloroplasts, with or best only a very rudimentary nucleus (central without pyrenoids. The chloroplasts contain body) and without a proper chromatophore, the same chlorophylls as Chlorophyceae, the photosynthetic pigments being diffused beta-carotene and xanthophylls unlike through the peripheral cytoplasm. The pig- Chlorophyta. Food reserve is paramylum; ments present are chlorophyll, carotene, nutrition may be holophytic, holozoic or sap- phycocyanin and phycoerythrin, the last two rophytic. There are one or two contractile being in varying proportions and the colour vacuoles at the anterior end of the cell, which of the cells being very commonly blue green. are connected with a reservoir, which in turn The products of photosynthesis are sugars is connected with the cell’s exterior by a and glycogen. No motile stages are known narrow gullet ( Euglena ). and all the members have a membrane 3 . Chrysophyta – The members have yellowish- around the cell. There is no sexual reproduc- green to golden-brown pigment because of tion. The members of this class are of simple the predominance of carotenes and xantho- organization and many propagate entirely by phylls. The food reserves include a complex simple division or by vegetative means. Most carbohydrate leucosin and oils. Some mem- types are fi lamentous, many of them with a bers are with cell wall made up of silica and peculiar ‘false’ branching. They occur very are composed of two overlapping halves. abundantly in freshwaters and in terrestrial Cells may be fl agellated or non-fl agellated, habitats and are not common in the sea. An solitary or united in colonies of defi nite or example is Spirulina. indefi nite shape. Sexual reproduction is usu- But in 1950, Smith proposed seven divisions ally isogamous by a union of fl agellated and of algae in his system of classifi cation as follows: non- fl agellated gametes, e.g. members of 1. Chlorophyta present-day Xanthophyta (Vaucheria ) and 2. Euglenophyta Bacillariophyta (Nitzschia ). 3. Chrysophyta 4 . Phaeophyta – The Phaeophyta or brown algae 4. Phaeophyta have many celled complex type of plant body 5. Pyrrophyta that is usually of macroscopic size and distinc- 6. Cyanophyta tive shape. The chromatophore or pigment- 7. Rhodophyta bearing organelles are yellowish brown in 1.3 Algal Classifi cation 7

colour due to the presence of xanthophylls in cystocarp. Pigments are localized in chro- greater amount than that of chlorophyll and matophores. In addition to chlorophylls, carotenes. The two principle reserve foods are carotene, xanthophyll and R-phycoerythrin laminarin, a polysaccharide, and mannitol. and R-phycocyanin are present. Zoospores or gametes are pyriform with two Prescott (1984 ) fi rst classifi ed the algal king- laterally inserted fl agella of unequal length. dom into seven phyla like other groups of bio- Reproductive organs are of two kinds – the one logical kingdom. Each phylum is again divided celled or unilocular reproductive organ is into different classes and orders as follows: always a sporangium and born on a diploid thal- I. Phylum Chlorophyta lus. The other kind of reproductive organ is (i) Class – Chlorophyceae (17 orders) many celled and with each cell containing a (ii) Class – Charophyceae (1 order) single gamete or single zoospore. Most of the II. Phylum Euglenophyta members of Phaeophyta have a life cycle in III. Phylum Chrysophyta which there is alternation of two independent (i) Chrysophyceae multicellular generations, haploid and the other (ii) Bacillariophyceae is diploid. The two generations may be identical (iii) Heterokontae in size and structure, in others they are dissimi- IV. Phylum Pyrrophyta lar in both size and structure (Ectocarpus ). (i) Desmokontae 5 . Pyrrophyta – Members of this division are (ii) Dinokontae greenish to golden brown. The pigments are V. Phylum Phaeophyta Chl a , Chl c , beta-carotene and four xantho- (i) Isogeneratae phylls. Photosynthetic compounds are reserved (ii) Heterogeneratae as starch and also oil. The nucleus is distinc- VI. Phylum Rhodophyta tive in which chromatin lies in numerous bead- Subphylum – Bangioideae (4 orders) like structures on thread. Cell wall when Subphylum – Florideae (6 orders) present contains cellulose. VII. Phylum Cyanophyta 6 . Cyanophyta – The Cyanophyta or blue-green Subphylum – Coccogoneae algae are a distinctive group sharply delim- Subphylum – Hormogoneae ited from other algae (prokaryotic algae). Among the old classical algal taxonomy, Their pigments are not localized on chro- Bold and Wynne’s ( 1985 ) system of classifi cation matophores; rather they are present in the is the most well-accepted one. He divided the peripheral portion of the protoplast and algal kingdom into nine divisions and introduced include chlorophyll a , carotenes and distinc- a new division Charophyta, which is considered tive xanthophylls. In addition, there is a blue as progenitor of land plants. pigment (C-phycocyanin) and a red pigment (C-phycoerythrin). The unique feature of Divisions Cyanophyta is the presence of primitive type I. Cyanophyta and Prochlorophyta of nucleus within the cell (central body) II. Chlorophyta (16 orders) which lacks a nucleolus and a nuclear mem- III. Charophyta brane. They lack any fl agellated structure and IV. Euglenophyta devoid of sexual reproduction (Oscillatoria ) . V. Phaeophyta (13 orders) 7 . Rhodophyta – The Rhodophyta or red algae VI. Chrysophyta (6 class) have multicellular thalli of microscopic or Chrysophyceae macroscopic size and often of distinctive Prymnesiophyceae shape. Red algae differ from all other algae Xanthophyceae in structure of their sexual organs, in mode Eustigmatophyceae of fertilization followed by formation of a Raphidophyceae spore- producing structure, the so-called Bacillariophyceae 8 1 A Brief Introduction to Phytoplanktons

VII. Pyrrophyta Protista, Mycota, Metaphyta and Metazoa, as VIII. Rhodophyta follows: IX. Cryptophyta 1. Kingdom: Monera (prokaryotic organisms) 2. Kingdom: Protista (primitive eukaryotic Charophyta organisms) Commonly known as stoneworts, small plantlike, 3. Kingdom: Mycota (exclusively fungi) basal rhizoidal part rootlike and upper region 4. Kingdom: Metaphyta (advanced eukaryotic differentiated into nodes and internodes. At the plants) nodal region primary and secondary laterals are 5. Kingdom: Metazoa (all multicellular animals) present. Branching is also prominent. Small In this classifi cation, all the cyanobacterial leafl ike stipules and bracts are present. genera or prokaryotic algae are placed in Reproduction is oogamous type. Male repro- ‘Monera’, together with prokaryotic bacteria. ductive structure antheridia and female repro- All unicellular members are included in ‘Protista’, ductive structure oogonia are covered by sterile including protozoa of animal kingdom and jacket, shield cell and tube cell, respectively. unicellular algae of plant kingdom. Multicellular They share many characters with land plants. higher plants including algae are placed in the They possess unilateral type of fl agellar root – kingdom ‘Plantae’ together with bryophytes and in contrast to cruciate types in the members of pteridophytes. Chlorophyta. Mitosis – open type, i.e. they lack According to this classifi cation, Monera nuclear membrane in late prophase, whereas it represent the most primitive group of organisms. is closed types in other members of Chlorophyta The Monera are thought to have given rise to ( Chara, Nitella ). Protista from which the three other kingdoms of Bold and Wynne ( 1985 ) mentioned about organisms, namely, the fungi, plants and animals, Prochlorophyta together with Cyanophyta in evolved along separate lines. Fungi are thought to their system of classifi cation. Prochlorophyta fi rst to appear from Protista. Later, about a billion were considered as a new division by Lee (1980 , years ago, some protists must have evolved into 1989 , 1999 ) with the prokaryotic members primitive multicellular animals. Still later, prob- having Chl b ( Prochloron ). But later on, other ably about 350 million years ago, some protists characters are also considered including molecu- must have evolved into higher forms of plants. lar markers and it was found that those are noth- Like all systems of classifi cation, the fi ve- ing but Chl b -bearing cyanobacteria. kingdom classifi cation has also certain merits and demerits. However, it is largely the most accepted system of modern classifi cation mainly 1.3.2 Modern System of Algal because of the phylogenetic placing of different Classifi cation groups of living organisms. This system of classification looks more In modern approach, the classifi cation is based scientific and natural because of the following on the evolutionary process of the biological considerations: kingdom. The entire kingdom or individual 1. All the prokaryotes are placed into an inde- groups are divided into several kingdoms or pendent kingdom. It is justifi able because they classes considering different characters, refl ect- differ from all other organisms in their general ing the evolution and phylogeny. Together with organization. morphological parameters, other characters, 2. The kingdom Protista contains all the unicel- like biochemical and molecular data, are also lular eukaryotes. It solved many problems, considered. particularly related to the position of some Whittaker’s (1969 ) system of biome classifi - unusual organisms like Euglena . cation is one of such example, where the entire 3. Separation of the group fungi to a separate biome is divided into fi ve kingdoms, viz. Monera, kingdom is justifi able since fungi totally differ 1.3 Algal Classifi cation 9

from other primitive eukaryotes like algae and ultrastructural and biochemical and more recently protozoans. the molecular data are also considered for algal 4. The fi ve-kingdom classifi cation gives a clear classifi cation together with the morphological indication of cellular organization and modes characters of algal thallus. Since then the science of nutrition. of phycology has sustained major conceptual However, the fi ve-kingdom classifi cation has changes. The increased resolution of the electron some demerits also, particularly with reference to microscope revealed the presence and structure the lower forms of life: of fl agella, fl agellar hairs, fl agellar roots, eyespots, 1. The kingdoms Monera and Protista include chloroplast, endoplasmic reticulum, etc., which both photosynthetic (autotrophic) as well as were found to be important in basic systematics non-photosynthetic (heterotrophic) organisms of algae especially the green algae. Important and organisms which have cells with cell wall observations were made by Pickett- Heaps (1967 , as well as without cell wall. 1969, 1972a , b , 1975 ), which revealed that 2. The three higher kingdoms or multicellular different types of microtubular arrangements are lines have originated from Protista several involved in cytokinesis of green algae. In some times (polyphyletic). orders of Chlorophyta, cell divisions are charac- 3. Unicellular or colonial green algae like terized by the collapse of the interzonal spindle Chlamydomonas and Volvox have not been apparatus after mitosis, which give rise to a included under Protista because of their ‘phycoplast’ with the microtubules oriented in resemblance to other green algae. the plane of cell division, viz. Volvocales, 4. Slime moulds are different from other members Tetrasporales, Chlorococcales, Oedogoniales of Protista. and Ulotrichales. On the other hand, some 5. Viruses have not been given proper place in members together with land plants have a persis- this system of classifi cation. tent spindle and develop a cleavage and furrow Nevertheless, the fi ve-kingdom classifi cation (Klebsormidiales) or a ‘phragmoplast’ in which has found a wide acceptance with biologists all the microtubules are oriented perpendicular to over the world. the plane of cytoplasmic division (Coleochaetales, Charales and Conjugales). At the same time, bio- Status of Viruses chemical analysis also clarifi ed the presence and The position of viruses in the biological kingdom structure of algal pigments, storage products and is one of the unsolved mysteries. Due to the cell wall constituents. Considering all these absence of a cellular organization, viruses cannot parameters, Stewart and Mattox (1975 ) classifi ed be placed with either prokaryotes or eukaryotes. the green algal division Chlorophyta into fi ve They are considered as intermediate between classes, considering comparative cytology, viz. living and nonliving systems. Viruses are active Chlorokybales, Zygnematales, Klebsormidiales, and show reproduction only inside the host cell. Coleochaetales and Charales. In the free state, they are totally inactive. They may even be purifi ed and crystallized like chemi- 1.3.2.1 Algal Chloroplast cal substances. Viruses have a genetic material in Classifi cation represented by either DNA or RNA, surrounded Mereschkowski (1905 ) fi rst studied about the by a protein sheath. Viruses reproduce by using nature and origin of chloroplast in eukaryotic the metabolic machinery and raw materials of the algae and the evolutionary pattern among them. host cell. Because of these peculiarities, viruses In 1905, he published the most extensive paper do not fi t into any of the fi ve kingdoms of life. on the origin of chloroplast based on the idea From 1975 onwards, with the advent of elec- that eukaryotic algal cell originated by the pro- tron microscopy and other sophisticated instru- cess of endosymbiotic events between the cya- ments like high-resolution SEM, TEM, HPLC nobacterial cell and the primitive eukaryotic and HPTLC, fi ne characters of algal cells like phagocytotic protozoa. He was with the opinion, 10 1 A Brief Introduction to Phytoplanktons as he observed many characters of unicellular endosymbiosis, where the two-membrane photosynthesizing motile algae similar to that of chloroplast evolved by primary endosymbiosis heterotrophic protozoa like, cell structure, their and the three-membrane algal chloroplast by sec- movement, fl agellar structure. On the other hand, ondary events (Group III of Lee’s classifi cation). chloroplast also has its own DNA and self- In the third evolutionary line, the phagocytotic replication process. But at that time this hypoth- protozoan took up a red alga into a food vesicle. esis was not accepted. Later on, with the advent The nucleus of red alga reduced to a nucleo- of electron microscope and other sophisticated morph. This protozoan along with its algal sym- instruments, some evidences, especially the pep- biont was taken up by a second phagocytotic tidoglycan wall surrounding the glaucophycean protozoan into a food vesicle. The nucleus of the chloroplast, proved the endosymbiotic events fi rst protozoan took over the functioning of the in chloroplast evolution. The hypothesis was cellular apparatus, and the nucleus of the second accepted almost after 75 years of Mereschkowski’s protozoan was lost. Also the food vesicle mem- original hypothesis, and Lee (1980 ) fi rst accepted brane of the second protozoa and the outer this hypothesis in his system of classifi cation. nuclear envelope of the fi rst protozoa were also Lee (1980 ) also adopted the endosymbiotic lost. Ultimately the four-membrane chloroplast theory and proposed that chloroplast evolution evolved. The outer membrane of the chloroplast took place in three lines of evolution. endoplasmic reticulum was the plasmalemma of In the fi rst line of evolution for chloroplast the fi rst protozoa and the inner membrane of development, a prokaryotic algal cell was cap- chloroplastic endoplasmic reticulum was derived tured in a food vesicle by a phagocytotic non- from the food vesicle membrane of the fi rst photosynthetic protozoan. The protozoans protozoan. instead of digesting the algal cells started it Therefore, Lee (1980 ) fi rst brought the revolu- maintaining as endosymbiont. The endosymbi- tionary changes in algal classifi cation and pro- onts are used to get shelter from the host, whereas posed four distinct evolutionary groups within the host is used to get the supply of photosyn- algae on the basis of cell structure (prokaryotes thetic products from the endosymbiont. In the and eukaryotes) and chloroplast ultrastructure, course of evolution, the endosymbiont turned and it was accepted by all. Lee’s classifi cation into the photosynthetic cell organelle or chloro- was further revised on 1989, 1999 and 2008. plast – modifying the photosynthetic protozoa to According to this classifi cation there are four dis- eukaryotic algal cell. Eventually, in the process tinct evolutionary groups. of evolution, the plasma membrane of the endo- According to Lee’s classifi cation the group- symbiont became the inner membrane of the ings are mainly done on the basis of evolutionary chloroplast and the food vesicle membrane of pattern of algal chloroplast and fl agellar ultra- the host became the outer membrane of the chlo- structure and mainly divided into four groups as roplast envelope (chloroplast of Glaucophyta follows: represents the intermediate stage). This process The members of the fi rst group are prokary- is termed as primary endosymbiosis. otic in nature and lack membrane-bound chloro- In the second line of evolution, a chloroplast plast having only free thylakoids embedded in of a eukaryotic alga was taken up into a food cytoplasm. All the cyanobacteria are included in vesicle by a phagocytotic protozoa. Eventually, this group. the food vesicle membrane of the host became In the second group, the chloroplasts with basic the single membrane of chloroplast endoplasmic structure, i.e. double membrane-bound (chloro- reticulum surrounding the two chloroplastic enve- plast envelope) organelle enclosing the ground lope and the process is known as secondary substance stroma and the membrane- bound saclike 1.3 Algal Classifi cation 11 structure thylakoids embedded in it, are present in The starch is similar to that of higher plant and three divisions of algae, viz. Glaucophyta, is composed of amylose and amylopectin. Rhodophyta and Chlorophyta (group II). These A pyrenoid is a differentiated region within the algae evolved through primary endosymbiosis. chloroplast that is composed of polypeptides Among these three algal divisions, in chloro- with enzymatic properties of ribulose-1,5- plast of Glaucophyta, thylakoids are arranged bisphosphate carboxylase that are capable of equidistantly at peripheral region of chloroplast fi xing carbon dioxide. Storage products are fre- (like cyanobacterial cell). There are similarities quently associated with pyrenoids. The pyrenoid between chloroplast of Glaucophyta and cyano- is denser than the surrounding stroma and may or bacterial cell as follows: may not be traversed by thylakoids. • They are about the same size. The chloroplast of group III algal divisions, • They evolve oxygen in photosynthesis. viz. Euglenophyta, Dinophyta and Apicomplexa, • They have 70S ribosomes. is surrounded by two membranes of the chloro- • They have circular prokaryotic DNA without plast envelope and one membrane of chloroplast basic proteins. endoplasmic reticulum, which is not continuous • They have peptidoglycan wall surrounding the with nuclear membrane. The thylakoids are chloroplast envelope. grouped in bands of three. Major pigments For this reason chloroplast of Glaucophyta is present are Chl a and b (Euglenophyta); Chl a termed as ‘cyanelles’ or the incipient chloroplast. and c2 with peridinin as major xanthophylls The chloroplast of Rhodophyta (rhodoplast) is (Dinophyta); and rudimentary chloroplast also surrounded by two chloroplastic membranes (Apicomplexa). with no chloroplast ER. Inside the chloroplast, In addition, some accessory chloroplasts are thylakoids occur singly and the DNA molecule present in Dinophyta (originated from further occurs as microfibrils and the phycobilin endosymbiotic process between dinofl agellate pigments are localized into phycobilisomes on cell and Cyanophyta or Bacillariophyta or the surface of the thylakoids (similar to Rhodophyta) giving characteristic colour. Cyanophyceae). Chl a and d are present inside The membranes of the fourth evolutionary the thylakoids. Among the carotenoids zeaxan- group Heterokontophyta contain chloroplast thin is found in the greatest quantities. having four membranes (two chloroplast enve- Phycobiliproteins include R-phycocyanin, allo- lopes and two chloroplastic endoplasmic phycocyanin and three forms of phycoerythrin reticula). in maximum amounts. The chloroplast of Phaeophyta is known as In Chlorophyta, chloroplasts are highly phaeoplast. Phaeoplast is a four-membrane- evolved like higher-plant chloroplast, with two bound structure having three thylakoids per band. membranes of chloroplast envelope; thylakoids Membrane-bound structures are also present are stacked to form grana which are embedded in between chloroplast envelope and chloroplast the matrix called stroma. Chloroplast pigments ER. The chloroplast contains Chl a , c 1 and c 2 are also similar to higher plants. Chlorophylls a with major carotenoid, fucoxanthin. Pyrenoids of and b are present and the main carotenoid is Phaeophyceae are stalklike structures which set lutein. Extraplastidic carotenoids are sometimes off from the main body of chloroplast containing present (haematochrome). granular substances not traversed by thylakoids. The chloroplastic DNA is partially looped Surrounding the pyrenoid is a saclike structure and ribosome is of 70S type. Starch is formed in containing the reserve food matters, generally the chloroplast in association with pyrenoid. present (laminarin as major component). 12 1 A Brief Introduction to Phytoplanktons

1.3 Algal Classifi cation 13

1.3.2.2 Outline of Lee’s (2008) band and no chloroplast ER, fl oridean starch Classifi cation with Basic grain synthesized in the cytoplasm, no fl agella, Characters of Different Groups pit connections between the cells. Reproductive In this system of algal classifi cation, the entire algal unit spermatia and carpogonia. Post fertilization kingdom is classifi ed into four distinct groups: change prominent. I. Prokaryotes Single class – Rhodophyceae II. Eukaryotic algae with chloroplast with two Chlorophyta: Members have chlorophylls a and b membranes and starch is the reserve food matter formed III. Eukaryotic algae with chloroplast with one within the chloroplast. Chloroplast with two chloroplast ER (total three membranes) membranes only, thylakoids form the grana. IV. Eukaryotic algae with chloroplast with two Both freshwater and marine in habitat with wide chloroplast ER (total four membranes) range in morphology. Flagella isokont type with Group I: fi ne hairs if present. Flagellar root cruciate type 1. Cyanobacteria or unilateral type. Eyespot present. Group II: Four classes: , Charophyceae, 1. Glaucophyta Ulvophyceae and Chlorophyceae 2. Rhodophyta Euglenophyta: Euglenoid fl agellate, unicellular, 3. Chlorophyta surrounded by pellicle. Chloroplast with two Group III: chloroplastic membranes and one chloroplastic 1. Euglenophyta endoplasmic reticulum containing Chl a and b . 2. Dinophyta Marine or freshwater in habitat. Cytosome or 3. Apicomplexa gullet-like structures are present at the anterior Group IV: region of the cell. 1. Cryptophyta Single class: Euglenophyceae 2. Heterokontophyta Dinophyta : Unicellular with two halves, epi- 3. Prymnesiophyta cone and hypocone, made up of thecal Cyanobacteria: Prokaryotic members containing plates. Chloroplast with two chloroplastic chlorophyll a and phycobiliproteins. Some membranes and one chloroplastic endoplas- members contain chlorophyll b and are known mic reticulum with Chl a and c2 and the as green cyanobacteria (Prochlorophyta). Cell carotenoids peridinin and neoperidinin as wall is similar to Gram-negative bacteria major pigments. Storage product is starch. containing peptidoglycan layer outside the Two fl agella – one longitudinal and one cell membrane. Naked circular DNA present transverse. at the central portion of the cell. Cyanophycin, Single class: Dinophyceae the polymer of arginine and aspartic acid; Apicomplexa carboxysome; polyphosphate bodies; and Unicellular having reduced colourless plastid polyglucan granules are the other cellular called apicoplast . Apicoplast and dinofl agellate inclusions. Gas vacuoles, containing a large plastids originated from red algae by a single number of gas vesicles, are present. endosymbiotic event. The apical complex consists Glaucophyta : Members unicellular with primitive of a polar ring and a conoid formed of spirally type of chloroplast, showing many characters coiled microtubules. Apicomplexa are endopara- similar to cyanobacterial ancestor and are sites that cause some of the most signifi cant known as cyanelle. Pigments are similar to tropical diseases like malaria or diarrhoea. The cyanobacteria. Members are unicellular parasite attaches to the host cell with the conoid fl agellates. protruding to produce a stylet that forms a tight Rhodophyta : Both marine and freshwater in habitat. junction with the host cell. The apicomplexan Unicellular to huge thallus, especially for marine cell is taken up into the host cell in the parasi- . Chloroplast with one thylakoid per tophorous vacuole. 14 1 A Brief Introduction to Phytoplanktons

Cryptophyta Bremer (1985 ) combined charophytes and Cells with chlorophylls a and c , phycobilipro- embryophytes into a single division Streptophyta , teins and nucleomorph present between inner and based on ultrastructure and molecular characters outer membranes of chloroplast ER starch grains as they share many similar characters and also stored between inner membrane of chloroplast consider charophytes as progenitor of land plants. ER and chloroplast envelope, periplast inside Cavalier (1981 ) proposed the term plasma membrane and tripartite hairs on to comprise the true green plants including green fl agella. algae and higher plants as an arguably monophy- Single class: Cryptophyceae letic group based on ultrastructure of fl agella Heterokontophyta (stellate structure in fl agellar transition region) Cells are with tripartite hairs; anterior tinsel and plastid characters (Chl a , Chl b ). fl agellum and posterior whiplash fl agellum. Members of phytoplankton belonging to Pigments are chlorophylls a and c and fucoxan- different groups of algae and cyanobacteria thin. Storage product usually chrysolaminarin contain different types of pigments in different present in vesicles of cytoplasm. compositions, which are important in algal tax- These divisions include 12 classes: onomy. These pigments play an important role in 1. Chrysophyceae oceanographic research as they act as tracers to 2. Synurophyceae elucidate the composition and fate of phytoplank- 3. Eustigmatophyceae ton in the world’s ocean and are also associated 4. Pinguiophyceae with important biogeochemical cycles like carbon 5. Dictyochophyceae dynamics. Pigments of phytoplanktons often 6. Pelagophyceae change the colour of the water indicating the 7. Bolidophyceae biomass growth rate, which are also used in their 8. Bacillariophyceae estimation in situ and in remote-sensing applica- 9. Raphidophyceae tion. By analysing these pigments using HPLC or 10. Xanthophyceae HPTLC, presence or absence of picoplanktons 11. Phaeothamniophyceae can be determined. These techniques have 12. Phaeophyceae allowed identifi cation of many new pigments. Prymnesiophyta (Haptophytes) Therefore, pigment analysis of phytoplanktons Two whiplash fl agella, haptonema present, is very important in oceanographic research chlorophylls a and c , fucoxanthin, scales com- especially for chemotaxonomic purpose. From mon outside cell, storage product usually chryso- 1997 onwards HPLC- linked mass spectrometry laminarin in vesicles in cytoplasm. is used for marine plankton analysis. Single class: Prymnesiophyceae Phytoplankton biomass of the ocean is gener- McFadden ( 2001) introduced another division ally determined by measuring the ocean colour of algae in his classifi cation, where the members from space; therefore, in situ pigment measure- possess four-membrane chloroplast with Chl a ments have become high-priority areas for and b as the major pigments. oceanographic research (Jeffrey et al. 1997a ; Nair et al. 2008 ). 1.3.2.3 Other divisions of Algae In recent years to develop the map of microalgal Chloroplast derived from a green alga, chloro- population, the major pigments of a particular phylls a and b present, nucleomorph between group are considered for field study. Many inner and outer membrane of chloroplast ER. new algal genera have been identifi ed on the Chloroplast with four membranes – two chlo- basis of pigment composition (e.g. members of roplastic membranes and two chloroplastic Herptophyton) (Zapata et al. 2004 ). They recov- endoplasmic reticula. Vegetative cells are ered many new members of chlorophyll c and naked, uninucleate with amoeboid projections. fucoxanthin families from different phytoplankton An example is Chlorarachnion . genera. Jeffrey et al. (1997b ) published a very 1.4 Classifi cation of Phytoplanktons 15 important book, Phytoplankton Pigments in groups) from a protistan perspective has been Oceanography: Guidelines to Modern Methods proposed by Adl et al. ( 2005), which is mainly (SOR-UNESCO volume). They listed 12 micro- used in oceanographic literature. According to algal classes as common members of phyto- them the traditional ‘kingdoms’, such as Metazoa, , viz. diatoms, dinofl agellates, Fungi and Plantae, are recognized as deriving haptophytes, chrysophytes, rhodophytes, raphi- from monophyletic protist lineages. The authors dophytes, cryptomonads, chlorophytes, eugleno- grouped the molecular phytogenies into six clus- phytes, , cyanobacteria and ters as follows: prochlorophytes. 1. Opisthokonta: animals, fungi, choanofl agellates The use of advanced HPLC and ultrahigh- and Mesomycetozoea performance liquid chromatography (UPLC) 2. Amoebozoa: traditional amoebae, slime helps to identify different phytoplankton taxa in moulds, etc. addition to it considering culture code and gene 3. Rhizaria: foraminifera, radiolarian, heterotro- bank references. phic fl agellates, etc. A new system of classifi cation of eukaryotes 4. Archaeplastida: red algae, green algae, (including only photosynthetic microalgal Glaucophyta and Plantae

Classifi cation scheme of Adl et al. (2005 ) Super groups First rank Second rank (examples of photosynthetic eukaryotes) Rhizaria Cercozoa Chlorarachniophyta, Paulinella Archaeplastida Glaucophyta Glaucophyceae Rhodophyceae Subdivisions uncertain according to Adl et al. (2005 ) Chloroplastida Charophytaa , Chlorophyta, Mesostigma, Prasinophyta Chromalveolata Cryptophyceae Cryptomonadales Haptophyta Pavlovophyceae, Prymnesiophyceae Stramenopiles Bacillariophyta, Bolidomonas, Chrysophyceae, Dictyochophyceae, Eustigmatales, Pelagophyceae, Phaeophyceae a , Phaeothamniophyceae, Pinguiochrysidales, Raphidophyceae, Synurales, Xanthophyceae Alveolata Apicomplexa, Dinozoa Excavata Euglenozoa Euglenida a Clades with multicellular groups

Interestingly, in earlier studies picoplanktons were 1.4 Classifi cation referred only to ‘heterotrophic picoplanktons’ that of Phytoplanktons are presently known as ‘’ (Sieburth 1978 ). In later periods, chroococcoid 1.4.1 On the Basis of Size Variations cyanobacteria were observed in oceanic samples along with other eukaryotic taxa that are presently Phytoplanktons show a wide range of size varia- referred as ‘’ (Johnson and Sieburth tions. The earliest work on phytoplankton classifi - 1979 ; Li et al. 1983 ). Several other terms have cation on the basis of size variations was proposed also been introduced like ‘ultrananoplankton’ that by Schütt (1892 ). During the 1950s, development referred to algae that were less than 2 μm (Dussart of different types of nets, fi lters and screens with and Roger 1966 ) and ‘ultraplankton’. The use of different pore sizes leads to identifi cation of this term was mainly dependent on the discretion micro-, nano- and ultraplanktons. Picoplanktons of the author and the size which ranged from are the smallest in cell size with a diameter of 0.5 to 15 μm (Hutchinson 1967 ; Reynolds 1984). 0.2–2.0 μm, followed by nanoplankton (2.0– Some scientists used the term ‘net plankton’ for 20 μm), microplankton (20–200 μm), mesoplank- those planktons that were >45 μm in size ton (0.2–2.0 mm) and macroplankton (2–20 mm). (Throndsen 1978 ). 16 1 A Brief Introduction to Phytoplanktons

Picoplanktons have gained considerable diversity, picoplanktons have been categorized interests among plankton biologists in the later as ‘prokaryotic picocyanobacteria’ and ‘eukaryotic part of the twentieth century. Several studies phototrophs’. Unfortunately taxonomic identifi ca- have indicated that in oligotrophic waters, pico- tion of picoplanktons on the basis of morphological planktons are the primary population that consti- variations is very diffi cult to enumerate. Thus, tutes 50–70 % of the total productivity of oceanic pigment composition and analysis by molecular ecosystems (Caron et al. 1985 ). Thus, based methods are increasingly been used as possible upon their pigment composition and genetic tools to understand picoplankton populations.

Table showing the classifi cation of planktons on the basis of size variations Group Size range Examples Megaplankton (20+ mm) Metazoans, e.g. jellyfi sh, ctenophores, salps and pyrosomes (pelagic Tunicata), Cephalopoda Macroplankton (2–20 mm) , amphipod, polychaete Mesoplankton (0.2–2 mm) Protozoa, Foraminifera, Hydrozoa Microplankton (20–200 μm ) Dinofl agellates (e.g. Dinophysis , Gymnodinium , Ceratium ), diatoms (e.g. Biddulphia , Thalassiosira , Coscinodiscus ) Nanoplankton (2–20 μm) (Distephanus , Thalassomonas , Tetraselmis ) Picoplankton (0.2–2 μm) Cyanobacteria (Synechococcus) Femtoplankton (<0.2 μm) Mostly viruses

1.4.2 On the Basis of Habitat dominance of periphytic algae like diatoms and desmids. Phytoplanktons are widespread in their distri- 3. The sublittoral zone which extends down to bution in different aquatic habitats around the the compensation point. world. They live in freshwater, brackish and 4. The profundal zone which occurs below the salt water, ice, moist soil and other damp compensation depth where the phytoplankton places. population is mainly composed of colourless The freshwater lentic ecosystems like lakes heterotrophic algal cells and resting spores of and ponds can be divided into different zones photosynthetic algae. (Fig. 1.1 ): In lotic ecosystems like oceans and seas, there 1. The supralittoral zone which is above the are two main divisions: edge of the standing water that gets wet only 1 . Pelagic species are those that live near the sur- due to wave actions and splash during windy face of the ocean during all or most part of seasons. Here, algal populations remain sparse their life cycle. The pelagic diatoms are fur- due to the drying nature of the habitat along ther divided into oceanic and neritic species. with other deterrents like the abrasive effects (a) Oceanic species are those capable of living of sand and gravel. and reproducing entirely in the open 2. The littoral zone which extends to about 6 m ocean. Oceanic taxa are mostly reported in depth from the water edge into the water from depth in excess of 200 m. Thus, the body. This zone is a highly productive area in oceanic province can be subdivided into lotic systems in terms of productivity with two distinct zones: 1.4 Classifi cation of Phytoplanktons 17

Neritic Oceanic

High tide Euphotic 200 m Low tide

S L p i Sublittoral l t Aphotic a t s o Bathyal h r a z l 4000 m o n e Abyssal

Fig. 1.1 Zonation of marine ecosystem

(i) Euphotic or epipelagic zone which 200 m. This zone mainly consists extends from the surface to a depth of large seaweeds belonging to of 200 m. Photosynthetic activities Rhodophyta and Phaeophyta. The occur mainly in the upper portion of availability of these seaweeds at this zone. different depth depends on the tur- (ii) Aphotic zone which extends from a bidity and light penetration along the depth of 200 m. Here light is insuffi - water column. cient to support planktonic photosyn- (ii) Bathyal zone which extends from a thetic activity. depth of 200–4,000 m, correspond- (b) Neritic species are those which have their ing to the continental slope, the origin near the coast and reproduce most geomorphic province beyond the effi ciently under coastal conditions. It is continental shelf. not easy to clearly distinct between neritic (iii) Abyssal zone which represents and oceanic species. depths beyond 4,000 m. 2 . Benthic environment that represents the ocean Both oceanic and neritic species may be bottom. This environment can be further cat- further divided into three main groups accord- egorized as: ing to the latitude in which they are most com- (a) Littoral region which extends from high monly found or have had their origin. Thus, we tide to low tide zone speak of arctic, temperate and tropical oceanic (b) Deep-sea region which includes the entire species and arctic, temperate and tropical neritic ocean beneath the low tide mark. This species. Subdividing these again, we have boreal region can be further subdivided into (northern but not arctic species), north temper- three distinct zones: ate, south temperate and subtropical species. (i) Sublittoral zone which extends from Some species are ubiquitous, others restricted the low tide mark to a depth of within rather defi nite regions. There are a number 18 1 A Brief Introduction to Phytoplanktons of species which it is still impossible to place in atom. Chlorophyll content ranges from 0.3 % of any defi nite group. The boundaries of the regions the dry weight among different algal genera of are variable and the fl ora of each locality is con- different classes. Chlorophyll has two main tinually changing with seasonal changes and absorption bands in the red light region at movements of the water. 663 nm and the other at 430 nm. Most of the coastal or neritic species have a Unlike chlorophyll a , other types of chloro- special adaptation, the resting spores, which phylls have a more limited distribution and serve as protection against changing conditions function as accessory photosynthetic pigments. (e.g. diatoms). The spores sink into deeper Chlorophyll b is found in the Euglenophyta, water and may be found there for several Chlorophyta and Chlorarachniophyta. Chlorophyll months after the species has disappeared from b functions as a light-harvesting pigment trans- the surface. The majority remains on the bottom ferring absorbed light energy to chlorophyll a . in shallow coastal water until conditions favour Chlorophyll b has two main absorption maxima their germination (Gross 1937). Resting spores in acetone or methanol, one at 645 nm and the must be the means by which many species con- other at 435 nm. tinue in coastal waters in spite of the fact that Chlorophyll c has two components which are conditions are more variable there than in the spectrally different, viz. chlorophyll c 1 and c 2. open ocean and may be favourable to diatoms The ratio of chlorophyll a to chlorophyll c ranges for only a limited part of each year (members of from 1.2:2 to 5:1. Chlorophyll c probably func- Biddulphiales). tions as an accessory pigment to photosystem II. Chl c is soluble in ether, acetone, methanol and ethyl acetate but is insoluble in water and petro- 1.5 Algal Pigments leum ether. Chlorophyll c 1 has main absorption maxima at 634, 583 and 440 nm in methanol, Algae are photosynthetic organisms and they whereas chlorophyll c2 has maxima at 635, 586 possess chlorophyll in their chloroplasts. The and 452 nm. primary photosynthetic pigment of algae is Chlorophyll d is a minor component present chlorophyll and is the light receptor in photo- in many members of Rhodophyta. It is soluble system I of light reaction. There are different in ether, acetone, alcohol and benzene and very types of chlorophyll like Chl a , b , c ( c 1, c 2), d slightly soluble in petroleum ether showing and e present in algal cells. Among them Chl a three main absorption bands at 696, 456 and is universal and present in all members of auto- 400 nm. trophic algae (with a few exception of hetero- Carotenoids are yellow, orange or red trophic algae). Due to presence of Chl a , hydrocarbons present in algal members as members of cyanobacteria are also considered accessory pigments and usually occur inside as prokaryotic algae by algologist. Chlorophyll the plastid but may be outside in certain cases. a is soluble in alcohol, diethyl ether, benzene Carotenoids can be divided into two classes: and acetone but insoluble in water. Chlorophyll (1) oxygen-free hydrocarbons, the carotenoids, is composed of a porphyrin ring system that is and (2) their oxygenated derivatives, the xan- very similar to that of haemoglobin but has a thophylls. The most common algal carotene is magnesium atom at the centre instead of an iron the β-carotene. 1.5 Algal Pigments 19

20 1 A Brief Introduction to Phytoplanktons

Chemical confi guration of few major pigments of algae

There are a large number of different xantho- macromolecular protein and are known as chro- phylls present in different groups of algae. moproteins (coloured proteins). They have the Fucoxanthin is the principal xanthophylls in the prosthetic group (nonprotein part of the molecule) golden-brown algae (Chrysophyta, Bacillariophyta, or chromophore. Chromophore is a tetrapyrrole Prymnesiophyta and Phaeophyta), giving these (bile pigment) known as phycobilin and is tightly algae their characteristic colour. Like the chloro- bound by covalent linkages to its apoprotein phyll, the carotenoids are also fat-soluble pigment (protein part of the molecule). As the pigment is being soluble in alcohols, benzene and acetone but tightly bound to the apoprotein, the term phyco- insoluble in water. biliprotein is used. The apoproteins are again of Among all the algal pigments, phycobilipro- two types, α and β, which together form the basic teins – present in Cyanobacteria, Rhodophyta unit of the phycobiliproteins. The major ‘blue’ and Cryptophyta – are water-soluble blue or red chromophore is called the phycocyanobilin and is pigments. They are located on (Cyanophyta, present in phycocyanin and allophycocyanin, and Rhodophyta) or inside (Cryptophyta) the thylakoids the major ‘red’ chromophore phycoerythrobilin of algal chloroplasts. They are associated with is present dominantly in phycoerythrin. 1.5 Algal Pigments 21

Each phycobiliprotein usually consists of a posed of allophycocyanin, with the peripheral basic aggregate of three molecules of α- apopro- rods containing phycocyanin and phycoerythrin. tein and three molecules of β-apoprotein and the The length of the peripheral rods varies, being chromophores attached to the apoproteins. The dependent on the wavelength of light under basic aggregate is designated as (αβ) 3 . In some which the cells are grown. This phenomenon is a cases the basic aggregate is double of this along form of chromatic adaptation (Bryant 1994 ). with a linker polypeptide and can be designated Two classes of phycobilisomes exist: (1) the as (αβ)6 . Different linker polypeptides interact hemi-ellipsoidal phycobilisomes and the hemi- with the same phycobiliprotein to give complexes discoidal phycobilisomes in the red algae, blue- with physical properties determined by the linker green algae and the cyanelles (endosymbiotic polypeptides (Yu et al. 1981 ). A third apoprotein, blue-green algae). γ, is present in B- and R-phycoerythrins. It is believed that the light energy transfers in The core of the phycobilisome is probably com- the following pathway during photosynthesis:

Phycoerythrin→ phycocyanin→ allophycoocyanin→ allophycocyanin B → chlorophyll a ()llmax= 565() max =− 620 638 ()llmax650() max = 670 or Phycoerythrocyanin ()l max568 () Glazer et al. 1985

The effi ciency of energy transfer from the exceeds more than 90 % in intact cells (Porter phycobilisome to chlorophyll a in the thylakoids et al. 1978 ).

Table showing different pigment compositions of various groups of algae with thallus organization Division/class Thallus organization Pigments Cyanobacteria Members of Cyanobacteria are in the Chl a , Chl b (in Prochlorophyta, now called green form of unicells, or colonies, up to cyanobacteria) and traces of MgDVPa 2 mm in size. Picoplanktonic forms Phycobilins: phycocyanin, phycoerythrin, are 1–2 μm in diameter; fi lamentous allophycocyanin. forms are unbranched, Carotenoids: β-carotene, myxoxanthophyll, pseudobranched or branched zeaxanthin, echinenone, canthaxanthin, oscillaxanthin, nostoxanthin, aphanizophyll, 4-keto-myxoxanthophyll. Jeffrey and Wright ( 2006 ) categorized fi ve different types of pigment composition, cyano-1–5 Glaucophyta Bifl agellated unicells, oblong or Chl a coccoid, dorsiventral, 10–30 μm Carotenoids: β-carotene, zeaxanthin, β-cryptoxanthin diameter; also in palmelloid stage Biliproteins: phycocyanin, allophycocyanin Rhodophyta Coccoid unicells, fi lamentous, simple Chl a or polysiphonous, thalloid leafl ike Carotenoids: β-carotene, zeaxanthin; Biliproteins: phycoerythrin, phycocyanin (less amount, allophycocyanin) Chlorophyta Small green fl agellates, naked, or Chlorophylls a and b , MgDVP; Carotenoids: lutein, ovoid in form,10–40 mm in diameter, violaxanthin, neoxanthin, antheraxanthin, β-carotene, unicellular, coccoid, colonial, β,ε-carotene, zeaxanthin, β,ψ-carotene (trace), fi lamentous – simple uniseriate to astaxanthin and two pigment types are recognized: branched form CHLORO-1 and CHLORO-2 (Jeffrey and Egeland 2008 ) (continued) 22 1 A Brief Introduction to Phytoplanktons

(continued) Division/class Thallus organization Pigments Euglenophyta Unicellular, ovoid or fusiform; most Chl a and b , MgDVP; Carotenoids: eutreptiellanone, species have a fl exible pellicle, which diadinoxanthin, diatoxanthin, 9′-cis-neoxanthin, allows movement by deformation; β,β- carotene, β,ε-carotene (Jeffrey and Wright 1997 ) other species have a rigid lorica Dinophyta Mostly unicellular (5–200 μm), with a Chlorophylls: Chl a , c 2, MgDVP; Carotenoids: transverse girdle groove into an upper peridinin, diadinoxanthin, diatoxanthin, dinoxanthin, epicingulum and a lower peridininol, pyrrhoxanthin and β,β-carotene hypocingulum; unarmoured or Five combinations of pigments: the major armoured with cellulose plates dinofl agellate carotenoid peridinin containing DINO-1 or with their endosymbiont pigments, e.g. haptophytes (DINO-2), diatoms (DINO-3), cryptophytes (DINO-4) or prasinophytes (DINO-5) (Jeffrey and Wright 2006 ) Heterokontophyta Unicellular or colonial forms. Chlorophylls: Three combinations of pigment are (Bacillariophyceae Cells are covered by characteristic distinguished on the basis of Chl c derivatives (Zeffry – diatoms) siliceous with two et al. 2011) overlapping halves. -1: Chl a , Chl c 1, Chl c 2, MgDVP Morphology of diatoms is based on DIATOM-2: Chl a , Chl c 2, Chl c 3, MgDVP radial (centric) or bilateral symmetry DIATOM-3: Chl a , Chl c 1, Chl c 2 c 2, Chl c 3, (pennate) MgDVP(trace) Carotenoids: fucoxanthin, diadinoxanthin, diatoxanthin, β,β-carotene, 19′-butanoyloxyfucoxanthin, violaxanthin, antheraxanthin, zeaxanthin Bolidophyceae Picoplanktonic cells: round or heart Chl a , c 3 shaped Chrysophyceae Colonial with coccoid or ovoid cell, Chl a , c 1, c 2 fl agellated or amoeboid Carotenoids: β,β-carotene, fucoxanthin, violaxanthin, antheraxanthin, zeaxanthin Dictyochophyceae Picoplanktonic or larger, unicellular, Chl a , c 2, c 3 naked or inside a siliceous skeleton Carotenoid: β-carotene, fucoxanthin, diatoxanthin, diadinoxanthin Eustigmatophyceae Unicellular, coccoid or ovoid, Chl a , MgDVP fl agellated Carotenoids: β,β-carotene, antheraxanthin, vaucheriaxanthin, violaxanthin, zeaxanthin Pelagophyceae Unicellular or colonial. Cells coccoid Chl a , c 2 or ovoid, fi lamentous, palmelloid Carotenoids: diadinoxanthin, diatoxanthin, fucoxanthin, beta-carotene, gyroxanthin diester Haptophyta Unicellular, 5–20 μm in diameter; HAPTO-1 almost exclusively fl agellates, cells Chlorophylls: Chl a , c 1, c 2, MgDVP elongated Carotenoids: fucoxanthin, diadinoxanthin, diatoxanthin, β-carotene HAPTO-2 Chlorophylls: Chl a , c 1, c 2, MgDVP Carotenoids: fucoxanthin, diadinoxanthin, diatoxanthin, β-carotene Cryptophyta Ovoid asymmetrical unicells Chlorophylls: Chl a and c 2, MgDVP (6–20 μm), often fl attened A unique Carotenoids: alloxanthin, crocoxanthin, cell covering or pellicle is made up of monadoxanthin, β,ε-carotene lipoproteins, red or blue a ridged periplast superimposed on an phycobiliproteins inner layer of thin proteinaceous plates; no microtubular cytoskeleton a MgDVP – Mg-3,8-divinyl-pheoporphyrin a5 monomethyl ester 1.6 Ecological Signifi cance 23

region of thermocline. To protect themselves 1.6 Ecological Signifi cance from grazing also, many species produce protec- tive spores, gelatinous coats, or grow fast to pro- Phytoplanktons play an important role in aquatic duce a large population. Grazing rate of ecosystems, both in freshwater and in marine envi- may be reduced due to thick growth ronment. They are the primary producer organ- of algae or sometimes due to production of unpal- isms, therefore, supporting zooplanktons, fi shes atable species such as blue-green algae. and other members of aquatic fauna. Thus, they are placed at the base of the trophic strata or at the bottom of the aquatic food web. Phytoplanktons 1.6.1 Phytoplankton Bloom also play a major role in global carbon dioxide fi xation. In marine environment they fi x almost A rapid increase or accumulation in the popula- 48 Pg C. year−1 [1 Pg = 1 × 1015 g], which is almost tion of algae (typically microscopic) in an aquatic 48 % of the total fi xed carbon on the earth’s sur- system is regarded as an ‘’. Many of face (Geider et al. 1997). Phytoplanktons also the planktonic genera form the blooms. maintain the oxygen level of the water body, which Phytoplankton population generally grows in is designated as dissolved oxygen or DO. a series of pulses or blooms. Blooms occur when The phytoplankton population, controlling the cell numbers exceed their annual average or life cycle of each species, is again controlled by background concentration manifolds or when a several factors, like the availability of nutrients, certain high cell number is reached, for example, degree of thermal stratifi cation, algal move- 5 × 106 cells/L. A bloom can colour the water. ments relative to the water current, In temperate region, the fi rst bloom is initiated grazing, intra-algal competition and parasitism in spring due to increased sunlight; subsequently, by protozoans, fungi, bacteria or viruses. It is the growth is terminated in autumn when light observed in many places that the chlorophyte, decreases in water. On the other hand, in tropical chrysophyte, cryptophyte and euglenophyte regions growth may be nearly continuous when algae often dominate and form in the summer suffi cient nutrients are available. In polar region peak due to an ability to take up nutrients at low only a short period of growth can be observed level and to maintain their positions by swim- mainly of diatoms as the sunlight and ice-free ming. In some lakes, they also exist below the periods are very brief. thermocline and at greater depths. In productive lakes of temperate regions, Different genera of phytoplanktons evolved holoplanktons, i.e. the algae which always remain various strategy to overcome the nutrient deple- in planktonic form, fl ourish more during spring tion and grazing. They generally produce differ- time, like the diatom genera – Asterionella, ent types of enzymes, some of which are directly Fragilaria and Tabellaria – forming the spring involved in nutrient uptake and others responsi- blooms. Excessive growth of chytrid fungi, zoo- ble to secrete some chelators or siderophores plankton grazing or protozoans interference may which form complex with the nutrients and make affect the algal bloom. them available for uptake. Due to diatom bloom Meroplanktonic genus Melosira, which is the nutrient level becomes depleted especially only sometimes in planktonic form, appears in silica (SiO2 ) – required for diatom large number in winter. Actually due to resuspen- growth. Phytoplanktons can move directly or sion of live cells of Melosira , i.e. germination of fl oat through water current. Movement by swim- resting spores from the sediments in favourable ming or a change in cell density may allow them season, resulted in changes in population pattern to reach new sources of nutrients actively or pas- and the bloom appeared. Melosira has a slow sively. In adverse environmental conditions, growth rate, but they are quite able to take the some algae produce resting spores, remain active advantage of the high nutrient levels and benefi ts at the junction of epilimnion and hypolimnion from low levels of competition and grazing. 24 1 A Brief Introduction to Phytoplanktons

The other meroplanktonic cyanobacterial taxa nitrogen in ocean water is increased. Nitrogen- like Aphanizomenon , Anabaena and Microcystis fi xing cyanobacteria generally form the surface fl ourish more in warm lakes in summer and falls, bloom and supply the nitrogen to N-depleted but the diatoms grow at a faster rate in winter of ocean water. Ocean water is generally unproduc- a tropical country. They produce the resting spore tive and can be called as oligotrophic in nature. In or thick-walled cell during winter to withstand the early times, it was believed that marine cya- the unfavourable season. Moreover, cyanobacte- nobacteria are very few in numbers. But since the ria can regulate their buoyancy by their minute 1970s with the advent of high-resolution fl uores- gas vesicles and are able to adopt themselves in cence microscopy, electron microscopy, HPTLC, thermocline of different seasons at different etc., it is proved that the oceanic primary produc- depths. Many cyanobacteria and eukaryotic algae tivity is mainly maintained by pico (≤5 μm)- and have an ability to take up nutrients like phosphate nanoplanktonic (5–20 μm) cyanobacteria and ammonia at low levels. A few of them can together with comparatively less microplank- also fi x atmospheric nitrogen gas. All other algal tonic (≥20 μm) cyanobacterial members. Marine groups as well as many other cyanobacteria lack planktonic cyanobacteria are represented by uni- this ability. Therefore, cyanobacterial blooms cellular (Synechococcus , Prochlorococcus , appear in comparatively low nutrient level even Synechocystis , Aphanothece ), colonial at nitrogen-depleted condition. Among the algal (Merismopedia ), fi lamentous non-heterocystous divisions cyanobacteria and dinofl agellate mem- (Lyngbya , Oscillatoria , Phormidium , Spirulina , bers produce bloom very frequently in different Trichodesmium) and heterocystous taxa ecological conditions and are also ecologically (Anabaena , Aphanizomenon , Nodularia , Richelia ). signifi cant. Picoplanktonic genera of Synechococcus , Prochlorococcus and Synechocystis constitute 30–50 % of phytoplankton biomass and therefore

1.6.2 Cyanobacterial Bloom control the primary productivity by fi xing CO 2 . Cyanobacterial taxa grow in different ecological Cyanobacteria grow profusely, congregate and conditions forming bloom. The free-fl oating make the lake water coloured soup. This phe- Trichodesmium erythraeum , the non-heterocys- nomenon is called ‘cyanobacterial bloom’. Due tous taxa, forms a dense colony, ensheathed with to huge growth of buoyant cyanobacteria, the polysaccharidic sheath, therefore producing an lake and ocean water turned coloured and the O 2-free microenvironment on sea surface and transparent water suddenly became soupy in fi xing atmospheric N 2 . Another N 2 -fi xing fi la- appearance often turned into bright blue, grey, mentous genus Richelia grows inside the diatom tan or even red in colour. Rhizosolenia and fi xes atmospheric N2 in ocean Generally chlorophyll production of bloom is water. Heterocystous planktonic genera, Nodularia , 10 mg μm−3 (ca 20,000 cells mL −1 ). Bloom for- Aphanizomenon , etc., grow in estuarine entropic mation is mainly the function of the environment; environment and fi x considerable amount of both freshwater ecosystem and the oceanic sur- atmospheric nitrogen. face are suitable for cyanobacterial bloom The cyanobacterial taxa having gas vesicles formation. form the surface bloom like planktonic fi lamen- Marine planktonic cyanobacteria control the tous Anabaena and Aphanizomenon or colonial biogeochemical cycle and the trophic status of form Microcystis , etc. Cyanobacterial blooms marine environment. They control the marine form the surface scum at early morning, as the production and nutrient cycling in two main ways internal carbohydrate is generally consumed at

– fi rstly they fi x CO 2 to a greater extent at bloom- night. During daytime when photosynthetic rate ing condition, therefore controlling the C-cycling, is increased and carbohydrate is accumulated and secondly some of them can fi x atmospheric within the cell, the gas vesicles collapsed due to

N2 ; as a result the level of soluble bioavailable the increased turgor pressure. As a result the 1.6 Ecological Signifi cance 25 organisms descend out of the surface scum and 3. Application of biological control: Inoculation the bloom disappeared. Afterwards they reappear of cyanophage (virus that infects cyanobacte- the next morning, when the stored carbohydrate rial cell) for controlling cyanobacterial bloom is consumed. Due to some physiological dam- is a common phenomenon. ages like photoinhibition, photo-oxidation and 4. Use of different algicides like copper sulphate dehydration, persistent surface blooms can for bloom controlling is a regular phenome- appear which indicate the failure of buoyancy non for common people. But the toxic effects regulation. According to Pearl and Ustach (1982 ), of chemicals also hamper the total ecological the surface blooms are a part of an ecological balance. Application of CaCO3 in fi sh pond to strategy for optional use of photosynthetically control algal bloom is a common practice. active radiation and atmospheric carbon dioxide. 5. Light shielding: Light is the major factor for Surface bloom also affects light penetration bloom formation. Light shielding is therefore through the water column, not only by covering an easy process for bloom control. Shielding the water surface but also by scattering the light can be done by covering with some dark sheet by the gas vesicles. Due to light scattering by or by fl oating angiospermic plants like cyanobacterial gas vesicles, the planktons of Eischornia and Lemna . euphotic zone have an advantage of intercepting more light. 1.6.3 Dinofl agellate Bloom 1.6.2.1 Cyanobacterial Bloom Control Bloom formation can be controlled by nutrient Occasionally large populations of dinofl agellate, concentration and/or controlling the light and i.e. dinofl agellate blooms, appear on the surface temperature. Mixing is another process by which of lakes, estuaries and ocean as red covering of the turbulent environment of lakes or streams the water body and are visible in the naked eye. can be initiated which affect the natural phenom- Dinofl agellate blooms are usually known as ‘red enon of bloom formation. The following are few tide’, e.g. bloom of Peridinium in alpine lake. practiced process by which bloom can be Most of the members of dinofl agellates can controlled: quickly regulate their position by swimming. 1. By collapsing gas vesicles: To prevent buoy- They are comparatively larger and can move fast ancy, if the cyanobacterial population is and are phototactic in nature. They generally exposed to a hydrostatic pressure of 0.4 MPa, swim to the surface of water in the morning for a signifi cant proportion of gas vesicles would photosynthesis and then swim down again in late be collapsed; therefore, the bloom would dis- afternoon. appear. Circulation of water containing sur- Dinofl agellate members like Peridinium and face scum of cyanobacteria up to a depth of Ceratium generally grow fast in summer and 90 m can destroy the gas vesicles – therefore, autumn and are quite able to swim actively to get the surface water would be free of cyanobac- the positions of favourable light and nutrients. terial scum. The algae are positively phototactic and may 2. Artifi cial mixing: Cyanobacterial members form reddish-brown surface patches, called red prefer stable water column together with tides. Nutrient requirements of dinofl agellate high nitrate and phosphate level for bloom members are complex and may include organic formation. Artifi cial mixing of water column substrate due to their heterotrophic nutrition. is the effective process for controlling cyano- Dinofl agellate’s population may decline due to bacterial bloom. After the removal of the heavy zooplankton grazing, competition from cyanobacteria, other members of diatoms or other algae and possibly nutrient depletion. The dinofl agellates may appear in blooming con- growth cycles of different algae actually depend dition in turbulent environment with high on both physical and chemical factors and there- nutrient levels. fore is a complex phenomenon. Large colonies 26 1 A Brief Introduction to Phytoplanktons rise or sink faster than unicellular or fi lamentous winds allowed onshore transport of water. This form. Large size and unpalatability prevent seri- accounted for transportation of estuarine waters ous loss to zooplankton grazing. into the coastal zone that led to the breakdown of Recently, harmful algal blooms (HABs) have vertical stratifi cation and promoted horizontal become a cause of concern due to their toxic stratifi cation with the formation of thermal and nature mainly composed of dinofl agellate salinity fonts. Thus, it can be said that develop- members and a few other algae including cyano- ment of ‘blooms’ is not only a nutrient-regulated bacteria. A harmful algal bloom (HAB) is an phenomenon but also involves physical processes algal bloom that causes negative impacts to other as well. organisms via production of natural toxins above Similar algal blooms occur in freshwater as the permissible level, mechanical damage to well as in marine environments. Typically, only other organisms or by other means. HABs are one or a small number of phytoplankton species often associated with large-scale marine mortal- are involved in bloom formation, and some ity events and have been associated with various blooms may cause characteristic discolouration types of shellfi sh poisonings. Harmful algal of the water resulting from the high density of blooms have been observed to cause adverse pigmented cells. If the algal bloom results in a effects to varying species of marine mammals high enough concentration of algae, the water and sea turtles, with each presenting specifi c may become discoloured, varying in colour from toxicity- induced reductions in developmental, purple to almost pink, normally being red or immunological, neurological and reproductive green (Fig. 1.2 ). capacities. HABs occur in many regions of the world, and Dinofl agellates constitute approximately 50 % in the USA, these are recurring phenomena in of all species and 75 % of all HAB multiple geographical regions. The Gulf of Maine species (Sournia 1973 ; Smayda 1997 ); therefore, frequently experiences blooms of the dinofl agel- research related to dinofl agellate ecology is late Alexandrium fundyense that produces saxi- essential for understanding the red tide and HAB toxin , the neurotoxin responsible for paralytic phenomena. The well-known ‘Florida red tide’ shellfi sh poisoning . California coastal waters that occurs in the Gulf of Mexico is an HAB also experience seasonal blooms of Pseudo- caused by Karenia brevis that produces breve- nitzschia , a diatom known to produce domoic toxin , causing neurotoxic shellfi sh poisoning . acid, responsible for amnesic shellfi sh poisoning . Bloom of Karenia brevis is a recurrent phenom- Off the west coast of South Africa , HABs caused enon in the West Florida Shelf as well. This by Alexandrium catanella occur in every spring. increase in the population mainly originates in These blooms used to cause severe intoxication the oligotrophic offshore water which is subse- of fi lter-feeding shellfi sh which affects the entire quently transported to the West Florida Shelf via food chain (Fig. 1.3 ). winds and tidal currents (Steidinger and Haddad At the end of the growing season, the dead 1981). These thermal fonts not only act as a bar- and decomposed planktonic biomass depletes rier but also as transport mechanism to concen- the oxygen from the water together with the trate Karenia brevis population in the shelf increased loading of organic matter into the waters. Thus, the resultant bloom is not due to the water body. This causes massive death of aquatic excessive productivity but the concentration pro- animals due to suffocation and intoxication, cess. A study on this phenomenon from October which ultimately produce the dead zone. Dead 1998 to January 2002 showed that the cell den- zones are hypoxic (low- oxygen) areas in the sity ranged from 1 to 5.4 million cells/L under an world’s oceans – the observed incidences of N-limited but P-enriched condition (Vargo et al. which have been increasing as oceanographers 2001 ). It was reported that during these periods, recorded since the 1970s. These occur near wind mixing as well as upwelling favouring inhabited coastlines , where aquatic life is most 1.6 Ecological Signifi cance 27

Fig. 1.2 A red tide off the coast of La Jolla, San Diego, California (Source: www. wikipedia.com )

Fig. 1.3 (a ) Satellite image of phytoplankton swirling Devon and Cornwall in England, in 1999 (Source: www. around the Swedish island of Gotland in the , wikipedia.com ) in 2005, and ( b ) an algae bloom off the southern coast of concentrated. In March 2004, when the recently 1.6.4 Algal Toxins established UN Environment Programme published its fi rst Global Environment Outlook Year Book The toxicity of some algal genera including cya- ( GEO Year Book 2003), it reported 146 dead nobacteria has been known since early times. zones in the world’s oceans where marine life Most of these taxa are planktonic causing delete- could not be supported due to depleted oxygen rious effect on marine and freshwater fauna and levels. Some of these were as small as a square fl ora. Generally the concentration of these tox- kilometre (0.4 mi2 ), but the largest dead zone ins, viz. , paralytic shellfi sh poison covered 70,000 km 2 (27,000 mi 2). A recent study (PSP) or domoic acid (DA), increase when the counted 405 dead zones worldwide. secreting taxa appear in blooming condition, 28 1 A Brief Introduction to Phytoplanktons causing intoxication or death of other organisms dinofl agellate toxins are neurotoxins. These especially the mammals. toxins act either as depolarizing agents or as non- depolarizing agents in membranes of excit- 1.6.4.1 Cyanotoxin able cells. Dinofl agellate toxins are a matter of The toxins secreted by cyanobacteria or the cya- public health concern as they infect many marine notoxins are the most common toxins of both products through the food chain especially during freshwater and marine habitat. Different types of red tide formation. have been recorded with varied The water-soluble toxins, , are chemical structure. The most commonly occurring produced by members of Gonyaulax , a tetrahydro- toxins are anatoxin-a, , microcystin, purine composed of two guanidinium moieties. scytophycin, cyanobactrin, lyngbyatoxin, etc. These toxins are categorized as follows: Depending on the toxic effect of the cyanotoxins, 1. Neosaxitoxin – 1(N )hydroxysaxitoxin (class I it can be categorized into different types like paralytic shellfi sh poison) neurotoxins, hepatotoxin and cytotoxins. 2. Sulfated 11 hydroxyl substitution (class II) – Neurotoxins are chemically nitrogen- gonyautoxins 1,2,3 and 4 containing compounds of low molecular weight, 3 . N-sulfoconjugation on the carbamoyl position for example, anatoxin and saxitoxin. They gener- (class III) – gonyautoxins 5 and 6 ally block the signal transmission from neurone 4. Dual sulfoconjugation at the 11 hydroxyl and to neurone and neurone to muscle. The neuro- carbamoyl positions (class IV) toxic amino acid L -beta-N -methylamino-l - Lipid-soluble toxins (Florida red tide toxin) alanine was shown to be produced by diverse are produced by: cyanobacterial taxa. In acute intoxication it may 1 . Ptychodiscus brevis – be fatal due to respiratory arrest. Cyanobacterial 2 . Gymnothora javanicus – ciguatoxin taxa like Anabaena fl os-aquae , Aphanizomenon 3 . Prorocentrum lima – okadaic acid fl os-aquae , Oscillatoria and Trichodesmium pro- 4 . Dinophysis fortii – methyl okadaic acid duce neurotoxins. The dinofl agellate toxins act predominantly The most common hepatotoxin is microcystin by altering transmembrane fl uxes of cations, secreted by Microcystis aeruginosa . It is a chemi- primarily sodium. Only maitotoxin acts in a cally cyclic hepatic peptide. A total of seven pep- sodium- independent manner. They block the tides are involved to form the structure of a inward fl ow of sodium ions without affecting microcystin, and the molecular formula is (2S,3S, the potassium channel. Ciguatoxin enhances 8S,9S,4E,6E)-3-amino-9-methoxy-2,6,8- the inward fl ow of sodium ions. Saxitoxin trimethyl-10-phenyl-4,6-decadienoic acid. It con- binds to specifi c receptors in the nerve membrane, tains D -alanine (D -ala) and D - METHYL-ASPARTATE whereas maitotoxin possesses a specifi c calcium- (Masp). Microcystis poisoning was fi rst reported dependent transport. about 1,000 years ago in southern China, when a Chinese general reported the death of his troops who drank green-coloured water from a river. 1.7 Algae in Wetlands Another hepatotoxin is nodularin, secreted by other cyanobacterial taxa including Nodularia . Wetlands are waterlogged ecosystem with a peri- A large number of cyanobacterial taxa produce odic fl uctuation in water depth. Most of the wet- cytotoxic compounds which are active against cell lands are with a depth of less than 2 m (<2). tissue line and have antitumor activities. Wetlands occur in every continent except Antarctica. According to Mitsch and Gosselink 1.6.4.2 Dinofl agellate Toxins (1993 ), wetlands comprise as much as 6 % of Toxins produced by marine dinofl agellates are global land area. It is also reported that 14 % land among the most potent nonproteinaceous area of Canada is wetland – most of which are lethal materials known. The most notorious of the confi ned to northern peatlands. 1.7 Algae in Wetlands 29

Wetlands are important for their high produc- therefore, high entropic condition resulted in tivity as they are considered as nutrient sinks periodical phytoplankton bloom. Effl ux from (Dolan et al. 1981 ; Reeder 1994 ), fl ood control the sediments is a major source of nutrients to buffers and the breeding ground of different the water column. Signifi cant water input from aquatic animals like waterfowl and others (Batt the adjacent lake, river or streams is the main et al. 1989 ). Wetland research is carried out in source of nutrients and algal inocula for lake- different countries by various scientists (Barica shore and riverside wetlands. Nutrient effl ux due et al. 1980 ; Hanson and Butler 1994 ; Moss 1983 ). to various anthropogenic factors is another source of nutrients for wetlands; waste water from dif- ferent sources like industrial waste and municipal 1.7.1 Role of Phytoplanktons waste also increases the nutrient level in wetland in Wetlands ecosystem, especially in stagnant wetlands. Limnologists are of the opinion that freshwa- In wetland ecosystem, phytoplanktons are one of ter wetlands are generally P limited, though there the fundamental players of physical, chemical and are exceptions also. In north temperate wetland biological processes that characterize the wetland of North America, the N–P ratio in the water col- ecosystems. They mostly act as primary producer, umn is mostly >10 (Barica 1990 ). The nutrient therefore placed in the wetland food web. Pinckney defi ciency of northern wetlands is due to the vari- and Zingmark ( 1993 ) calculated the relative pri- ation in phytoplankton population there. Murkin mary production of different types of algal com- et al. (1991 ) estimated the alkaline phosphatase munity of wetlands and obtained as much as activity, ammonia uptake rate and the ratios of 22–38 % of epipelagic algae, 10–17 % for P–Cl, N–P, N–C and chlorophyll–C composition macroalgae and 30–59 % for vascular plants. The ratio and found severe N and P defi ciency in sum- average C fi xation rate of freshwater marsh phyto- mer due to insuffi cient nutrient loading. But other planktons varied from 3 to 16 μ L−1 h −1 as esti- wetlands enriched by cattle feedlot effl uent did mated by different authors (Kotak and Robinson not have any nutrient-defi cient symptoms. 1991 ; Mitsch and Reeder 1991 ). Whereas in peat Campeau et al . ( 1994) studied the ecological bogs, it was 5–32 μg L−1 h −1 (Henebry and Cairna effect of the addition of N and P to a nutrient- 1984 ); in salt marsh it was recorded as poor marsh and observed the stimulation in bio- 100 g m −2 year−1 (Vernberg 1993 ), and in tundra mass production of phytoplanktons together with ponds, it was at minimum level of 0.6–0.9 g−2 year−1 epiphyton and metaphyton but not the epipelon. (Stanley 1976 ). Generally shallow wetlands are dominated by The importance of wetland phytoplanktons as phytoplanktons (Barica et al. 1980 ), but some a resource of food to herbivores depends on their wetlands with deepwater levels have abundant availability throughout the year. Their variation macrophytes and associated epiphytes. in size, species composition and productivity Physicochemical parameters and allelopathic support the zooplankton and other aquatic fauna effects of different organisms also play a major as continuous food source. role in wetland ecology and phytoplankton abun- Generally the levels of phytoplankton chlorophyll dance together with water depth. in wetlands varied from 50 to >200 μg L −1 during Sometimes there is a direct role of fl uctuating periodic cyanobacterial bloom (Barica 1975 ). water depth on wetland nutrient status. It is already reported that exposure of sediments during draughts promotes the decomposition of 1.7.2 Nutrient Status of Wetland organic matter and the nutrients are liberated Ecosystem during subsequent refl ooding (Kadlec 1986 ; Schoenberg and Oliver 1988). van der Valk In a wetland ecosystem, nutrient effl ux from ( 1994 ) reported that in late stage of fl ooding, different sources enriches the nutrient level; macrophytes are killed by fl ood stress and their 30 1 A Brief Introduction to Phytoplanktons decomposed biomass releases N and P (Murkin down in existing wetland or the low level of water et al. 1989 ). Moreover, both algae and higher by early fl ooding of a new wetland. Epipelic plants of wetland ecosystem release a diverse algae are predominant in this type forming a crust type of soluble organic substances into the water on the bottom sediment. column during their growth and decompositions (Hall and Fisher 1985 ; Briggs et al. 1993 ). 1.7.3.2 Open State Therefore, due to abundance of organic N and P An open state wetland is with deep and turbulent species, the algal community may also continue water column. This type of wetland may arise by their heterotrophic nutrition. Pip and Robinson two ways: by gradual fi lling of dry state wetland (1982) experimented with radiolabelled mixture or by biomanipulation of phytoplankton- of glucose, fructose and sucrose and observed dominated lake state wetland. Open state wet- that most of the algal genera including cyanobac- lands are dominated by macrophytes, and with teria can also utilize the organic carbon sources. abundant epiphyton biomass on them, compara- tively phytoplanktons and epipelic algae are less. 1.7.2.1 Physical Factors Affecting Wetland Ecosystem 1.7.3.3 Sheltered State I. Light: Light penetration in water column of In some wetland areas, nutrient load is very high, shallow wetlands is affected greatly by wind- but the area is shady due to bordering vegetations driven sediment resuspension which also and excessive growth of macrophytes. These increases the productivity of shallow wetlands metaphytes remain covered by epiphytic growth. (Klarer and Millie 1992 ). The bottom sedi- These epiphytic algal mats sometimes detach ments are also subjected to regular distur- from their substratum and fl oat on the water sur- bances by the benthivorous carp fi shes face as metaphytons. Whitton ( 1970 ) recorded (Cyprinus carpio ) and other macrophytes high nutrient status, high irradiance, alkaline pH, (Meijer et al. 1990 ). Sometimes fl oating algal high calcium and low N–P ratios as the main con- mats or Lemna mats disrupt light penetration; tributors for metaphyton growth. therefore, the population productivity of wet- land fl ora is greatly affected, where it becomes 1.7.3.4 Lake State light limited rather than nutrient limited. Lake state wetlands are characterized by high II. Temperature: In wetland ecosystem differ- water column and nutrient levels, therefore ideal ences in temperature with depth are minor, as for phytoplankton growth. Due to high depth of the wetlands are shallow and the wind-driven water, macrophyte growth is checked together mixing minimizes the temperature gradient of with the epiphytic and metaphyton growth. The wetland water column. Sometimes the thick water column is turbid due to phytoplankton algal mats or fl oating mat of duckweed may growth. Lake state wetland may develop by rapid increase the temperature variation in water water input to other types of wetlands, by natural column reducing the temperature. process or by anthropogenic manipulation. This leads to the death of macrophytes and epiphy- tons, leading to a growth of lake state wetlands. 1.7.3 Types of Wetlands

Based on the depth and duration of the water- 1.8 Key to Identifi cation logged condition of the wetland and their respec- of Common Phytoplankton tive algal fl ora, the limnologists classifi ed Genera wetlands into different types. 1.8.1 Division: Cyanobacteria 1.7.3.1 Dry State In dry state wetland, water levels occur at very Cells smaller, blue green in colour, cells with- low level after a long period of draught, i.e. draw out membrane-bound cell organelles; pigments 1.8 Key to Identifi cation of Common Phytoplankton Genera 31 diffused throughout peripheral portion of the 6. Cells ellipsoidal or cylindrical 7 protoplast; water-soluble pigments like phy- with round ends cocyanin and phycoerythrin present; photo- 7. Cells single or 2–4 together, erect Synechococcus synthetic storage products are glycogen and without a common mucilage 8. Cells without any regular or 9 glycoproteins; defi nite nucleus and chromo- defi nite arrangement some absent, mucilage conspicuous, hydro- 8. Cells with defi nite arrangement 14 static gas vacuoles present, reproduction by in distinct colonies fi ssion and by fragmentation, sexual reproduc- 9. Cells in a general amorphous 10 tion absent. mucilage, without or with a few distinct sheaths round the individual cells 1.8.1.1 Class: Cyanophyceae 9. Cells with distinct individual 12 Unicellular/multicellular without true nucleus envelope or sheaths, colonial or chromatophore; chlorophyll a and phyco- mucilage not homogenous biliproteins are main pigments that are com- 10. Cells typically well packed Microcystis posed of allophycocyanin, phycocyanin and into microscopic colonies of defi nite shapes, mostly phycoerythrin; photosynthetic product glyco- planktonic gen or glycosides, no starch; reproduction by 10. Cells loosely arranged, mostly 11 division or through fragmentation of thallus, not planktonic, forming endospores, exospores, hormogones, motile macroscopic colonies fl agellate cells absent; sexual reproduction 11. Cells spherical Aphanocapsa almost absent. 11. Cells ellipsoidal to cylindrical Aphanothece 12. Individual sheaths vesicular 13 and broad and formed one in 1.8.1.2 Key to Orders another Thallus unicellular or colonial, sometimes form- 12. Individual sheaths not Chroococcus ing pseudofi lamentous colony, no trichome vesicular, cells spherical organization, no differentiation into base and 13. Cells spherical Gloeocapsa apex, endospores not formed in sporangia, no 13. Cells ellipsoidal to cylindrical Gloeothece exospores, nanocysts present – Chroococcales 14. Colony with cells arranged 15 in a tabular or cubical or 3D colony 1.8.1.3 Key to Family 14. Colony a hollow sphere with 16 Cells unicellular or forming colonies, not forming cells arranged along the margin fi lament-like growth – Chroococcaceae uniformly 15. Cells in regular transverse Merismopedia 1.8.1.4 Key to Genera and longitudinal rows, tabular or fl at colonies 16. Cells spherical, colonial Coelosphaerium 1. Cells single or few together in a 2 mucilage homogenous shapeless colony 16. Cells pear shaped or weakly Gomphosphaeria 1. Cells generally many in a single 8 spherical, colonial mucilage colony not homogenous, cells with 2. Cells spherical 3 distinct mucilage sheaths 2. Cells elongated 5 3. Without individual mucilage Synechocystis envelopes 3. With distinct envelope 4 4. Vesicular sheath Gloeocapsa 1.8.2 Division: Chlorophyta 5. Cell division transverse, with Gloeothece a fi rm vesicular sheath Grass-green chloroplasts, chloroplasts often with 5. Cell division transverse, without 6 pyrenoids, food reserve starch, cell wall com- such a sheath posed of cellulose and pectic compounds 32 1 A Brief Introduction to Phytoplanktons

1.8.2.1 Class: Chlorophyceae 1.8.3 Order: Volvocales Unicells (sometimes motile), simple or well- organized colonies, simple or branched fi laments, Both vegetative and reproductive cells are motile; partitioned coenocytes and true coenocytes (fi la- 2, 4 or rarely 8 fl agella, generally a conspicuous ments without cross walls). Reproduction both pigment spot, cup-shaped parietal chloroplasts; sexual and asexual reproduction by cell division, by zoospores, by isogametes or by heterogametes. 1.8.2.2 Key to Orders 1.8.3.1 Key to Families 1. Motile in the vegetative condition; Volvocales fl agella 2 or 4, rarely 8, equal in 1. Cells possessing a defi nite 2 length; organism 1 celled or colonial wall and sometimes a 1. Not motile in the vegetative condition 2 mucilaginous sheath; solitary 2. Cells embedded in copious mucilage Tetrasporales or united in colonies (homogenous or lamellated), united 2. Cells solitary 3 in colonies of indefi nite shapes or 2. Cells united in colonies 5 forming gelatinous strands 3. Cell wall not bivalved, 4 (pseudofi laments) or mucilage not fl attened invested, some unicellular or forming dendroid colonies which are epiphytic 4. Cells with protoplasts located Haematococcaceae or epizoic, cells often with false at some distance within the (in part) fl agella (pseudociliates) returning to cell wall and connected to it by a motile condition without resorting radiating cytoplasmic strands to reproductive stage 4. Cells without radiating Chlamydomonadaceae 2. Cells not embedded in mucilage 3 cytoplasmic strands 3. Thallus fi lamentous, composed 4 5. Cells united to form fl at or Volvocaceae of cells adjoined end to end in globular colonies, evenly defi nite series, sometimes interrupted dispersed, although sometimes closely arranged within 3. Thallus not composed of cells 15 colonial mucilage arranged to form fi laments; unicellular or colonial; or if fi lamentous, occurring as coenocytes without cross walls 4. Filaments unbranched; attached 5 1.8.4 Order: Chlorococcales or free fl oating 4. Filaments with branches, the 13 branches sometimes closely One celled or colonies of defi nite shapes; cells appressed, forming may be adjoined or merely enclosed by colo- pseudoparenchymatous masses nial mucilaginous envelope. No cell division 5. Filaments composed of a single 6 in vegetative state. Asexual reproduction by series of cells zoospore formation, sexual reproduction 5. Filaments composed of more 12 isogamous than one series of cells; cells adjoined; thallus a hollow tube or ribbon/frond-like expansion 1.8.4.1 Key to Families 6. Chloroplasts 1 to several, large, Zygnematales in the form of spiral bands, stellate 1. Unicellular or colonial; 2 masses or broad plates; pyrenoid cells varied in shape but not conspicuous; reproduction irregular; wall of uniform thickness by conjugation and not defi nitely lamellated; free 7. Thallus a single cell or a colony Chlorococcales living or attached, rarely subaerial of defi nite or indefi nite form; cells 2. Free fl oating or adherent on soil 3 with various shapes that range from 3. Cells cylindrical and forming Hydrodictyaceae spherical, pyramidal to polygonal; a macroscopic network or no vegetative reproduction, triangular or polyhedral and united reproduction by autospores, to form either a fl at and circular or zoospores or isogametes a globose coenobium (colony) 1.8 Key to Identifi cation of Common Phytoplankton Genera 33

3. Cells not cylindrical and not 4 sculptured. Valve mantle usually forming colonies as above strongly developed . 4. Unicellular, solitary or sometimes Chlorococcaceae Subfamily – Melosirinae gregarious, free fl oating (usually on Common genera – Melosira , moist soil if adherent), reproduction by zoospores (rarely aplanospores) Stephanopyxis which do not adhere to one another Key to Genera but which are liberated separately Cells globose, elliptical or cylindrical, from the parent cell closely united in straight, beadlike 4. Colonial or solitary, not 5 reproducing by zoospores chains by the centres of the valves. 5. Thallus not a globose, hollow 6 Valves either simply punctate or coenobium punctate and areolate. Intercalary 6. Cells not in a peripheral 7 bands none or many and narrow. arrangement with no coloured Melosira mucilage Cells oblong, oval or nearly circular, 7. Cells solitary or in colonies of Oocystaceae defi nite or indefi nite shape; cells with hexagonal areolations. Usually variable in form (spherical, ovate, in short chains. lunate, polyhedral, etc.), not Stephanopyxis adjoined to one another; (b) Cells short or elongated–cylindrical, reproduction by autospores bound into close chains by delicate 7. 2–8 cells adjoined together or adherent to form a pattern of siliceous projections or gelatinous defi nite shape (a linear series, threads. Cell wall usually weakly stellate or cruciate); reproduction siliceous . by the formation of autocolonies Subfamily – Skeletoneminae within the cells of the parent coenobium Common genera – Skeletonema , Thalassiosira Key to Genera Cells circular, lens-shaped, oblong, 1.8.5 Division: Bacillariophyta (Diatoms) or cylindrical. Valves circular, somewhat arched, without dis- 1.8.5.1 Order: Centrales tinct structure, with a row of fi ne Valves with a concentric or radiating sculpture spines at the edge of the valve around a point or points, central or lateral. Without parallel to longitudinal, pervalvar raphe or pseudoraphe. Cells circular, oval or ellip- axis. Spines interlock midway tical, sometimes polygonal, rarely crescent shaped between adjacent cells and unite or spindle shaped. Processes common cells into chains. I. Suborder: Discoideae Skeletonema Cells disc shaped or cylindrical. Valves circu- Cells similar to those of Coscinodiscus , lar, surface fl at or convex, sometimes hemi- usually drum or disc shaped, united spherical. Spines frequent. Without horns or in fl exible chains by a cytoplasmic knobs; when present, small or gelatinous thread or living in 1. Valves circular. Not divided into defi nite formless gelatinous masses or sel- sectors by ribs, rays or undulating sectors. dom solitary. One or more interca- Sculpturing sometimes arranged in bun- lary bands to each valve. Valves with dles, long spines often present . areolae or delicate radial rows of Family – Coscinodiscaceae punctations. Structure often diffi cult (a) Cells lens shaped, round or cylindrical. to see. Marginal capsule or little Usually united into more or less long spines present, usually distinct . typical chains. Intercalary bands often Thalassiosira 34 1 A Brief Introduction to Phytoplanktons

(c) Cells disc or drum shaped, solitary. Cell wall usually of several layers, Valve surface slightly convex, some- the individual membranes punctu- times nearly fl at or slightly concave, ated; puncta in crossing lines and with prominent sculptures (commonly more or less strongly areolated . hexagonal). Intercalary bands hyaline Actinoptychus or rarely very delicately sculptured. 3. Valves usually radially waved, eyes or Valve mantle not particularly well knobs on the elevations or valves fl at and developed. then with singly placed wartlike elevations Subfamily – Coscinodiscinae or circle of needles. Common genera – Coscinodiscus , Family – Eupodisceae Cyclotella, Planktoniella (a) Valves with knobs. Only one genus . Key to Genera Subfamily – Aulacodiscinae Cells disc or box shaped, single or in Common genus – Aulacodiscus twos immediately after cell divi- Key to Genera sion. Valves circular, without large Cells discoid or box shaped. Valves knobs or processes, with hexagonal with a circular outline, fl at or areolae arranged in various ways or slightly lower in the middle or con- fi ne round puncta . vex, with four or more conical pro- Coscinodiscus cesses symmetrically arranged near Cells single, disc shaped, with a hya- the margin. Areolated. Intercalary line winglike expansion all around bands present . consisting of extracellular cham- Aulacodiscus bers strengthened by radial rays. II. Suborder: Solenoideae The winglike expansion weakly Valves oval or circular in cross section. Cells siliceous, an organ of fl otation. elongated, cylindrical or subcylindrical, with Valves areolated like those of numerous intercalary bands, without internal Coscinodiscus excentricus . septa. Valve structure arranged in relation to Planktoniella an excentric pole. Cells united into chains by 2. Valves circular. Divided into distinct, com- their valves plete or incomplete sectors by radial ribs or As above – Family: Solenieae undulations or by wide hyaline rays from a (a) Valves fl at or raised, with or without characteristically constructed centrum. marginal spines. Excentric process or Without horns or prominent spines . asymmetrical spine absent. Family – Actinodisceae Subfamily – Lauderiinae (a) Valves divided into sharply distinct Common genera – Corethron , sectors by radial ridges uniformly run- Leptocylindrus ning from the margin to the hyaline Key to Genera central area. Small but distinct spines Cells living singly. Cylindrical with usually at the marginal ends of these rounded valves having a crown of ridges. Alternate sectors generally long thin spines or setae at the mar- depressed . gin directed outwards at an angle. Subfamily – Actinoptychinae Numerous intercalary bands, scale- Common Genus – Actinoptychus like, often very indistinct . Key to Genera Corethron Cells disc shaped, single. Valves Cells long, cylindrical, united into chains divided into sectors which are alter- by whole valve surface. Valves fl at, nately raised and depressed. Smooth without spines or processes . central area. No intercalary bands. Leptocylindrus 1.8 Key to Identifi cation of Common Phytoplankton Genera 35

(b) Valves with a single often very short Horns short and thick or with claws at the end spine or process, usually excentrically of long horn. Cells united into chains by placed, thus destroying the symmetry the ends of the horns. Valvar plane circular of the cell. Valves fl at or convex or elliptical, usually with one to several Subfamily – Rhizosoleniinae poles and multiangled. Intercalary bands Common genus: Rhizosolenia and septa often present. Mainly plank- Key to Genera tonic, partly littoral. Majority of species Cells cylindrical with greatly elon- marine . gated pervalvar axis, living singly Family – Biddulphiaceae or in compact or loose chains. (i) Knobs and horns without claws on Cells usually straight or more the end Valves bipolar. Cell wall rarely curved, forming spirally weakly siliceous. Plankton forms . twisted chains. Cross section ellip- Subfamily – Eucampiinae tical or circular . Common genus – Eucampia Rhizosolenia Key to Genera III. Suborder: Biddulphioideae Valves elliptical in surface view Cells box shaped. Pervalvar axis generally with two blunt processes, with- shorter, sometimes slightly longer, than the out spines or setae. Numerous valvar axis. Valves usually oval, sometimes intercalary bands diffi cult to see polygonal, circular or semicircular; unipolar, in water mounts. Chains spirally bipolar or multipolar, each pole represented curved. Large apertures between by an angle or by a horn or spine or by both the cells . angles and horns. Eucampia Valves with long setae, longer than the cells. Valves tripolar to multipolar, some- Cells united into chains by basal part of times with bipolar varieties. the setae. Seldom living as single cells. Angles not bearing domelike pro- Intercalary bands only seldom present. trusions or horns. Intercalary Valves circular or oval. All species pelagic . bands frequently present. Marine Family – forms, usually littoral, a few Common genera: , Chaetoceros pelagic . Key to Genera Subfamily – Triceratiinae Cells cylindrical, in cross section circular. Common genera – Ditylum , Bound into loose chains by the fusion of Lithodesmium , Triceratium the more or less numerous setae that are Key to Genera regularly arranged around the margin of Cells elongated, prismatic to box the cells. Setae of two adjacent cells are shaped. Solitary except immedi- fused for a certain distance beyond the ately after division. Valves three base, farther out divided again . to four cornered, seldom bipolar, Bacteriastrum with a strong central siliceous hol- Cells with oval section to almost or rarely low spine and a marginal ridge completely circular in valve view; in broad strengthened by ribs . girdle view quadrangular with straight Ditylum sides and concave, fl at or slightly convex Cells united in usually long, straight ends. Valve with more or less fl at end sur- chains with concealed apertures. face or valve surface and a cylindrical part Valves three cornered. Valves or valve mantle which is bound together with marginal pervalvar- directed without a seam . membrane by which adjacent Chaetoceros cells are joined. Long, thin, hol- 36 1 A Brief Introduction to Phytoplanktons

low spine in the centre of valve. blunt projections or processes near Intercalary bands present, collar their margin, attached to adjacent like . cell by means of a fi ne, small, curved, Lithodesmium hairlike process which fi ts into the Valves bipolar, tripolar or multipolar. valve of the adjacent cell. Intercalary Each angle with a domelike pro- bands numerous, annular . trusion or a horn. Usually strongly Cerataulina siliceous and forms chains. Cells single or united in chains. Predominantly littoral, but some- Valves elliptical in section, with times pelagic. A few species are two narrow, pointed, more or less typically planktonic and are then long processes at the ends of the more weakly siliceous . apical axis, parallel to pervalvar Subfamily – Biddulphiinae axis . Common genus – Biddulphia Hemiaulus Key to Genera Cells without horns. Valves without Cells box shaped to cylindrical. internal septa. Valves semicircu- Valves elliptical, with two poles lar, broader than long. Intercalary or three- or four sided (rarely fi ve bands very seldom present. Cells sided). At the corners or at the in girdle view cuneate. ends of the apical axis, more or Family – Euodieae less strongly developed processes Common genus – Hemidiscus or horns may be present . Key to Genera Biddulphia Cells shaped like a sector of a sphere, Valves unipolar. Cells in broad girdle in girdle view wedge shaped, nar- view rhombic or trapezoid. Large rowing from the dorsal towards to very large, robust marine forms. the ventral side. Valve semicircu- Littoral. lar to asymmetrically elliptical. Subfamily –Isthmiinae Valves fl at with short valve man- Common genus – Isthmia tles. Intercalary bands and septa Key to Genera absent, pervalvar axis not particu- Cells cylindrical–box shaped with larly elongated . elliptical valve surface and usu- Hemidiscus ally longer pervalvar axis. Intercalary bands absent . 1.8.5.2 Order: Isthmia Valves elongated, bilaterally symmetrical. (ii) Horns with claws on the end Outline generally boat shaped or rod shaped, Valves bipolar, tripolar or quadripo- sometimes oval, cuneate, crescent shaped or lar. Each angle with a long verti- sigmoid; markings generally pinnate or transverse. cal horn tipped with a claw . True raphe, or hyaline median line (pseudora- Family – Hemiaulineae phe), or raphe obscured by lateral wings or keel Common genera – Cerataulina , (cryptoraphe) always present. Processes absent. Hemiaulus Cell capable of spontaneous movement if a true Key to Genera raphe is present. Cells cylindrical, usually in chains. 1. Raphe absent. Pseudoraphe usually present. Valves slightly arched, with two Suborder – Araphidineae 1.8 Key to Identifi cation of Common Phytoplankton Genera 37

Cells in general rod shaped to tabular prism shaped or with tabular girdle view. shaped, in valve view usually more or less Intercalary bands sometimes present, but linear, seldom club shaped. In girdle view lin- always without or with only very rudimen- ear to tabular rectangular. Intercalary bands tary septa . and septa frequently present. Valves with Subfamily – Fragilariieae transapical striae or ribs, sometimes Common genera – Fragilaria, Synedra, areolated–punctated, often with mucilage Thalassionema, Thalassiothrix, Asterionella pores. Without a true raphe, but usually with Key to Genera a median pseudoraphe. Chromatophores Cells united into more or less long bands by usually more or less numerous small plate- the whole valve sides, occasionally with lets, seldom a single large plate . regular apertures between the cells. Family – Fragilarioideae Connection of the cells with one another Cells in valve view usually linear, more seldom often assisted by tiny spines on the valve wedge shaped, frequently with transapical margin . infl ations or constrictions. In girdle view usu- Fragilaria ally linear to tabular, seldom wedge shaped. Cells single or united into fanlike to clustered Intercalary bands and septa always present starlike colonies, seldom in short bands. In and distinct. Valvar plane not bent in the per- general with greatly elongated apical axis, valvar direction, the two valves of a cell usu- rodlike, sometimes bent in the direction of ally entirely alike. Cells usually united into the apical axis. bands. Marine and freshwater forms . Synedra Subfamily – Tabellarieae Cells forming zigzag bands or star-shaped Common genera – Rhabdonema, colonies, adjacent cells united to each other Grammatophora by small gelatinous cushions on one cell Key to Genera end. In girdle view linear . Cells in girdle view rectangular with rounded Thalassionema corners, usually united into zigzag chains . Cells living singly or forming star-shaped Grammatophora colonies, zigzag bands or bunches, united Cells with poles of apical axis unlike. In girdle to one another by a gelatinous cushion on view, as in valve view, wedge shaped. the end of the cell. In girdle view narrow Intercalary bands and septa present. Cells linear. stalked and often united into strongly Thalassiothrix branched colonies . Marine. Cells united by one end (the larger end) into Subfamily – Licmophorinae star- shaped colonies or spirally curved, Common genus – Licomophora sometimes straight, comb-shaped bands. Key to Genera Asterionella Cells with wedge-shaped girdle band side and Valves with transapical ribs that are, however, wedge- or club-shaped valve. Two interca- sometimes limited to one valve of a cell or lary bands in resting cells, with a more or to one single middle rib. Freshwater or less long penetrating septum on the head marine forms. Cells as a rule united into pole. Valves with transapical punctated closed or zigzag bands . striae, seldom with weak transapical ribs Subfamily – Diatominae and extremely delicately punctated interca- Common genus – Diatoma lary space . 2. One valve of the cell always with Navicula - Licomophora like raphe, the other without a raphe or with a Cells usually rod shaped. Usually linear in rudimentary raphe knot . both valve and girdle view, seldom wedge Suborder – Monoraphideae 38 1 A Brief Introduction to Phytoplanktons

Cells with linear, lanceolate or elliptical valvar raphe; usually without a keel or strongly plane, more or less distinctly bent about the developed wings, but when present always apical or transapical axis. Valves some- without marginal canal and keel puncta. times with polar pseudosepta. The mem- Family – Naviculoideae brane lying between the transapical rows Cells as a rule of symmetrical construction, stronger, often thickened, riblike. The two transapical axis only seldom with unlike valves of a cell usually considerably differ- ends. In girdle view usually rectangular, entiated in regard to the structure as well as valves elliptical, linear or lanceolate, often to the development of the raphe. S shaped, seldom club shaped or crescent Family – Achnanthoideae shaped. Raphe usually in the valvar plane. Cells bent about the transapical axis, some- Cells usually solitary, sometimes in gelati- times also about the apical axis; the valve nous tubes or on a gelatinous stalk. with the raphe, concave; the one without a Subfamily – Naviculeae raphe, convex. One valve always with a Key to Genera developed raphe, the other without, seldom Cells usually free, motile. In plankton species with a very short raphe knot or with a rudi- usually united into ribbon-like chains. mentary raphe. Outline of valve usually lin- Valves linear to elliptical, with rounded, ear–lanceolate, seldom elliptical. Intercalary capitate or rostrate ends . bands sometimes present, true septa absent . Navicula Subfamily – Achnanthaceae Valves linear or lanceolate. Usually sigmoid. Key to Genera Axial area very narrow. Central area small. Cells single or united into ribbon-like bands, Striae punctate, in transverse and longitu- with or without a gelatinous stalk to hold dinal rows . the chains to the substrate. Seldom pelagic. Gyrosigma Valves usually linear–lanceolate, seldom Valves linear to lanceolate, usually sigmoid. elliptical; in girdle view in general rectan- Raphe usually sigmoid, central or excen- gular, but more or less strongly broken tric. Striae fi nely punctate in oblique and along the transapical axis . transverse lines. Central nodule usually Achnanthes small and rounded . Cells elliptic to near round, rapheless valve Pleurosigma with slightly radial transapical striae, pseu- Raphe on a keel or wing that usually lies in the doraphe narrow, valve with raphe with midline of the valve. Cells usually twisted radial punctuate striae. about the apical axis. Subfamily – Cocconeideae Subfamily – Amphiproroideae 3. Both valves with developed raphe. Key to Genera Suborder – Biraphideae Cells single or in ribbon-like chains. Cells con- Cells of various types as regards to structure of stricted in the middle. Valves lanceolate, membrane, cell contents and general form. convex, with raphe, central nodule and a sig- All forms with a similar characteristic raphe moid keel. One-half of keel lies on each side system: outer and inner fi ssures and accom- of the chain axis. Terminal nodules present . panying end and central knots. Knots often Amphiprora greatly reduced or in many species only Keel with canal raphe lying in the valvar slightly developed. Inner and outer fi ssures plane, often displaced transapically as far often diffi cult to distinguish from each as to the valve margin. Both valves with other. Raphe usually in the valvar plane, canal raphe. Keel with puncta. generally distinct, not developed as a canal Family – Nitzschiaceae References 39

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Smith, G. M. (1950). Fresh water algae of the United & Fanning, K. (2001). In: G. M. Hallegraeff, S. I. States . New York/Toronto/London: McGraw-Hill. Blackburn, C. Bolch, & R. J. Lewis (Eds.), IOC of Sournia, A. (1973). La production primaire planctonique UNESCO (pp. 157–160). en Mediterranee, Essai de mise en jour. Bulletin Etude Vernberg, F. J. (1993). Salt-marsh processes: A review. en Commun de la Méditerranée, 5 (no sp.), 128pp. Environmental Toxicology and Chemistry, 12 , Stanley, D. W. (1976). Productivity of epipelic algae in 2167–2165. tundra ponds and a lake near Barrow, Alaska. Ecology, von Meyer, H. A., & Möbius, K. (1865–1872). Fauna der 57 , 1015–1024. Kieler bucht . Leipzig: W. Engelmann. Steidinger, K. A., & Haddad, K. D. (1981). Biologie and Whittaker, R. H. (1969). New concepts of kingdoms hydrographic aspects of red tides. Bioscience, 31 (11), or organisms. Evolutionary relations are better repre- 814–819. sented by new classifi cations than by the traditional Stewart, K. D., & Mattox, K. R. (1975). Comparative two kingdoms. Science, 163 (3863), 150–160. cytology, evolution and classifi cation of the green Whitton, B. (1970). Biology of Cladophora in freshwa- algae with some consideration of the origin of other ters. Water Research, 4 , 457–476. organisms with chlorophylls a and b. The Botanical Yu, M. H., Glazer, A. N., & William, R. C. (1981). Review, 41 , 104–135. Cyanobacterial phycobilisome. Phycocyanin assem- Throndsen, J. (1978). Productivity and abundance of ultra- bly in the rod substructure of Anabaena variabilis and nanoplankton. Oslofjorden, 63 (4), 273–284. phycobilisomes. Journal of Biological Chemistry, Van der Valk, A. G. (1994). Effects of prolonged fl ooding 256 , 13130–13136. on the distribution and biomass of emergent species Zapata, M., Jeffrey, S. W., Wright, S. W., Rodriguez, F., along a freshwater wetland coenocline. Vegetatio, 110 , Garrido, J. L., & Clementson, L. (2004). Photosynthetic 185–196. pigments in 37 species (65 strains) of Haptophyta: Vargo, G. A., Heil, C. A., Spence, D., Neely, M. B., Implications for oceanography and chemotaxonomy. Merkt, R., Lester, K., Weisberg, R. H., Walsh, J. J., Marine Ecology Progress Series, 270 , 83–102. Physicochemical Environment of Aquatic Ecosystem 2

Influence of physical and chemical environment can be attributed to absorption and refraction, a of a water body together with the growth pattern phenomenon known as vertical light attenuation of individuals plays important roles in phyto- which can be mathematically expressed as plankton dynamics. −k Ez()= Ee()0. z []Beer Lamberts Law ddd

2.1 Physical Factors where Ed(0) and Ed(z) are light intensity at surface and at depth z respectively. Among the physical factors light and temperature Light and temperature are the most widely are the major ones which control the phytoplank- studied environmental parameter that affects ton growth. algal growth, both in in situ and in vitro studies. Surface waters of different ecosystems get light and heat from solar irradiation on earth surface, 2.1.1 Light and Temperature and as a result different distinct vertical zones are developed. Actually sunlight enters into the water Pelagic ecosystems are dominated by phyto- of ocean or lake and is converted into heat, as a plankton populations that cover 70 % of the result of which euphotic zone develops. In an world’s surface (Reynolds 2006). Falkowski aquatic ecosystem, the depth up to which light (1995) also opined that 45 % of the earth’s photo- penetrates is called ‘euphotic zone’. It is consid- synthesis is accounted by phytoplankton popula- ered as the depth up to which 1 % of the surface tions around the world. Light absorption ability irradiance is reached in the water column. of natural phytoplankton populations is directly Turbidity of the water column can act as an related to the spectral nature of the light-­ important regulator of the light availability in the harvesting capabilities of the pigment mole- water column in an aquatic ecosystem. An cules present in the phytoplankton population increase in turbidity is mainly caused due to SPM (Bergmann et al. 2004). It is well known among (suspended particulate matter) load and colloidal plant biologists that maximum light absorption of matter in the water column, including both inor- chlorophyll is achieved in blue-violet and red ganic (e.g. dispersed sediment particles) and regions of the spectrum, while the accessory pig- organic (e.g. phytoplankton, zooplankton). Thus, ments like carotenoids and xanthophylls absorb it can be said that there will be an exponential mainly in the blue-green region with phycobilip- decrease in light availability with depth at a rate roteins showing maximum absorption efficiency which is dependent on the particle content of the in yellow-red region of the spectrum. The expo- water column. Thus, the euphotic zone may reach nential decrease in light intensity due to depth from a few meters in coastal and estuarine waters

R. Pal and A.K. Choudhury, An Introduction to Phytoplanktons: Diversity and Ecology, 43 DOI 10.1007/978-81-322-1838-8_2, © Springer India 2014 44 2 Physicochemical Environment of Aquatic Ecosystem

Fig. 2.1 Specific zonations on the basis of light and temperature Solar irradiance variations at different depths of the water column

Water surface Epilimnion

Metalimnion Thermocline (region of chlorophyll Hypolimnion maxima)

to more than 100 m in the Mediterranean Sea and hypolimnion. Cells present in the hypolimnion the Pacific gyre. Many plankton biologists have undergo passive sedimentation due to cellular considered this depth as the lower limit beyond senescence or overwintering phase. Different which phytoplankton cells become incapable of planktonic species of the epilimnion like the photosynthetic activity. Exceptionally, there may migrate to the hypolimnion are reports that picoplanktonic form like periodically for nutrient supplementation under Prochlorococcus can photosynthesize at 0.01 % nutrient replete conditions of the epilimnion. of surface irradiance availability (Goericke et al. Thus, sampling by depth samplers and sedimen- 2000). With an increase in depth, light availability tation chambers at different depths of the water decreases and the spectral range narrows to the column can provide important insights in the blue region since the blue wavelength is least overall ecosystem functioning. attenuated in a water column. So it can be said Temperature also follows the similar trend as that phytoplankton cells have the ability to accli- was found for light, and the variation in tempera- matize to depth and light availability by increas- ture is directly related to solar irradiance. This pro- ing their pigment content and by shifting their cess divides the water body into distinct layer or pigment composition (e.g. Prochlorococcus has strata, called stratification. In lakes, the euphotic the ability to increase their Chl b:Chl a ratio since zone is divided into upper warm and less dense chlorophyll b absorbs optimally blue wave- layer, termed epilimnion, and the lower cooler and length). Under high irradiance (top 20 m in oli- denser layer is called the hypolimnion (Fig. 2.1). gotrophic waters), photosynthetic activity of Between these two layers is an intermediate­ layer, phytoplanktons becomes photoinhibited due to the metalimnion, with a sharp decline in water damage of the photosystem core proteins by UV temperature that gives rise to a prominent temper- exposure. Cells counteract these detrimental ature gradient called the ‘thermocline’. If metalim- effects by increasing the amount of photoprotec- nion region lies in the euphotic zone, then tive pigments such as zeaxanthin or diatoxanthin. maximum phytoplankton concentrates here, giv- Thus, the diversity in a water column is depen- ing rise to the zone of ‘chlorophyll maxima’. dent on the vertical distribution of algal popula- A vertical gradient in ocean ecosystem due to tion. On the basis of light variation, vertical differences in salinity or temperature is called distribution can be separated into two different ‘pycnocline’. Thermal stratification in aquatic heads: high light, epilimnion, and low light, ecosystem has important consequences for 2.1 Physical Factors 45 phytoplankton growth and abundance. The upper Windrows on surface warmer region with maximum light intensity is most suitable for plankton growth. Moreover, the nutrient mixing is predominant in this region due to various forms of water motion developed by interactions of air current and other forces. In recent times, excessive fossil fuel burning has enhanced the emission of ‘green house Downwelling Upwelling Downwelling gases’, mainly CO2, that have become a major cause of concern among ecologists. This is Fig. 2.2 Cross-sectional views of adjacent Langmuir cells which rotate in opposite directions, creating regions mainly due to the high solubility of atmospheric of downwelling (where the windrows occur) and upwell- CO2 in oceanic water that results in an increase of ing. Accumulation of foam and positively buoyant algae sea surface temperature (SST). Increase in SST is (green circles) occurs in the downwelling region, whereas responsible for thermal expansion of water that negatively buoyant algae (grey circles) accumulate in the upwelling regions beneath the surface results in dissolution of more land mass along the low-lying coastal areas. Reports from the Sunderbans provide further evidence to this phytoplankton population to a greater extent. The alarming issue where an average of 0.09 °C rise buoyant genera with different floating devices like in sea surface temperature has been observed, presence of vacuoles, flagella, other processes much higher than the global average of (setae, horns, etc.) and with less dense cell sap 0.6 ± 0.2 °C (IPCC 2001). This has resulted in a (with high concentration of K+ ion instead of Na+ sea level rise of 1.9 mm/year in the past 5 years ion) generally overcome the combined force and around Sagar Island that have resulted in extinc- float on the water surface. Different planktons dif- tion of islands like Lohachara, Bedford, fer in their tolerance of turbulence due to structural Kabasgadi and Mathabhanga. Moreover, such and physiological variations (Fogg 1991), directly increase in temperature can alter the partial pres- affecting the growth pattern and bloom formation. sure in CO2 as well as the mixed layer depth that Following are the water motions that significantly causes drastic shifts in phytoplankton communi- affect the ecology of phytoplanktons: ties (Tortell et al. 2002; Kim et al. 2006). Other When the wind speed of adjacent water bodies works have also suggested that similar increases like lakes, etc., is 11 km · h−1 or more, then some in temperature may result in shifts in population elongated wind-driven surface rotations are from diatom dominance to diatom recedence due formed and move spirally according to wind to decrease in nitrate reductase at elevated tem- directions in opposite ways. These are marked by peratures (Lomas and Gilbert 1999). Many work- conspicuous lines of foams called ‘windrows’, ers have also opined that phytoplankton taxa may developed from wave action. This type of wind-­ respond differently to temperature changes by driven surface rotations is called convection cells expanding or contracting their ranges (Hays et al. or Langmuir cells. Adjacent convection cells 2005) or by shifting size and/or community rotate in opposite directions creating alternate composition, although these responses may not upwelling and downwelling regions. Buoyant be consistent between different algal groups and phytoplankton like Microcystis sp. (with cyano- trophic levels (Edwards and Richardson 2004). phycean vesicles) can survive in the region of downwelling. In the region of upwelling, nega- tively buoyant planktons concentrate (Fig. 2.2). 2.1.2 Turbulence When wind blows in a particular direction, it generates the waves on the water body which A combination of forces from rotation of the earth, move from one side to the other (north to south). winds, solar irradiation and the tidal cycle generate But after crushing of the wave on the opposite different types of water motion which affect the shore, the force will return again to the north 46 2 Physicochemical Environment of Aquatic Ecosystem

Fig. 2.3 The convergence of the Oyashio and Kuroshio trated along the boundaries of these eddies. The swirls of currents. When two currents with different temperatures colour visible in the waters southeast of Hokkaido (upper and densities (cold, Arctic water is saltier and denser than left), show different kinds of phytoplankton that are using subtropical waters) collide, they create eddies. Phytop- chlorophyll and other pigments to capture sunlight for lankton growing in the surface waters becomes concen- photosynthesis (Source: www.wikipedia.com) shore with a subsurface return force and act like a called ‘eddies’ or ‘loops’. Besides this, the coastal conveyor belt. Some fraction of this force also water is enriched by nutrients by upwelling water flows to east and west coast. Here also buoyant together with wave action towards the coast or species like Microcystis sp. can survive against away from the coast (Fig. 2.3). This is brought the wind force, but the member about by the combined action of wind and the like Ceratium sp. floats with the help of return Coriolis force of the earth’s rotation. For these force along the subsurface area. reasons, nutrient statuses of coastal waters vary In oceanic environment, sometimes by tre- from place to place, thereby controlling the phy- mendous wind speed along with gravitational toplankton diversity. and other forces, a special type of water current develops. Due to this current, a portion of the entire ecosystem including phytoplanktons, zoo- 2.2 Major Nutrients planktons, fishes and other aquatic organisms is pinched off from the whole system with varying Four major nutrient elements like carbon, nitro- diameters (100–200 km) and forms discrete eco- gen, phosphorus and silica (C, N, P and Si) are systems. These wind-driven water currents are regarded as the major chemical factors that 2.2 Major Nutrients 47 control the phytoplankton productivity in any covariation of nitrate, phosphate and non-calcite type of aquatic ecosystem. Thus, the spatial and contribution to total inorganic C in deep seawa- temporal distributions of these elements play an ter, whereas biologists use a ratio of 106:16:1 important role in plankton dynamics. Other based on Fleming’s analysis of the average factors like uptake, growth, grazing and sedimen- elemental composition of marine organisms tation also interact with the chemical nutrients. (Goldman et al. 1979). The Redfield C:N has its Many authors investigated the relationships main application in oceanography for calcula- between the distribution of phytoplankton and tion of export production and for nutrient-based major nutrients. The distribution of individual productivity calculations as well as in models of species can sometimes be correlated with the ocean productivity. The Redfield N:P ratio of concentration of the major ions. Thus, Harris and 16:1 is often regarded as a standard value to dis- Vollenweider (1982) observed that increase in tinguish between N-limited and P-limited habi- Coscinodiscus (estuarine inhabitant) cell counts tats among the different water bodies especially in English Lakes was due to urban run-offs and with reference to oceans (Behrenfeld and the use of salts on the roads in winter. Light and Falkowski 1997; Tyrell 1999). Accordingly, it nutrients are perhaps the two most important has often been suggested that if N:P < 16, the parameters that regulate the quantity, the distri- system is N-limited, whereas it is P-limited when bution and structure of phytoplankton ­populations N:P > 16. in natural aquatic habitats (Huisman and Weissing However, some works on oceans in periods of 1995; Diehl 2002; Hansen 2002). Unlike light glacial maxima showed that the generally and temperature which tend to have a unidirec- accepted ratio of 16:1 may not hold true and can tional flow in a natural ecosystem, nutrients can reach as high as 25 mol N:mol P (Broecker and be recycled. In natural aquatic habitats, nutrients Henderson 1998). Keeping in view of these find- can be well mixed in a water column with homo- ings, Falkowski (2000) opined that “the upper geneous distribution (mixing condition) or it can bounds of N/P ratios in the dissolved inorganic accumulate in deeper layers (under stratified phase in the oceans is almost certainly a conse- conditions). quence of the intrinsic chemical composition of marine phytoplankton” although no numerical value for this upper boundary was suggested by 2.2.1 Redfield Ratio him. It is remarkable that most oceans around the world have a deep water N:P ratio of approxi- The Redfield ratio has remained as one of the mately 16, although several biochemist and phys- tenets among both biologists and geochemists iologists have questioned the plasticity of the with regard to aquatic biogeochemistry. Named elemental composition of phytoplankton popu- in honour of Alfred Redfield, this concept lations both in field and in laboratory cultures attempts to establish the relationship between (Hecky et al. 1993). Redfield later acknowl- organism composition and water chemistry. edged this fact and opined that the deep water Redfield 1958( ) opined that the elemental com- constancy of N:P ratio is due to a complex position of plankton was ‘uniform in a statistical balance between several biological processes sense’ and that quantitative variations in inor- including nitrogen fixation and denitrification ganic C, N and P content in seawater were (Redfield 1958). ‘almost entirely as a result of the synthesis or decomposition of organic matter’. In this obser- vation the C:N:P content in plankton was 2.2.2 Carbon reported as 106:16:1. With regard to Redfield ratio, biologists and Carbon (C) is the main element that regulates the geochemists interpret it differently. Geochemists functioning of natural waters because of the use a C:N:P stoichiometry 105:15:1 based on the intricate equilibrium that exists between CO2, 48 2 Physicochemical Environment of Aquatic Ecosystem bicarbonate and carbonate that determine the Further experimental studies revealed that an acidity or alkalinity of natural waters. Moreover, excessive increase in pCO2 may result in a shift this is the central element required in maximum towards diatom dominated population. quantity by photosynthetic organisms. The main Phytoplankton abundance in relation to con- source of carbon in water is the dissolved CO2 centration of carbon depends upon the form it from air. It is generally considered that about exists. Some taxa (dinoflagellate Amphidinium

90 % C in seawater exists as bicarbonate, 10 % as carterae and Heterocapsa oceanica) require CO2 carbonate ion and approximately less than 1 % as their inorganic carbon source. Therefore, in remains as unionized CO2. The presence of the marine environment, they depend upon the bicarbonate as the main source of C results in carbon concentrating mechanism (CCM) to get − 2 − slightly alkaline nature of habitat that is about CO2 from HCO3 or CO3 . Almost all members 7.9 for seawater and 6–9 for freshwater respec- of Heterokontophyta are with CCM present tively. In slightly acidic waters (pH ≤ 6), aerial inside the cell and can thrive well exploiting − CO2 dissolved in water to form carbonic acid HCO3 of marine environment.

(H2CO3). For freshwater phytoplankton H2CO3 is available as the pH level of freshwater lakes and 2.2.2.1 CCM in Phytoplanktons rivers remains slightly acidic (pH 6–6.5): Algal cells primarily assimilate environmental

CO2 through C3 pathway (Calvin cycle) using HC23OH 22OC+ O ; 2− RuBisCO. But very few algal forms also assimilate HO22+ 22CO  HCO3 CO2 by following alternative pathways in CO2 But in marine water, where pH ranges from starvation due to the weak binding affinity of 7.5 to 8.4, bicarbonate ions become predominant. RuBisCO as carboxylase. Thus, under these But above pH 10, carbon exists in the form of conditions, algal cells tend to produce phospho- insoluble carbonate. Thus, pH level regulates the glycolate as a by-product during RuBisCO per- carbonate–bicarbonate–CO2/H2CO3 equilibrium formance as oxygenase. The phosphoglycolate in freshwater or marine habitats. Therefore, total thus produced inhibits RuBisCO activity which carbon pool in aquatic ecosystems can be repre- is further alleviated by formation of glycolate by sented as follows: the enzyme phosphoglycolate phosphatase. The glycolate thus produced can be excreted out by TCOC= OH+ CO + HCOC−− +  O2 . 22[][]23 33   algal cells or can be further utilized as a substrate

As natural waters are open systems, addition or during photorespiration. In cyanobacteria CO2 is removal of CO2 is a common feature of these converted to bicarbonate in the wall of the thyla- habitats, especially in marine systems. The solu- koids. They also accumulate bicarbonate ion bility of CO2 is much higher in water than oxygen. using plasma membrane transporter. This bicar-

Over the last century the burning of fossil fuels bonate ion is converted to CO2 by the enzyme for energy generation has resulted in atmospheric carbonic anhydrase (CA) present in carboxy- CO2 increase from 280 to 390 μ atm and a conse- somes. In eukaryotic phytoplankton genera, quential decrease in surface ocean pH by diverse types of CCM are available. Among

0.12 units. The current CO2 emission scenario is them, CA enzymes and membrane transporter are predicted to raise CO2 to 700 μ atm over the important. In some algal genera, pyrenoids also next 100 years, which will decrease seawater pH help in CCM. CCM that is operative in algae − by a further 0.3 units, and raise the sea surface pumps HCO3 from outside the algal cell via the temperature (SST) by 2–6 °C (IPCC 2007). plasma membrane and the chloroplast membrane

Climatic changes due to an increase in CO2 into the algal chloroplast. Within the chloroplast, − concentrations can enhance algal growth (Wolf-­ HCO3 remains unchanged due to the alkaline Gladrow et al. 1999; Hutchins et al. 2007) nature of the stroma. A significant proportion of this − which may also affect by HCO3 is subsequently passed into the thylakoid reducing the calcification rates (Tortell et al. 2002). lumen. The enzyme carbonic anhydrase (CA) 2.2 Major Nutrients 49

− attached to the thylakoid membrane converts in oxygen-rich water, nitrite (NO2 ) ion in moder- − + HCO3 in the lumen to CO2 at a rate hundred times ate oxygen level and ammonium (NH4 ) ion in faster than nonenzymatic conversion of the same: water body with less oxygen with high BOD. Previously it was assumed that nitrogen was the HCOH−+++CO HO 32 2 universal limiting nutrient in marine waters.

This CO2 formed by CA rapidly diffuses away Although planktonic populations are capable of from the thylakoid lumen to the chloroplast assimilating different forms of nitrogen, the more stroma that inhibits oxygenase activity of preferred form is ammonia as it directly gets RuBisCO and promotes carboxylase activity of ­utilized in the biosynthesis of amino acids. In RuBisCO initiating the carbon reduction cycle. cyanobacterial species ammonia is considered to

Some algae have C4-like photosynthesis be a complete inhibitor of nitrogen fixation and where enzyme PEP carboxylase traps inorganic heterocyst formation. In contrast, conversion of carbon. Among these CCM processes, CA is the nitrate to ammonia is a more energy-requiring most abundant among algal genera. CA may be process and requires the enzyme nitrate reduc- secreted externally (Skeletonema costatum) or tase. Thus, to minimize the energy currency, present at periplasmic space (Chlamydomonas ammonia is often preferred by natural phyto- reinhardtii). Some algae excrete protons (H+) plankton populations especially cyanobacteria. across the cell membrane to get CO2 from exter- In natural habitat like oceans and lakes, the nal bicarbonate source, which is on the other dynamics of nitrogen cycling is complex as it hand related to CaCO3 deposition (calcification). involves the interconversion between four dis- Presence of HCl in the intermembrane space solved inorganic forms which can be achieved between chloroplast membrane and chloroplast only by bacterial action in the environment or

ER (endoplasmic reticulum) also converts CO2 within living cells. It is opined that more than − from HCO3 in the group Heterokontophyta that 90 % of oceanic N presents as molecular N2 and allows it to acclimatize in marine environment. the rest in other forms. Thus, it is believed that Organic carbon is also used by phytoplankton the concentrations of these nutrients primarily genera like Chlorella spp., Cocconeis spp., etc. depend on the degradation of biological material Lewitus and Kana (1994) reported about the use synthesized by the biotic components in the sur- of glucose as carbon source by Closterium at face waters of these habitats. The supply of − estuarine region. NO3 in the surface waters from the cooler hypolimnetic nutrient-rich waters depends upon vertical advection and eddy diffusion 2.2.3 Nitrogen across the thermocline. Due to the high rate of nitrification and ubiquitous presence of oxygen Phytoplankton productivity and their diversity in the surface waters of natural lotic systems, − are highly controlled by nitrogen. Presence and NO2 concentrations are much lower as compared − cycling of nitrogen in ocean and lakes is a com- to NO3 concentrations. The higher concentra- plex phenomenon because it exists in four dis- tions can only be expected at deeper waters solved forms of inorganic nitrogen (dissolved N2 beyond the thermocline where oxygen concentra- − − + gas, NO3 , NO2 and NH4 ). Both atmospheric tions are relatively low as compared to that of nitrogen and dissolved inorganic nitrogen (DIN) surface waters. − of water bodies play an important role in control- In oligotrophic waters, NO3 is the domi- ling phytoplankton population. Organic nitrogen nant form of DIN (dissolved inorganic nitro- sources like urea and amino acids are present in gen) because of the high rate of nitrification ocean surfaces. Nitrogen is primarily present in and the even distribution of oxygen, leading to water as dissolved inert nitrogen gas. In ocean, the more oxidized form of nitrogen. In con- almost 95 % of nitrogen occurs as N2. Dissolved trast, for eutrophic waters, the utilization of − inorganic nitrogen includes the nitrate (NO3 ) ion oxygen is more for decomposition processes in 50 2 Physicochemical Environment of Aquatic Ecosystem the deep waters and the sediment layers. This 2.2.4 Phosphorus would allow the build-­up of other reduced forms of nitrogen as well, released primarily Phosphorus concentrations in surface waters are from organic sources. In the temperate region, mainly accounted by geochemical processes that winter mixing brings up nitrogen from the deep occur in a basin adjoining an aquatic habitat. oceans mainly as nitrate. Thus, sources of Unlike N, P remains mostly in bound forms in nitrogen for natural phytoplankton populations clay minerals and different soil components can be (a) surface water DIN, (b) DIN brought (Vollenweider et al. 1998). Thus, while studying up in the surface waters from deep waters P availability, mainly two sources of P are to be through physical processes like upwelling and considered: (1) DIP (dissolved inorganic phos- vertical advection, and (c) localized inputs phate) and DOP (dissolved organic phosphate) brought down by rivers and ground water as and (2) particulate P mainly accounted for bio- well as seasonal precipitation. logical availability. Unlike N, for P the more 3 − In locations like the central subtropical common form of the element is PO4 that is oceans, recycling of surface waters is the main abundant both in biomolecules and in the envi- source of DIN where upwelling events are not ronment. The requirement of phosphorus by phy- prominent due to the existence of a vertical ther- toplankton populations is much smaller as mocline. Moreover, due to the remoteness of compared to carbon, nitrogen and silicon. Thus, these locations, localized coastal inputs are also phytoplankton populations flourish even under not very common. On the other hand, in coastal nanomolar phosphorus concentrations, as can be oceanic waters, upwelling, vertical advection as observed in the Eastern Mediterranean and the well as localized inputs from riverine sources Aegean Sea. cumulatively contribute to nitrogen concentra- DIP is mostly constituted by orthophosphate 3 − tions in these waters. During spring as the water (PO4 ) with much lower concentration of mono- 2 − stratifies, phytoplankton population increases phosphates (HPO4 ) and dihydrogen phosphate and absorbs nitrate that eventually depletes to (H3PO4). Phytoplanktons primarily utilize DIP as nanomolar levels in the surface layers. In marine a phosphorus source, but under limiting condi- environment, cyanobacterial taxa Trichodesmium tions extracellular alkaline phosphatase (AP) erythraeum appear as a surface bloom, turning promotes utilization of phosphate bound to the ocean water red. They fix 2N from dissolved organic substances. Thus, level of AP activity is nitrogen of ocean water. In most temperate oli- an indication of phosphate limitation in aquatic − gotrophic and mesotrophic freshwaters, NO3 is habitats (Rengefors et al. 2003). Under P-limited present in comparatively more amount together conditions, if there is a sudden pulse of soluble with phosphorus. In highly eutrophic waters reactive phosphorus (SRP), planktonic algal cells + − NH4 and NO2 are also present in both surface have the unique ability to make ‘luxury consump- − and subsurface area. If oxygen is present, NO2 tion’ and develop polyphosphate bodies, thereby − is converted to NO3 , whereas in anoxic waters, creating an internal pool of phosphorus to deal + it is reduced to NH4 . In nitrate-enriched water with phosphate shortage. maximum plankton diversity can be recorded. In oligotrophic waters, DIP turnover rate is Green algal genera like spp., very low in winter and accounts for only 10 % of Chlorococcum spp., Kirchneriella spp., total phosphorus (TP). This results in low phyto- Ankistrodesmus spp., etc., generally flourished plankton populations with low growth rates. In in mesotrophic to moderately eutrophic waters. coastal marine waters, DIP builds up in periods of − + But in NO3 - and NH4 -enriched water, phyto- vertical mixing. Under stratification, DIP pool is plankton genera like Spirulina spp. and depleted that results in species-wise drop in phy- Trichodesmium spp. appear in large quantities, toplankton populations. In contrast, in eutrophic sometimes resulting in algal blooms. freshwater, DIP may constitute 100 % of TP due 2.2 Major Nutrients 51 to uncontrolled discharges from point (industrial following the protocols of APHA (1998). The effluents, sewage) and nonpoint sources (runoffs values thus obtained are fitted to a standard curve from agricultural and urban areas) (Capone et al. prepared for determination of nutrient concentra- 2005). The increased concentration of DIP may tions of water samples. be surplus to algal requirements, thereby building The procedures are mentioned below: up in water column, with a slow turnover rate. Nitrate This excess phosphorus provides an opportunity Reagents required: Silver sulphate solution, phe- for cyanobacteria populations to develop and can nol disulphonic acid, liquid ammonia. even reach blooming proportions. Procedure: An aliquot of 50 mL filtered sample water is taken in a conical flask to which an equivalent amount of silver sulphate solution 2.2.5 Silicon is added and heated slightly to precipitate any chloride content that may be present. The Small amounts of silicon are required by all filtrate of sample thus obtained is evaporated planktons for protein synthesis. In freshwater, to dryness in a porcelain basin. The residue soluble reactive silica (SRSi) exists as monosi- obtained is dissolved in 2 mL of phenol licic acid (H4SiO4) that ranges from 0.7 to 7 mg/L disulphonic acid and the contents are diluted, (25–250 μM). In oceanic environment, maximum if necessary. Subsequently, 6 mL of liquid concentrations of SRSi (~3 mg/L) present in ammonia is added to the solution to develop upwelling zones. Utilization of SRSi by diatom a yellow colour. for development leads to reduce the levels of Absorbance is recorded at 410 nm. Concentration SRSi in both freshwater and oceanic habitats. of nitrate was calculated from standard curve, pre- During periods of summer stratification, concen- pared from known nitrate concentration. tration of SRSi may reach below detectable levels Nitrite (<0.1 μM) and becomes a limiting nutrient in Reagents required: EDTA solution, sulphanilic these habitats. acid, α-N-napthylethylene amine, sodium ace- Diatom cell covering or frustule is made up of tate solution. polymerized silica that increases the density of Procedure: Filtered sample water of known vol- diatom cell. Thus, development and abundance ume (50 mL) is taken in a conical flask. To it, of diatoms is dependent on turbulent mixing 2 mL of each of EDTA solution, sulphanilic conditions that render them buoyant in the acid, α N–napthylethylene amine and sodium euphotic zone of the water column. Polymerized acetate solution is added in succession. The silica decomposes slowly (~50 days) which is a reagents are thoroughly mixed and allowed to possible hindrance in rapid recycling of silicon stand for 5 min. A wine red colour developed. in the epilimnion of shallow lakes. Dead diatom Absorbance is recorded at 543 nm. Concentration cells often reach the benthos in intact forms and of nitrite is calculated from standard curve. settle down as sediments. Dissolved silicon is Ammonia available in surface waters of habitat by external Reagents required: Nessler’s reagent. inputs and turnover of the water column during Procedure: 50 mL filtered sample water is taken mixing conditions. In oceans, as the mixing in a conical flask. To it, 2 mL of Nessler’s depth is much greater than lakes, silicon in dia- reagent is added. The reagent is thoroughly tom valves redissolves between the surface and mixed and is allowed to stand for 5 min. A about 1,000 m depth. pale yellow colour developed. Absorbance is Parameters like nitrate, nitrite, ammonia, dis- recorded at 640 nm. Concentration of ammo- solved inorganic nitrogen (DIN), dissolved inor- nia is calculated from standard curve. ganic phosphate (DIP) and dissolved silicate Dissolved Inorganic Phosphate (DIP) (DSi) contents can be measured spectrophoto- Reagents required: Ammonium molybdate solu- metrically within 30 min of sample collection tion, stannous chloride solution. 52 2 Physicochemical Environment of Aquatic Ecosystem

Procedure: An aliquot of 50 mL of filtered sample Therefore, according to Michaelis–Menten water is taken in a clean conical flask and 2 mL model, the nutrient uptake pattern is as follows: of ammonium molybdate is added to it. This is ρρ=+SK/ S subsequently followed by addition of five maxt() drops of stannous chloride solution. A blue colour developed. Absorbance is recorded at 690 nm after 5 min but before 12 min of the 2.2.6.2 Droop Model addition of the last reagent. Concentration of Droop (1983) proposed an equation for establish- phosphate in the sample water is calculated ment of growth rate and internal nutrient quota as from a standard curve. follows: Dissolved Silicate (DSi) µµ= 1–/QQ Reagents required: Ammonium molybdate solu- max ()0 tion, 1(N) hydrochloric acid, oxalic acid. Procedure: 50 mL of filtered sample water is where μ is the gross growth rate or the rate of taken in a clean conical flask and 2 mL of reproduction and μmax is the maximum rate of ammonium molybdate is added to it. This is reproduction. Q is the internal quota of nutrient. subsequently followed by addition of 0.5 mL When Q approaches Q0, then μ is zero. of 1(N) hydrochloric acid. After thorough mix- By this model, we can understand the relation- ing, 2 mL of oxalic acid is added. A bright yel- ship between the growth rate and the nutrient low colour developed. Absorbance is recorded storage within the phytoplankton cell. When phy- at 530 nm. Concentration of dissolved silicate toplankton can store nutrient at higher level, i.e. in the sample water is calculated from a stan- Q is more, then growth rate will also be more. dard curve. When internal storage is exhausted, i.e. Q is ‘zero’, then growth also stops.

2.2.6 Nutrient Uptake Model References During the growth of phytoplanktons, the min- erals are consumed and several models have APHA. (1998). Standard methods for the examination of been proposed to establish the relations between water and wastewater (20th ed.). Washington, DC: APHA-AWWA-WPCF. the rate of nutrient uptake, their storage inside Behrenfeld, M. J., & Falkowski, P. G. (1997). A con- the cell and ultimately the growth pattern of the sumer’s guide to phytoplankton primary productiv- phytoplankton. ity models. Limnology and Oceanography, 42(7), 1479–1491. Bergmann, S., Ihmels, J., & Barkai, N. (2004). Similarities 2.2.6.1 Michaelis–Menten Model and differences in genome-wide expression data of six (1913) organisms. PLoS Biology, 2, E9. This model was based on the kinetics of enzyme Broecker, W. S., & Henderson, G. M. (1998). The function where is considered as the nutrient sequence of events surrounding Termination II and ρ their implications for the cause of glacial-interglacial transport rate ( mole of nutrient per cell per μ CO2 changes. Paleoceanography, 13(4), 352. minute). The term ρmax is the maximum velocity Capone, D. G., et al. (2005). Nitrogen fixation by of the nutrient transport, and S is the substrate Trichodesmium spp. An important source of new nitro- concentration. approaches to , when the gen to the tropical and subtropical North Atlantic ρ ρmax Ocean. Global Biogeochemical Cycles, 19(GB2024), substrate concentration S is high and the internal 17. doi:10.1029/2004GB002331. store of that same nutrient (Q) is low. Kt is the Diehl, S. (2002). Phytoplankton, light, and nutrients in a half saturation constant, which equals to the val- gradient of mixing depths: Theory. Ecology, 83, ues of S where = ½ , and unit of K is same as 386–398. ρ ρmax t Droop, M. R. (1983). 25 years of algal growth kinetics – A −1 that of substrate (μ mol L ). personal view. Botanica Marina, 26, 99–112. References 53

Edwards, M., & Richardson, A. J. (2004). Impact of cli- IPCC. (2007). Summary for policymakers. In: S. Solomon, mate change on marine pelagic phenology and trophic D. Qin, M. Manning, Z. Chen, M. Marquis, K. B. mismatch. Nature, 430, 881–884. Averyt, M. Tignor, & H. L. Miller (Eds.), Climate Falkowski, P. G. (2000). The global carbon cycle: A test of Change 2007: The physical science basis. Contribution of our knowledge of earth as a system. Science, Working Group I to the Fourth Assessment Report of the 290(5490), 291–296. Intergovernmental Panel on Climate Change (996pp.). Falkowski, P. G. (1995). Ironing out what controls pri- Cambridge/New York: Cambridge University Press. mary production in the nutrient rich waters of the open Kim, J. M., Lee, K., Shin, K., Kang, J. H., Lee, H. W., ocean. Global Change Biology, 1, 161–163. Kim, M., Jang, P. G., & Jang, M. C. (2006). The effect

Fogg, G. E. (1991). The phytoplanktonic ways of life. The of seawater CO2 concentration on growth of a natural New Phytologist, 118, 191–232. phytoplankton assemblage in a controlled mesocosm Goericke, R., Olson, R. J., & Shalapyouok, A. (2000). A experiment. Limnology and Oceanography, 51(4), novel niche for Prochlorococcus sp. in low-light sub- 1629–1636. oxic environments in the Arabian Sea and the Eastern Lewitus, A. J., & Kana, T. M. (1994). Responses of estua- Tropical North Pacific. Deep-Sea Research, 47, rine phytoplankton to exogenous glucose: Stimulation 1183–1205. versus inhibition of photosynthesis and respiration. Goldman, J. C., McCarthy, J. J., & Peavey, D. G. (1979). Limnology and Oceanography, 39, 182–189. Growth rate influence on the chemical composition Lomas, M. W., & Gilbert, P. M. (1999). Interactions

of phytoplankton in oceanic waters. Nature, 279, between NH4 and NO3 uptake and assimilation: 212–215. Comparison of diatoms and dinoflagellates at several Hansen, P. J. (2002). Effect of high pH on the growth and growth temperatures. Marine Biology, 133, 541–551. survival of marine phytoplankton: Implications for Michaelis, L., & Menten, M. L. (1913). Die Kinetik der species succession. Aquatic Microbial Ecology, 28, Invertinwirkung. Biochemische Zeitschrift, 49, 279–288. 333–369. Harris, G. P., & Vollenweider, R. A. (1982). Paleolimnological Redfield, A. C. (1958). The biological control of chemical evidence of early in lake Erie. Canadian factors in the environment. American Scientist, 46(3), Journal of Fisheries and Aquatic Sciences, 39, 205–221. 618–626. Rengefors, K., Ruttenberg, K. C., Haupert, C. L., Taylor, Hays, G. C., Richardson, A. J., & Robinson, C. (2005). C., Howes, B. L., & Anderson, D. M. (2003). Climate change and marine plankton. Trends in Experimental investigation of taxon-specific response Ecology & Evolution, 20(6), 337–344. of alkaline phosphatase activity in natural freshwater Hecky, R. E., Campbell, P., & Hendzel, L. L. (1993). The phytoplankton. Limnology and Oceanography, 48(3), stoichiometry of carbon, nitrogen, and phosphorus in 1167–1175. particulate matter of lakes and oceans. Limnology and Reynolds, C. S. (2006). The ecology of phytoplanktons. Oceanography, 38(4), 709–724. Cambridge, UK: Cambridge University Press. Huisman, J., & Weissing, F. J. (1995). Competition for Tortell, P. D., DiTullio, G. R., Sigman, D. M., François,

nutrients and light in a mixed water column: A theo- M., & Morel, M. (2002). CO2 effects on taxonomic retical analysis. The American Naturalist, 146(4), composition and nutrient utilization in an Equatorial 536–564. Pacific phytoplankton assemblage. Marine Ecology Hutchins, D. A., Fu, F. X., Zhang, Y., Warner, M. E., Feng, Progress Series, 236, 37–43. Y., Portune, K., Bernhardt, P. W., & Mulholland, M. R. Tyrell, T. (1999). The relative influences of nitrogen and

(2007). CO2 control of Trichodesmium N2 fixation, phosphorus on oceanic primary production. Nature, photosynthesis, growth rates, and elemental ratios: 400, 525–531. Implications for past, present, and future ocean bio- Vollenweider, R. A., Giovanardi, F., Montanari, G., & geochemistry. Limnology and Oceanography, 52(4), Rinaldi, A. (1998). Characterization of the trophic 1293–1304. conditions of marine coastal waters with special refer- IPCC. (2001). Climate change 2001: The scientific basis. ence to the NW Adriatic Sea: Proposal for a trophic Contribution of Working Group I to the third assess- scale, turbidity and generalized water quality index. ment report of the Intergovernmental Panel on Climate Environmetrics, 9, 329–357. Change (J. T. Houghton, Y. Ding, D. J. Griggs, M. Wolf-Gladrow, D. A., Bijma, J., & Zeebe, R. E. (1999). Noguer, P. J. van der Linden, X. Dai, K. Maskell, & C. Model simulation of the carbonate chemistry in the A. Johnson, Eds., 881pp.). Cambridge/New York: microenvironment of symbiont bearing foraminifera. Cambridge University Press. Marine Chemistry, 64(3), 181–198. Phytoplanktons and Primary Productivity 3

Phytoplanktons have a unique ability to sequester kind of diversity and productivity, mainly three dissolved as well as free carbon dioxide from different mechanisms have been proposed: aquatic ecosystems and convert them as storage 1. Complementary use of resources (comple- product. This phenomenon is regarded as the pri- mentary effect) mary productivity of that ecosystem. As proposed 2. Facilitation between species in highly diverse by Field et al. (1998), about 50 % of global pro- communities (facilitation hypothesis) ductivity through carbon sequestration is carried 3. Higher probability that highly diverse com- out in aquatic ecosystems due to the compara- munities include a highly productive species tively higher solubility of CO2 than O2 in natural (sampling or selection effect) water. Falkowski opined that about 98 % of pro- It is a well-known fact that chlorophyll con- ductivity in oceans is accounted for phytoplank- taining cells can fix CO2 through light-assisted ton populations. Thus, studies on productivity by photosynthetic carbon fixation with the production phytoplankton populations in natural lotic habitat of oxygen (O2). Thus, dissolved oxygen content of estuaries and coasts have gained considerable in aquatic ecosystems is actually a measure of the attention by the plankton biologists. photosynthetic efficiency of phytoplankton popu- The total primary productivity of a population lations. Thus, estimation of DO contents under under optimal conditions of light and tempera- different conditions of light availability can be a ture is regarded as the gross primary productivity possible proxy for estimation of primary produc- (GPP). Although aquatic autotrophs are the only tivity of aquatic ecosystems. Based upon this source of primary productivity, yet this produc- concept, Winkler (1888) proposed a set of proce- tion is consumed by the entire microbial floral dures and formulae for estimation of DO as well and faunal populations of aquatic ecosystems. as productivity of aquatic habitats. Thus, through respiration, often regarded as Initially, sample waters from specific habitat are community respiration rate (CRR), fixed carbon collected in specially designed BOD bottles is utilized as a source of energy which thereby (125 mL/250 mL) below the surface of water at causes a considerable decrease in the total pro- specific depths and are immediately stoppered ductivity of the entire ecosystem known as net below the water surface to avoid any external primary productivity (NPP). Thus, it can be rep- exchanges. The sample thus collected is immedi- resented as ately fixed by addition of manganese sulphate NPPG==PP –,CRR or GPPNPP + CRR (MnSO4) and alkaline potassium iodide (KI). This method of precipitation is done to stop any biologi- The relations between diversity and produc- cal activity by planktonic organisms that may alter tivity in planktonic populations are not always the actual DO content. This bottle is designated as cause and effect relationship. Based upon the initial bottle (IB). The precipitate on dissolution by

R. Pal and A.K. Choudhury, An Introduction to Phytoplanktons: Diversity and Ecology, 55 DOI 10.1007/978-81-322-1838-8_3, © Springer India 2014 56 3 Phytoplanktons and Primary Productivity acids is titrated using sodium thiosulphate with content play a well-orchestrated role in the starch as indicator. The DO content is subsequently overall primary productivity in aquatic ecosys- calculated from the following formula: tems. In oligotrophic waters, due to the clear nature of the water column, light penetration is x ××.,025 81× 000 DO()mg / L = very high that enhances the epilimnion to depths VV−v 21() of up to 60 m, as found in the Aegean Sea, V1 Eastern Mediterranean region. In contrast to the where: general feeling, net primary productivity is not

V1 = total volume of sample taken (125 mL) very high in these oligotrophic waters, although

V2 = volume taken for titration (100 mL) the PAR (photosynthetically active radiations) v = 2 mL of reagents (1 mL MnSO4 + 1 mL alka- availability is quite high in the water column. line KI) This is mainly due to the nutrient status of the x = volume of Na2S2O3 consumed for titration habitat where phosphate concentrations often These processes are repeated for two other reach nanomolar levels. In these limiting condi- sample bottles as well and are designated as tions, phytoplankton species that can acquire light (LB) and dark bottles (DB) respectively. phosphate from organic sources by using extra- LB is incubated in natural light and DB is cellular alkaline phosphatase (AP) constitutes removed from light and kept in complete dark- the phytoplankton population. Thus, the plank- ness for equal periods of time. After incubation, ton population is dominated by nano- and pico- DO contents of both LB and DB are determined planktonic forms with significantly low in the same way as has been mentioned in the chlorophyll a content and low cellular biovol- previous section. The different parameters of umes. This accounts for the relatively low pri- productivity are determined from the following mary productivity of the Eastern Mediterranean formulae: as compared to other eutrophic habitats around the world. ()OLBO–,()DB  ×1 000 GPP =  22 An entirely different scenario is observed for PQ×t eutrophic waters like the Bhagirathi–Hugli estu- ary. Although both light and nutrients are opti- ()OL22BO–,()IB  ×1 000 mally present in these habitats, yet the high SPM NPP =   (suspended particulate matter) load in the water PQ×t column inhibit PAR availability at different depths ()OIBO–,()DB  ×1 000 of the water column. This low availability of PAR CRR =  22 t tends to reduce the photosynthetic efficiency of phytoplankton taxa that culminates in reducing the where: primary productivity of the aquatic ecosystem. GPP = gross primary productivity In eutrophic water, the nutrient-enriched habi- NPP = net primary productivity tat promotes diversification of microbial popula- CRR = community respiration rate tion that includes bacterial population as well.

O2 LB = DO content of the BOD bottle after incu- As can be expected for a food web, bacterial bation in sunlight for 3 h population acts as decomposer. For the purpose

O2 IB = DO content of the BOD bottle immedi- of decomposition, oxygen acts as a major source ately after sampling for oxidation–reduction reactions. The require-

O2 DB = DO content of the BOD bottle after incu- ment of O2 by microbial population for biochem- bation in dark for 3 h ical decomposition of organic matter is regarded PQ = photosynthetic quotient (≡ 1.2) as biochemical oxygen demand (BOD). In a t = time period of incubation (light/dark) (in hours) eutrophic habitat, the high nutrient status pro-

A combination of factors like light, CO2 con- motes survival of diverse life forms which subse- centration, species composition and chlorophyll quently add up to the organic decomposable References 57 matter load on course of their death and decay. BODm()gL/ =−()DO05days DO days Thus, ­eutrophic habitats tend to represent under saturated DO levels with high BOD values with Thus, a combination of different factors is an increase in heterotrophic population. indicative of the overall trophic status as well as For determination of biochemical oxygen the primary productivity of different study areas demand (BOD), the water samples are to be at different ecosystems around the world. kept under optimum conditions of light and temperature without fixation with addition of 1 mL of each of K2HPO4, Na2HPO4, 7H2O, References MgSO4, anhydrous CaCl2 and FeCl2 and 6H2O. After 5 days from the day of sampling, DO Field, C. B., et al. (1998). Primary production of the bio- contents are subsequently measured (Winkler sphere: Integrating terrestrial and oceanic compo- nents. Science, 281, 237–239. 1888). Winkler, L. W. (1888). The determination of dissolved BOD values were determined from the fol- oxygen in water. Berichte der Deutschen Chemischen lowing formula: Gesellschaft, 21, 2843. Community Pattern Analysis 4

Phytoplankton communities in aquatic ecosystems 1. Bottle samplers are the most important component that varies 2. Plankton pumps significantly on the basis of the available environ- 3. Plankton nets mental conditions and trophic status of the habitat. Thus, analysis of the phytoplankton com- munity is highly indicative of the condition of 4.1.1 Bottle Samplers the habitat. Interpretation of plankton data from an ecological perspective depends upon the Sampling of water by bottle sampler is probably sampling strategy and the area of study. Thus, the simplest but well-recommended method to cor- strategies of phytoplankton sampling may vary rectly determine the quantitative composition of depending upon the ecosystem dynamics which the phytoplankton. A water bottle sample generally is different for standing water (lakes and wetlands) contains all but the rarest organisms in the water as compared to lotic habitats (rivers and estuaries). mass sampled and includes the whole size spec- For proper and precise data, collection sampling trum from the largest entities, like diatom colonies cannot remain restricted to a particular station to the smallest single cells. Bottle sample method or site. Several sites/stations should be sampled is the simplest method which is mainly used for the on the same instance to reduce uneven horizontal collection of water samples from any desired depth distribution (patchiness). Accordingly, sample of shallow systems like the nearshore water, estuaries collection for phytoplankton community analysis and mangroves (Fig. 4.1). The sample volume as is an important aspect for correct community well as the depth at which samples are to be col- pattern analysis. From time to time the proce- lected can be easily controlled as per the discretion dures for phytoplankton sample collection have of the plankton biologists. Thus, this simple improved significantly. Thus, in this section, we method can be utilized by both inexperienced stu- will discuss about the more commonly used dents and experienced researchers for collection of phytoplankton sampling methods applicable both phytoplankton samples in a water column. in estuarine and marine habitats. 4.1.1.1 Meyer’s Water Sampler (Fig. 4.2) This type of water sampler consists of ordinary 4.1 Phytoplankton Sampling glass bottles of 2 L capacities which are enclosed with a metal band. This apparatus is weighted In an attempt to determine the cell count of below with a lead weight and there are two strong phytoplankton populations, different methods nylon graduated ropes: one tied to the neck of the have been implemented as follows: bottle and the other to the cork that caps the open

R. Pal and A.K. Choudhury, An Introduction to Phytoplanktons: Diversity and Ecology, 59 DOI 10.1007/978-81-322-1838-8_4, © Springer India 2014 60 4 Community Pattern Analysis

open by a strong pull of the cork rope. Water flows into the bottles and then the cork rope is released to keep the cork closed. Afterwards, using the neck rope, the bottle containing the water sample as well as the biotic variables is taken out of the water columns. This apparatus can only be used up to the depths of 20 m.

4.1.1.2 Friedinger’s Water Sampler This water sampling apparatus is made of Plexiglas or Perspex with two hinged covers. While operation, the sampler is sent down in an open state to the desired depth and can be closed by a drop weight messenger, which falls down inside on sliding rail and closes the covers and makes the bottle water tight. By this way, the water together with the planktonic organisms of the specified Fig. 4.1 Simple graduated bottles for collection of phyto- plankton water samples. The nozzle in front allows the column is trapped inside. observer to squeeze out the measured portions of sample for study 4.1.1.3 Niskin Water Sampler (Fig. 4.3) This is a more sophisticated apparatus that is mainly used for collection of large samples in river systems as well as in oceans. It is employed for taking water samples for phytoplankton enu- meration from subsurface levels to various depths. In this apparatus, several non-metallic, free-flushing bottles are used for general water sample collection. These samplers can be indi- vidually or serially attached on a hydro cable and activated by a messenger, or placed in any kind of multisampling system (like G.O., Sea Bird, Falmouth Scientific, and small multisam- pling system), and activated by remote or pre- programmed command.

4.1.2 Plankton Pumps

Plankton pumps are integrating samplers that pump a continuous stream of water to the surface and the phytoplankton can then be rapidly concen- trated by continuous filtration. Because the pumps can collect continuously as the tube is lowered Fig. 4.2 A simple Meyer’s water sampler through the water column, the samples are inte- grated from the surface to the desired depth. end of the bottle. During sample collection, the This method has its disadvantages like breaking corked up apparatus (closed bottle) is brought down up of colonies or large Chaetoceros setae or long to the desired depth where the stopper is jerked pennate cells like Thalassiothrix spp. 4.1 Phytoplankton Sampling 61

Fig. 4.3 A Go-Flo rosette Niskin water sampler

4.1.3 Plankton Nets

Phytoplankton nets are most popularly used device for sampling. Plankton nets may vary in design that range from basic tow nets (conical or Fig. 4.4 Image of a typical phytoplankton net being with truncated neck) to more complicated device hauled for phytoplankton collection (Image courtesy: fitted apparatus for more specific sample collection www.nearhus.gr) (Fig. 4.4). Nets permit quantitative studies, since the mesh size will select the type of phytoplankton is made of monofilament nylon material as collected. Sampling by nets is highly selective, described earlier and is followed by again a non- depending on the mesh size of the gauze, net filtering portion of khaki cloth. To the latter, a towing speed and the species present in the water. metal net bucket provided with a stopcock is tied Chaetoceros setae, for instance, may form a fine with a strong twine. The determination of the network inside the gauze and very small single volume of water filtered through any plankton net cells, which in other cases pass through the is essential for the estimation of the standing crop. meshes, are retained. On the other hand, nets The volume of water traversed by the net is with very fine meshes (5 or 10 μm) often filter too determined as an approximate value by the formula little water to provide an adequate diatom v = π · r2d, where V is the volume of the water fil- sample. The most useful mesh size for collecting tered by the net, r is the radius at the mouth of the diatoms is 25 μm. Net hauls have the advantage net and d is the distance through which the net is of a simultaneous collection and concentration of towed. The water collected through the different the plankton providing sufficient for species water samplers is either centrifuged or passed identification. A typical plankton net usable in through fine mesh nylon or filter papers to sepa- the surface layers is conical in shape and has the rate the plankton present in it. The smaller the following constituents: a net ring made up of subsample, the fewer number of rare species will stainless steel, wrapped and sealed with polythene be obtained. On the other hand, there is no point tubing, present anteriorly. To this, a non-filtering in concentrating large quantities of a sample rich portion made of a coarse khaki cloth is attached in one or a few species. Concentration by settling, using button and hole system. The filtering portion concentration by centrifugation and concentration 62 4 Community Pattern Analysis

Table 4.1 Showing net mesh sizes and types of planktons of the net aperture and the distance it travelled to be harvested through a flow meter (Eaton et al. 2003). The Size of Approximate basic drawback for this hauling method is that it aperture open area (%) Types of planktons will accommodate both phytoplanktons and 1,024 58 Largest zooplankton and zooplanktons. Thus, phytoplankton biologists often use a zooplankton sampler within a phytoplankton 752 54 Larger zooplankton and ichthyoplankton sampler to reduce the number of zooplanktons 569 50 Large zooplankton and in the sample, although there remains a risk that ichthyoplankton larger-sized phytoplankton may get arrested in 366 46 Large microcrustacea the zooplankton net. Thus, on completion of 239 44 Zooplankton – microcrustacea the hauling process, samples are collected by 158 45 Zooplankton – microcrustacea unscrewing the end fitting and subsequent collec- and most rotifers tion in sample tubes/containers. 76 45 Net phytoplankton – 64 33 macroplankton and 4.1.3.1 Preservation and Fixation 53 – microplankton 2 – of Plankton Samples Generally 2–5 % formalin is used for preserva- tion and fixation of phytoplankton samples. by filtration are the most used methods. Plankton Commercially available formaldehyde is suitably concentration is generally used to overcome the diluted to desired conditions for fixation. Marine damages caused, to certain groups of phytoplank- samples are mostly preserved in 5 % neutralized ton especially the setoid diatoms and dinoflagel- formalin in seawater. Excess seawater is generally lates, by vacuum filtration and centrifugation. removed by filtration for 1–2 days to reduce pre- The simple plankton concentrator, which is quite cipitation of salts from seawater. Eighty percent of gentle in its action, consists of a stiff tube (1.2 cm pure methyl alcohol was also used as an effective dia.: 10 cm height) of Perspex or PVC to the preservative although it often produces shrinkage bottom of which a filter is attached. A filter paper and discolouration. Formalin–acetic acid–alcohol (Whatman No. 42) or membrane filters supported (FAA) is a good preserving and killing agent by monofilament nylon netting which serves as the for cytological studies of planktonic populations filter are glued at the bottom of the tube with the except dinoflagellates. In case of dinoflagellates, aid of ethylene dichloride. While using the tubes it causes loosening of thecal plates that often are dipped slowly into a beaker containing the causes improper fixation of samples. In recent phytoplankton sample. Through the filter water times, Lugol’s iodine solution has popularized as flows slowly upwards into the tube and is removed a preserving agent for phytoplankton especially of with a large pipette. By forcing the tube down- small sizes. The iodine component fixes, preserves wards, the rate of flow through the filter can be and colours the plankton, whereas the other increased. On the basis of mesh size, different component, acetic acid, preserves the flagella and types of planktons can be harvested using different cilia. This acts as an excellent preservative if the plankton nets (Table 4.1). samples are stored in the dark. The phytoplankton net can be hauled horizon- tally, vertically or obliquely on the basis of sampling requirements. A vertical haul is more appropriate 4.2 Biomass Estimation for collection of composite sample of the entire water column, whereas a horizontal haul remains Quantification of phytoplankton biomass is an restricted to surface water composite samples only. important aspect as it works as a possible proxy In case of horizontal haul, the volume of water for primary productivity in aquatic ecosystems sampled can be estimated by determining the area and gives a measure of the amount of organic 4.2 Biomass Estimation 63 material available for zooplankton consumption. the photosynthetic efficiency of the taxa. As an Thus, phytoplankton population can be quantified example, spherical cells of pico- and microplankton under two different heads: may have similar cell counts, but due to their dimensions, microplankton will be more productive Total Biomass as compared to picoplankton in a natural ecosystem. In this measurement, the entire biomass is mea- In case of cyanobacteria, the S/V (surface sured. Chlorophyll a estimation has remained as area–volume) value is an important parameter the most preferred method for this estimation as due to the buoyant nature and hydrographic chlorophyll a acts as the main light-harvesting properties. Thus, although the cell counts may be pigment in all groups of phytoplankton taxa the same for two different cyanobacterial taxa, the recorded as in case of higher plants as well. sinking rate in a water column can be significantly different as evident from Stoke’s law. Moreover, Species and Group Biomass the pigment composition can also be a determining Here, indirect estimates of populations are made factor in the overall productivity of the phyto- on the basis of cellular counts and biovolumes. In plankton population as it is the primary regulator these cases, determination of group-specific of photosynthetic efficiency of algal cells with photopigment contents can be an ideal proxy. regard to carbon sequestration from aquatic The importance of such estimates lies not only in habitats. So a mere calculation of cell counts with assessing the productivity but can also be a inadequate taxonomic identification of phytoplank- possible reference for the determination of the ton taxa may not be a correct representation of diversity of the study area. For phytoplankton the phytoplankton community composition at the community pattern analysis, different parameters species level. Thus, cell counts provide us with have to be considered to determine the contri-­ data on abundance and density of specific taxa in bution of individual phytoplankton taxa to the a population of phytoplankton. entire phytoplankton population. Some of the commonly used parameters are as follows: 4.2.2 Utermohl Sedimentation Method for Cell Counts 4.2.1 Cell Counts Collected phytoplankton samples are preserved Cell count is an important parameter that is to be in Lugol’s solution so as to make them heavier investigated to determine the diversity of phyto- for easier sedimentation. In this method, a glass plankton populations. Earlier plankton biologists tubing of specific length is selected and one end implemented this method as it provided data on is sealed with a large cover slip using waterproof the abundance as well as density of individual adhesive (Fig. 4.5). A specific volume of the pre- taxa in a population. Furthermore, cell count data served samples is poured in these chambers and of single taxa from a mixed population provide allowed to settle overnight. Once the phytoplankton us with the information about the proportion of settles on the floor of the tube, i.e. the cover the population contributed by those taxa. This slip, it is immediately observed under an inverted allows the scientific community to apply different microscope for enumeration of phytoplankton biotic indices to make an assessment of the taxa. This is done by employing an ocular diversity of the population in question. Thus, micrometer by standardization with stage such calculations are indicative about not only micrometer. This measurement technique would the species composition but also of the ecosystem allow the estimation of phytoplankton cell functioning. The drawback for this method is that counts for a specific area of the sedimentation it does not take into consideration the shape and chamber cover slip. Precautions are to be taken volume of the cell which may significantly affect so as to count every representative field of view. 64 4 Community Pattern Analysis

Fig. 4.5 A typical Utermohl sedimentation tube (Image courtesy: www.aquaticresearch.com)

4.2.3 Biovolume Although plankton biologists around the world understood the need to estimate biovolumes, yet no Cellular biovolumes of individual algal taxa as standardized formula or calculations were pro- well as phylogenetic group have long been used as posed. Afterwards, the formulae were mostly an important parameter in determining the species developed at the discretion of the scientists that composition of phytoplankton populations at an were working on different populations (Rott 1981). individual species level. Microalgal biovolume is The problem was especially more pronounced for commonly calculated to assess the relative abun- complex-shaped genera like dinoflagellates, dia- dance (as biomass or carbon) of co-occurring­ toms and desmids. Scientists like Kovala and algae varying in shape and/or size. This is mainly Larrance (1966) used an accurate but complex due to the highly diverse shapes and sizes of algal approach, whereas Edler (1979) applied fairly sim- cells that range from the picoplanktonic prochlo- ple methods that might not have accurately repre- rophytes to that of diatoms which measure more sented cell shape (Hillebrand et al. 1999). than 1 mm in diameter (Reynolds 1984). In natural In recent times, more advanced methods like mixed phytoplankton populations, high numbers electronic particle counting (Boyd and Johnson of small-sized species might actually contribute 1995), flow cytometry (Steen 1990), micro­ only a minor fraction of the overall biomass. Other scopic image analysis (Krambeck et al. 1981; larger-sized species that are much less abundant in Estep et al. 1986) and combined systems numbers might dominate the overall biomass. (Sieracki et al. 1998) have been implemented to Thus, determinations of cell counts are often inad- measure phytoplankton cellular biovolumes. equate as a measure of relative algal biomass However, different drawbacks and expensive (Smayda 1978; Wetzel and Likens 1991). equipments do not allow us to recommend a sin- Biovolumes are also calculated for conversion of gle most accurate technique for the measurement cell counts to carbon equivalents so as to estimate of cellular biovolumes. The flow cytometry the fluxes of organic carbon in aquatic communi- method is limited to the level of easily discern- ties. Phytoplankton carbon calculation from bio- ible groups (e.g. algae of different classes or pig- volume eliminates the error due to detrital ment composition). This method often gives particulate matter contained in particulate organic erroneous results for benthic samples that are carbon (Montagnes et al. 1994). often cohesive and ­contaminated with sediment 4.2 Biomass Estimation 65

Table 4.2 Geometric shapes and equations for the calculation of biovolume (Hillebrand et al. 1999) Shape Equation 1. Sphere V = 4/3 π ⋅ r3 = π/6 ⋅ d3 2. Prolate spheroid V = π/6 ⋅ d2 ⋅ h 3. Ellipsoid V = π/6 a ⋅ b ⋅ h 4. Cylinder V = π ⋅ r2 ⋅ h = π/4 ⋅ d2 ⋅ h 5. Cylinder + 2 half spheres V = π ⋅ r2 ⋅ h + 4/3 ⋅ π ⋅ r2 = π ⋅ d2 ⋅ (h/4 + d/6) 6. Cylinder + 2 cones V = π/4 ⋅ d2 ⋅ h + 2 ⋅ π/12 ⋅ d2 ⋅ z = π/4 ⋅ d2 ⋅ (h + z/2) 7. Cones V = 1/3 ⋅ π ⋅ r2 ⋅ z = π/12 ⋅ d2 ⋅ z 8. Double cone V = 2/3 ⋅ π ⋅ r2 ⋅ z = π/6 ⋅ d2 ⋅ z 9. Cone + half sphere V = 1/3 ⋅ π ⋅ r2 ⋅ z + ½ ⋅ 4/3 π ⋅ r3 = π/12 ⋅ d2 ⋅ (z + d) 10. Rectangular box V = a ⋅ b ⋅ c 11. Prism on elliptic base V = π/4 a ⋅ b ⋅ c 12. Elliptic base with transapical constrictions Same as above, where means of c are considered 13. Prism on parallelogram base V = ½ a ⋅ b ⋅ c 14. Half-elliptic prism V = ½ ⋅ ¼ ⋅ π ⋅ a ⋅ 2b ⋅ c = π/4 a ⋅ b ⋅ c 15. Sickle-shaped prism V = ¼ ⋅ π ⋅ c ⋅ (a ⋅ b − a2 ⋅ b2) 16. Monoraphidioid 2 2 ()2bd−+ab⋅π ()2 −+da Vd=⋅/ 4  +   12 2  17. Cymbelloid V = 4/6 π ⋅ b2 ⋅ a ⋅ β/360 18. Prism on triangle base V = ½ ⋅ l ⋅ m ⋅ h 19. Pyramid V = 1/3 ⋅ l1 ⋅ l2 ⋅ h 20. Elliptic prism with transapical inflations V = π/4 ⋅ c ⋅ (a ⋅ b + i2) where V volume, r radius, d diameter, h height, a apical axis (length), b transapical axis (width), c pervalvar axis (height), z height of cone, l length of one side (l1 and l2, if sides are unequal), m height of a triangle, β angle between the two transapical sides and i diameter of inflation particles. Computer-­mediated image analysis phylogenetic groups was prepared and each technique is more applicable for bacterial sys- taxa was given a specific shape. Based upon tems (Psenner 1993) where taxonomic resolution that, for each shape, specific formulae for mea- is inadequate. Moreover, for proper measure- suring the biovolume (V) were recommended. ments, these methods are time consuming and are In recent times, this set of formulae has been related to direct microscopic measurements (cf. accepted as the more authenticated method for Krambeck et al. 1981). More recently, Sieracki measurements of cell biovolumes around the et al. (1998) proposed a new flow-through ana- world (Table 4.2). lysing system for plankton samples, but this sys- tem sacrifices taxonomic information as well. Hillebrand et al. (1999) worked out and pro- 4.2.4 Chlorophyll and posed a more conclusive method for the deter- Photopigments mination of biovolumes on the basis of geometric shapes of algal cells. A standard set Phytoplankton is perhaps the most important of 20 geometric shapes was developed on the component of pelagic ecosystem since it traps basis of the morphology of different microalgal almost all the energy used by the ecosystem. cells. This method proposed that cell biovol- Consequently, phytoplankton biomass esti- umes should be calculated on an individual cell mates with respect to algal carbon content are basis even for coenobial, colonial and filamen- highly important. Unfortunately such estima- tous forms. In this work, a comprehensive list tions are often extremely difficult due to the size of individual algal taxa belonging to different variations of phytoplankton taxa. Accordingly, 66 4 Community Pattern Analysis such estimates are made from other parameters, different solvents, and absorbance is read at which require many calculations and/or the use wavelengths from 450 to 700 nm. Different for- of imprecise conversion factors (Geider et al. mulae have been developed to estimate different 1997). Measurements of photopigment concen- fractions of chlorophyll from natural phytoplank- trations are widely used to estimate algal bio- ton samples. Some of the more well-known mass (Smayda 1978). Chlorophyll a is common methods are given below. to all photosynthetic organisms. Furthermore, it is the most abundant photosynthetic pigment 4.2.4.1 Formulae of Chlorophyll and it is relatively easy and rapid to quantify. Estimation (90 % Acetone Consequently, its concentration is used exten- Extract) sively for estimating phytoplankton biomass. Chlorophyll a A variety of techniques are at present avail-  −3  able, offering varying degrees of accuracy. Chlma  gm  =−()− −−11 However, the ratio of chlorophyll a to cell car- 11..85 DD663−665 1540647 .08 Dv630 lV bon depends on external and internal factors, such as phytoplankton taxonomic composition, D = absorbance at wavelength indicated by sub- cellular physiological conditions, temperature, script, after correction by the cell-to-cell blank nutrient concentrations and light intensity and subtraction of the cell-to-cell blank cor- (Reynolds 1984). rected absorbance at 750 nm The relationship between chlorophyll a and v = volume of acetone phytoplankton biovolume has been widely stud- l = cell (cuvette) length ied (Kalchev et al. 1996), where both linear and V = volume of filtered water allometric relationships have been found between these parameters (Tolstoy 1977; Desortová Chlorophyll b 1981). The spatiotemporal variations among  −3  chlorophyll and biovolume mainly depend upon Chlmb  gm  =−()+− −−11 the taxonomic composition of phytoplankton 54..32DD663−665 1032647 .66 Dv630 lV populations, like the life form of the predominant group and their average cell size. Influence of D = absorbance at wavelength indicated by sub- environmental factors like changes in available script, after correction by the cell-to-cell blank light intensities, nutrient load or species predom- and subtraction of the cell-to-cell blank cor- inance is some of the other parameters that can rected absorbance at 750 nm influence the ‘chlorophyll maxima’ in natural v = volume of acetone aquatic ecosystems. l = cell (cuvette) length Earlier, the fluorometric method was mainly V = volume of filtered water used for the quantitative analysis of chlorophyll a and phaeopigments. However, the presence of Chlorophyll c chlorophyll b and/or chlorophyll c produced  −3  erroneous results. Chlorophyll b generally not Chlmc  gm  =−()−+ −−11 abundant in surface water can be as high as 16..77DD663−665 62647 45. 2 Dv630 lV 0.5 times of chlorophyll a concentration in the region of deep chlorophyll maxima, causing D = absorbance at wavelength indicated by sub- underestimations of the chlorophyll a concentra- script, after correction by the cell-to-cell blank tion and overestimations of the phaeopigment and subtraction of the cell-to-cell blank cor- concentrations. Divinyl chlorophyll also accounted rected absorbance at 750 nm for such incorrect estimations. v = volume of acetone Thus, natural water samples are collected, fil- l = cell (cuvette) length tered through specific filters and extracted using V = volume of filtered water 4.2 Biomass Estimation 67

Fig. 4.6 Selected chemotaxonomic biomarker carotenoids

As mentioned before, the interference of ‘chemotaxonomy’ where class-specific photosyn- phaeopigments and other fractions of chloro- thetic accessory pigments (PAPs) are estimated phyll often produced incorrect estimates. Thus, through HPLC, e.g. chlorophyll b (chlorophytes), in recent times a different approach is imple- fucoxanthin plus chlorophyll c (chrysophytes, mented where after estimation of chlorophyll a, diatoms and relatives), gyroxanthin-diester­ the entire fraction is acidified to convert all chlo- (Florida red tide, Karenia brevis), peridinin (dino- rophyll to phaeopigments. Subsequent fluoro- flagellates) and the divinyl chlorophyllsa /b (pro- metric readings are taken for phaeopigments and chlorophytes). Additionally, there are many both values are taken for calculations by apply- taxon-specific (or abundant, ‘zea’) photoprotector- ing a correction factor for phaeopigment inter- ant pigments (PPPs), such as zeaxanthin (‘zea’, cya- ference (Holm-­Hansen and Riemann 1978; nobacteria), myxoxanthophyll (cyanobacteria), Herbland et al. 1985). keto-carotenoids (echinenone, canthaxanthin, cya- In recent times, pigment analyses have not nobacteria), lutein (chlorophytes) and alloxanthin only remained restricted to chlorophyll but other (cryptophytes), that are estimated as well (Fig. 4.6). pigments have also been analysed as well as a Pigment-based chemotaxonomy has gained proxy for biomass estimates with respect to spe- increasing favour for rapid spatiotemporal inves- cies composition. This method is regarded as tigations of microalgal communities, such as 68 4 Community Pattern Analysis phytoplankton distributions in lakes and oceans. Shannon to quantify the entropy (uncertainty or It is possible to assign a numerical relationship information content) in strings of text. The idea is between the marker pigment and chlorophyll a, that the more different letters there are, and the the biomass marker. The percent composition of more equal their proportional abundances in the the community is calculated by the relative abun- string of interest, the more difficult it is to cor- dance of the taxon-specific chlorophylla . rectly predict which letter will be the next one Pigment-based chemotaxonomy can be in the string. The Shannon entropy quantifies extremely advantageous and cost-effective in the uncertainty (entropy or degree of surprise) large-scale ecosystem research and monitoring associated with this prediction. It is calculated programs. Recently, uses of CHEMTAX soft- as follows: ware are in practice, where HPLC data for R class-­specific photopigments helps in determin- ′ Hp=−∑ iilog p ing the quantitative species composition of the i =1 phytoplankton population. Although it is a Here, pi can be represented as ni/N – where ni well-­established process, it cannot possibly be is the number of individuals of ith species in a a replacement for taxonomic identification and population and N is the total number of subsequent biovolume or cell count estimates. ­individuals of all species recorded in the popula-

The drawback of the chemotaxonomy method tion. In ecology, pi is often the proportion of is that it deals only a class or division level and individuals belonging to the ith species in the cannot be applied at a taxon-specific level. data set of interest. Then the Shannon entropy Thus, diversity assessment by application of quantifies the uncertainty in predicting the spe- biotic indices cannot be done in this type of cies identity of an individual that is taken at ran- community composition study. dom from the data set. The base of the logarithm used when calculat- ing the Shannon entropy can be chosen freely. 4.3 Species Diversity Index Shannon himself discussed logarithm bases 2, 10 and e each of which corresponds to a different mea- Species diversity index is a statistical measure surement units, which have been called binary dig- that indicates the abundance of species in a par- its (bits), decimal digits (decits) and natural digits ticular population. This clearly suggests that the (nats) for the bases 2, 10 and e, respectively. population with more number of taxa will show a Simpson index is used to measure the degree higher diversity index as compared to another of concentration when individuals are classified population where the number of individuals for into types. The measure equals the probability each species may be same but the total number of that two entities taken at random from the data set taxa or species is less as compared to the previous of interest represent the same type: population of similar organisms. The commonly R used diversity indices are simple transformations 2 λ = ∑pi of the effective number of species or taxa, but i =1 each diversity index can also be interpreted in its This also equals the weighted arithmetic mean own right as a measure corresponding to some of the proportional abundances pi of the types of real phenomenon. interest, with the proportional abundances them- The Shannon–Weiner’s Index is one of the more selves being used as the weights. Proportional commonly used diversity indices in ecological abundances are by definition constrained to val- literature, where it is also known as the Shannon ues between zero and unity, but their weighted diversity index, the Shannon–Wiener index, the arithmetic mean, and hence λ, can never be Shannon–Weaver index, the Shannon entropy, etc. smaller than 1/S, which is reached when all types The measure was originally proposed by Claude are equally abundant. 4.3 Species Diversity Index 69

Since mean proportional abundance of the ascertaining that the habitat is more suitable for types increases with decreasing number of types proliferation of selected taxa that have favour- and increasing abundance of the most abundant able environmental conditions. Thus, under type, λ obtains small values in data sets of high blooming conditions, species evenness shows diversity and large values in data sets of low minimum value as in that period a single species diversity. The other popular indices have been the dominates with almost negligible representa- inverse Simpson index (1/λ) and the Gini– tives of other taxon. Simpson index (1–λ). Both of these have also been called the Simpson index in the ecological literature, so care is needed to avoid accidentally 4.3.2 Species Richness comparing the different indices as if they were the same. Species richness is a measure of the number of different species represented in a set or collec- tion of individuals in a natural population. 4.3.1 Species Evenness Species richness is simply a count of species, and it does not take into account the abundance Species evenness refers to how close in numbers of the species or their relative abundance and each species in an environment is. Mathematically distributions. The purpose of such estimation it is defined as a diversity index, a measure of can be different on the basis of the quantifying biodiversity which quantifies how equal the com- individuals that are taken into consideration. munity is numerically. The evenness of a com- Thus, for correct estimation of species rich- munity can be represented by Pielou’s evenness ness, identification of individuals is important. index: Habitat heterogeneity is another determining factor in calculation of species richness. If H ′ J ′ = samples are collected from different habitats, H ′ max the build-up in the number of new species in each habitat will be higher as compared to where H′ is the number derived from the Shannon samples collected from the same habitats. diversity index and H′max is the maximum value Thus, species diversity and richness are a of H′, equal to closely knit phenomenon where although they are mutually interdependent, species diversity S 11 index is a more authenticated approach as it H max =−∑ ln = ln S i =1 SS takes into consideration the number of individ- J′ is constrained between 0 and 1. The lesser the uals of each species as well. variation in communities between the species, Thus, here, the species diversity index (H′) the higher J′ is. Thus, species evenness provides is – 2.091923, species evenness (J′) is 0.908, us with an opportunity to determine the contri- and species richness is 10 calculated on the bution of individual taxon to the total popula- basis of Table 4.3. tion. High species evenness suggests that every In recent times, plankton studies have not taxon in the population has almost a similar remained restricted to morphometric analysis only, number of individual representatives in the pop- but molecular phylogenetic analyses have gained ulation. This also emphasizes that the habitat considerable impetus as well. Most of the present allows diversification of different populations works have focussed on as they are with different requirements and life strategies. not very easily detectable under the light micro- On the contrary, low species evenness is indica- scope. Furthermore, it has been opined by different tive of the fact that the contribution of individual groups of scientists that due to their low surface– taxon to the total population is variable, thereby volume ratio, they have the ability to remain 70 4 Community Pattern Analysis

Table 4.3 Calculation for biotic indices biotic and abiotic variables can be well represented No. of in a single graphical representation. James and Species individuals (ni) pi (ni/N) pi lnpi McCulloch (1990) also opined that ‘It is no longer A 123 0.134 −0.26933 possible to gain a full understanding of Ecology and B 46 0.049 −0.14778 Systematics without some knowledge of multivari- C 72 0.078 −0.198982 ate analysis’. Thus, here we make an attempt to dis- D 22 0.024 −0.089513 cuss some of the more commonly used multivariate E 89 0.097 −0.226305 procedures that are presently being employed for F 182 0.198 −0.32066 phytoplankton study, which includes data prepara- G 111 0.121 −0.255547 tion as follows: H 56 0.061 −0.170609 I 19 0.021 −0.081127 J 201 0.218 −0.33207 Total 921 1.001 −2.091923 4.4.1 Preparation of Data Sets Species evenness: H′/LnS = −2.091923/Ln (10) = −2.091923/ 2.302585 = 0.908 The initial multivariate data set consists of a table of objects in rows and measured variables for those objects in columns. It is essential to buoyant, thereby showing greater photosynthetic correctly identify as to what are the objects and efficiency. Furthermore, results from different parts variables respectively. This distinction among of the world have shown that in oligotrophic waters, objects and variables is essential to correctly the majority of planktonic population is accounted implement multivariate analysis because pro- by picoeukaryotes. Thus, community composition cedures that analyse relationships among study on the basis of molecular studies is a well- objects or among variables are different. It is practiced method. Many of the works available assumed that objects are independent, whereas have focussed on 18S rRNA gene for community variables are interconnected or interrelated analysis due to their highly conserved nature among each other during representation in a through evolutionary timescale with works from multivariate analysis. the equatorial Pacific Ocean (Staay et al. 2001), the Antarctic Polar Front (Lo’pez-Garcı’a et al. 2001), the Mediterranean and Scotia Sea as well as the 4.4.2 Data Transformations North (Dı’ez et al. 2001). The use of target gene sequences for molecular analysis has In multivariate data tables, measured variables can not remained restricted to 18S rRNA genes only, be binary, quantitative, qualitative, rank ordered, but other sequences like ITS and rbcL have been classes, frequencies or even a mixture of those exploited as well. types. If variables are measured in different ranges, then units of measurements (e.g. environ- mental parameters) of the variables have to be 4.4 Multivariate Analysis transformed in an appropriate format before ­performing further analyses. These ­transformations Several studies over the years have conclusively will help in developing ‘dummy’ numerical values established that planktonic populations in natural for original values of qualitative variables that are habitat are not dependent on a single parameter, but subsequently utilized in multivariate procedures. a combination of biotic and abiotic variables regu- Data transformations can be categorized into two late the spatiotemporal dynamics of phytoplank- main types: tons. Thus, a multivariate statistical approach should • Standardization is a method mainly used to be taken for this, where interrelationships among minimize the effects of magnitude difference 4.4 Multivariate Analysis 71

with respect to scales or units. This type of sets, and the possible explanation for those transformation is mainly applied for envi- patterns in the data set depends solely on the ronmental parameters where range and expertise and discretion of the researcher who is scale of measurement are often different implementing these methods. Thus, care should from each other. A common procedure is to be taken in regard to data transformation methods apply the z-score transformation to the val- as well as the selection of the specific multivariate ues of each variable. For each variable, it procedure that the researcher wishes to implement consists of: for desired results. 1. Computing the difference between the original value and the mean of the variable 4.4.3.1 Cluster Analysis and (i.e. centring) Association Coefficients 2. Dividing this difference by the standard The basic purpose of cluster analysis is to group deviation of the variable the objects on the basis of dissimilarities in a • Normalization transformations are mainly group of variables. In other words, cluster analy- implemented to correct the distribution shapes sis maximizes between group variations and min- of certain variables, which depart from normal imizes within group variations, so as to reduce distribution. This would help to obtain more the dimensionality of the data sets only to a few homogenous variances for variables that groups or rows (James and McCulloch 1990; would allow better application of multivariate Legendre and Legendre 1998). Cluster analysis is procedures. Different mathematical transfor- mainly used for microbial diversity study or to mations can be used to normalize the x values determine the differences between DNA or amino of a variable like: acid sequences in different group of samples. The arcsin (√x) transformation can be applied Cluster analysis of a data table is mainly car- to percentages or proportions. ried out in two parts. Firstly, a specific associa- Log(x + c) to variables departing strongly from tion coefficient is to be found on the basis of a normal distribution. which similarity or dissimilarity matrix is to be √(x + c) where c is a constant generally added developed. Secondly, the given data set is anal- to avoid mathematically undefined computations. ysed accordingly and the calculated matrix is The c constant is generally chosen so that the represented either as a horizontal tree (hierarchi- smallest nonzero value is obtained. The constant cal clustering) or as a distinct group of objects should also be of the same order of magnitude as (k-means clustering). The choice of appropriate the variable (Legendre and Legendre 1998). and ecologically meaningful association coeffi- To make community composition (either pres- cients is particularly important because it directly ence–absence or abundance) data containing affects the values that are subsequently used for many zeros suitable for analysis by linear meth- the categorization of objects. ods, Hellinger transformation is the preferred method to yield good results of multivariate anal- 4.4.3.2 Principal Component ysis (Legendre and Gallagher 2001). These trans- Analysis (PCA) formations are important where samplings are PCA has been applied to numerous phenotypic done more randomly with no specific pattern of and genotypic (e.g. fingerprinting patterns) data sample collection and data mining. sets, and it is one of the most popular exploratory analyses. The PCA procedure basically calculates new synthetic variables (principal components), 4.4.3 Exploratory Analysis which are linear combinations of the original ­variables. The aim is to represent the objects Multivariate exploratory methods are imple- (rows) and variables (columns) of the data set in a mented to understand the specific patterns in data new system of coordinates (generally on two or 72 4 Community Pattern Analysis three axes or dimensions) where the maximum and the original variables are useful to identify amount of variation from the original data set can which variables mainly contribute to the varia- be depicted. PCA plots can be developed either on tion in the data set, and this is referred to as the the basis of variance–covariance matrix or on a loading of the variables on a given axis. correlation matrix. The first approach is followed when the same units or data types are used 4.4.3.3 Correspondence Analysis (CA) (e.g. abundance of different species). The aim is CA has generally been used in microbial ecol- then to preserve and to represent the relative posi- ogy to determine whether patterns in microbial tions of the objects and the magnitude of variation OTU distribution could reflect differentiation in between variables in the reduced space. PCA on a community composition as a function of sea- correlation matrix is rather used when variables sons, geographical origin or habitat structure are measured in different units or scales (e.g. dif- (Olapade et al. 2005; Edwards et al. 2006; ferent environmental parameters). The two Kent et al. 2007). The overall aim of the method approaches lead to different principal components is to compare the correspondence between sam- and different distances between projected objects ples and species from a table of counted data (or in the ordination; hence, the interpretation of the any dimensionally homogenous table) and to relationships must be made with care. Indeed, for represent it in a reduced ordination space (Hill correlation matrices, variables are first standard- 1974). Noticeably, instead of maximizing the ized (i.e. they become independent of their origi- amount of variance explained by the ordination, nal scales), and so distances between objects are CA maximizes the correspondence between also independent from the scales of the original species scores and sample scores. The technique variables. All variables thus contribute to the is popular among ecologists because CA is par- same extent to the ordination of objects, regard- ticularly recommended when species display less of their original variance. PCA results are unimodal relationships with environmental generally displayed as a biplot (Jolicoeur and gradients. Mosimann 1960), where the axes correspond to the new system of coordinates, and both samples 4.4.3.4 Nonmetric Multidimensional (dots) and taxa (arrows) are represented. The Scaling (NMDS) direction of a species arrow indicates the greatest NMDS is generally efficient at identifying under- change in abundance, whereas its length may be lying gradients and at representing relationships related to a rate of change. Depending on whether based on various types of distance measures. The a distance or a correlation biplot is chosen, differ- NMDS algorithm ranks distances between ent interpretations can be made from the ordina- objects and uses these ranks to map the objects tion diagram. The interpretation of the nonlinearly onto a simplified, two-dimensional relationships between samples and species differs ordination space, so as to preserve their ranked and is directly affected by the scaling chosen. differences, and not the original distances PCA is successful when most of the variance (Shepard 1966). In NMDS ordination, the prox- is accounted for by the largest (generally the first imity between objects corresponds to their simi- two or three) components. The amount of vari- larity, but the ordination distances do not ance accounted for by each principal component correspond to the original distances among is given by its ‘eigenvalue’. The cumulative per- objects. Because NMDS preserves the order of centage of variance accounted for by the largest objects, NMDS ordination axes can be freely components indicates how much proportion of rescaled, rotated or inverted, as needed for a better the total variance is depicted by the actual ordina- visualization or interpretation. NMDS is more tion. High absolute correlation values between computer intensive than eigenanalyses such as the synthetic variables (principal components) PCoA, PCA or CA. References 73

pandora’s box? Annual Review of Ecology and References Systematics, 21, 129–166. Jolicoeur, P., & Mosimann, J. E. (1960). Size and shape Boyd, C. M., & Johnson, G. W. (1995). Precision of size variation in the painted turtle. Growth, 24, 339–354. determination of resistive electronic particle counters. Kalchev, R. K., Beshkova, M. B., Boumbarova, C. S., Journal of Plankton Research, 17, 41–58. Tsvetkova, R. L., & Sais, D. (1996). Some allometric Desortova, B. (1981). Relationships between chlorophyll- and non-allometric relationships between chloro- ­a concentration and phytoplankton biomass in several phyll-­a and abundance variables of phytoplankton. reservoirs in Czechoslovakia. Internationale Revue Hydrobiologia, 341, 235–245. der gesamten Hydrobiologie und Hydrographie, 66, Kent, A. D., Yannarell, A. C., Rusak, J. A., Triplett, E. W., & 153–169. McMahon, K. D. (2007). Synchrony in aquatic micro- Diez, B., Pedros-Alio, C., & Massana, R. (2001). Genetic bial community dynamics. ISME Journal, 1, 38–47. diversity of eukaryotic picoplankton in different oce- Kovala, P. E., & Larrance, J. D. (1966). Computation of anic regions by small-subunit rRNA gene cloning and phytoplankton cell numbers, cell volume, cell surface sequencing. Applied and Environmental Microbiology, and plasma volume per liter from microscopical counts 67, 2932–2941. (Special Report 38; 21 +Appendix). Seattle: Department Eaton, D. R., Brown, J., Addison, J. T., Milligan, S. P., & of Oceanography, University of Washington. Fernand, L. J. (2003). Edible crab (Cancer pagurus) Krambeck, C., Krambeck, H. J., & Overbeck, J. (1981). larvae surveys off the east coast of England; implica- Microcomputer-assisted biomass determination of tions for stock structure. Fisheries Research, 65, plankton bacteria on scanning electron micro- 191–199. graphs. Applied and Environmental Microbiology, Edler, L. (Ed.). (1979). Phytoplankton and chlorophyll: 42, 142–149. Recommendations on methods for marine biological Legendre, P., & Gallagher, E. D. (2001). Ecologically studies in the Baltic Sea (Baltic Marine Biologists meaningful transformations for ordination of species Publication No. 5, p. 38). Uppsala, Sweden. data. Oecologia, 129, 271–280. Edwards, I. P., Burgmann, H., Miniaci, C., & Zeyer, J. Legendre, P., & Legendre, L. F. J. (1998). Numerical ecol- (2006). Variation in microbial community composi- ogy (pp. 1–870). Amsterdam: Elsevier. tion and culturability in the rhizosphere of Lopez-Garcia, P., Moreira, D., & Rodriguez-Valera, F. Leucanthemopsis alpina (L) heywood and adjacent (2001). Diversity of free-living prokaryotes from a bare soil along an alpine chronosequence. Microbial deep-sea site at the Antarctic Polar Front. FEMS Ecology, 52, 679–692. Microbiology Ecology, 36, 193–202. Estep, K. W., MacIntyre, F., Hjorleifsson, E., & Sieburth, Montagnes, D. J. S., Berges, J. A., Harrison, P. J., & J. M. (1986). MacImage: A user friendly image-­ Taylor, F. J. R. (1994). Estimating carbon, nitrogen, analysis system for the accurate mensuration of marine protein, and chlorophyll a from volume in marine organisms. Marine Ecology Progress Series, 33, phytoplankton. Limnology and Oceanography, 39, 243–253. 1044–1060. Geider, R. J., MacIntyre, H. L., & Kana, T. M. (1997). Olapade, O. A., Gao, X., & Leff, L. G. (2005). Abundance Dynamic model of phytoplankton growth and accli- of three bacterial populations in selected streams. mation: Responses of the balanced growth rate and the Microbial Ecology, 49, 461–467. chlorophyll a: Carbon ratio to light, nutrient-limitation Psenner, R. (1993). Determination of size and morphol- and temperature. Marine Ecology Progress Series, ogy of aquatic bacteria by automated image analysis. 148, 187–200. In P. F. Kemp, B. F. Sherr, E. B. Sherr, & J. J. Cole Herbland, A., Bouteiller, A. L., & Raimbault, P. (1985). (Eds.), Handbook of methods in aquatic microbial Size structure of phytoplankton biomass in the equato- ecology (pp. 339–345). Boca Raton: Lewis Publishers. rial Atlantic Ocean. Deep Sea Research Part A. Reynolds, C. S. (1984). The ecology of freshwater phyto- Oceanographic Research Papers, 32(7), 819–836. plankton (pp. 1–396). Cambridge: Cambridge Hill, M. O. (1974). Correspondence analysis: A University Press. neglected multivariate method. Applied Statistics, 23, Rott, E. (1981). Some results from phytoplankton count- 340–354. ing intercalibrations. Schweizerische Zeitschrift für Hillebrand, H., Dürselen, C. D., Kirschtel, D., Pollingher, Hydrologie, 43, 34–62. U., & Zohary, T. (1999). Biovolume calculation for Shepard, R. N. (1966). Metric structures in ordinal data. pelagic and benthic microalgae. Journal of Phycology, Journal of Mathematical Psychology, 3, 287–315. 35(2), 403–424. Sieracki, C. K., Sieracki, M. E., & Yentsch, C. M. (1998). Holm-Hansen, O., & Riemann, B. (1978). Chlorophyll a An imaging in-flow system for automated analysis for determination: Improvements in methodology. Oikos, marine microplankton. Marine Ecology Progress 30(3), 438–447. Series, 168, 285–296. James, F. C., & McCulloch, C. E. (1990). Multivariate Smayda, T. J. (1978). From phytoplankton to biomass. In analysis in ecology and systematics: Panacea or A. Sournia (Ed.), Phytoplankton manual (Monographs 74 4 Community Pattern Analysis

on oceanographic methodology 6; pp. 273–279). Flow cytometry and sorting (2nd ed., pp. 11–25). New Paris: UNESCO. York: Wiley-Liss. Staay, S. Y. M., Wacher, R. D., & Vault, D. (2001). Tolstoy, A. (1977). Chlorophyll-a as a measure of phyto- 18srDNA sequences from picoplankton reveal unsus- plankton biomass. Acta Universitatis Uppsaliensis, pected eukaryotic diversity. Nature, 409, 607–609. 416, 1–30. Steen, H. B. (1990). Characters of flow cytometers. In M. Wetzel, R. G., & Likens, G. E. (1991). Limnological anal- R. Melamed, T. Lindmo, & M. L. Mendelsohn (Eds.), yses (2nd ed., 391 pp). New York: Springer. Case Study 5

5.1 Studies from Eastern statistical methodology by Vollenweider and Mediterranean Region: Kerekes (1982 ) as well as by Vollenweider et al. A Review (1998 ). Similar assessments were also performed from selected areas of the Aegean Sea (Saronikos Several reports are available from different Gulf, Island of Rhodes, Mytilini Island) with the ecological niche. An important example is the use of nutrient and/or phytoplankton species data Mediterranean region where most of the water and the application of statistical analyses bodies represent oligotrophic condition. Many (Ignatiades et al. 1992 ; Stefanou et al. 2000 ), eco- works have concentrated on the Eastern logical indices (Karydis and Tsirtsis 1996 ) and Mediterranean Sea, an extreme oligotrophic simulation modelling (Tsirtis 1995 ). environment (Krom et al. 2003) at the far end of A detailed study was carried out on the chlo- a prominent west–east with increasing oligotro- rophyll a and primary productivity in the Aegean phy gradient (Turley et al. 2000 ). This ultra- Sea from the northern to the southern open sea oligotrophic condition is testifi ed by high light environment (Ignatiades et al. 2002 ) and from penetrance (Berman et al. 1984a ; Ignatiades inshore to offshore waters (Ignatiades 2005 ). 1998 ); low nutrient concentrations; very low val- Although this area primarily represents oligot- ues for phytoplankton; primary productivity and rophy, due to localized nutrient enrichment, there cell abundance (Sournia 1973 ; Berman et al. are mesotrophic as well as eutrophic conditions 1984a , b ; Dowidar 1984 ; Azov 1986 ; Bonin et al. also developed. Thus, experimental work was 1989 ; Psarra et al. 2000 ; Christaki et al. 2001 ), carried out from northern and southern Aegean with a dominance of small-size phytoplankton Sea along with inshore and offshore waters of (Li et al. 1993; Yacobi et al. 1995 ; Ignatiades Saronikos Gulf. Samples were collected from 1998; Ignatiades et al. 2002); and outstandingly depths of 1–120 m (Ignatiades et al. 2002 ) in the low bacterial abundance and production (Robarts Aegean Sea, whereas samples were collected et al. 1996 ). Several groups from the Mediterranean from 1 to 60 m depth at the Saronikos Gulf. countries have worked on the phytoplankton spe- Abiotic variables like salinity, temperature, cies composition and productivity from the chlorophyll a and primary productivity were Eastern Mediterranean region. Assessments of measured in situ for each sampling depth. the trophic status of habitat by application of Samples thus collected for primary productivity 14 empirical indices, statistical analysis and other estimates were incubated with C–NaHCO3 , analytical methods have drawn signifi cant atten- and 14C incorporation were measured in a liquid tion from different groups of plankton biologists scintillation counter. Statistical methods were from this region. Such characterization have been used to establish the relation between Chl a and carried out in the Adriatic region using the OECD primary productivity.

R. Pal and A.K. Choudhury, An Introduction to Phytoplanktons: Diversity and Ecology, 75 DOI 10.1007/978-81-322-1838-8_5, © Springer India 2014 76 5 Case Study

Results showed that a distinct gradient was Thus, like the previous part, this work was evident from the northern to the southern open also carried out in the Aegean Sea, an area located waters of the Aegean Sea and from inshore to off- between the Black Sea and the other seas of the shore coastal waters of the Saronikos Gulf. The eastern basin of the Mediterranean region (Ionian open water was cooler than the inshore–offshore and Levantine Seas). Due to the involvement of waters whereas salinity levels in the northern so many different marine systems with variable Aegean were lower than in the southern Aegean. salinity and nutrient status, signifi cant variability As expected, the open and offshore waters were is observed in regard to the oligotrophic status of nutrient poor as compared to the inshore waters. the Aegean Sea at different sections. Thus, as a Based on the nutrient scaling criteria as proposed part of the EU project, this work was taken up to by Ignatiades et al. ( 1992), the nutrient levels of assess the organic carbon partitioning between the open waters (northern and southern Aegean) autotrophic and heterotrophic plankters of differ- were oligotrophic, whereas those of the offshore ent sizes and to investigate the carbon fl ow in the (Saronikos) waters were mesotrophic and inshore photic zone among the different areas of the were eutrophic. Depending upon optical classifi - Aegean Sea. cation of seawater by Jerlov ( 1997), the habitat Here again, southern and northern Aegean Sea waters of the sampling stations were also catego- were taken into consideration for sampling that rized as oligotrophic (the northern and southern represented different degree of oligotrophy. Aegean Sea), mesotrophic (the offshore waters of Samplings were done on board R/V AEGAEO in the Saronikos Gulf) and eutrophic (the inshore two contrasting seasons of March and September, waters of the Saronikos Gulf). Analysis of the when the water column was well mixed and strati- results of Chl a and primary productivity clearly fi ed. Total seven stations were selected from North suggested that the concentration levels of both Aegean Sea (N1–N7) and 4/5 stations were parameters are related to the origin of the water selected from South Aegean Sea (S1–S3 and S6, samples. S7). Hydrographic measurements (temperature, In another work, carbon fl ux of planktonic pressure, conductivity) were carried out by CTD food web was studied along with oligotrophic sampler from Niskin bottles, and inorganic nutri- gradient (Siakou-Frangou et al. 2002 ). It has long ents, phytoplankton biomass and production, been proposed that carbon fl ux in ocean is regu- bacteria biomass and production, heterotrophic lated by the magnitude of primary production nanofl agellates (HNAN) and ciliates were col- and biogeochemical processes within the photic lected at 2–100 m depths. Inorganic nutrients zone. Moreover, the complexity of pelagic food were measured on board spectrophotometrically. webs and the interactions between its different Water samples were size fractionated and chloro- components are mainly responsible for the regu- phyll concentrations were measured as a proxy lation of carbon fl ow. In oligotrophic waters like for carbon biomass using the conversion factor of the Mediterranean region, different studies have Malone et al. ( 1993 ). Photosynthetic productivity established that both carbon and nutrients are is also measured in situ by 14 C method. Incubation 14 remineralized and recycled within a complex experiments with C–NaHCO3 was done and microbial community dominated by minute pro- hourly measurements were recorded using a liq- ducers and consumers (Caron et al. 1999 ; Azam uid scintillation counter. Epifl uorescence micros- et al. 1983 ; Sherr and Sherr 1988 ; Roman et al. copy was used to determine heterotrophic 1995 ). Thus, simultaneous estimates of the pro- bacteria and heterotrophic nanofl agellate popula- duction and biomass of phytoplankton, bacteria, tion as described by Christaki et al. (1999 ). heterotrophic nano- and microplankton and Bacterial abundance data were converted into mesozooplankton are important parameters for biomass (Lee and Fuhrman 1987), and biovolume– the assessment of the carbon fl ux (Nielsen et al. carbon conversion was done for fl agellates 1993 ; Nielsen and Hansen 1995 ; Richardson (Børsheim and Bratbak 1987 ). Bacterial produc- et al. 1998 ; Bradford-Grieve et al. 1999 ). tion (BP) was estimated by the 3 H-leucine method 5.1 Studies from Eastern Mediterranean Region: A Review 77

(Kirchman 1993 ; Christaki et al. 1999 ). Similar autotrophic component outnumbers the hetero- counts and subsequent biovolume–carbon con- trophic components. The study area showed a versions and productivity measurements were gradual decrease in the autotrophic component done for ciliates as well. Larger mesozooplank- with a subsequent increase in the heterotrophic ton populations were hauled. Since calanoid component from northern to southern regions copepods dominated the population, grazing of which were probably due to the abundance autotrophs were measured from gut fl uorescence microheterotrophs. Thus, this work further estab- and gut evacuation rates (Dam and Peterson lished the oligotrophic condition for the Aegean 1988 ). Sea as was found for other regions of Eastern Results from hydrographic studies showed Mediterranean as well (Berman et al. 1984a ; that stratifi cation in the North Aegean was much Krom et al. 1993; Robarts et al. 1996 ; Mazzocchi pronounced as compared to South Aegean Sea. et al. 1997 ) in regard to low nutrient, plankton Nutrient concentrations represented a highly con- biomass and productivity. It further establishes trasting status as compared to the eutrophic sta- an oligotrophic gradient from north to south in tus, as observed by the present authors during the Aegean Sea. Although nutrient concentra- their study in coastal West Bengal, India. Nitrate tions were similar in the entire sampling area, concentrations ranged from 0.05 to 2.5 μM and there was a gradual differentiation in plankton phosphate concentrations ranged from 0.02 to community from Northeast to South Aegean. An 0.08 μM in the entire area, starting from North to inverse correlation between nutrient concentra- South Aegean Sea, with low seasonal variations. tions and autotrophic biomass in the North Phytoplankton counts were comparatively higher Aegean can be characterized as ‘an anomalous in March than in September, yet seasonal varia- interrelationship’ that has been recorded previ- tions were not very pronounced. ously in the Gulf of California (Hernandez- Autotrophic biomass was relatively high Becerril 1987 ). Experimental studies have shown (1,488–2,568 mg C m 2 ) with no signifi cant dif- that there is nutrient infl ow from the Black Sea ference between the areas. At all the sampling that caused localized enrichment, but due to the areas, picoplanktons (<3 μm) dominated the high rate of assimilation, nutrient concentrations autotrophic component, although there were dif- are often depleted. Abundance patterns of bacte- ferences in the population of nanophytoplanktons ria, ciliates, heterotrophs and microheterotrophs at the two sampling regions. Whereas in North further establish microheterotrophs as an essen- Aegean Sea they were <10 μm, at South Aegean tial component in regulating the spatial and tem- Sea they were mostly larger than 10 μm. poral of carbon partitioning in the Aegean Sea. Moreover, the abundance of coccolithophorids Thus, from the studies it can be said that lotic was higher in North Aegean as compared to aquatic ecosystems around the world represent South Aegean Sea. signifi cant variations with regard to the habitat. It Among the heterotrophic populations, distinct can range from ultra-oligotrophic to highly eutro- patterns were observed. Although bacterial com- phic conditions. Moreover, light penetration can ponent accounted as the largest contributor to the be signifi cantly altered due to suspended matter carbon content, their biomass did not vary sig- load in the water column. This may in turn result nifi cantly between regions. On the other hand, in reduction in the photic zone ratio in the water although ciliates accounted for a very small pro- column. Thus, although the incident radiation portion of the biomass, the abundance was sig- may be high, the net reproductivity as well as the nifi cantly higher in the south as compared to the dissolved oxygen content in the habitat may not northern region. In contrast, mesozooplankton complement the incident radiation. Planktonic population decreased signifi cantly from northern populations are highly responsive to such altera- to southern region. tion in the habitat including light availability. The carbon partitioning picture in this area did Thus, sudden shift in abiotic variables like light not quite replicate the typical picture, where and temperature can account for major oscillations 78 5 Case Study in the water column properties which in turn Bose (1944). Roy et al. (1981) further reported cascades in regulating the phytoplankton popula- the use of Kolkata municipal waste for tion of the study area. Bidyadhari–Kulti Fishery complex. The general ecology and biodiversity of Fauna of many ponds have also been recorded by many authors 5.2 Case Study I: Phytoplankton (Mukherjee 1996; Chakraborty 1988; Jana 1998; Diversity of East Calcutta Mukherjee et al. 2002). Mukherjee et al. (2010) Wetland: A Ramsar Site also reviewed that a Bheri is a biological complex system both at quantitative levels as compared to The phytoplankton study in Indian subcontinent rain water as well as waste water-fed ponds. extensively started in the mid-twentieth century and Pradhan et al. (2008) suggested that phytoplank- was primarily focused on the diversity and taxo- ton growth could be an important factor respon- nomic study. The value of phytoplanktons and sible for greater fi sh production and could also other algae as direct or indirect feed for fi shes and act as biomonitor for water quality assessment in their usefulness as indicator of water quality has the Bheris. However, over growth of plankton long been well recognized. With the progress of results in bloom which could be a problem for inland fi sheries in India, studies on productivity and pond management. Fishes also play a crucial role diversity of phytoplanktons in Inland waters have by maintaining a proper balance of phytoplank- gained considerable importance. Many aquatic ton growth, and the planktons convert the nutri- ecosystems especially the sewage-fed ponds are ents available from waste into consumable form generally affected by eutrophication, which indi- as food for fi sh (Ghosh 1999). The water and cates the inorganic nutrient supplies exceeding the effl uent generated form Bheris are used for culti- phytoplankton growth demands (Fischer et al. vation of vegetables, which were found to show 1988; McComb et al. 1995). Bioassay tests were no harmful accumulation (Ray Chaudhuri et al. conducted by several authors to determine the rela- 2007). In the present study phytoplankton diver- tion between nutrient characteristics and phyto- sity of waste-fed fi sh pond and their taxonomic plankton abundance (Redfi eld 1958; Ryther and documentation have been done in detail. Dunstan 1971; Pearl et al. 1990; Siep 1994). The practice of fi sh culture in shallow waste ponds is quite popular in Indian subcontinent. 5.2.1 Study Area Different aspects of wastewater ecology and pro- ductivity of this type of ecosystem have been One such freshwater eutrophic fi sh pond of the studied by a number of authors (Sen 1941). Ramsar site was our study pond – the Captain According to Ray Chaudhuri et al. (2008), shal- Bheri. It is situated at eastern region of Kolkata low fi sh-producing water bodies in West Bengal, between 88°27′ east latitude and 22°27′ north lati- India (called Bheris) have distinct architecture, tude, at the south of Salt Lake City on Eastern resulting in extensive purifi cation of waste. Such bypass, covering an area of 450 m 2 . This pond freshwater fi sh ponds of East Kolkata Wetland serves the dual purpose of recycling sewage water Complex (22°27′N 88°27′E) are also declared as of Kolkata metropolitan city and for cultivating a ‘Ramsar site’, by Ramsar Convention in 19 fi shes extensively. The sewage water includes August 2002. (Ramsar Bureau List was established municipal waste and small-scale industrial effl uents under the Article 8 of Ramsar Convention.) The of Eastern Kolkata’s urban and semiurban areas. Government of India declared this wetland as The variation in physicochemical factors ‘Wetland of International Importance’. recorded throughout the year was also recorded. Thus, East Calcutta Wetland can be cited as The temperature of water varied from 15.3 to best example of integrated resource recovery. 31 °C, pH from 7.5 to 8.62. This suggests the The utility of Kolkata municipal waste on life and alkaline nature of the habitat water. Different growth of fi sh was reported by Nayar (1944) and nutrients like nitrate, nitrite, phosphate, ammonium 5.2 Case Study I: Phytoplankton Diversity of East Calcutta Wetland: A Ramsar Site 79 nitrogen, etc., were also measured. Nitrate was Table 5.1 (continued) found to vary between 0.0775 and 0.286 mg/ml. S. No. Name of taxa Nitrite was found to range from 0.885 to Chlorophyta 4.4 mg/L. Phosphate ranged from 0.057 to 10. Chlorococcum humicola 0.277 mg/L. Ammonium nitrogen concentration 11. Pediastrum duplex varied between 0.45 and 0.187 mg/L. 12. Pediastrum duplex var. clathratum 13. Pediastrum tetras var. tetras 14. Pediastrum tetras var. tetraodon 5.2.2 Results 15. Coelastrum microporum 16. Coelastrum proboscideum A total of 55 taxa were recorded during the study 17. Ankistrodesmus falcatus 18. Ankistrodesmus falcatus var. tumidus period which were found to belong to the groups 19. Kirchneriella lunaris of Cyanobacteria, Chlorophyta, Bacillariophyta 20. Kirchneriella contorta and Euglenophyta. Chlorophyta population was 21. Selenastrum bibraianum found to comprise of 30 species. On the other 22. Tetraedron minimum hand 9 taxa of Cyanophyta, 8 taxa of Euglenophyta 23. Tetraedron muticum and 8 taxa of Bacillariophyta were also recorded 24. Tetraedron trigonum (Table 5.1 ). From the pie chart of the population, it 25. Tetraedron caudatum is evident that chlorophytes were found to be max- 26. Crucigenia apiculata imum comprising of 55 % of the total population, 27. Crucigenia quadrata followed by cyanobacteria with 16 % of the total 28. Crucigenia crucifera population, and then euglenophytes and bacillari- 29. Crucigenia tetrapedia ophytes (15 % and 14 %, respectively) (Fig. 5.1 ). 30. Scenedesmus abundans Description of few taxa are given below which 31. Scenedesmus acuminatus were restricted to this area only; the rest are given 32. Scenedesmus bicaudatus in case studies II and III 33. Scenedesmus bijuga Division – Cyanophyta 34. Scenedesmus dimorphus Class – Myxophyceae 35. Scenedesmus quadricauda var. parvus 36. Scenedesmus obliquus Order – Chroococcales 37. Scenedesmus acutus Family – Chroococcaceae 38. Scenedesmus quadricauda Chroococcus dispersus (Keissl.) Lemmermann 39. Scenedesmus ecornis (Plate 5.1 , Fig. 1) Euglenophyta Lemmermann 1904 p. 102; Prescott 1982 , Pl. 100, 40. Euglena gracilis Fig. 7 41. Euglena viridis 42. Phacus helikoides Table 5.1 Showing name of the phytoplankton taxa 43. Phacus nordstedii recorded 44. Phacus tortus S. No. Name of taxa 45. Phacus chloroplastes Cyanophyta 46. Phacus curvicauda 1. Chroococcus dispersus 47. Euglena proxima 2. Coelosphaerium dubium Bacillariophyta 3. Merismopedia glauca 48. Pleurosigma angulatum 4. Merismopedia minima 49. Cyclotella meneghiniana 5. Merismopedia trolleri 50. Amphora coffeaeformis 6. Synechococcus elongatus 51. Navicula halophila 7. Planktolyngbya contorta 52. Navicula microspora 8. Arthrospira platensis 53. Navicula lanceolata 9. Spirulina subsalsa 54. Nitzschia actinastroides (continued) 55. Aulacoseira granulata 80 5 Case Study

Ovate or irregularly shaped colony of 4–6 spheri- 15% 16% bacillariophyceae cal cells, free fl oating and fl attened; cells are 14% euglenophyceae either single or arranged in small clusters, 55% cyanophyceae evenly distributed at some distance from one clorophyceae another in the mucilaginous envelop; individ- ual cell sheaths not evident; cell contents Fig. 5.1 Pie chart showing percentage abundance of phy- bright blue green, cells 3–4.5 μ in diameter toplankton population of the study area

Plate 5.1 (1 ) Chroococcus dispersus , ( 2 ) Merismopedia var . tumidus , ( 9 ) Crucigenia apiculata , (10 ) Crucigenia trolleri , (3 ) Planktolyngbya circumcreta , ( 4 ) Synechococcus quadrata , ( 11 ) Crucigenia crucifera , (12 ) Kirchneriella elongatus , (5 ) Arthrospira platensis , (6 ) Spirulina subsalsa , contorta , ( 13 ) Chlorococcum humicola , ( 14 ) Coelastrum ( 7 ) Coelosphaerium dubium , (8 ) Ankistrodesmus falcatus microporum , ( 15 ) Coelastrum proboscideum 5.2 Case Study I: Phytoplankton Diversity of East Calcutta Wetland: A Ramsar Site 81

Coelosphaerium dubium Grunow in Rabenhorst Division – Chlorophyta (Plate 5.1 , Fig. 7) Class – Chlorophyceae Rabenhorst 1865, p. 55; Prescott 1982, Pl. 106, Order – Chlorococcales Fig. 1 Family – Chlorococcaceae Spherical or sometimes irregularly shaped col- Chlorococcum humicola (Naeg.) Rabenhorst ony, cells densely arranged. Cells spherical, (Plate 5.1 , Fig. 13) free fl oating, prominent colonial mucilage to Rabenhorst 1868, p. 58; Prescott 1982 , Pl. 45, form a peripheral layer, cell contents blue Fig. 1 green, cells 5–7 μ in diameter; compound col- Unicellular green alga, prominent cell wall, pari- onies as much as 300 μ in diameter etal chloroplast, cells spherical, solitary or in Merismopedia trolleri Bachmann (Plate 5.1 , small clumps, variable in size within the same Fig. 2) plant mass; cells 8–25 μ in diameter Bachmann 1920, p. 350; Prescott 1982 , Pl. 101, Family – Hydrodictyaceae Fig. 5 Pediastrum duplex var. clathratum (A. Braun) Colonial, each cell with a distinct sheath, 8–16 Lagerheim (Plate 5.2 , Fig. 6) spherical cells evenly arranged within a trans- Lagerheim 1882, p. 56; Prescott 1982 , Pl. 48, parent colonial mucilage; cell contents with Figs. 6 pseudovacuoles, appearing brownish or pur- Green algal colony, colony with larger perfora- plish because of light refraction; cells 2–3.5 μ tions than in the typical form; walls with deep in diameter emarginations; apices of lobes of peripheral Synechococcus elongatus Nag. (Plate 5.1 , Fig. 4) cells truncate; cells 12–20 μ in diameter Desikachary, 1959 , pl no. 25, fi g 7 Pediastrum tetras var . tetraedon (Corda) Cells cylindrical, 1.4–2 μ broad, 1.5–3 times as Rabenhorst (Plate 5.2 , Fig. 7) long as broad, contents homogeneous and Rabenhorst 1868, P. 78; Prescott 1982 , pl no. 50, light blue green Fig 7 Order – Oscillatoriales Colony 4–8 celled, outer margins of the periph- Family – Oscillatoriaceae eral cells with deep incisions; the lobes Planktolyngbya circumcreta (G.S. West) Anagno- extended into sharp, horn-like process; cells stidis et Komarek (Plate 5.1 , Fig. 3) 12–15 μ in diameter, 16–18 μ long Kommarek 2005 , p. 160, fi g 194 Pediastrum tetras (Ehrenb.) Ralfs var . teras Filamentous, solitary, free fl oating, spirally (Plate 5.2 , Fig. 9) coiled, 2–2.5 μ wide, coils 33–39 μ broad, Ralfs 1844, p. 469; Prescott 1982 , Pl. no 50, making 2–3 turns, sheathes thin, colourless, Figs 3, 6 trichomes light pale blue green Colony entire; inner cells (frequently none) with Arthrospira platensis (Nordst.) Gomont 4–6 straight sides but with one margin deeply (Plate 5.1 , Fig. 5) incised; peripheral cells crenate, with a deep Desikachary, 1959 pl no. 35, fi g 2 incision in the outer free margin, their lateral Spiral thallus blue green in colour, trichomes margins adjoined along two third of their slightly constricted at the cross walls, 6–8 μ length; cells 8–16 μ in diameter broad, distance between spirals 8–10 μ, end Family – Coelastraceae cells broadly rounded Coelastrum microporum Naegeli (Plate 5.1 , Spirulina subsalsa Oernst. ex Gomont (Plate 5.1 , Fig. 14) Fig. 6) A. Braun 1855, p. 70; Prescott 1982 , Pl. 53, Fig. 3 Desikachary, 1959 pl no. 36, fi gs 3, 9 Coenobium spherical, composed of 8–68 Spiral thallus, trichomes 1–2 μ broad, bright blue sheathed globose cells (sometimes ovoid, with green or yellowish green thallus, irregular spi- the narrow end outwardly directed); cells rals, spirals very close to each other, spirals interconnected by very short, scarcely dis- 3–5 μ broad cernible gelatinous processes, leaving small 82 5 Case Study

Plate 5.2 (1 ) Selenastrum bibraianum, (2 ) Tetraedron cau- acutus, ( 9) Pediastrum tetras var. tetras, ( 10) Scenedesmus datum, (3 ) Tetraedron muticum, ( 4) Tetraedron minimum, (5 ) quadricauda var. parvus, (11 – 12) Scenedesmus bicaudatus , Tetraedron trigonum, ( 6) Pediastrum duplex var. clathratum , (13 ) Scenedesmus ecomis, (14 ) Scenedesmus abundans, ( 15 ) (7 ) Pediastrum tetras var. tetraodon , (8 ) Scenedesmus Scenedesmus acuminatus, (16 ) Scenedesmus obliquus

intercellular spaces; cells 8–20 μ in diameter Family – Oocystaceae including the sheath Ankistrodesmus falcatus var. tumidus (West & Coelastrum proboscideum Bohlin (Plate 5.1 , West) G.S. West (Plate 5.1 , Fig. 8) Fig. 15) West 1904, p. 224; Prescott 1982 , Pl. 56, Fig. 9 Bohlin 1897, p. 33; Prescott 1982 , Pl. 53, Unicellular, cells lunate or fusiform, the ventral mar- Figs. 4, 5, 8 gin decidedly tumid in the midregion, 4.5–6.5 μ Coenobium pyramidal or cubical (rarely in diameter, 61–73 μ long polygonal), composed of 4-8-16-32 trun- Kirchneriella contorta (Schmidle) Bohlin cate cone shaped cells with the apex of the (Plate 5.1 , Fig. 12) cone directed outward, the inner or basal Bohlin 1897 p. 20; Prescott 1982 , Pl. 57, wall of the cell concave, the lower lateral Figs. 7, 8. walls of the cells adjoined about a large Colonial, free fl oating, usually of 16 twisted, space in the centre of the colony; cells arcuate, cylindrical cells with broad, convex 8–15 μ in diameter; 4-celled colony as apices, lying irregularly scattered throughout much as 35 μ in diameter the homogeneous, gelatinous envelope, 5.2 Case Study I: Phytoplankton Diversity of East Calcutta Wetland: A Ramsar Site 83

chloroplast covering the entire wall of cells, Schmidle 1901, p. 234; Prescott 1982 , Pl. 65, Fig. 3 which are 1–2 μ in diameter, 5.8–10 μ long Colonial, 4 ovate rhomboidal or somewhat trian- Selenastrum bibraianum Reinsch (Plate 5.2 , gular cells arranged cruciately, cells 3–7 μ in Fig. 1) diameter, 5–10 μ long; colony 6–12.5 μ wide, Reinsch 1867, p. 64; Prescott 1982 pl no. 57, fi g. 9 9–8 μ long Colony ovate in outline, composed of 4–16 lunate Crucigenia quadrata Morren (Plate 5.1 , Fig. 10) or sickle shaped cells with sharp apices and Morren 1830, pp. 415, 426; Prescott 1982 , Pl. 65, arranged so that the convex surfaces are Fig. 10 apposed and directed towards the centre of the Colony free-fl oating, consisting of a circular colony; cells 5–8 μ in diameter, 20–38 μ long; plate of 4 triangular cells, arranged about a distance between apices 16–42 μ small central place, chloroplasts parietal discs, Tetraedron minimum (A. Braun) Hansgirg as many as 4 in a cell; pyrenoids not always (Plate 5.2 , Fig. 4) present; cells 2.5–6 μ in diameter, 3.7 μ long; Hansgirg 1888, p. 131; Prescott 1982 , pl no. 60, multiple quadrate colonies formed by the fi gs 12–15 close arrangement of component quardets Unicellular, cells small, fl at, tetragonal, the Crucigenia crucifera (Wolle) Collins (Plate 5.1 , angles rounded and without spines or pro- Fig. 11) cesses, lobes sometimes cruciately arranged; Collins 1909, p. 170; Prescott 1982 , Pl. 65, Fig. 4 margins of the cell concave with one fre- Colony consisting of 4-sided cells arranged about quently incised; cells 6–20 μ in diameter a central square opening, the outer free walls Tetraedron muticum (A. Braun) Hansgirg longer and concave, the outer free angles of (Plate 5.2 , Fig. 3) the cells rounded, the lateral adjoin other cells, Hansgirg 1888, p. 131; Prescott 1982 , pl no. 60, the inner walls colonies resulting from the fi gs. 16, 17. adherence of quartets of cells by persisting Unicellular; cells small, fl at, triangular; the mother cell walls; cells 3.5–5 μ in diameter, angles without spines or furcations; sides of 5–7 μ long; colony 9–11 μ wide, 14–16 μ long the cell emarginated or slightly convex; cells Scenedesmus abundans (Kirch.) Chodat 6–18 μ in diameter (Plate 5.2 , Fig. 14) Tetraedron trigonum (Naeg.) Hansgirg (Plate 5.2 , Chodat 1913, p. 77; Prescott 1982 , pl. 62, fi g 21 Fig. 5) Cells oblong or ovate, in a linear series of 4, the Hansgirg 1888, p. 130; Prescott 1982 , pl no. 61, terminal cells with 1 or 2 polar spines and 2 fi gs. 11, 12. spines on the lateral wall, the inner cells with Cells fl at, 3-angled, the angles tapering to sharply the spines at each pole, cells 4–7 μ in diame- rounded, spine-tipped apices; margins convex; ter, 7–12 μ long sides of the cell body concave or straight; cells Scenedesmus acuminatus (Lag.) Chodat (Plate 5.2 , are 19–29.8 μ in diameter Fig. 15) Tetraedron caudatum (Corda) Hansgirg Chodat 1902, p. 211, G.W. Prescott 1982, pl (Plate 5.2 , Fig. 2) no. 62, Fig no. 16 Hansgirg 1888, p. 131; Prescott 1982 , pl no. 59, Cells arranged in a curved series of 4 (rarely 8) fi gs. 17, 24, 25. cells strongly lunate, with sharply pointed api- Cells fl at, 5-sided, the angles rounded and tipped ces, the convex walls adjoined inwardly, the with a short sharp spine; the sides between the concave faces directed outwards; cells 3–7 μ angles concave, but with one margin narrowly in diameter, 30–40 μ long and deeply incised; cells in their longest Scenedesmus bicaudatus Deuds (Plate 5.2 , Figs. dimension 8-15-(22) 11 and 12) Family – Scenedesmaceae Jaiswal & Tiwari, p. 94 pl. 13, fi g 8 Crucigenia apiculata (Lemn.) Schmidle Coenobium 2–8 celled, with linear or slightly (Plate 5.1 , Fig. 9) alternate in arrangement, cells elongated, 84 5 Case Study

outer cells with a long curved spine at alternate Euglena viridis (O.F. Müller) Ehrenberg (Plate 5.3 , poles; inner cells without spines, oval to cylin- Fig. 4) drical, length 10–12 μ, width 4–6 μ Large cell, 40–65 μm long, 14–20 μm wide; ante- Scenedesmus obliquus (Turp.) Kuetzing rior end rounded, posterior end pointed; fusi- (Plate 5.2 , Fig. 16) form during locomotion; highly plastic when Kuetzing 1833, p. 609; Prescott 1982, pl no. 63, stationary; chloroplasts more or less band- Fig 17 form, radially arranged; nucleus posterior Colony composed of 2–8 (usually 4 or 8) fusi- Phacus chloroplastes Prescott (Plate 5.3 , Fig. 8) form cells arranged in a single series; apices Prescott 1982 , pl no. 87, fi gs. 15, 16. of the cells apiculate; wall smooth; cells Cells broad, pyriform; at posterior end a straight 4.2–9 μ in diameter, 14–21 μ long or vey slightly defl ected caudus is formed. Scenedesmus quadricauda var . parvus G.M. broadly rounded anterior end with a median Smith (Plate 5.2 , Fig. 10) papilla; periplast longitudinally striated; mar- Smith 1916a, p. 480; Prescott 1982 , pl no 64, gin of cell entire, chloroplasts in parietal Fig 6 bands, cells 20–22 μ in diameter, 29–31 μ long Colony composed of 2–16 cylindrical–ovate cells Phacus curvicauda Swirenko (Plate 5.3 , Fig. 7) arranged in a single series; outer cells with a long Swirenko 1915 , p. 333 G.W. Prescott 1982 , spine at each pole; inner cells with spineless pl no. 87, figs. 14 walls; cells 4–6.5 μ in diameter, 12–17 μ long Cells broadly ovoid to sub orbicular in outline, Scenedesmus ecornis (Ehrenb.) Chodat (Plate 5.2 , slightly spiral in the posterior part, which is Fig. 13) extended into a caudus that curves obliquely, Colonies of 4 cells attached side by side along chloroplasts numerous, 24–26 μ in diameter, 3/4 of their side, arranged in a zigzag way; cell 28–30 μ long body elliptical; cell wall smooth, inner spaces Phacus nordstedtii Lemmermann (Plate 5.3 , absent, without spiny or dented projections, Fig. 5) 7–20 μ long, 4–10 μ in diameter Lemmermann 1904 , p. 125; Prescott 1982 , pl no. Scenedesmus acutus Meyen (Plate 5.2 , Fig. 8) 88, fi gs. 1 Jaiswal & Tiwari, p. 95 pl. 13, fi g 12 Cells napiform, nearly spherical and with a long Colony 4 celled, cells linear or slightly alternate straight sharply pointed caudus, broadly in arrangement, terminal cells with concave rounded anteriorly, periplast spirally striated, outerface, length 20–24 μ and breadth 5–7 μ cells 18–19 μ in diameter, 35–40 μ long Division – Euglenophyta Phacus tortus (Lemm.) Skvortzow (Plate 5.3 , Class – Euglenophyceae Fig. 10) Order – Euglenales Skvortzow 1928 , p. 110; Prescott 1982 , pl no. 88, Family – Euglenaceae fi gs. 20 Euglena gracilis Klebs (Plate 5.3 , Figs. 1 and 2) Cells broadly fusiform, broadest at the anterior Klebs 1883, p. 303; Prescott 1982, pl no. 85, fi g. 17 end of the cell, tapering and spirally twisted in Unicellular, comparatively larger cell, grass green the posterior position to form a long straight in colour, cells short fusiform to ovoid; chloro- caudus, cells 38–50 μ in diameter, 85–95 μ long plast many evenly distributed throughout the Phacus helikoides Pochmann (Plate 5.3 , Fig. 6) cell, cell 8–20 μ diameter, 35–50 μ long Pochmann 1942, p. 212; Prescott 1982, pl no. 87, Euglena proxima Dangeard (Plate 5.3 , Fig. 3) fi g. 9 Dangeard 1902 , p. 154; Prescott 1982, pl no. 85, Cells elongate fusiform, twisted throughout the fi g. 25 entire length, briefl y narrowed anteriorly and Larger fusiform cells, narrowed posteriorly to a bilobed, tapering posteriorly to a spirally blunt tip, periplast spirally striated, chloro- twisted long straight caudus, margin entire plast numerous, cells 14–21 μ in diameter, with two or three bulges, cells 30–50 μ in 50–95 μ long diameter, 70–120 μ long 5.2 Case Study I: Phytoplankton Diversity of East Calcutta Wetland: A Ramsar Site 85

Plate 5.3 ( 1 – 2 ) Euglena gracilis , (3 ) Euglena proxima , (11 ) Navicula halophila , (12 ) Navicula micropora , ( 4 ) Euglena viridis , ( 5 ) Phacus nordstedtii , ( 6 ) Phacus (13 ) Navicula lanceolata (side view ), ( 14 ) Amphora cof- helikoides , ( 7 ) Phacus curvicauda , (8 ) Phacus choloro- feaeformis , (15 ) Pleurosigma angulatum , (16 ) Cyclotella plastes , ( 9 ) Nitzshia actinastroides , ( 10 ) Phacus tortus , meneghiniana

Division – Bacillariophyta Frustules discoid in valve view, rectangular and Class – Bacillariophyceae undulated in girdle view; margin well defi ned, Order – Thalassiophysales coarsely striated and striae wedge shaped. Family – Catenulaceae Diameter 11–30 μ Amphora coffeaeformis Agardh (Plate 5.3 , Fig. 14) Order – Naviculales Frustules in girdle view very prominent elliptic Family – Naviculaceae lanceolate, truncate. Valves arcuate on the dor- Navicula microspora Kant & Gupta (Plate 5.3 , sal margin and straight or slightly concave on Fig. 12) the ventral margin. Striae delicate Kant and Gupta 1998, p. 27, pl. 127, fi g. 12. Order – Frustules elliptical to lanceolate, rostrate apices, Family – Stephanodiscaceae pseudoraphae at the centre, axial area broad, Cyclotella meneghiniana Kutz. (Plate 5.3 , Fig. 16) striation not visible in fresh material, longer Venkataraman, 1939 , p. 303, fi g 11 than broad, 42–54 μ long and 10–14.5 μ broad 86 5 Case Study

Navicula lanceolata (Agardh) Ehrenberg Chakraborty, S. (1988). East Kolkata Wetlands (Plate 5.3 , Fig. 13) its signifi cance, preservation protection and Valves linear–lanceolate to lanceolate, with very developments. Meenbrata (Special issue on slightly protracted, bluntly rounded apices. Wetland), 58–60. Striae radiate at the centre, becoming convergent Chodat, R. (1902). Algues vertes de la Suisse. 1 at the apices, with a broadly rounded to squarish (No. 3, pp. 1–373). central area. Length 28–70 μ, width (8)-9-12 μ Chodat, R. (1913). Monograp;hie dialuges en Navicula halophila (Grun.) Cleve (Plate 5.3 , culture pure . Ibd., 4 (Fasc. 2, pp. 1–226). Fig. 11) Collins, F. S. (1909). The green algae of North Valves lanceolate with slightly produced and cap- America (Tufts College Studies, pp. 79–170). itate ends. Axial area narrow, linear, central Scientifi c series 2. area slightly widened in the middle. Striations Deshikachary, T. V. (1959). Cyanophyta (pp. parallel and slightly convergent at the ends 1–686). New Delhi: Indian Council of Family – Pleurosigmataceae Agricultural Research. Pleurosigma angulatum (Quekett) W. Smith Fischer, T. R., Harding, L. W., Stanley, D. W., & (Plate 5.3 , Fig. 15) Ward, L. G. (1988). Phytoplankton, nutrients, Valves lanceolate, slightly sigmoid, ends sub- and turbidity in the Chesapeake, Delaware and acute, 116 μ long, 16.5 μ broad; raphae more Hudson estuaries. Estuarine and Coastal Shelf sigmoid than valve, excentric near the ends Science, 27 , 61–93. Order – Bacilllariales Ghosh, D. (1999). Participatory management in Family – Bacillariaceae wastewater treatment and reuse in West Nitzschia actinastroides Van Goor (Plate 5.3 , Fig. 9) Bengal . Huber – Pestalozii 1942, p. 472, pl. CXXXVIII, Hansgirg, A. (1888). Ueber die Susswasser— fi g. 560. gattungen Trochiscia Ktz [Astericium Corda, Rustules straight, liner, much longer than broad, Polyedrium Nag., Cerasterias Reinsch]. 60–90 μ long and 2–4 μ broad, striation not Hedwigia 27 , 126–132. clearly visible in fresh material, 4–5 frustules Huber-Pestalozii, G. (1942). Das phytoplankton des joined at one end Süßwassers. 2 (Teil, 2. Hälfte, 545 p). Stuttgart: Schweizerbart’she Verlagsbuchhandlung. References Hustedt, F. (1952). Neue und weing bekannte Agardh, C. A. (1827). Aufzählung einiger in den Diatomeen, IV. Botaniska Notiser Hf4, 366– östreichischen Ländern gefundenen neuen 410. 134 Figs, Flora 10 (40), 625–640. Gattungen und Arten von Algen, nebst ihrer Jadhav, S. B. (2008). Studies on quality of Lentic Diagnostik and beigefügten . Bemerkungen. water resources of Wadi Ratnagiri (162 p). Bachmann, H. (1920). Merismopedia trolleri nov. M.Phil. thesis, Shivaji University Kolhapur. spec. Zeitschrift für Hydrologie, 1 (3–4), 350. Jaiswal, K. K., & Tiwari, G. L. (2003). Barinova, S., et al. (2010). The infl uence of the Chlorococcales (green algae) . Allahabad: monsoon climate on phytoplankton in the Bioved Research Society. Shibpukur pool of Shiva temple in Burdwan, Jana, B. B. (1998). Sewage fed aquaculture: The West Bengal, India. Limnological Review, Kolkatas model. Ecological Engineering, 11 , 12 (2), 47–63. 73–85. Bohlin, K. (1897). Die Algender ersten Regnell’schen Kant, S., & Gupta, P. (1998). Algal fl ora of Ladakh Expedition. I. Protococcoideen. Bih. (341 p). Jodhpur: Scientifi c Publication. Bose, B. C. (1994). Calcutta sewage-fi sheries Klebs, G. (1883). Über die Organisation einiger culture. Proceedings of the National Institute Flagellatengruppen und ihre Beziehungen zu of Sciences of India, 10 , 443–459. Algen und Infusorien. Untersuchungen aus Braun, A. (1855). Algarum unicellularum genera dem Botanischen Institut zu Tübingen, 1 , nova velminus cognita (p. 70). Pls. 1–6. 233–362. 5.2 Case Study I: Phytoplankton Diversity of East Calcutta Wetland: A Ramsar Site 87

Komarek, J., & Anagnostidis, K. (2008). cultivation. American Journal of Cyanoprokaryota . Heidelberg: Spectrum . Environmental Sciences, 4 , 406–411. Krishna Kumari, L., et al . (2002). Primary pro- Prescott, G. W. (1982). Algae of the Great ductivity in Mandovi-Zuari estuaries in Goa. Western Lakes area (pp. 1–997). Dubuque: Journal of the Marine Biological Association W.C. Brown Co. of India, 44 (1&2), 1–13. Rabenhorst, L. (1864–1868). Florae Europaea Kützing, F. T. (1834 [1833]). Synopsis diato- Algaum Aque dulcis et submarinae (3 Vols.). mearum oder Versuch einer systematischen Leipzig. Zusammenstellung der Diatomeen. Linnaea 8 , Ralfs, J. (1844). On the British Desmidieae. 529–620, Plates XIII–XIX [79 fi gs]. Annals and Magazine of Natural History, Lagerheim, G. (1882). Bidrag till kannedomen om 14 (Ser. 1), 469. Stockholmstraktens Pediasteer, Protococcaceer Ray Chaudhuri, S., Salodkar, S., Sudarsan, M., & och Palmellaceer. Oefv. Kongl. Sv, Vet.-Akad, Thakur, A. R. (2007). Integrated resource Forhandl., 39 (No. 2, pp. 47–81; Pls. 2, 3). recovery at East Calcutta Wetland: How safe Lemmermann, E. (1904). Das Plankton schwed- ISB this? American Journal of Agricultural ischer Gewasser. Arkiv för Botanik, 2 (2), and Biological Sciences, 2 , 75–80. 1–209. Pls. 1, 2. Ray Chaudhuri, S., Mishra, M., Nandy, P., & McComb, A. J., & Lukatelich, R. J. (1995). In Thakur, A. R. (2008). Waste management: A A. J. McComb (Ed.), The Peel-Harvey estua- case study of ongoing traditional practices at rine system, Western Australia . east Calcutta wetland. American Journal of Morren, C. (1830). Memoire sur un vegetalmi- Agricultural and Biological Science, 3 , croscopique dun nouveau genre, propose sous 315–320. le nomme Microsoter, ou conservateau des Redfi eld, A. C. (1958). The biological control of perites choses. Annales des Sciences chemical factors in the environment. American Naturelles – Biblioteca, 20(Ser. 1), 404–426. Scientist, 46 , 205–222. Mukherjee, M. (1996). Pisciculture and environ- Reinsch, P. F. (1867). Die Algenfl ora des mit- ment: An economic evaluation of sewage-fed tleren Theiles von Franken, enthaltend die fi sheries in East Kolkata. Science, Technology vom Autor bis jetzt in diesen Gebieten and Development, 14 (2), 73–79. beobachteten Susswasseralgenetc. Abh Naturh Mukherjee, M., Nath, U., Kashem, A., & Ges Nurnberg, 3 , 64. Chattopadhyay, M. (2002). Peri-urban aqua- Roy, P., Saha, S. B., & Banerjee, K. K. (1981, culture and its environmental status: Kolkata December 11–13). A case study of Calcutta experience. Fishing Chimes, 22 (i), 9–15. municipal wastes for fi sh culture in Mukherjee, I., Bhaumik, P., Mishra, M., Ranjan Bidyadhari-Kulti complex. W.B. interna- Thakur, A., & Ray Chaudhuri, S. (2010). Bheri-a tional symposium of water resources conser- unique example of biological complex system. vation, pollution and abatement, University Journal of Biological Sciences, 10 (1), 1–10. of Roorkee. Nayar, K. K. (1994). The effect of Calcutta sew- Ryther, J. H., & Dunstan, W. M. (1971). age of fi sh life. Proceedings of the National Nitrogen, phosphorus and eutrophication in Institute of Sciences of India, 10 , 147–156. the coastal marine environment. Science, Pearl, H. W., Rudek, J., & Mallin, M. A. (1990). 171 , 1008–1013. Stimulation of phytoplankton production in Schmidle, W. (1901). Algologische Notizen. XV. coastal waters by natural rainfall inputs: Allg Bot Ges, 19, p. 234. Nutritional and trophic implications. Marine Sen, S. (1941). Fisheries of West Bengal . Alipore: Biology, 107 , 247–254. West Bengal Government Press. Pradhan, A., Bhaumik, P., Das, S., Mishra, M., Sewell, R. B. S. (1935). A study of fauna of Salt Khanam, S., et al. (2008). Phytoplankton Lake, Calcutta. Records of the Indian Museum, diversity as indicator of water quality for fi sh 36 , 45–49, 58–60. 88 5 Case Study

Shafi , N., et al. (2013). Phytoplankton dynamics The land is constantly moulded and altered by of Nigeen Lake in Kashmir Himalaya. tidal action, with erosion along estuaries and International Journal of Environment and deposition of silts from seawater. The Sunderbans Bioenergy, 6 (1), 13–27. consist of three wildlife sanctuaries (Sundarbans Siep, K. L. (1994). Phosphorous and nitrogen West, East and South) including the man eater limitation of algal biomass across trophic gra- Royal Bengal Tiger. dients. Aquatic Sciences 56 , 16–28. Sunderbans’ beauty lies in its unique natural Smith, G. M. (1916). A monograph of the algal surroundings. Thousands of meandering genus Scenedesmus based upon pure culture streams, creeks, rivers and estuaries have studies. Transactions of the Wisconsin enhanced its charm. Forest areas are dominated Academy of Sciences Arts and Letters, 18 , by typical mangrove plants, like Sundri and 422–530. Gewu and patches of Nypa palm. Sunderban is Sterner, R. W. (1994). Seasonal and spatial pat- the natural habitat of the world famous Royal terns in macro and micronutrient limitation in Bengal Tiger, spotted deer, crocodiles, jungle Joe Pool Lake, Texas. Limnology and fowl, wild boar, lizards, monkey and an innu- Oceanography, 39 , 535–50. merable variety of beautiful birds. The entire Thajuddin, N., & Subramanian, G. (1992). area is fl ooded with brackish water during high Survey of Cyanobacterial Flora of the tides which mix with freshwater from inland Southern East Coast of India, Botanica rivers. The monsoon rains, fl ooding, delta for- Marina (Vol. 35, pp. 305–314). mation, and tidal infl uence combine in the Venkataraman, G. (1939). A systematic account Sundarbans to form a dynamic landscape that is of some south Indian diatoms. In Proceedings constantly changing. The ecology and the biodi- of the Indian Academy of Sciences (Vol. X, versity of the Sunderban algae have been stud- No. 6, Sec. B). ied by a very few authors (Prain 1903; Naskar West, W., & West, G. S. (1904). Fresh water algae and Mandal 1999; Sen and Naskar 2003). from the Orkneys and Shetlands (p. 224) Several authors studied the mangrove ecosys- Edinburgh: Transactions of the Botanical tem with reference to human habitation and Society. settlement, development of agricultural fi elds and brackish water fi sheries. The algal fl ora of Suderbans has extensively studied by the pres- 5.3 Case Study II: Phytoplankton ent group from taxonomic point of view and as Diversity of Indian a potential source for biodiesel (Mukhopadhyay Sunderbans and Pal 2002; Choudhury and Pal 2008; Satpati et al. 2013) The Sunderbans mangrove forest is one of the Phytoplankton population of Sunderbans riv- largest mangrove forest in the world (140,000 ha). ers varied to a greater extent with salinity gradi- It is situated in the southeast part of Asia or the ent. In present study, phytoplanktons were southeastern coast of India and Bangladesh, on collected from the different islands of Sunderbans the delta of the Ganges, Brahmaputra and like Basanti, Patharpratima, Bakkhali and Meghna rivers on the mouth of Bay of Bengal. Lothian Islands and surroundings river systems The Indian site lies between 21°31′ to 22°53′N like Vidya river, Kholnar khal, Muriganga river, and 88°37′ to 89°09′E. Due to its beauty and Saptamukhi river, Matla river and Bishalakshi richness of wildlife, it was declared a world natu- khal. Mid river samplings were done for phyto- ral heritage site by UNESCO on 1974. The site is plankton collection. Sampling section represents intersected by a complex network of small- from freshwater zone to marine zone. Salinity forested islands and mudfl ats and some intercon- varies from 0 to 22 psu, temperature profi les nected tidal rivers, creeks and canals, therefore were recorded as 22–34 °C and an average pH forming a complex network of tidal waterways. was measured as 7.98. 5.3 Case Study II: Phytoplankton Diversity of Indian Sunderbans 89

Phytoplankton community was dominated by 5.3.2 Taxonomic Account of a Few diatoms (Biacillariophyceae) followed by Phytoplankton Taxa Recorded Chlorophyceae, and other algal groups recorded from Sunderbans (Rest Are were Cyanophyceae, Euglenophyceae and in Case Studies I and III) Dinophyceae. A total of 34 taxa belonging to 5 groups were recorded. Species diversity was Division – Euglenophyta found to be maximum in summer (March) and Class – Euglenophyceae minimum in winter season (November) in all the Order – Euglenales sample stations. Family – Euglenaceae Euglena polymorpha Dangeard (Plate 5.4 , Fig. A) [Dangeard, 1902 , p. 175. Pl. 85, Figs. 21, 22; 5.3.1 List of Phytoplankton Genera Prescott, 1982 , p. 393.] Recorded from Sunderbans Cells ovoid to pyriform to subcylindric, nar- rowed gradually posteriorly to a short blunt tip; periplast with spiral striations; chloro- Cyanobacteria 1. Merismopedia glauca plasts many and disc-like with lacinate mar- 2. Merismopedia minima gins, with one pyrenoid; cells 20–26 μ in 3. Spirulina platensis diameter, 80–90 μ long 4. Gloeocapsa punctata Phacus segretii var. ovum Prescott (Plate 5.4 , Fig. B) Chlorophyceae 5. Chlorococcum infusionum [Prescott, 1982 , p. 369, pl. 88, fi g. 23.] 6. Pediastrum tetras Cells larger than in the typical form, broadly 7. Crucigenia tetrapedia μ μ 8. Scenedesmus quadricauda ovoid, 29 in diameter and 40 long. ′ 9. S. bijuga Occurrence, Jharkhali pond (N 22°01.142 , E ′ 10. S. dimorphus 088°41.168 ), fresh water 11. Closterium tumidium Division – Heterokontophyta Euglenophyceae 12. Euglena gracilis Class – Bacillariophyceae 13. E. polymorpha Order – Pennalales 14. Phacus longicauda Suborder – Araphidineae 15. P. segretii Family – Fragilariaceae Bacillariophyceae 16. Achnanthes hauckiana Subfamily – Fragilarioideae 17. Pleurosigma angulatum Fragilaria brevistriata Grun. forma elongata f. nov 18. P. normanii (Plate 5.4 , Fig. F) 19. Navicula halophila [Venkataraman 1939 , p. 305, fi g. 25, 26] 20. N. cincta Valves linear lanceolate with rounded ends. Striae 21. N. minima short and marginal. Pseudoraphae broad. Length 22. N. ignorata 31.20 μ, breadth 4.31 μ, striae 13 in 10 μ 23. N. peregrina Fragilaria oceanica Cleve. (Plate 5.4 , Fig. H) 24. Coscinodiscus excentricus [Subrahmanyan 1946 , p. 165, fi gs. 336–339] 25. C. excentricus 26. Cyclotella meneghiniana Frustules in girdle view linear–rectangular, 27. Cyclotella striata forming a very compact ribbon-like chain. 28. Nitzschia obtuse Valves broadly lanceolate with rounded ends, μ μ 29. N. amphibian 11.5 long, and 6.5 broad 30. Melosira nummuloides Suborder – Monoraphidineae 31. Fragilaria intermedia Family – Achnanthaceae 32. F. oceanic Subfamily – Achnanthoideae Dinophyceae 33. Ceratium hirundinella Achnanthes hauckiana var. rostrata (Plate 5.4 , 34. Noctiluca scintillans Fig. I) [Schulz 1926, p 191, fi g. 40] 90 5 Case Study

Plate 5.4 (A ) Euglena polymorpha , ( B ) Phacus segretii , ( G ) Navicula cincta , (H ) Fragilaria oceanica , ( C ) Melosira numuloides , ( D ) Ceratium hirudinella , ( I ) Acnanthes hauckiana , ( J ) Noctiluca scintillans ( E ) Navicula ignorata , (F ) Fragilaria brevistriata , 5.3 Case Study II: Phytoplankton Diversity of Indian Sunderbans 91

Valves elliptic lanceolate with slightly truncate Cells with polygonal plates, epicone usually ends. Raphe thin, thread-like, axial area nar- larger than hypocone; cells are triangular with row, central areas somewhat broadened. The horns with prominent transverse furrows; cells length is 20.41 μ and breadth 6.806 μ. Number are 45 μ long and 15 μ broad of striae 20 in 10 μ Suborder – Biraphidineae References Family – Naviculaceae Agardh, C. A. (1827). Aufzählung einiger in den Subfamily – Naviculoideae östreichischen Ländern gefundenen neuen Navicula cincta (Ehr.) Kutz., var. Heufl eri Grun. Gattungen und Arten von Algen, nebst ihrer (Plate 5.4 , Fig. G) Diagnostik and beigefügten . Bemerkungen. [G. Venkataraman 1939 , p. 326, Fig 89] Choudhury, A., & Pal, R. (2008). Diversity of Valves linear lanceolate with obtuse ends. Axial planktonic diatoms from West Bengal coast area narrow. Central area small broadened. with special reference to taxonomic accounts. Striations at the end convergent, 26.56 μ Phytomorphology , ISPM, 58 (1 and 2), long and 5.81 μ broad, number of striations 29–42–41. 10 in 10 μ Hustedt, F. (1952). Neue und weing bekannte Navicula ignorata Krasske (Plate 5.4 , Fig. E) Diatomeen, IV. Botaniska Notiser Hf4, 366– [Hustedt, 1952, p. 442, fi g. 819; Foged 1979 , 410. 134 Figs, Flora 10 (40), 625–640. p. 87, pl. XLIII, fi g. 5] Mukhopadhyay, A., & Pal, R. (2002). A report Valves linear–lanceolate, with somewhat bent ends. on biodiversity of algae from coastal West The length is 57.44 μ and the breadth is 3.59 μ Bengal (South & North 24-parganas) and Class – their cultural behavior in relation to mass cul- Order – Melosirales tivation programme. Indian Hydrobiology, Family – Melosiraceae 5(2), 97 –107. Melosira nummuloides var. lesdiana Pantocsek Naskar, K. R. & Mandal, R. N. (1999). Ecology (Plate 5.4 , Fig. C) and biodiversity of Indian mangrove (Vols. 1 [Agardh, 1827, p. 307, fi g -312.] & 2). New Delhi: Daya Publishing House. Cells cylindrical to subspherical, forming chains. Prain, D. (1903). Flora of sundarbans. Records of Valve face fl at or domed, covered with small the Botanical Survey of India, 2 , 231–390. spines or granules; a more or less well- Presscott, G. W. (1982). Algae of the Western developed corona Great Lakes area (2nd ed.). Dubuque: WM Division – Dinophyta Brown & Co. Class – Dinophyceae Satpati, G. G., Barman, N., & Pal, R. (2013). A Order – Noctilucales study on green algal fl ora of Indian sundar- Family – Noctilucaceae bans mangrove forest with special reference to Noctiluca scintillans (Macartney) (Plate 5.4 , morphotaxonomy. Journal of Algal Biomass Fig. J) Utilization, 4 (1), 26. Large, round to kidney-shaped cells, with a stri- Schulz, P. (1926). Die Kieselalgen der Danziger ated tentacle, one fl agellum and a eukaryotic Bucht mit Einschluss derjenigen aus glazialen nucleus; cytoplasm may contain photosyn- und postglacialen Sedimenten. Bot Arch thetic symbionts and gametes are gymnodi- Königsberg, 13 (3/4), 149–327. noid, phagotrophic with food vacuoles Sen, N., & Naskar, K. (2003). Algal fl ora of sundar- containing prey; chloroplasts absent; cells are bans Mangal . New Delhi: Daya Publishing House. 200–250 μ in diameter Subrahmanyan, R. (1946). A systematic account Ceratium hirudinella (O.F. Muell.) Dujardin of the marine plankton diatoms of the Madras (Plate 5.4 , Fig. D) Coast. Proceedings of the Indian Academy of [Prescott, 1982 , p. 437, pl. 92, fi gs. 4, 5] Science, 24B , 85–197. 92 5 Case Study

the state capital of West Bengal, India (Fig. 5.2 ). 5.4 Case Study III: Just upstream of this coastal station, Rupnarayan Phytoplankton Dynamics River merges with the Hugli River which is of Eastern Indian Coast further joined by the Haldi River at a distance of 20 km downstream. As this coastal station is 5.4.1 Study Area located at the upstream region of the Bhagirathi– Hugli estuary, accordingly, salinity was relatively The Bhagirathi–Hugli estuary, situated at the low (0–4.5 psu) and reached as low as 0 psu in eastern coast of India, is a deltaic offshoot of the the monsoon months. Thus, this station was des- River Ganges and lies approximately between ignated as the freshwater station (Fig. 5.2 ). Our 21°31′–23°20′N and 87°45′–88°45′E. It is a second sampling station Kakdwip (21°53′0″N, tropical coastal estuary and is associated with the 88°11′0″E) is located at a distance of 36 km from Sunderbans Mangrove Biosphere Reserve which Diamond Harbour and was considered as an estu- is part of world’s largest delta, the Ganges– arine location (salinity, 4–17 psu). At this station, Brahmaputra delta. The estuary is funnel shaped the mixing conditions were more prevalent with the breadth and cross-sectional area at the between the freshwater of Bhagirathi–Hugli and mouth being 25 km and 156,250 m 2 , which marine waters of the Bay of Bengal, which decreases to 6 km and 36,799 m 2 at the head end. resulted in the mesohaline conditions of this Climatic condition is dominated by NE and SW region (Fig. 5.2 ). monsoon where the annual rainfall varied For our marine samples along a relatively high between 188 and 245 cm, with 75–85 % of the salinity gradient (26–36 psu), two coastal stations total annual rainfall occurring in the monsoon were chosen (Junput, 21°43′N, 87°49′E, and months . The pronounced infl uence of south west Digha, 21°37′N, 87°31′E) from the confl uence of monsoon winds resulted in heavy seasonal pre- the Hugli River and Bay of Bengal and were cipitation which may be as high as 500 mm in a together designated as the coastal marine region month. This being a tropical coastline showed a (Fig. 5.2 ). prolonged summer (April–May–June) with an average temperature of 35 ± 5 °C and a long mon- soon season (July–August–September) with an 5.4.2 Nutrient and Phytoplankton average temperature of 35 ± 2 °C. Winter Dynamics of Coastal West (November–December–January) is compara- Bengal tively mild in this region of the world with the mean temperature of 12 ± 5 °C. Thus, this region Phytoplankton population at coastal West Bengal shows a progressive increase in temperature from is in a dynamic state and brought about primarily January to May followed by a decline with the by interplay of several physicochemical and bio- onset of southwest monsoon from June onwards logical factors. Environmental variables and and reaches minimum during the end of the year. nutrient concentrations fl uctuated signifi cantly From the estuarine and coastal area, we selected both on a monthly as well as on a seasonal basis. four main stations for our study which was Such variability in the nutrient status and physi- mainly based on the salinity gradient of each cochemical environment of the habitat brought sampling station (Diamond Harbour, Kakdweep, about fl uctuations in the phytoplankton popula- Junput and Digha). The sampling stations were tion as well as in the biotic indices. Accordingly, designated as freshwater zone (Diamond the fi ndings have been represented in different Harbour), estuarine zone (Kakdweep) and marine sections as follows: zone (Junput and Digha). (a) Phytoplankton diversity of the study area Diamond Harbour (22°8.78′N and 88°9.0′E) (b) Analysis of physicochemical parameters of is located at a distance of 56 km from Kolkata, the study area 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 93

Fig. 5.2 Map of the study area at Coastal West Bengal 94 5 Case Study

(c) Phytoplankton population study (cell count) Table 5.2 (continued) by application of biotic indices S. No. Name of taxa (d) Estimation of Primary productivity (GPP, 27. Thalassiosira decipiens NPP and CRR) and Oxygen Concentrations 28. Cyclotella meneghiniana (DO and BOD) 29. Cyclotella striata (e) Implementation of Multivariate Procedures for 30. Coscinodiscus granii community pattern analysis of the study area 31. Coscinodiscus excentricus 32. Coscinodiscus excentricus var. 5.4.2.1 Phytoplankton Diversity fasciculata 33. f. subsala of the Study Area 34. Leptocylindrus danicus The phytoplankton population of the study area was 35. Bacteriastrum delicatulum represented by 75 taxa belonging to three different 36. Bacteriastrum varians algal divisions like Cyanobacteria, Chlorophyta 37. Chaetoceros curvisetus and Bacillariophyta. Among the taxa recorded, 38. Chaetoceros diversus 8 species were from Cyanobacteria, 17 species 39. Chaetoceros messanensis belonged to Chlorophyta and 51 species from 40. Chaetoceros wighami Bacillariophyta (Table 5.2 ). As evident, diatoms 41. Eucapmia zoodiacus 42. Ditylum brightwellii 43. Biddulphia alternans Table 5.2 List of phytoplankton genera recorded from 44. Odontella aurita the entire study area (viz. freshwater station, estuarine sta- tion and coastal marine region) 45. Biddulphia dubia 46. Biddulphia heteroceros S. No. Name of taxa 47. Biddulphia mobiliensis 1. Gloeocaspapunctata 48. Odontella rhombus 2. Microcystis aeruginosa 49. Thalassionema nitzschoides 3. Merismopedia glauca 50. Thalassiothrix frauenfeldii 4. Merismopedia minima 51. Asterionella japonica 5. Merismopedia punctata 52. Cocconeis dirupta 6. Gloeothece rupestris 53. Gyrosigma beaufortianum 7. Spirulina meneghiniana 54. Gyrosigma acuminatum 8. Spirulina platensis 55. Gyrosigma obtusatum Chlorophyta 56. Pleurosigma normanii 9. Pediastrum duplex var. rotundatum 57. Pleurosigma salinarum 10. Pediastrum simplex 58. Diploneis weissfl ogii 11. Pediastrum simplex var. duodenarium 59. Diploneis interrupta 12. Pediastrum tetras 60. Navicula minima Grunow 13. Ankistrodesmus falcatus 61. Navicula mutica fo. cohni 14. Ankistrodesmus falcatus var. stipitatus 62. Navicula peregrina 15. Dictyosphaerium pulchellum 63. Navicula quadripartita 16. Shroederia judayi 64. Amphiprora gigantea 17. Kirchneriella lunaris 65. Cymbella naviculiformis 18. Scenedesmus bijuga 66. Bacillaria paradoxa 19. Scenedesmus dimorphus 67. Nitzschia amphibia 20. Scenedesmus quadricauda 68. Nitzschia bilobata var. minor 21. Crucigenia rectangularis 69. Nitzschia ignorata 22. Crucigenia tetrapedia 70. Nitzschia obtusa 23. Tetrastrum staurogeniaeforme 71. Nitzschia punctata 24. Rhizoclonium riparium 72. Nitzschia sigmoidea Bacillariophyta 73. Nitzschia delicatissima 25. Aulacoseira granulata var. angustissima 74. Nitzschia pacifi ca 26. Skeletonema costatum 75. Surirella fastuosa var. recedens (continued) 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 95 accounted for the bulk of the phytoplankton popu- sented by 54 taxa. The population at marine coastal lation which represented about 69 % of the total region (Digha and Junput) was represented by 41 population. Although diatom taxa were recorded diatom genera only. The population at the estua- from all the three sampling areas of freshwater rine location (Kakdweep) was least diverse as it zone, estuarine zone and marine zone, cyanobacte- was represented by 25 algal taxa altogether. Each rial population was restricted to the freshwater site exhibited distinct seasonal phytoplankton zone, i.e. Diamond Harbour only. On the other assemblages which varied spatiotemporally in hand, green algal genera were recorded from the response to different environmental conditions. freshwater and estuarine locations, but none were The phytoplankton population at freshwater recorded from the marine coastal region. Among zone (Diamond Harbour) was represented by 54 the different members of Bacillariophyta, centric phytoplankton taxa of which 8 species were blue diatoms were more abundant at the estuarine to green, 16 taxa were green algae and 30 genera were marine region, whereas pennate diatoms were of diatoms (Table 5.3). The phytoplankton popula- recorded from freshwater to estuarine region. On tion showed distinct patterns where green algal an individual site basis, the phytoplankton popula- population was mostly observed during the warmer tion at Diamond Harbour was most diverse, in summer and monsoon months whereas diatoms comparison to other two zones, and was repre- were more available in the cooler months of

Table 5.3 Floristic list of phytoplankton genera recorded during the study period from the freshwater station (Diamond Harbour) Division Name of genera Period of availability Abundance Cyanobacteria Merismopedia minima (MM) July to Nov + Merismopedia punctata (MP) August to Nov + Merismopedia glauca (MG) June, July + Spirulina platensis (SP) Apr to Sept + Spirulina meneghiniana (SM) July, Aug + Gloeocapsa punctata (Glcsp) Apr to July + Gloeothece rupestris (Glthc) July + Microcystis aeruginosa (MAero) Oct to Dec + + Chlorophyta Ankistrodesmus falcatus (AF) Apr to Sept + Ankistrodesmus falcatus Apr to June + var. stipitatus Kirchneriella lunaris (KL) Apr to Nov + Shroederia judayi (SJ) Mar to Aug + Crucigenia rectangularis (CR) May, June + + Crucigenia tetrapedia (CT) May, June + Crucigenia quadrata (CQ) Rare + Scenedesmus quadricauda (SQ) Mar to June + + Scenedesmus bijuga (Sbi) Mar to June + + Scenedesmus dimorphus (Sdi) Mar to June + Pediastrum simplex June, July + + Pediastrum tetras (Ptet) Mar to June + Pediastrum duplex var. Mar to June + + Rotundatum (Pdro) Pediastrum simplex var. Mar to June + duodenarium (Psduo) Dictyosphaerium pulchellum Mar, Apr + + (Dictyo) Rhizoclonium riparium (RR) Mar to Sept (irregular) + (continued) 96 5 Case Study

Table 5.3 (continued) Division Name of genera Period of availability Abundance Bacillariophyta Odontella aurita (OAu) Nov to Feb + Biddulphia dubia (Bdu) Nov to Feb + Gyrosigma obtusatum (GOb) irregular + Gyrosigma acuminatum (GAcu) Aug to Oct + + Gyrosigma beaufortianum (Gbeau) Oct to Apr + Pleurosigma salinarum (Psal) Oct to Mar + + Cyclotella meneghiniana (CM) Sept to Oct + + Cyclotella striata (CS) Mar and Sept + Coscinodiscus excentricus (CE) Mar and Sept + + Actinocyclus normanii f. subsala (AN) Oct to Apr + Stephanodiscus hantzschii (SH) Nov to Feb + Ditylum brightwellii (DB) Mar, Apr + Bacteriastrum varians (BV) Sept, Oct + Bacteriastrum delicatulum (Bdeli) Aug to Oct + Aulacoseira granulata (Aug) Aug to Oct + Thalasiothrix frauenfeldii (TF) Nov to Feb + + Thalassionema nitzschioides (TN) Nov to Mar + + Bacillaria paxillifer (Bpax ) Nov to Feb + Amphiprora gigantea (AG) Nov to Jan + Leptocylindrus danicus (LD) Feb to Sept + + + Cymbella naviculiformis (CN) Nov to Feb + Navicula peregrina (Nper) Feb to June + Navicula quadripartita (Nquad) Oct to Mar + Nitzschia ignorata (Nig) Nov, Dec + Nitzschia amphibia (Namp) Rare + Nitzschia obtusa (Nob) Oct to Dec + Nitzschia punctata (Npu) Nov to Feb + + Nitzschia delicatissima (Ndeli) Nov to Feb + + Navicula minima (Nmi) Oct to Feb + + Navicula mutica (Nmu) Rare + + + = ≤1 × 10 4 cells/L + + = ≥1 × 10 4 to ≤5 × 104 cells/L + + + = ≥5 × 10 4 to ≤1 × 105 cells/L + + + + = ≥1 × 105 to 20 × 105 cells/L post-monsoon and winter. Appearance and abun- Table 5.4 Showing percentage abundance of dominant dance of cyanobacterial population was restricted phytoplankton genera at the freshwater zone (Diamond mainly to the monsoon and post- monsoon periods. Harbour) The most dominant taxon recorded during the Maximum entire sampling period was Leptocylindrus danicus contribution to total Season Dominant species population (%) (Table 5.4). Other abundant phytoplankton genera Summer Leptocylindrus 9.53 were Thalassiothrix frauenfeldii , Thalassionema danicus nitzschoides , Pediastrum tetras , P. duplex var. Monsoon Leptocylindrus 18.54 rotundatum , P. simplex var. duodenarium and danicus Scenedesmus spp. In an analysis of the seasonality Post- monsoon Microcystis 21 of phytoplankton species composition throughout aeruginosa the study period, following trends were noted in the Winter Nitzschia 10.07 delicatissima freshwater zone. 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 97 a b 5.09% 33.32% 24.133%

16.77% 59.10% 61.59%

Cyanophyta Chlorophyta Cyanophyta Chlorophyta c d 0.55%% 24.55% 3.64%

71.81% 99.45 %

Cyanophyta Chlorophyta Cyanophyta

Fig. 5.3 Percentage seasonal contributions of different algal divisions to the total phytoplankton population: (a ) summer, ( b ) monsoon, ( c ) post-monsoon and (d ) winter at the freshwater station (Diamond harbour)

In summer, green algal population was high and 10.54 % of the total phytoplankton population. made up to 61.59 % of the total phytoplankton popu- The cyanobacterial population was composed of lation whereas diatom and blue-green algae taxa like Spirulina spp., Merismopedia spp., accounted for 33.32 % and 5.09 % of the population, Microcystis aeruginosa , etc. respectively (Fig. 5.3a). Interestingly, it was observed In post-monsoon period, as seasonal precipita- that the most abundant taxon was the diatom genus tion reduced, a further shift in phytoplankton spe- Leptocylindrus danicus that made up 9.53 % of total cies composition was observed (Fig. 5.3c ). The population, followed by green algal genera like green algal availability decreased further and con- Pediastrum duplex var. rotundatum, Ankistrodesmus tributed to only 3.64 % of the population. On the falcatus and Pediastrum simplex var. duodenarium other hand, diatom population continued to increase contributing to 8.94 %, 8.82 %, and 7.32 % of the and made up to 71.81 % of the total population in total phytoplankton population, respectively. this period. Cyanobacterial population also fl our- In monsoon period, dominance of diatoms per- ished in this period and Microcystis aeruginosa sisted (59.1 % of the total population), although appeared as the most abundant taxon, contributing there was a rise in cyanobacterial population 24.55 % of the total population. Diatom population (24.13 % of total population) together with green was represented by several genera, among which algae, contributing to 16.77 % of the total popula- the more abundant taxa were Thalassionema tion (Fig. 5.3b ). On a generic level, dominance of nitzschoides , Pleurosigma salinarum , Nitzschia the diatom genus Leptocylindrus danicus persisted amphibia and Gyrosigma obtusatum each of which contributing to 18.54 % of the total population. made up more than 5 % of the total population. Among the green algal genera, the most abundant As winter appeared, almost the entire popula- taxon was Kirchneriella lunaris that made up tion was represented by diatoms (99.45 %), rest 98 5 Case Study

Table 5.5 Floristic list of phytoplankton genera recorded during the study period from the estuarine station Division Name of genera Period of availability Abundance Chlorophyta Kirchneriella lunaris (KL) Mar to Sept + + Ankistrodesmus falcatus (AF) Mar to Oct + + Scenedesmus bijuga (Sbi) Mar to June + + Scenedesmus dimorphus (Sdi) Mar to June + + Scenedesmus quadricauda (Squa) Apr to May + Crucigenia tetrapedia (CT) Apr to Sept (irregular) + Rhizoclonium riparium (RR) + + Bacillariophyta Thalassiothrix frauenfeldii (TF) June to Feb + + Cyclotella meneghiniana (CM) May to Nov + + Cyclotella striata (CS) May to Nov + + Ditylum brightwellii (DB) May to Nov + + Gyrosigma obtusatum (GOb) May to Nov + + Gyrosigma acuminatum (GAcu) May to Nov + + Bacteriastrum varians (BV) Sept to Oct + Bacteriastrum delicatulum (Bdeli) Aug and Sept + Stephanodiscus hantzschii (SH) irregular + Thalassionema nitzschoides (TN) Oct to Apr + Aulacoseira granulata (AuG) Oct to Apr + Pleurosigma salinarum (PS) Oct to Apr + Amphiprora gigantea (AG) Oct to Mar + Coscinodiscus excentricus (CEx) Oct to Mar + Nitzschia delicatissima (Ndeli) Oct to Apr + Odontella aurita (Oau) Nov to Mar + Biddulphia dubia (Bdu) Nov to Mar + + = ≤1 × 104 cells/L + + = ≥1 × 10 4 to ≤5 × 104 cells/L + + + = ≥5 × 10 4 to ≤1 × 105 cells/L + + + + = ≥1 × 105 to 20 × 105 cells/L were green algae without any blue green algal as compared to other sampling stations. The members (Fig. 5.3d). Total phytoplankton cell population was represented by green algae and count was signifi cantly higher in this period as diatoms only with no record of cyanobacterial compared to other seasons. This was due to increase taxa. The phytoplankton population at the estua- in cell count of individual taxa. The most abundant rine zone was represented by 25 taxa, out of taxon was Nitzschia delicatissima that contributed which 8 species were green algae and 17 genera to 10.07 % of the population (Table 5.4 ). Pennate were diatoms (Table 5.5 ). Here also, a distinct diatom availability tended to be higher and was rep- pattern of phytoplankton population was resented by taxa like Thalassionema nitzschoides , recorded, where green algae fl ourished mainly in Pleurosigma salinarum , Bacillaria paxillifer (syn. the summer and monsoon months, but diatoms Nitzschia paradoxa , www.itis.gov ) Thalassiothrix were more abundant in the post-monsoon and frauenfeldii , etc. Each of the taxon accounted for winter periods. Here, unlike other stations, a more than 5 % of the population. Centric diatom single genus could not be ascertained as most taxa like Biddulphia dubia and Coscinodiscus abundant taxon. excentricus also made signifi cant contributions to In summer, green algal population was domi- the phytoplankton population. nant, contributing to 69.46 % of the total phyto- At Kakdweep, the estuarine coastal station, plankton population along with diatoms that minimum phytoplankton diversity was recorded accounted for 30.54 % of the population (Fig. 5.4a). 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 99 a b 14.66 30.54

69.46 85.34

Bacillariophyta Bacillariophyta c d 2.006

97.994 100 Bacillariophyta Bacillariophyta

Fig. 5.4 Percentage seasonal contributions of different algal groups to the total phytoplankton population: (a ) summer, (b ) monsoon, ( c ) post-monsoon and (d ) winter at the estuarine station (Kakdweep)

The most abundant taxon was Kirchneriella lunaris Table 5.6 Showing percentage abundance of dominant that made up to 13.81 % of total population. Other phytoplankton genera at the estuarine zone (Kakdweep) dominant taxa were Scenedesmus brevicauda and Maximum S. dimorphus that contributed to 12.53 % and contribution to 11.43 % of the population, respectively (Table 5.6 ). Season Dominant species total population In monsoon, a shift in phytoplankton species Summer Kirchneriella lunaris 13.81 Monsoon Thalassiothrix 13.73 composition was recorded with a drop in green frauenfeldii algal population (14.66 %) and a rise in diatom Post- monsoon Thalassionema 15.54 population (85.34 %) (Fig. 5.4b ). On a generic nitzschoides level, the most abundant taxon was Thalassiothrix Winter Thalassionema 20.49 frauenfeldii with a contribution of 13.73 % to the nitzschoides total population (Table 5.6 ). Other major genera that fl ourished in this period were Ditylum bright- of the total phytoplankton population. On the other wellii and Stephanodiscus hantzschoides , each of hand, diatom population continued to increase and which accounted for more than 10 % of the popu- made up to 98 % of the total population in this lation. Green algal population was represented by period (Fig. 5.4c ). Diatom population was repre- genera like Rhizoclonium riparium , Kirchneriella sented by several genera, among which the most lunaris , Ankistrodesmus falcatus and Crucigenia abundant taxa was Thalassionema nitzschoides tetrapedia although their total counts were much contributing more than 15 % of the total popula- lower as compared to diatoms. tion. The other dominant genera were Paralia In the post-monsoon period, as seasonal pre- sulcata , Nitzschia delicatissima , Aulacoseira cipitation reduced, phytoplankton species compo- granulata and Thalassiothrix frauenfeldii . sition changed. The green algal availability As winter appeared, almost the entire popula- decreased further and contributed to only 2.006 % tion was represented by diatoms (Fig. 5.4d ). Total 100 5 Case Study cell count was signifi cantly higher in this period as In monsoon also, the centric diatom population compared to other seasons with an increase in cell was high as compared to pennate population count of individual taxa. The most abundant taxon (Fig. 5.5b). The population of Odontella rhom- was Thalassionema nitzschoides that contributed bus continued as dominant genus in monsoon to 20.49 % of the population. Centric diatom abun- months, accounting for 13.48 % of total popula- dance tended to be higher as compared to pennate tion. Other relatively abundant taxa were taxa, represented by genera like Aulacoseira gran- Odontella mobiliensis and Ditylum brightwellii , ulata, Pleurosigma salinarum, Coscinodiscus each with cell counts of > 100 cells/mL. Members excentricus and Biddulphia dubia. Each genus of Chaetoceros spp. appeared only during mon- accounted for more than 5 % of the population. soon period at this zone. Taxa like C. diversus Pennate diatom taxa like Thalassiothrix frauen- (7.64 %) and C. messanensis (7.73 %) were quite feldii , Nitzschia delicatissima and Amphiprora abundant at this time. During this period, there gigantea also made signifi cant contributions to the was a steady rise in abundance of centric diatoms phytoplankton population (Table 5.6). which made up to 80.48 % of total count. At the coastal marine region, the phytoplank- During post-monsoon period, population of ton population was represented by 41 taxa centric diatoms (62.4 %) began to recede with a belonging to 26 genera. The phytoplankton fl ora rise in pennate population (37.6 %). The most was represented mainly by diatoms. Only two abundant genus was Biddulphia alternans con- genera of Dinophyta, namely, Dinophysis and tributing to 16.05 % of population (Fig. 5.5c ). Gymnodinium , were recorded during the study Other dominant centric members were Biddulphia period (Table 5.7 ). A few genera like Bacillaria dubia and Odontella aurita . Among pennate paxillifer , Nitzschia pacifi ca , Amphiprora gigan- members, taxa like Thalassiothrix frauenfeldii , tea , Biddulphia heteroceros , Aulacoseira granu- Thalassionema nitzschoides, Diploneis weissfl o- lata , Coscinodiscus granii , Surirella fastuosa , gii and Diploneis interrupta were important Chaetoceros curvisetus, Eucampia zoodiacus members of the total phytoplankton population. and Aulacodiscus johnsonii occurred rarely in the As winter approached, there was a signifi cant study area. From the present study a distinct sea- drop in freshwater input to the coastal marine sonal trend in phytoplankton population of this waters along with a gradual decrease in tempera- coastal station could be elucidated as follows. ture as well. This further resulted in shifting of In summer, a total of 12 taxa represented the species composition of the population. In this phytoplankton population. Centric diatom genera period, there was a sharp rise in pennate diatom (82.69 %) were more abundant as compared to population primarily due to a high growth rate of pennate genera (17.31 %) (Fig. 5.5a ). The most the taxon Asterionella japonica . Pennate genera abundant taxa were Odontella rhombus and contributed for >80 % of total population with Asterionella japonica , with contributions of A. japonica contributing for 77.35 % of the popu- 24.06 % and 11.59 % to the total population, lation (Fig. 5.5d ). Centric diatom population was respectively (Table 5.8 ). The population of represented by several taxa like Coscinodiscus Odontella rhombus gradually increased in the spp., Biddulphia spp., Paralia sulcata , Ditylum summer months with cell count of > 700 cells/mL brightwellii , Stephanodiscus hantzschii , etc. in June 2005. Cocconeis dirupta appeared in the month of May 2005 that accounted for 25 % of the 5.4.2.2 Analysis of Physicochemical phytoplankton population. Rest of the diatom gen- Parameters of the Study Area era contributed 5–25 % of the total phytoplankton The eastern coast of India is rich in nutrients and population and appeared seasonally. The sudden light which is suffi cient to support phytoplankton appearance of Skeletonema costatum with a high population. Therefore, light and nutrients never cell count was another major taxon recorded in the acted as limiting factors in the study area although month of June 2006 that contributed to 50.31 % of the phytoplankton production was hampered due the total plankton population. to the silt contents along with other anthropogenic 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 101

Table 5.7 Floristic list of phytoplankton genera recorded during the study period from coastal marine region Division Name of genera Period of availability Abundance Bacillariophyta Asterionella japonica (AJ) Almost throughout the year + + + + Odontella rhombus (OR) Apr to Oct + + + Odontella mobilensis (OM) Mar to Oct + + Odontella aurita (OAu) Oct to Mar + + Biddulphia alternans (Balt) Aug to Jan + + Biddulphia dubia (Bdu) Oct to Mar + + Biddulphia heteroceros (BH) Oct, Nov + Gyrosigma obtusatum (GOb) Mar to July + Gyrosigma acuminatum (GAcu) Feb to Apr + Pleurosigma normanii (PN) Dec to Mar + Cyclotella meneghiniana (CM) Almost throughout the year + + Coscinodiscus perforatus (CP) Almost throughout the year + + Coscinodiscus centralis (CC) Nov to Apr + + Coscinodiscus excentricus (CE) Apr to July + + Actinocyclus normanii f. subsala (AN) June to Oct + + Coscinodiscus granii (CG) Oct, Nov + Nitzschia delicatissima (ND) Apr to July + + Nitzschia sigmoidea (NS) Apr + Cyclotella striata (CS) May to Sept + Stephanodiscus hantzschoides (SH) Nov (2006) + + Thalassiosira decipiens (TD) Mar (2007) + Cocconeis dirupta Aug to Mar Rare Ditylum brightwellii (DB) May (2005) + + Chaetoceros curvisetus Almost throughout the year + + Surirella fastuosa (SF) June, July (2005) Rare Bacteriastrum varians (BV) June, Oct + Chaetoceros diversus (CD) Mar + Diploneis interrupta (DI) July to Sept + + Diploneis weissfl ogii (DW) July to Nov + Aulacoseira granulata (AuG) Oct, Nov + Chaetoceros wighami (CW) July to Nov + Chaetoceros messanensis (ChM) July to Oct + Thalassiothrix frauenfeldii (TF) July to Oct + + Thalassionema nitzschioides (TN) Aug to Oct + + Bacillaria paxillifer (BPax) Aug to Feb + + Nitzschia pacifi ca n. sp. (Npac) Nov to Jan + + Amphiprora gigantea (AG) Mar, Oct + Eucampia zoodiacus Oct, Nov + Oct, Nov Rare Skeletonema costatum June (2006) Rare March (2006) Rare Dinophyta Gymnodinium sp. May (2005) Dinophysis sp. May (2005) + = ≤1 × 104 cells/L + + = ≥1 × 104 to ≤5 × 104 cells/L + + + = ≥ 5 × 104 to ≤1 × 105 cells/L + + + + = ≥1 × 10 5 to 20 × 10 5 cells/L 102 5 Case Study ab 17.31% 19.52%

82.69% 80.48% centric pennate centric pennate cd18.00% 37.60%

62.40% 82.00% centric pennate centric pennate

Fig. 5.5 Percentage seasonal contributions of centric and pinnate diatoms to the total phytoplankton population: (a ) summer, ( b ) monsoon, (c ) post-monsoon and (d ) winter at the coastal marine region (Junput and Digha)

Table 5.8 Showing percentage abundance of dominant from 7 to 8.3 in the entire study area. The nutrient phytoplankton genera at the coastal marine zone (Junput content especially with respect to dissolved inor- and Digha) ganic nitrogen (DIN) and dissolved inorganic Maximum phosphate (DIP) were comparatively higher in contribution to total the freshwater station and estuarine station than Season Dominant species population (%) at the marine region. On the contrary, dissolved Summer Skeletonema 26.63 costatum silicate (DSi) contents showed an opposite trend Monsoon Odontella rhombus 13.48 with higher values at the marine region in com- Post- monsoon Biddulphia 16.05 parison to the other stations. alternans Results showed that the habitat water of the Winter Asterionella 77.35 freshwater station was weakly alkaline with the japonica pH ranging from 7.0 to 8.3 with the mean pH of 7.57 (Fig. 5.6a ). During the drier months of sum- factors. Salinity variations were pronounced that mer and winter, the pH was relatively high, rang- varied from 0 to 36 psu. Seasonal precipitation ing from 7.5 to 8.3 showing pH maxima in and heavy riverine infl ow especially in the mon- summer for both 2005 and 2006. As expected, soon months played an important role in lower- water temperature was also maximum in summer ing the salinity levels at all stations. This being a and minimum in winter. Salinity was relatively tropical coastline, there is a prolonged summer low with a mean of 2.2 psu which reached as low (April–May–June) with an average temperature as 0 psu in monsoon period due to high infl ux of of 35 ± 5 °C and a long monsoon season (July– freshwater from perennial rivers, along with August–September) with an average temperature heavy seasonal precipitation (Fig. 5.6c ). of 35 ± 2 °C. Winter (November–December– Maximum salinity at this hypo saline station was January) is comparatively mild with a mean recorded in winter, reaching as high as 5 psu in temperature of 12 ± 5 °C. The pH level varied January 2006, when seasonal precipitation as 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 103 ab 8 35 pH Water temp. 7.8 30 7.6 25 7.4 20 7.2 C pH o 7 15

6.8 10

6.6 5 6.4 0 July, 05 May, '06 May, '07 July, '06 March'07 March'06 July, 05 November May, '06 May, '07 July, '06 September September January'07 January'06 March'06 March'07 November November'06 September September January'06 January'07 November'06 Months Months

c 18 Salinity 16 14 12 10

psu 8 6 4 2 0 July, 05 May, '07 May, '06 July, '06 March'07 March'06 November September September January'07 January'06 November'06 Months

Fig. 5.6 Monthly variations in ( a) pH, ( b) water temperature and ( c) salinity at the freshwater station (Diamond Harbour) well as riverine infl ow of freshwater was mini- (DIP) content of the habitat water varied from mal. In monsoon, minimum values for both salin- 2.23 to 9.44 μM, showing maximum value in ity and pH were recorded. September 2005 (9.44 μM) and minimum in DIN contents of the habitat water were high December 2006 (2.23 μM) (Fig. 5.7c ). Dissolved along the entire study period, which ranged from silicate (DSi) contents in the habitat waters were 50.12 μM (February 2007) to 104.36 μM comparatively higher – ranging from 42.61 (September 2006) (Fig. 5.7a ). The concentrations (September 2005) to 90.77 μM (November 2005) of nitrite (1.086–11.263 μM) and ammonia (Fig. 5.7d ). Seasonally, both DIN and DIP con- (0.294–4.41 μM) (Fig. 5.7a , b) nitrogen were low tents of the habitat waters were maximum in in comparison to nitrate (43.66–95.42 μM) nitro- monsoon (DIN, 90.22 μM; DIP, 7.45 μM in gen. Nitrate nitrogen accounted for 85–90 % of 2005), intermediate in post-monsoon (DIN, DIN (Fig. 5.7a). Dissolved inorganic phosphate 75.31 μM; DIP, 5.17 μM in 2005) and minimum 104 5 Case Study ab 120 5 Nitrate Ammonia 4.5 100 Nitrite DIN 4 80 3.5 3 60 uM 2.5 uM 40 2 1.5 20 1 0 0.5 0 July, 05 May, '06July, '06 May, '07 5 r 6 6 r 7 March'06 March'07 06 November September , 0 '0 '06 ' '0 '07 September January'06 January'07 er h November'06 ly mbe ch y, u te b a J p vember May, July, '0 m M e Mar Marc S No January'06 Septembe January'07 Months Nove

Months c d 10 100 DIP DSi 9 90 8 80 7 70 6 60 5

uM 50 uM 4 40 3 30 2 20 1 10 0 0

July, 05 March'06May, '06July, '06 March'07May, '07 November September January'06 September January'07 July, 05 May, '06July, '06 May, '07 November'06 March'06 March'07 SeptemberNovemberJanuary'06 September January'07 November'06

Months Months

Fig. 5.7 Monthly variations in ( a) DIN (dissolved inorganic nitrogen), (b ) ammonia, (c ) DIP (dissolved inorganic phosphate) and (d ) DSi (dissolved phosphate) at the freshwater station (Diamond Harbour) in winter (DIN, 54.24 μM; DIP, 3.21 μM in signifi cant positive correlation with DSi ( R 2 = 0.26, 2005–2006). This trend persisted for the entire r = 0.51 at p < 0.05) (Fig. 5.8b ) but negative cor- study period with insignifi cant inter-annual vari- relation with seasonal temperature variations ation. DSi represented an opposite pattern where ( R2 = 0.36, r = −0.6 at p < 0.05) (Fig. 5.8c ). lower values were recorded in the monsoon In the habitat water of the estuarine station months and higher values in winter months. (Kakdweep), the pH level ranged from 7 to 7.8 Signifi cant negative correlation was estab- (Fig. 5.9a) and the water temperature from lished between DIN and phytoplankton cell 13.9 °C (January 2007) to 30 °C (June 2007) counts (R 2 = 0.25, r = −0.49 at p < 0.05) (Fig. 5.8a ). (Fig. 5.9b ). Maximum salinity level was recorded On the other hand, diatom population showed in summer (April and May 2006, April and June 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 105 ab

120 100 DIN Linear (DIN) 90 100 80 DSi Linear (DSi) 80 70 60

60 50 DIN (uM) DSi (uM) 40 40 30

20 20

10 0 0 0 500000 1000000 1500000 2000000 0 500000 1000000 1500000 2000000 R2 = 0.2456 cell counts/L R2 = 0.265 cell counts/L

c 35 Water temp. Linear (Water temp.) 30

25

20 C o 15

10

5

0 0 500000 1000000 1500000 2000000

R2 = 0.3636 cell counts/L

Fig. 5.8 Graphical representation of signifi cant correlation between (a ) cell count and DIN, (b ) cell count and DSi and ( c ) cell count and water temperature at the freshwater station (Diamond Harbour)

2007, 17 psu), which dropped in monsoon period (Fig. 5.10b ). Nitrite concentration was intermediate (August 2006, 4 psu) (Fig. 5.9c ). that ranged from 40.22 μM (August 2005) to DIN (dissolved inorganic nitrogen) contents 14.39 μM (November 2005). Phosphate concen- fl uctuated seasonally as well as temporally trations did not represent a very regular and (Fig. 5.10a ). Nitrate content was maximum in recurrent pattern of variation in the data set which August 2006 (87.25 μM) with minimum value in ranged from 2.15 to 9.37 μM (Fig. 5.10c ). Silicate June 2007 (45.32 μM), which suggested that concentration was quite high in comparison to comparatively low levels of nitrate in summer phosphate levels throughout the year, ranging and high amount during monsoon months. Unlike from 49.93 μM to 129.82 μM with highest nitrate, ammonia content was signifi cantly lower value in August 2005 and lowest in December with the mean concentration being only 0.69 μM 2006 (Fig. 5.10d ). Therefore, in the study area 106 5 Case Study ab 8 35 pH Water temp. 7.8 30 7.6 25 7.4 20

7.2 C o pH 7 15

6.8 10

6.6 5 6.4 0 July, 05 May, '06 May, '07 July, '06 March'06 March'07 July, 05 November May, '07 May, '06 July, '06 September September January'06 January'07 March'07 March'06 November September September January'06 January'07 November'06 November'06 Months Months

C 18 16

14

12

10

psu 8

6

4

2 Salinity 0 July, 05 May, '06 May, '07 July, '06 March'06 March'07 November September September January'07 January'06 November'06 Months

Fig. 5.9 Monthly variations in (a ) pH, (b ) water temperature and (c ) salinity at the estuarine station (Kakdweep) nutrient concentration was maximum in monsoon tive correlation was established between cell period and minimum in the winter and summer count and temperature only ( R2 = 0.31, r = −0.55, months. p < 0.05) (Fig. 5.12c ). Correlation matrix and 2-D scatter plots were The marine coastal region showed different performed based on Pearsonian ‘r ’ values which physicochemical statuses in comparison to the showed that cell count had negative signifi cant other two stations. The temperature and pH value correlation with nitrite (R 2 = 0.27, r = −0.52, of the coastal water of the study area ranged from p < 0.05) (Fig. 5.11a), ammonia (R 2 = 0.21, 15–30 °C to 7–7.6, respectively (Fig. 5.13a , b). r = −0.45, p < 0.05) (Fig. 5.11b), DIN (R 2 = 0.2, Minimum temperature was observed in winter r = −0.45, p < 0.05) (Fig. 5.12a ) and DSi (R 2 = 0.51, and minimum pH value in monsoon. Maximum r = −0.71, p < 0.05) (Fig. 5.12b) with no signifi - salinity level was recorded in winter (36 psu), cant correlation with nitrate and DIP (Table 5.7 ). which dropped in monsoon period (26 psu) Among the physical parameters signifi cant nega- (Fig. 5.13c ). As evident from Fig. 5.16, DIN con- 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 107 ab 140 1.2 nitrate ammonia nitrite 120 1 DIN 100 0.8 80 0.6 uM 60 uM

40 0.4

20 0.2

0 0

July, 05 May, '06July, '06 May, '07 March'06 March'07 July, 05 SeptemberNovemberJanuary'06 September January'07 March'06May, '06July, '06 March'07May, '07 November November'06 September January'06 September January'07 November'06 Months Months c d 10 140 DIP DSi 9 120 8 7 100 6 80 5 uM uM 4 60 3 40 2 20 1

0 0

July, 05 July, 05 May, '06July, '06 May, '07 March'06May, '06July, '06 March'07May, '07 March'06 March'07 November SeptemberNovemberJanuary'06 September January'07 September January'06 September January'07 November'06 November'06 Months Months

Fig. 5.10 Monthly variations in (a ) DIN (dissolved inorganic nitrogen), (b ) ammonia, (c ) DIP (dissolved inorganic phosphate) and (d ) DSi (dissolved phosphate) at the estuarine station (Kakdweep) tent was maximum in October 2006 (28.48 μM) Maximum phosphate concentration was estimated with minimum value in December 2005 in August 2005 (9.41 μM) and minimum in (14.32 μM) (Fig. 5.14a ). Like the freshwater and December 2005 and January 2006 (2.23 μM; estuarine stations, nitrate concentrations were Fig. 5.14c ). Therefore, in the study area nutrient primarily responsible for the variations of DIN concentration was maximum in monsoon period. contents of the habitat waters. Nitrite concentra- Silicate concentration was quite high in compari- tions were intermediate which was maximum in son to nitrate and phosphate levels throughout September 2005 (3.67 μM) and minimum in the year, ranging from 19.97 to 127.32 μM with March 2007 (1.45 μM). Ammonia concentra- highest value in August 2005 and lowest in tions remained low and seldom reached above January 2006 (Fig. 5.14d ) favouring the diatom 1 μM levels in the habitat waters (Fig. 5.14b ). growth. 108 5 Case Study a b 45 1.2 nitrite ammonia 40 Linear Linear (ammonia) 1 35

30 0.8 25 0.6 20 Nitrite(uM) 15 ammonia (uM) 0.4 10

5 0.2

0 0 50000 100000 150000 200000 250000 0 0 50000 100000 150000 200000 250000 R2 = 0.2737 cell counts/L R2 = 0.2061 cell counts/L

Fig. 5.11 Graphical representation of signifi cant correlation between (a ) cell count and nitrite and (b ) cell count and ammonia at the estuarine station (Kakdweep)

Correlation matrix (Table 5.9 ) and 2-D scatter (Fig. 5.16). Seasonal variation with respect to plots were performed based on Pearsonian r values, cell count was well evident at all the sampling which showed that cell count had signifi cant stations, where winter season was the most pro- negative correlation with DIN (R 2 = 0.28, ductive and monsoon was the least. Gradual r = −0.52, p < 0.05) (Fig. 5.15a ) and dissolved decreases in cell count were recorded from the silicate ( R2 = 0.23, r = −0.48, p < 0.05) (Fig. 5.15b ) summer to monsoon period whereas gradual and nonsignifi cant with phosphate and temperature increases in cell count from the post-monsoon but positive signifi cant correlation with salinity to the winter period were observed. Cell count (R 2 = 0.3, r = 0.54, p < 0.05) (Fig. 5.15c ) and pH of individual species may have played a signifi - (R 2 = 0.22, r = 0.57, p < 0.05) (Fig. 5.15d) at n = 24 cant role in determining the diversity of this (Table 5.8 ). coastal region. At the freshwater region, total cell counts ranged from 65 cells/mL (August 5.4.2.3 Phytoplankton Population 2006) to 1,820 cells/mL (December 2005). At in Terms of Cell Count and Their the estuarine location, it ranged from 9 cells/ Biotic Indices mL (August 2006) to 203 cells/mL (December The fi ndings of our study showed that along 2005). Likewise, cell count ranged from coastal West Bengal, a signifi cant variation of 345 cells/mL (April 2006) to 2,020 cells/mL phytoplankton population was related to seasonal (January 2006) at the marine coastal region. variations and physicochemical parameters of Diversity of phytoplankton population at habitat waters. On an average, among all the sam- coastal West Bengal showed distinct variations on pling stations, the total cell count was maximum a monthly as well as on a seasonal basis in terms at marine coastal zone (mean = 986 cells/mL) and of different biotic indices. Diversity, measured on minimum at the estuarine location (mean = 97 cells/ the basis of Shannon–Wiener Index (SWI), was mL) while the freshwater zone occupied an maximum at the freshwater station (Mean intermediate position (mean = 439 cells/mL) H′ = 2.67), intermediate at the estuarine station 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 109 ab 120 140 DIN DSi Linear (DIN) Linear (DSi) 120 100

100 80

80

60

DSi (uM) 60 DIN (uM)

40 40

20 20

0 0 0 50000 100000 150000 200000 250000 0 50000 100000 150000 200000 250000

R2 = 0.199 cell counts/L R2 = 0.507 cell counts/L

c 35 Water temp. Linear (Water temp.) 30

25

20 °C 15

10

5

0 0 50000 100000 150000 200000 250000 R2 = 0.3051 cell counts/L

Fig. 5.12 Graphical representation of signifi cant correlation between (a ) cell count and DIN, (b ) cell count and DSi and (c ) cell count and water temperature at the estuarine station (Kakdweep)

(Mean H′ = 2.278) and minimum at the marine Species evenness is a measure of the contribu- region (Mean H′ = 1.90) (Fig. 5.17 ). Higher values tions of individual taxa to the phytoplankton for SWI were recorded in the transition period population. It was found that seasonal variation (March) between winter and summer months at in species evenness was more pronounced at the the freshwater station, whereas it was maximum marine region as compared to the other stations. during post-monsoon period at the estuarine and At the freshwater station (Diamond Harbour), the coastal stations. On the other hand, minimum SWI varied from 2.13 to 3.23. On a monthly values for SWI were recorded in winter at marine basis, maximum value was recorded in November and estuarine region, whereas it was minimum in 2006 (H′ = 3.23) whereas minimum value was in monsoon at the freshwater station. October 2005 (H′ = 2.13) (Fig. 5.18 ). Maximum 110 5 Case Study a b 7.7 35 7.6 30 7.5

7.4 25 7.3 20 7.2 °C pH 7.1 15 7 10 6.9

6.8 5 6.7 0 6.6 5 6 0 05 er 06 06 07 6 , , b ' '06 t' 06 05 06 e s , , '06 r'0 n e, '06 be Octo ruary' October une tober'06 April, 05Ju April, Jun April June, 05 April, '06J August Decemberbruary Augu August, 05 December August'06 e October'0 February' Oc F Feb Decem Februar y'07 December' Months Months

c 40

35

30

25

20 psu

15

10

5

0

er 06 06 06 b r' '07 l, 05 y' st' e ne, 05 ar b u uary Apri Ju Octo cemberr to r e April, June,'06 Augu'06 c August, 05 D eb O F Feb December'06

Months

Fig. 5.13 Monthly variations in (a ) pH, (b ) water temperature and (c ) salinity at the coastal marine region (Digha and Junput) SWI was recorded in the transition period evenness was not very pronounced in this station between the summer and winter months (March). although seasonal fl uctuations were observed. The subsequent summer months (April–May– Seasonally, it was maximum during summer June) also showed a comparatively high SWI val- (e = 2.17) and minimum in winter ( e = 2.09) ues. SWI values were intermediate in the closely followed by the post-monsoon period post-monsoon period although there was signifi - (e = 2.1) (Fig. 5.20 ). cant interannual variations. On the contrary, min- At the estuarine coastal station (Kakdweep), imum SWI values were obtained in the monsoon SWI varied from 1.88 to 2.53. Highest value of months (Fig. 5.19). The mean species evenness SWI was recorded in the post-monsoon period (e ) was relatively high as compared to the other (October–November) whereas lowest value of coastal stations ( e = 2.13). Variation in species the same was recorded in winter (December– 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 111 ab

30 1.4 Nitrate

25 Nitrite 1.2 DIN

20 1

15 0.8 uM uM 10 0.6 Ammonia

0.4 5

0.2 0 6 0 '06 r' , '06 e 0 ne April, 05June, 05 October April, Ju tob 6 6 December August'06 t'0 August, 05 February'06 Oc February'07 l, '06 , '06 s er'06 December'06 tober ri une ob April, 05June, 05 Oc Ap J ugu mber'06 December A August, 05 February'0 Oct ece February'07 D Months Months cd 10 140 DIP Silicate 9 120 8 100 7

6 80 uM 5 uM 60 4

3 40

2 20 1 0 0 5 6 0 05 er 06 0 6 r' 06 ob e , 05 mber , '06 er'06 ne, '06 gust, Oct pril, '06u April, June, u05 ece A J April, 05June, 05 October April, '06June A D August'06 December August'06 February' Octob February'07 August February' Octob February'07 December'06 December'0 Months Months

Fig. 5.14 Monthly variations in (a ) DIN (dissolved inorganic nitrogen), (b ) ammonia, (c ) DIP (dissolved inorganic phosphate) and (d ) DSi (dissolved phosphate) at the coastal marine region (Digha and Junput)

January–February) (Figs. 5.20 and 5.21). The (e = 2.21) followed by the transition period subsequent summer months also showed a (March) and minimum in post-monsoon comparatively high SWI values which dropped ( e = 2.14) closely followed by summer ( e = 2.15) slightly in the monsoon periods. The mean spe- (Fig. 5.21 ). cies evenness ( e ) was higher as compared to the At the marine coastal region, SWI varied from freshwater station (e = 2.17). Variation in species 0.33 to 2.76. Highest value of SWI was recorded evenness was not very pronounced in this station in the post-monsoon period (October–November), although seasonal fl uctuations were observed. whereas lowest value of the same was recorded in Seasonally, it was maximum during monsoon winter (Fig. 5.22 ). A gradual increase in SWI was 112 5 Case Study

CRR

NPP

GPP

DO

BOD

Water temp. Water

pH

Saln

= 24) DSi N

< .05000 p DIP cant at

DIN

Cell count −0.60 0.65 0.52 −0.56 −0.80 0.06 0.45 −0.70 −0.71 −0.70 −0.20 −0.50 −0.75 0.51 0.61 0.21 −0.60 −0.64 0.72 0.89 0.91 0.05 Correlation matrix plot between cell count , productivity and environmental variables at the freshwater station station at the freshwater variables and environmental , productivity Correlation matrix plot between cell count −0.64 0.64 0.71 −0.21 −0.71 −0.49 0.45 −0.80 −0.68 −0.59 −0.33 0.05 −0.40 −0.35 0.30 0.49 0.47 −0.20 −0.33 0.19 0.17 −0.09 0.89 −0.60 −0.74 0.64 0.76 0.23 −0.71 −0.68 0.76 0.96 0.17 0.91 −0.49 −0.64 0.55 0.63 0.06 −0.70 −0.59 0.72 0.96 −0.09 0.61 −0.80 −0.78 0.59 0.46 −0.80 −0.71 0.79 0.76 0.63 0.49 −0.50 0.58 −0.36 −0.80 −0.42 0.65 0.64 −0.64 −0.60 −0.49 −0.40 −0.75 0.58 −0.59 −0.78 −0.63 0.52 0.71 −0.73 −0.74 −0.64 −0.35 0.51 −0.36 −0.59 0.59 0.22 −0.56 −0.21 0.44 0.64 0.55 0.30 0.72 −0.64 −0.73 0.44 0.79 0.24 −0.70 −0.80 0.76 0.72 0.19 0.21 −0.42 −0.63 0.22 0.46 0.06 −0.49 0.24 0.23 0.06 0.47 Cell count DIN DIP DSi Saln pH temp. Water BOD DO GPP NPP CRR correlations are signifi Correlations (marked Table Table 5.9 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 113 ab 30 140

120 25

100 20

80 15 60 DIN (uM) DSi (uM)

10 40

5 20

0 0 0 1000000 2000000 3000000 4000000 0 1000000 2000000 3000000 4000000

R2 = 0.2739 Cell counts/L R2 = 0.2309 cell counts/L cd 40 7.7

35 7.6

30 7.5

7.4 25

7.3

20 pH psu 7.2 15

7.1 10 7 5 6.9 0 0 1000000 2000000 3000000 4000000 0 1000000 2000000 3000000 4000000

R2 = 0.2936 cell counts/L R2 = 0.2158 cell counts/L

Fig. 5.15 Graphical representation of signifi cant correlation between (a ) cell count and DIN, (b ) cell count and DSi and (c ) cell count and salinity and (d ) cell count and pH at the coastal marine region (Digha and Junput)

recorded from July onwards reaching maximum Seasonally, the coastal marine region showed in October (2.76) (Fig. 5.22 ). In winter months, a similar pattern in diversity as was observed in SW Index dropped drastically when single spe- the freshwater and estuarine stations. Highest cies abundance of Asterionella japonica was very value of SWI was recorded in the post-monsoon high and contributed to more than 90 % of the period (October–November) whereas lowest total phytoplankton population (Fig. 5.23 ). value of the same was recorded in winter Similarly, SWI values were relatively low in (December–January–February) (Fig. 5.24 ). The summer months as well, when Odontella rhom- subsequent summer months also showed a com- bus population contributed to >47 % of the total paratively low SWI values which gradually population. increased in the monsoon and post-monsoon 114 5 Case Study

3500 Est 3000 FW MR 2500

2000

1500 cells/mL

1000

500

0

April, 05 June, 05 October April, '06June, '06 August, 05 December August'06 February'06 October'06 February'07 December'06

Months

Fig. 5.16 Monthly variations in total cell count (cells/mL) at the three sampling stations (FW freshwater station, Est estuarine station, and MR coastal marine region)

3.5

3

2.5

2

H' (SWI) 1.5

1

MR 0.5 Est FW

0

July, 05 May, '06 July, '06 May, '07 March'06 March'07 SeptemberNovemberJanuary'06 September January'07 November'06

Months

Fig. 5.17 Monthly variations in Shannon–Wiener Index at the three sampling regions (FW freshwater station, Est estuarine station, and MR coastal marine region) 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 115

3.5

3

2.5

2

1.5

bits/individual SWI

Sp.Evenness 1

0.5

0

July, 05 March'06 May, '06July, '06 March'07May, '07 SeptemberNovemberJanuary'06 September January'07 November'06

Months Fig. 5.18 Monthly variations in Shannon–Wiener Index (SWI ) and species evenness at the freshwater station (Diamond Harbour)

2.18 3.5 e

H' 3 2.16

2.5 2.14

2 e

2.12 H' 1.5

2.1 1

2.08 0.5

2.06 0 Summer monsoon Post - winter March monsoon Seasons

Fig. 5.19 Seasonal variations in Shannon–Wiener Index ( SWI) and species evenness at the freshwater station (Diamond Harbour) 116 5 Case Study

3

2.5

2

1.5 bits/individual 1

e 0.5 H'

0

July, 05 March'06 May, '06 July, '06 March'07 May, '07 SeptemberNovemberJanuary'06 September January'07 November'06 Months

Fig. 5.20 Monthly variations in Shannon–Wiener Index ( SWI ) and species evenness at the estuarine station (Kakdweep)

3 e H' 2.5

2 e H' 1.5

1

0.5

0 summer monsoon post - winter transition monsoon

Seasons

Fig. 5.21 Seasonal variations in Shannon–Wiener Index (SWI ) and species evenness at the estuarine station (Kakdweep) 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 117

3 H' e 2.5

2

1.5 bits/individual 1

0.5

0

April, 05 June, 05 June, '06 August, 05 April, '06 August'06 October’05 February'06 October'06 February'07 December’05 December'06

Months

Fig. 5.22 Monthly variations in Shannon–Wiener Index (SWI ) and species evenness at the coastal marine region (Junput and Digha)

periods. The mean species evenness (e ) was especially for diatoms. On an individual site much lower as compared to the other stations basis, phytoplankton productivity was maximum (e = 0.75). Variation in species evenness was pro- at the coastal marine region and minimum at the nounced in this station both on a monthly as well estuarine region with the freshwater station occu- as on a seasonal basis. Seasonally, it was maxi- pying an intermediate position. CRR values also mum during monsoon (e = 0.92) followed closely represented a similar pattern as was observed for by the post-monsoon period (e = 0.92) and mini- primary productivity. Seasonally, winter months mum in winter (e = 0.42) (Fig. 5.24 ). The pattern were most productive and monsoon periods were of variations for both SWI and species evenness least productive. DO values being a refl ection of was almost similar with signifi cant decrease in the photosynthetic effi ciency of phytoplankton winter and summer. population showed a similar seasonal pattern as was observed for primary productivity. In con- 5.4.2.4 Primary Productivity trast, BOD values were minimum in winter and (GPP and NPP) and Oxygen maximum in monsoon at all the sampling Concentrations stations. Results show that coastal West Bengal promoted At the freshwater station, winter months were phytoplankton production although there were most productive with respect to carbon equiva- signifi cant seasonal variations. The study area lents as was evident from GPP values. Typically, was highly suitable for the development and monsoon periods were least productive both in diversifi cation of phytoplankton populations respect to phytoplankton productivity (GPP) as 118 5 Case Study

25 A.japonica O.rhombus

20

15 cells/L 5

X10 10

5

0

April, 05June, 05 October April, '06 June, '06 August, 05 December August'06 February'06 October'06 February'07 December'06

Months

Fig. 5.23 Monthly variations of total cell counts of the two dominant species (Asterionella japonica and Odontella rhombus ) at the coastal marine region

Fig. 5.24 Seasonal 1 3 variations in SW Index and e species evenness at coastal 0.9 H' marine region 2.5 0.8

0.7 2 0.6 e

0.5 1.5 H'

0.4 1 0.3

0.2 0.5 0.1

0 0 summer monsoon post- winter monsoon Seasons 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 119

a 1000 CRR NPP 900 GPP 800 700 mgC 600 /m3/ h 500 400 300 200 100 0 July, 05 March'06 November'06 GPP

Months CRR

b 9 BOD 8 DO

7

6

5

mg/L 4

3

2

1

0

July, 05 May, '06 July, '06 May, '07 March'06 March'07 SeptemberNovemberJanuary'06 September January'07 November'06 Months

Fig. 5.25 Monthly variation in (a ) productivity (NPP, GPP and CRR) and (b ) oxygen concentrations (DO and BOD) at the freshwater station (Diamond Harbour) well as community productivity (NPP) with insig- tion between GPP and cell count (R 2 = 0.8, r = 0.9, nifi cant interannual variations. As can be p ≤ 0.05) was established (Fig. 5.26a ). expected, CRR varied signifi cantly as well, where Dissolved oxygen (DO) was present in opti- maximum CRR was in winter (178.67 mgC/m3 /h) mal quantity in the habitat waters that ranged and minimum in monsoon (86.37 mgC/m 3 /h) from 4.25 mg/L (July 2005) to 7.882 mg/L (Fig. 5.25a ). A highly positive signifi cant correla- (December 2005) (Fig. 5.25b ). Seasonally, DO 120 5 Case Study ab 1000 9

900 8

800 7 700 6 600 /h

3 5 500 GPP Linear (GPP) 4 mgC/m 400 DO (mg/L)

300 3

200 2

100 1

0 0 0 500000 1000000 1500000 2000000 0 500000 1000000 1500000 2000000 R2 = 0.8007 cell counts/L R2 = 0.5128 cell counts/L

c 9

8

7

6

5

4 DO (mg/L) 3

2

1

0 01234 BOD (mg/L) R2 = 0.643

Fig. 5.26 Graphical representation of signifi cant correlation between (a ) cell count and GPP, (b ) cell count and DO and (c ) BOD and DO at the freshwater station showed a similar trend with that of productivity and BOD ( R 2 = 0.64, r = 0.8, p ≤ 0.05, n = 24) and cell count that was maximum in winter (Fig. 5.26c ). (7.32 mg/L) and minimum in monsoon Phytoplankton productivity [Gross Primary (4.59 mg/L). DO contents in the habitat waters productivity (GPP)] at the estuarine station was had positive signifi cant correlation with cell maximum in December 2006 (227.77 mgC/ count (R 2 = 0.51, r = 0.68, p ≤ 0.05, n = 24) m3 /h) when total phytoplankton cell count was (Fig. 5.26b ) whereas BOD, which represented maximum as well (203 cells/mL) and minimum the heterotrophic oxygen requirements, showed in August 2006 (58.95 mgC/m 3 /h) (Fig. 5.27a ). an opposite pattern with maximum values in Seasonally, maximum productivity with respect monsoon and minimum values in winter. Thus, a to carbon equivalents was recorded in winter negative correlation was observed between DO when cell counts showed highest values as well 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 121

a 250 CRR NPP 200 GPP

mgC 150 /m3/ h 100

50

CRR 0 July, 05 February'06 September April, '07 Months

b 9 BOD 8 DO

7

6

5

mg/L 4

3

2

1

0

July, 05 March'06 May, '06July, '06 March'07May, '07 SeptemberNovemberJanuary'06 September January'07 November'06

Months

Fig. 5.27 Monthly variation in (a ) productivity (NPP, GPP and CRR) and (b ) oxygen concentrations (DO and BOD) at the estuarine station (Kakdweep)

(136 cells/mL). On the contrary, minimum pro- primary productivity (NPP), which was maxi- ductivity with respect to both carbon equivalents mum in November 2006 (137.78 mgC/m 3 /h) and as well as total phytoplankton cell counts was minimum in August 2006 (42.72 mgC/m 3 /h). An recorded in the monsoon months (cells/mL) intermediate signifi cant positive correlation was (Fig. 5.27a). Results of 2-D scatter plot shows established between phytoplankton cell count and highly signifi cant positive correlation between NPP (R 2 = 0.48, r = 0.7, p < 0.05, n = 24) (Fig. 5.28b ). total phytoplankton cell count and GPP as well Community respiration rate (CRR) being a mea- ( R 2 = 0.84, r = 0.92, p < 0.05, n = 24) (Fig. 5.28a ). sure of catabolic loss of carbon equivalents due Almost similar patterns were observed for net to respiration was minimum in April 2007 122 5 Case Study ab 250 160 GPP NPP Linear (GPP) 140 Linear (NPP) 200 120 /h) /h) 3 3 100 150

80

100 NPP (mgC/m

GPP (mgC/m 60

40 50 20

0 0 0 50000 100000 150000 200000 250000 0 50000 100000 150000 200000 250000

R2 = 0.8407 cell counts/L R2 = 0.4847 cell counts/L cd 9 9 DO DO 8 Linear (DO) 8 Linear (DO)

7 7

6 6

5 5

mg/L 4 4 DO (mg/L)

3 3

2 2

1 1

0 0 0 50000 100000 150000 200000 250000 0 0.5 1 1.5 2 2.5 3

R2 = 0.6632 cell counts/L R2 = 0.607 BOD (mg/L)

Fig. 5.28 Graphical representation of signifi cant correlation between ( a) cell count and GPP, ( b) cell count and NPP, ( c ) cell count and DO and (d ) BOD and DO at the estuarine station (Kakdweep)

(24. 158 mgC/m 3/h) whereas it was maximum in 2.45 mg/L, with highest value in monsoon December 2006 (72.2 mgC/m3 /h) (Fig. 5.27a ). (August 2006) and lowest in winter (January Dissolved oxygen content is a refl ection of the 2007) when DO content was high (Fig. 5.27b ). photosynthetic activity of the phytoplankton From the correlation matrix plot, it was observed biomass. Accordingly DO values were higher in that there was a positive correlation between cell those months where plankton count was high, count and dissolved oxygen content ( R 2 = 0.66, with a maximum of 7.88 mg/L in December 2005 r = 0.81, p < 0.05, n = 24) (Fig. 5.28c ) and nega- and minimum of 4.25 mg/L in July 2006 tive correlation with BOD (R 2 = 0.61, r = −0.46, (Fig. 5.27b). BOD value ranged from 1.18 to p < 0.05, n = 24) (Fig. 5.28d ). 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 123

a CRR 1400 NPP GPP 1200 1000 mgC 800 /m3/ h 600 400 200 0 CRR April, 05 December August'06 Months

b 7 BOD

6 DO

5

4 mg/L 3

2

1

0

April, 05June, 05 October April, '06June, '06 August, 05 December August'06 February'06 October'06 February'07 December'06 Months

Fig. 5.29 Monthly variation in (a ) productivity (NPP, GPP and CRR) and (b ) oxygen concentrations (DO and BOD) at the coastal marine region (Digha and Junput)

At the coastal marine region, maximum pro- in June 2006 (1,191.67 mgC/m 3/h) when GPP ductivity [GPP] was recorded in June 2006 was high as well although NPP was much low (1,330 mgC/m3 /h) and minimum productivity (83.33 mgC/m 3 /h) (Fig. 5.29a ). was recorded in July 2006 (77.78 mgC/m3 /h) On a seasonal basis, highest productivity was (Fig. 5.29a). Highest NPP value was recorded in recorded in winter, followed by summer with the December 2005 (788.88 mgC/m 3 /h) when GPP lowest productivity in monsoon. Regarding (913.34 mgC/m 3/h) also was relatively high whereas productivity, there was interannual variation it was minimum in July 2006 (44.44 mgC/m3/h). where productivity in post-monsoon period was An abruptly maximum CRR value was recorded higher than summer in 2005, unlike in 2006. 124 5 Case Study ab 1600 7 GPP DO Linear Linear (GPP) 1400 6

1200 5

1000 4 800 GPP

mg/L 3 600

400 2

200 1

0 0 0 1000000 2000000 3000000 4000000 0 500000 1000000 1500000 2000000 2500000 3000000 3500000 R2 = 0.8312 cell counts/L R2 = 0.3352 cell counts/L

c 7 DO Linear (DO) 6

5

4

3 DO(mg/L)

2

1

0 012345 y = -0.5455x + 6.5815 BOD (mg/L) R2 = 0.5447

Fig. 5.30 Graphical representation of signifi cant correlation between (a ) cell count and GPP, (b ) cell count and DO and (c ) BOD and DO at the coastal marine region

Gross productivity in 2006–2007 (440.863 mgC/ DO values were relatively low, with a maxi- m3 /h) was higher as compared to 2005–2006 mum of 6.22 mg/L in January 2006 and minimum (383.361 mgC/m3 /h). Net primary productivity of 4.3 mg/L in July 2006 (Fig. 5.29b ). DO content showed similar pattern as was with GPP with was maximum in winter and minimum in mon- highest values in winter, intermediate values in soon. BOD value ranged from 1 to 4 mg/l, with summer and post- monsoon with lowest in mon- highest value in monsoon (August 2005) and soon. On the contrary, CRR values were rela- lowest in winter (January 2006) when DO content tively higher in monsoon as compared to the was high. From the correlation matrix plot, there summer and post- monsoon periods was a positive correlation between cell count and 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 125

GPP

NPP

CRR

pH

Water temp. Water

DO

BOD

Saln.

DSi = 24) = 24) N

< .05000 DIP p cant at

DIN

Cell count −0.55 0.45 −0.23 0.70 −0.17 0.61 −0.70 −0.20 −0.54 −0.45 −0.60 Correlation matrix plot between cell count, productivity and environmental variables at the estuarine station at the estuarine station variables and environmental Correlation matrix plot between cell count, productivity −0.45 0.02 −0.71 −0.01 −0.46 0.81 −0.55 0.00 0.91 0.70 0.92 −0.46 0.87 0.07 0.58 −0.78 −0.78 0.61 −0.75 −0.35 −0.24 −0.57 0.91 −0.36 0.03 −0.58 −0.15 −0.35 0.71 −0.54 −0.15 0.70 0.89 0.92 −0.54 0.06 −0.65 0.07 −0.57 0.75 −0.60 0.07 0.89 0.82 0.70 −0.24 0.00 −0.45 −0.29 −0.24 0.34 −0.45 −0.26 0.70 0.82 −0.01 −0.75 −0.12 −0.28 −0.78 0.45 −0.17 0.94 −0.15 −0.29 0.07 −0.45 0.30 0.64 −0.75 0.87 −0.74 0.45 −0.74 −0.36 −0.24 −0.54 0.02 0.30 0.13 −0.12 0.07 −0.07 −0.23 −0.19 0.03 0.00 0.06 −0.71 0.64 0.13 −0.28 0.58 −0.78 0.70 −0.33 −0.58 −0.45 −0.65 0.81 −0.74 −0.07 −0.78 0.45 −0.78 −0.70 0.47 0.71 0.34 0.75 0.00 −0.74 −0.19 −0.33 0.94 −0.75 0.47 −0.20 −0.15 −0.26 0.07 Cell count DIN DIP DSi Saln BOD DO temp. Water pH CRR NPP GPP correlations are signifi Correlations (marked Table Table 5.10 126 5 Case Study

CRR

NPP

GPP

pH

Water temp. Water

DO

BOD

Saln

= 24) DSi N

< .05000 p DIP cant at

DIN

Cell count −0.34 0.47 0.44 0.67 −0.39 0.64 −0.85 −0.53 −0.58 −0.87 0.14 Correlation matrix plot between cell count, productivity and environmental variables at the coastal marine region at the coastal marine region variables and environmental Correlation matrix plot between cell count, productivity −0.52 −0.36 −0.48 0.54 −0.49 0.58 −0.34 0.46 0.91 0.56 0.59 −0.49 0.66 0.78 0.91 −0.78 −0.74 0.64 −0.77 −0.58 −0.65 −0.10 0.59 −0.12 0.02 −0.03 0.25 −0.10 0.08 0.14 0.09 0.60 −0.12 0.91 −0.53 −0.37 −0.56 0.52 −0.58 0.73 −0.58 0.47 0.71 0.60 0.56 −0.58 −0.48 −0.67 0.42 −0.65 0.86 −0.87 0.48 0.71 −0.12 0.54 −0.69 −0.65 −0.61 −0.78 0.45 −0.39 0.77 0.52 0.42 0.25 −0.52 0.62 0.54 −0.69 0.66 −0.48 0.47 −0.75 −0.53 −0.58 −0.12 −0.36 0.62 0.77 −0.65 0.78 −0.50 0.44 −0.73 −0.37 −0.48 0.02 −0.48 0.54 0.77 −0.61 0.91 −0.77 0.67 −0.71 −0.56 −0.67 −0.03 0.58 −0.48 −0.50 −0.77 0.45 −0.74 −0.85 0.46 0.73 0.86 0.08 0.46 −0.75 −0.73 −0.71 0.77 −0.77 0.46 −0.53 0.47 0.48 0.09 Cell count DIN DIP DSi Saln BOD DO temp. Water pH GPP NPP CRR correlations are signifi Correlations (marked Table Table 5.11 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 127

1.2

1.0

0.8

Cluster II Cluster I 0.6 Ib

Linkage Distance 0.4

Ia 0.2 IIb IIa

0.0 TF TN KL AF LD SP PS CS SD AN RR SQ MP AG CM Sbi GM MM Cex Nmi Ptet Bdu Npu Aug Oau Psal GOb AFst Pdro Nper Ndeli Psduo Nquad Gbeau

Fig. 5.31 UPGA cluster diagram based on seasonal abundance of different phytoplankton genera recorded from the freshwater station

dissolved oxygen content (R 2 = 0.34, r = 0.58, mainly separated from each other in accordance p ≤ 0.05, n = 24) (Fig. 5.30b ). Similarly, a signifi - to their preferences for different temperature gra- cant negative correlation was established between dients, i.e. Cluster I consists of taxa that had a DO and BOD (R 2 = 0.54, r = 0.74, p ≤ 0.05, n = 24) preference for the warmer periods whereas (Fig. 5.30c ) (Tables 5.10 and 5.11 ). Cluster II consists of taxa that were mainly abun- dant in the cooler months. 5.4.2.5 Multivariate Procedures Cluster I comprised of late spring (transition In the present work, cluster analysis (CA) was period), summer and monsoon population. This used to enumerate the diversity patterns in phyto- group primarily represented the populations of plankton populations along coastal West Bengal. the relatively warmer periods when the mean Moreover, we also tried to fi nd out the probable temperature was 28 ± 5 °C. In this group of phy- role of the measured environmental variables in toplankton population, green and blue-green analysing the diversity patterns with the applica- algal members were more abundant in compari- tion of principal component analysis (PCA). son to diatoms. Cluster Ia represented the popula- Figure 5.31 depicts the results obtained by tion of late spring and summer with predominance using the 34 most abundant species during the of green algal genera like Pediastrum spp. (P. tet- entire study period at the freshwater station ras , P. simplex var. duodenarium and P. duplex (Diamond Harbour). Two distinct groups of phy- var. rotundatum ) and Ankistrodesmus spp. ( A. fal- toplankton association were observed that are catus , A. falcatus var. stipitatus ) with only two designated as I and II. The ultimate outcome of species of diatoms which were Leptocylindrus the 34 taxa through cluster analysis reveals the danicus (LD) and Nitzschia peregrina (Nper). On presence of two major clusters among the inves- a closer observation in respect to linkage dis- tigated taxa, one comprising of 16 species and tances, the measured distances among members other 18 species. These two major clusters are of Pediastrum spp. and Ankistrodesmus spp. 128 5 Case Study

Fig. 5.32 PCA plot of Factor 1 vs. Factor 2 showing the pattern of species orientation based on environmental variables and magnitude of abundance at the freshwater station ranged from 0.02 to 0.1 which further testifi es the some centric diatoms appeared like Biddulphia very close association among these members in dubia (Bdu), Odontella aurita (Oau), Aulacoseira the community. Cluster Ib clustered species that granulata (Aug). were abundant only during monsoon that included The juxtaposition of taxa was further observed only the cyanobacterial members like Spirulina in principal component analysis (PCA) of inves- platensis (SP), Merismopedia minima (MM) and tigated taxa (Fig. 5.32 ). The results of PCA con- Merismopedia punctata (MP). fi rmed the results of the Cluster diagram. The Cluster II represented the population of the highly clustered appearance of species scores in autumn and winter periods with predominance of the PCA plot can be attributed to the low linkage diatoms. Cluster IIa accounted for the population distances between species in each subgroup of of autumn period which was mainly represented the cluster diagram. The principal component by pennate diatom taxa like Navicula minima analysis of data matrix (based on correlation (Nmi), Nitzschia quadripartita (Nquad), coeffi cient) resulted into extraction of 17 princi- Pleurosigma salinarum (Psal) and Gyrosigma pal components among the taxa. In PCA, princi- beaufortianum (Gbeau). Cluster IIb represented pal components exhibiting maximum amount of the population of winter months where along variations and having eigenvalues above 1.00 are with the pennate population of autumn period, generally considered. In the present investigation, 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 129 the fi rst six principal components are represented entire population may not be similar during the by eigenvalues greater than 1.0; however only the entire period of study when temperature was rela- fi rst two components (PC 1 and PC 2) explain tively high. A 3rd group of species was observed maximum amount of variations As such, the fi rst which was represented by few species with two components have been taken into consider- intermediate negative loadings along PC 1 and ation for preparation of PCA plot. PC 1 and PC 2 very high positive loadings along PC 2. This sug- together explain 80.03 % and 14.07 % of the vari- gests that genera like Merismopedia minima and ance, respectively, that cumulatively accounts for M. punctata mainly fl ourished under conditions 94.1 % of variance among the data. of intermediate temperature and very low salin- The two-dimensional diagram showed the dis- ity, being as low as 0 psu. tribution of taxa in all the four quadrants From the estuarine station (Kakdweep), simi- (Fig. 5.32 ). The distribution of taxa in the PCA lar cluster analysis and principal component plot follows the cluster formation of phenogram. analysis were performed with the 25 most abun- PCA also reveals the environmental variables dant taxa recorded. Here again, two distinct responsible for separation of taxa along the dif- groups of phytoplankton population were ferent dimensions. recorded which were designated as Cluster I and Based upon factor versus variables scores Cluster II, respectively. Cluster I comprised of 8 along each component, PC 1 can be designated as taxa whereas Cluster II comprised of 17 taxa. As a negative temperature gradient from right to left was observed for the freshwater, the grouping of (Fig. 5.32 ), whereas PC 2 can be designated as a phytoplankton population in the cluster diagram positive salinity gradient from top to bottom. As at the estuarine station was also based upon tem- evident from the PCA plot, mainly two groups of perature gradients, i.e. Cluster I consists of taxa phytoplankton populations could be observed. that had a preference for the warmer periods The 1st group consists of those species (e.g. whereas Cluster II consists of taxa that were Gyrosigma obtusatum , G. beaufortianum , mainly abundant in the cooler months (Fig. 5.33 ). Coscinodiscus excentricus , Amphiprora gigan- Cluster I comprised of late spring (transition tea , Odontella aurita , Actinocyclus normanii , period), summer and monsoon population. This Biddulphia dubia , Nitzschia delicatissima , cluster primarily represented the populations of Pleurosigma salinarum, etc.) that have a high the relatively warmer periods when the mean tem- positive loading along PC 1 with intermediate perature was 28 ± 5 °C. This cluster of phyto- negative loadings along PC 2. On closer observa- plankton was composed of green algae and tion, it can be further observed that the differ- diatoms with greater abundance of diatom genera. ences in loadings among the different members Cluster Ia represented the population of late in this group are low, thereby suggesting their spring and summer with 7 green algal taxa like similar patterns of occurrence with almost simi- Scenedesmus spp. ( S. dimorphus, S. brevicauda , lar affi nities to temperature and salinity. On the S. bijuga and S. quadricauda), Ankistrodesmus other hand, the 2nd group consists of those mem- falcatus, Kirchneriella lunaris and Crucigenia bers (e.g. Leptocylindrus danicus , Ankistrodesmus tetrapedia . On the contrary, Cluster Ib was repre- falcatus , A. falcatus var. stipitatus , Cyclotella sented by 10 phytoplankton taxa of which all meneghiniana , C. striata , Rhizoclonium ripar- except Rhizoclonium riparium were diatom. This ium , Nitzschia peregrina ) that have high negative cluster primarily represented the population that loadings along PC 1 with intermediate negative dominated the habitat waters during the late loadings along PC 2. Within this group variation monsoon and post-monsoon periods. The more in loading values of different species suggests abundant taxa in this cluster were Cyclotella greater variations as compared to the members of meneghiniana, Thalassiothrix frauenfeldii , group 1. This suggests that although the popula- Gyrosigma obtusatum, G. acuminatum , etc. The tion have similar preferences for temperature and comparatively high linkage distances between the salinity, their abundance and contributions to the different taxa within the same cluster suggest that 130 5 Case Study

Tree Diagram for Variables 0.5

0.4

Cluster I

0.3 Cluster II Ia

Ib 0.2 Linkage Distance

0.1

0.0 Bdu Ndeli AG AuG RR GAcu CS SH CM CT Squa Sbr KL Oau CEx PS TN GOb DB Bdeli BV TF AF Sbi Sdi

Fig. 5.33 UPGA cluster diagram based on seasonal abundance of different phytoplankton genera recorded from the estuarine station although their availability were recorded under The two-dimensional diagram showed the similar environmental conditions, their cell counts distribution of taxa in all the four quadrants varied signifi cantly during the sampling periods. (Fig. 5.34 ). The distribution of taxa in the Cluster II represented the population of the PCA plot follows the cluster formation of late post-monsoon and winter periods when phenogram. PCA also reveals the environmental diatoms were the only representative taxa with no variables responsible for separation of taxa availability of any green algae. Cluster II was along the different dimensions. mainly represented by both centric and pennate Here again, like our freshwater station, based diatom taxa. The pennate diatom population was on the factor loading values of each environmen- represented by taxa like Nitzschia delicatissima , tal variable along PC 1 and PC 2, PC 1 could be Thalassionema nitzschoides and Amphiprora designated as a negative temperature gradient gigantea whereas the centric diatom population from right to left (Fig. 5.34 ) whereas PC 2 can be was represented by Odontella aurita , Biddulphia designated as a positive salinity gradient from top dubia , Coscinodiscus excentricus , Paralia sul- to bottom. As evident from the PCA plot, mainly cata and Aulacoseira granulata . three groups of phytoplankton populations could In an attempt to better understand the phyto- be observed. The 1st group consists of those plankton species composition of the estuarine species (e.g. Biddulphia dubia , Odontella aurita , region as responses to environmental variables, Thalassionema nitzschoides , Amphiprora gigan- PCA was implemented by taking into account the tea , Aulacoseira granulata) that have a high posi- availability data of the 21 most abundant taxa. tive loading along PC 1 with low negative Based on eigenvalues, the PCA plot was done loadings along PC 2. On closer observation, it taking in consideration PC 1 and PC 2 that can be further observed that the differences in together explained 71.35 % of the variance within loadings among the different members in this the data set. group are low, thereby suggesting their similar 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 131

Fig. 5.34 PCA plot of Factor 1 vs. Factor 2 showing the pattern of species orientation based on environmental variables and magnitude of abundance at the estuarine station patterns of occurrence with almost similar affi ni- As evident in the spatial orientation of the ties to temperature and salinity. On the other different phytoplankton genera recorded from hand, the 2nd group consists of those members the estuarine habitat, the plot was more spatially (e.g. S. brevicauda, S. bijuga, S. quadricauda, distributed as compared to the PCA from our fresh- Ankistrodesmus falcatus ) that have intermediate water station. Accordingly, in an attempt to under- to high negative loadings along PC 1 with inter- stand whether if any seasonal succession pattern mediate negative loadings along PC 2. This was operative at this station, multidimensional suggests that the population have similar prefer- scaling (MDS) was performed. The applicability of ences for temperature and salinity, with almost this procedure was that the orientation in MDS plot similar patterns of abundance. A 3rd group of was done on two dimensional spaces where nonlin- species was observed which was represented by ear relationships between species scores were species with intermediate negative loadings along taken into consideration as well. PC 1 and very high positive loadings along PC 2 In the MDS plot (Fig. 5.35 ) of the phytoplank- (Ditylum brightwellii , Cyclotella meneghiniana , ton population at the estuarine station, 3 distinct C. striata , Gyrosigma obtusatum , G. acumina- groups were confi gured. Starting from an anti- tum , Bacteriastrum varians and Stephanodiscus clockwise direction (Group 1), members hantzschii). This shows that these genera mainly Scenedesmus spp. appeared along with fl ourished under relatively oligohaline conditions Kirchneriella lunaris (KL), Ankistrodesmus when temperature was comparatively low. falcatus (AF) and Crucigenia tetrapedia that 132 5 Case Study

Fig. 5.35 Multidimensional scaling (MDS ) of different species considering Dimension 1 and Dimension 2 at the estua- rine station

represented the population of the summer and monsoon period of November and fl ourished in early monsoon months. Rhizoclonium riparium the winter months and gradually diminished with (RR) began to fl ourish in late summer months and the approach of the summer months. continued to increase in population to the mon- Similar cluster analysis and principal compo- soon period. In the post-monsoon period, as sea- nent analysis were performed with the 36 most sonal precipitation receded, there were signifi cant abundant taxa recorded from the coastal marine alterations of the available nutrient concentration region. Here, three distinct groups of phytoplank- and accordingly the population fl uctuated with ton population were recorded which were desig- the abundance of diatom taxa (Group 2) like nated as Cluster I, Cluster II and Cluster. Cluster I Cyclotella meneghiniana (CM), C. striata (CS), comprised of 15 taxa, Cluster II comprised of 18 Gyrosigma obtusatum, G. acuminatum, Ditylum taxa and Cluster III was represented only by 3 brightwellii, Bacteriastrum varians and taxa. Unlike the freshwater and estuarine stations, Stephanodiscus hantzschii which were available the linkage distances were comparatively higher only in the months of October and November which suggest that the within cluster association with intermittent presence in the late monsoon between species was less specifi c with respect to months. In winter season a different population the period and magnitude of abundance, as was fl ourished which was represented by genera like observed for the other stations. Furthermore, each Biddulphia dubia (Bdu), O. aurita (OAu), N. deli- cluster was further divided into subgroups which catissima (Ndeli), Thalassionema nitzschoides represented different associations of phytoplank- (TN), Amphiprora gigantea (AG), Aulacoseira ton species assemblages (Fig. 5.36 ). granulata (AuG), Pleurosigma salinarum (PS) Cluster I was represented by 3 taxa, namely, and Coscinodiscus excentricus (CEx) (Group 3). Nitzschia sigmoidea (NS), Gyrosigma acumi- These genera appeared mostly in the late post- natum (Gacu) and Asterionella japonica (AJ). 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 133

Tree Diagram for Variables 1.2

Cluster III Cluster II Cluster I 1.0 IIa IIIa IIIb

0.8 IId

IIb 0.6 IIc

Linkage Distance 0.4

0.2

0.0 Ndeli BV CS CM DB SF TD Npac Bpax Oau TN CW Cdiv DI CG AG OaltGAcu PS GOb AN OM CP CEx OR SH CC Bdu TFCmass DW PN AuG Bhet NS AJ

Fig. 5.36 UPGA cluster diagram based on seasonal abundance of different phytoplankton genera recorded from the coastal marine region

All the taxa showed different periods of avail- the late monsoon and post-monsoon periods but ability. Among them, A. japonica showed a did not fl ourish signifi cantly. very high abundance in winter months and con- Cluster III comprised of two subgroups that tributed maximally to the phytoplankton popu- are represented as IIIa and IIIb. Subgroup IIIa lation of winter. consisted of 8 species which are Nitzschia deli- Cluster II consisted of four subgroups of catissima (Ndeli), Paralia sulcata (PS), which IIa was represented by the single species Bacteriastrum varians (BV), Gyrosigma obtusa- Nitzschia pacifi ca (Npac) that had a very tum (GOb), Cyclotella striata (CS), Actinocyclus restricted appearance only in the post-monsoon normanii (AN), Cyclotella meneghiniana (CM) period with low cell counts. Subgroup IIb was and Odontella mobiliensis (OM). These taxa pri- composed of fi ve species which were marily appeared in the early summer period Stephanodiscus hantzschii (SH), Bacillaria pax- (March and April) and continued to fl ourish in illifer (BPax), Coscinodiscus centralis (CC), the early monsoon months (July to September) Odontella aurita (Oau) and Biddulphia dubia with relatively low cell counts. Subgroup IIIb (Bdu). These taxa appeared as a component of was represented by 6 species like Odontella the phytoplankton population in the late mon- rhombus (OR), Coscinodiscus perforatus (CP), soon to post-monsoon periods and continued to Coscinodiscus excentricus (CEx), Thalassiosira fl ourish till the early summer months (March and decipiens (TD), Ditylum brightwellii (DB) and April) that accounted for a signifi cant proportion Surirella fastuosa (SF). These taxa appeared in of the phytoplankton population. Subgroups IIc the summer months (April–June) and continued and IId consisted of the taxa appeared mainly in to fl ourish in the monsoon to post-monsoon 134 5 Case Study

Fig. 5.37 PCA plot of PC1 vs. PC2 showing the pattern of species orientation based on environmental variables and magnitude of abundance at the coastal marine region periods with comparatively higher cell counts considering PC 1 and PC 2. These two components than in the subgroup IIIa. explained 37.43 % of the variation within the spe- As evident, the cluster analysis did not show cies data. The covariates in the PCA plot were well-demarcated species associations, as was grouped together based on their factor loading val- observed for the freshwater station. Accordingly, ues along PC 1/PC 2. Covariability between the to further understand the species-specifi c species plotted along PC 1 and PC 2 was relatively responses of phytoplankton populations to envi- high because the explained variance by the fi rst two ronmental variables, principal component analy- principal components is about 6.5 times higher than sis was carried out as well. it would have been if the time series of the 36 algal In our principal component analysis (PCA) species were not correlated at all. Thus, more than study of the species composition at the marine one-third of the variation in the 36 algal species dur- coastal region, the factor loading matrix indicates ing the study period is accounted for by the 1st and the correlation between each principal component 2nd principal components in our plot. On plotting to each of the species. In our study, species that PC 1 against PC 2, the variability in individual spe- appeared only once in the total sampling period cies occurrence becomes evident, where the dis- were not considered. Out of 36 species considered, tance between the plotted species points provide a 11 had their strongest correlation with highest factor relative measure of the degree of similarity/dissimi- loading with the fi rst two principal components (PC larity between species with respect to both their sea- 1 and PC 2). Accordingly the PCA plot was done sonal occurrence and magnitude of abundance. 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 135

The temporal pattern of occurrences of each water temperature is low, but with a decrease in individual species was also accounted by plotting both seasonal and riverine precipitation there is a PC 1 vs. PC 2. As evident from our PCA plot, rise in salinity. Accordingly, genera like (Fig. 5.37 ) a negative temperature gradient was Biddulphia dubia (BD), Odontella aurita (OAu) established along PC 1. Accordingly, genera with and Coscinodiscus centralis (CC) attained their a high positive factor loading along PC 1 fl our- peak growth in this period with high abundance ished in the cooler months with comparatively which culminated with a very high cell count of low water temperature. Thus, genera with positive A. japonica. Genera in the 3rd quadrant had factor loadings on PC 1 are more abundant in the intermediate negative factor loading for both PC post-monsoon and winter months when the average 1 and PC 2. Hence, these genera fl ourished in the temperature is about 12–18 °C. On the contrary, relatively warmer months when salinity was genera with negative factor loading along PC 1 about 32–35 psu but with a low cell count. had a preference to fl ourish in the summer months Nitzschia sigmoidea (NS) and Gyrosigma acu- when the average water temperature is compara- minatum (GAcu) were available only in the tively higher (30–36 °C). PC 2 axis represents the months of March and April. Nitzschia delicatis- relative degree of variation in temporal occur- sima (ND) and Paralia sulcata (PS) were exclu- rence with low to high gradient of species avail- sively available only in the months of April to ability during an annual cycle. As evident from July during the entire study period. Thus, the the plot PC 2 also represent a salinity gradient fi ndings clearly suggested that these genera rep- from top to bottom in which the species align as resented the population of the transitory period per their salinity requirement. Species having a from winter to summer months. Finally, the 4th high positive correlation with this vector gener- quadrant comprised of those genera which were ally exhibited a specifi c seasonal occurrence abundant in the warmer months but were signifi - where salinity requirement was low (as the gradi- cantly less in the winter months of December ent is from low to high). and January with a relatively high cell count of Accordingly, from the PCA plot (1st quad- individual species. Along with genera like O. rant) it was evident that Biddulphia alternans rhombus (OR) and C. excentricus (CE), genera (BA) along with other genera like Thalassionema like Odontella mobiliensis (OM), Cyclotella nitzschoides (TN), Diploneis interrupta (DI) and meneghiniana (CM) and Actinocyclus normanii Diploneis weissfl ogii (DW) are more abundant in f. subsala (AN) had negative loading on PC 1 but the post-monsoon and winter months. Taxa like intermediate positive loading along PC 2, sug- C. granii (CG), A. gigantea (AG) and Aulacoseira gesting their relatively even abundance with high granulata (AuG) have intermediate positive fac- density in the summer and monsoon periods. tor loading on PC 1 which are the representative For further confi rmation of this seasonal pat- of only the particular post-monsoon period with tern of species based upon their abundance data low or no availability in other seasons. Genera and preference for temperature and salinity, mul- like Chaetoceros wighami (CW), C. messanensis tidimensional scaling (MDS) was performed (ChM) and C. diversus (CD) had a very high (Fig. 5.38 ). The MDS confi guration plot of all positive loading along PC 2 with intermediate genera (Dimension 1 vs. Dimension 2) clearly factor loading along PC 1 which can be clearly demarcates distinct groups based upon the sea- explained by the fact that their availability was sonal preference of the individual species. restricted to the monsoon season (water temper- In the MDS plot 5 distinct groups were confi g- ature 28–32 °C) and they never fl ourished in any ured. Starting from an anticlockwise direction other season. Genera with a positive factor load- from summer months (Group 1), the genera O. ing on PC 1 but negative loading on PC 2 (2nd rhombus (OR), Coscinodiscus excentricus (CE) quadrant) were mostly available in the late post- and O. mobiliensis (OM) appeared together as monsoon to winter months with a high abun- the dominant genera of the summer months along dance. This is because during this period average with C. meneghiniana (CM) that was available in 136 5 Case Study

Fig. 5.38 Multidimensional scaling of different species considering Dimension 1 and Dimension 2 at the coastal marine region other seasons as well but had a preference for the specifi c which is evident from the fact that the summer months. Genera like Ditylum bright- different species of Chaetoceros do not fl ourish wellii (DB), Cyclotella striata (CS) and A. nor- at any other season of our sampling period except manii f. subsala (AN) began to fl ourish in the monsoon. In the post-monsoon period phyto- summer months and continued to increase in plankton population changes with the appearance population to the monsoon period and accord- of representative genera like B. heteroceros (BH), ingly they are representative of the transition A. granulata (AuG), A. gigantea (AG), C. granii from a summer to a monsoon season. With the (CG) and D. weissfl ogii (DW) (Group 3) which advent of the monsoon months there is signifi cant were available only in the months of October and alteration of the available nutrient concentration November with intermittent presence in the late and accordingly the population fl uctuates with monsoon months. In winter season a different the abundance of representative genera (Group 2) population fl ourished which was represented by like Chaetoceros wighami (CW), C. messanensis genera like Biddulphia dubia (BD), O. aurita (ChM) and C. diversus (CD). As monsoon is (OAu) Pleurosigma normanii (PN), B. paxillifer prolonged there is signifi cant enhancement of (BPax) and Coscinodiscus centralis (CC) (Group nutrient input but reduction in mean salinity. 4). These genera appeared mostly in the late post- Accordingly, phytoplankton population is highly monsoon period of November and fl ourished in 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 137 the winter months and gradually diminished with Venkataraman (1939 ) where he reported 98 taxa the approach of the summer months. This winter belonging to 33 genera. In another signifi cant population fi nally culminated with the abrupt rise work on Madras coast, 134 species belonging to in A. japonica (AJ) population where only a very 64 genera were reported by Subrahmanyan few individuals of other species developed. (1946 ). Later, a total of 57 species of diatoms Genera like G. acuminatum (GAcu) appeared in belonging to 36 genera were reported from the the late winter months of February and fl ourished Gulf of Kutch, western coast of India in March till the early summer months of April. (Gopalakrishnan 1972 ). In a 1-year study from Likewise Nitzschia sigmoidea (NS) and N. deli- the Mandovi–Zuari estuary a total of 48 phyto- catissima (ND) (Group 5) appeared in the early plankton species were identifi ed – of which 37 summer month of April and accordingly they are species were diatoms and only 2 taxa were blue- considered as representatives of the transitory green algae (Krishna Kumari et al. 2002 ). In a population between a winter and summer phyto- more recent work from the Zuari estuary, Goa, 66 plankton population. Surirella fustuosa (SF) and planktonic diatom species belonging to 29 genera N. pacifi ca (NPac) appeared irregularly with very were recorded, of them 36 species were Pennales, low cell count. On the contrary, Stephanodiscus whereas 30 species were of Centrales (Redekar hantzschoides (SH) appeared all throughout the and Wagh 2000 ). The dominance of diatoms as year and did not show any seasonal preference. a component from marine coastal regions has Accordingly, these genera appeared in the middle been reported from other stations along the Bay of the MDS confi guration in a scattered manner of Bengal as well (Madhupratap et al. 2003 ). and did not belong to any particular group. Thus, abundance of diatoms has been reported Phytoplankton population of coastal area is from all the Indian estuaries and coastal controlled by various physical, chemical and waters – where members of Chaetoceraceae, biological factors which ultimately regulates the Coscinodiscaceae and Naviculaceae are more phytoplankton dynamics of particular ecosystem. abundant (Venkataraman and Wafar 2005 ). Results showed that coastal West Bengal repre- Hence, our fi ndings in the present study along sented a diverse phytoplankton population coastal West Bengal were well in agreement with which is primarily composed of members of other records from different estuaries of the Cyanophyta, Chlorophyta and Bacillariophyta. Indian subcontinent. Members of Bacillariophyta or diatoms made up From the results it is evident that species com- the bulk of the population, followed by green and position pattern did not show signifi cant interan- blue-green algae. This was evident from the fi nd- nual variations. Here, almost the same genera ings which showed that out of the 75 phytoplank- appeared in the same pattern in successive years. ton taxa recorded, 51 were diatoms. In the Enormous freshwater run-offs from several major freshwater and estuarine region, the phytoplank- rivers may result in strong vertical stratifi cation ton fl ora was mainly represented by members of that inhibits vertical mixing (Gopalakrishnan and Cyanophyta, Chlorophyta and diatoms. On the Sastry 1985). According to them, lack of intense other hand, the marine coastal region was repre- upwelling of this coast is due to the equator ward sented by diatoms only. The diatom population fl ow of the freshwater plume, which resulted in primarily comprised of the members belong- overwhelming of the offshore Ekman transport in ing to the tribes Coscinodisceae, Chaetocerae, the coast of Bay of Bengal. These conditions Biddulphieae (Centrales) and Naviculeae accounted for the similar seasonal plankton (Pennales) (Cupp 1943 ). A high availability of dynamics with minimal interannual variability. diatoms as a major component of coastal and This lack of upwelling events can be further estuarine plankton population has been reported attributed to the fact that the Bay of Bengal, espe- from other parts of the Indian subcontinent as cially the northern parts, represents a very narrow well. A detailed account of the phytoplankton shelf (Qasim 1977 ; SenGupta et al. 1977 ; population along Madras coast was prepared by Radhakrishna et al. 1978 ). 138 5 Case Study

Among diatoms on a generic level, Bay, (Livingston 2001), Indian River Lagoon Coscinodiscus , Leptocylindrus , Chaetoceros , (Badylak and Phlips 2004 ), Florida and in many Biddulphia , Odontella , Gyrosigma , Ditylum , estuaries of North Carolina (Mallin 1994 ). Thalassionema , Thalassiothrix , Navicul a and The rise in larger-sized pennate diatoms Nitzschia have been recorded as dominant taxa along with colonial forms like Asterionella from this region. Along with the diatom genera, japonica , Thalassionema nitzschoides, green algal genera like Kirchneriella , Thalassiothrix frauenfeldii , Gyrosigma beaufor- Ankistrodesmus , Pediastrum , Scenedesmus and tianum , Pleurosigma salinarum , Bacillaria the blue green algal genera like Merismopedia paxillifer , Nitzschia sigmoidea , etc. during the and Microcystis were available in this region. cooler post- monsoon and winter months can be Abundance of Chaetoceros spp. and attributed to the strong northeastern winds (De Bacteriastrum spp. were observed only during Jonge and van Beusekom 1995 ). The availability the monsoon period mainly at the estuarine and of these taxa at highly diverse habitats at different marine region along coastal West Bengal. In parts of the world further suggests that these other reports, dominance of pennate members euryhaline phytoplankton genera are cosmopoli- like Nitzschia spp. have been reported from the tan in distribution and can develop under diverse freshwater regions while genera like physicochemical conditions. Coscinodiscus spp. were more abundant in the Diversity indices are calculated on the basis of high-salinity zones of both Zuari River and total biomass data obtained from cell count Mandovi River estuary (Matondkar et al. 2006 ). method and the number of individuals, which Dominance of members of Chaetoceros spp. indicate the community pattern of the particular from June to September (monsoon months) has ecosystem. Results showed that diversity was also been reported from the neritic zone of the highest at freshwater station and minimum at the Urdaibai estuary at northern Spain (Trigueros estuarine station, with marine coastal region and Orive 2001 ). occupying an intermediate position. This was in From our study along coastal West Bengal, it agreement with earlier reports from Santa was established that each station had different Catalina basin, off the coast of California and dominant representative taxa such as Norwegian Sea, where low diversity has been Leptocylindrus danicus at freshwater station, reported due to physical variability in the estua- Thalassiothrix frauenfeldii at estuarine station rine and the sandy coast (Jumars 1976 ). Our and Asterionella japonica at marine region. A study showed that, in the month of July or in similar high abundance of Asterionella japonica monsoon season, nutrient concentration was high in winter months has been reported from the with well mixing due to seasonal precipitation adjacent Orissa coast where it made up almost and riverine infl ux of nutrient rich water. This 99 % of the total population (Sasamal et al. resulted in the development of a suitable condi- 2005 ). In the estuarine and marine region, abun- tion for phytoplankton diversifi cation that dance of euryhaline taxa like Skeletonema costa- accounted for maximum SW Index in the post- tum , Thalassiosira decipiens , Thalassionema monsoon period with stabilized nutrient pool. nitzschoides was recorded. High abundance of Thus, in the present study, post-monsoon period chain forming diatom genera like Leptocylindrus (October–November) appeared to be most danicus , Thalassiosira decipiens and Skeletonema conducive for phytoplankton diversity showing costatum have been reported from the Alboràn maximum diversity index throughout the study Sea, a continuation of southwest Mediterranean area, although total phytoplankton cell counts Sea (Mercado et al. 2005 ). These taxa are com- were maximum in winter. Observation of maxi- mon in other estuaries around the world as well mum diversity in post-monsoon period agrees which are subjected to large salinity variations well with the earlier reports for Hugli estuary, due to precipitation and riverine discharge, north east coast of India (De et al. 1994 ) and including Apalachee Bay (Curl 1959 ), Perdido Vellar estuary (Hangovan 1987 ). 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 139

High species evenness with negligible varia- succession was clearly evident where each tions at the freshwater and estuarine stations sig- season was clearly represented by distinct spe- nifi es that the percentage contributions of cies assemblages. individual taxon to the total phytoplankton popu- Results showed that both productivity and cell lation were almost similar during the entire sam- counts were maximum at the coastal marine pling period. This was in contrast to the marine region and minimum at the estuarine region. region where it was maximum in monsoon Highly signifi cant correlations between phyto- months and minimum in winter. Decreasing ten- plankton cell counts and GPP clearly established dency of SW Index and species evenness indicate that GPP was actually the total photosyntheti- shifting of phytoplankton community from high cally fi xed carbon by the phytoplankton popula- species richness to bloom formation, as reported tion. Seasonally, as can be expected from cell by many authors in eutrophic and hypertrophic count data, productivity was maximum in winter lakes and reservoirs (Jacobsen and Simonsen and minimum during the monsoon period along 1993; Padisak 1993 ). Thus, the drop in biotic West Bengal coast. Planktonic photosynthetic indices in winter at the marine station was pri- productivity is one of the major contributors to marily due to very high abundance of Asterionella the overall productivity of open aquatic ecosys- japonica population that accounted for more than tems. The effi ciency of energy transfer from phy- 90 % of the phytoplankton population. A similar toplankton to consumers and ultimate production fi nding was recorded for the summer months at at upper trophic levels vary with algal species the coastal marine station as well with the devel- composition. It is well known that diatom- opment of a different population ( Odontella dominated marine upwelling systems sustain rhombus). In the monsoon period, the water col- more fi sh biomass per unit of phytoplankton bio- umn was highly disturbed due to seasonal pre- mass than cyanobacteria-dominated lakes, which cipitation, riverine infl ows and alternating air was also evident in coastal West Bengal. Unlike, currents due to cyclonic weather. As a result, the coastal marine and freshwater regions, the phytoplankton count was low with intermediate low productivity at the estuarine station can be value for species evenness in the monsoon period. attributed to the excessive fi shing activity and Results of cluster analysis and multidimen- transportation of vessels from Kakdweep. Such sional scaling further testifi ed the specifi c sea- commercial exploitation could have resulted in sonal patterns of phytoplankton availability. highly disturbed water column that may have Cluster analysis maximizes between group asso- accounted for an unstable stratifi cation, resulting ciations and minimizes within group association in decrease in productivity. NPP is a measure of (Ramette 2007 ). Thus, the very narrow distances available photosynthetically fi xed carbon after between the subgroups within each cluster sug- eliminating the catabolic loss of organic matter gest the close association between the different due to respiration (CRR). Accordingly, a drop in algal taxa. On the other hand, the high linkage NPP and rise in CRR clearly shows that carbon distances between each cluster further suggest utilization was comparatively high in comparison that each population is highly demarcated from to carbon assimilation. Such an observation can each other. MDS plots help in orienting variables be attributed to the fact that a rise in nutrient-rich in a two-dimensional space where nonlinear freshwater infl ux in the habitat waters under relationships are also taken into consideration. warm conditions led to an increase in the hetero- Thus, while understanding the seasonal patterns trophic population which accounted for the among phytoplankton population from both these enhanced carbon utilizations. A similar result multivariate procedures, it is clearly evident that was also obtained from the Mandovi River estu- seasonal succession at the freshwater station was ary (Verlencar and Qasim 1985) having highest not very pronounced. On the other hand, seasonal productivity in the post-monsoon season with patterns were more evident at the estuarine intermediate values in the pre-monsoon period station. At the coastal marine region, seasonal and the lowest productivity in monsoon. A drop 140 5 Case Study in primary productivity in the monsoon months a distinct preference for hypo-saline conditions and a rise of the same in the post-monsoon period with high temperature. Studies on cyanobacterial was also reported from Lake Tana in Ethiopia populations from other parts of the world further (Wondie et al. 2007 ). established this correlation between temperature Variations in DO contents showed a similar and blue-green algal abundance as was observed pattern of variation as was observed for cell at the Great Barrier Reef in Australia (Ayukai counts and productivity in both freshwater and 1992 ), the Mediterranean (Caroppo 2000) and estuarine stations. Thus, DO levels at the fresh- Indiana River Lagoon in Florida (Badylak and water station were comparatively higher than at Phlips 2004 ). Chlorophycean members were the estuarine station. Although the freshwater and mainly restricted from the freshwater to estuarine estuarine stations represented optimum DO lev- stations which suggest that green algal population els, DO levels at the marine coastal region repre- developed well under oligohaline to mesohaline sented an undersaturated condition although cell conditions when temperature was relatively high. counts were maximum among all the three sta- In contrast to green and blue-green algal taxa, dia- tions. During the monsoon months, heavy sea- toms fl ourished mainly under mesohaline to sonal precipitation promotes an enhanced hyper-saline conditions with low temperature. freshwater infl ow with high suspended matter Thus, diatoms were available from freshwater to content, resulting in a very turbid water column marine region although there was a shift in the at the marine region. This turbid nature of the population with increase in centric diatom popu- water column may result in a decrease in the pho- lation as the river approached the sea. tic zone. Thus, although the incident irradiance Results of PCA further underline the role of was high, the average irradiance in the water temperature and salinity in determining the spe- column was relatively low which may have cies composition at each coastal station. In PCA, accounted for the drop in DO levels in the habitat new synthetic ordinates are developed, based waters at the marine coastal region with low pho- upon the linear relationships between variables. tosynthetic activity. Another signifi cant observa- Accordingly, PCA plots of species abundance in tion was the rise in BOD levels in the monsoon relation to environmental variables clearly suggest months and a drop in the same during the winter that temperature and salinity are the most impor- periods. The signifi cant negative correlations tant factors that determine the species composi- between DO and BOD levels at all the sampling tion at all the stations along coastal West Bengal. stations indicate the high heterotrophic growth An increase in Bacillariophycean members under during the monsoon months which resulted in the conditions of low temperature in winter (fall) and decreased DO levels. spring has also been observed from Nakdong It is evident from the fi ndings that physico- River, South Korea (Ha et al. 1998 ), where almost chemical properties of habitats play a determin- similar conditions of temperature and salinity ing role in the development and proliferation of were observed as was along coastal West Bengal. phytoplankton populations at coastal West The pH level varied from 7 to 8.3 at the entire Bengal. In this tropical coastal area, optimal light sampling area which indicates the neutral to alka- and nutrient availability in association with other line nature of the habitat waters. Several reports physical parameters like pH, temperature and from different coastal regions of the world repre- salinity allowed diverse populations to develop sent similar neutral to alkaline pH gradients with high cell counts. (Skirrow 1975 ; Pegler and Kempe 1988 ; Temperature in association with salinity played Brussaard et al. 1996 ; Hinga 2002 ). Salinity a signifi cant role in determining the phytoplank- seems to play a signifi cant role in pH changes as ton species composition. The restrictive appear- it infl uences the various equilibrium constants of ance of cyanobacterial taxa in the freshwater temperature and alkalinity. region during summer and early monsoon period Phytoplankton development and succession is is a testimonial of the fact that cyanobacteria had dependent not only on physical parameters but 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 141 also on chemical factors like dissolved oxygen species composition and succession patterns at and nutrient availability (Reynolds 1984 ). coastal West Bengal, nutrient availability also Nitrogen and phosphorus are the most essential played an important role in phytoplankton components for development of biological popu- dynamics. lations with no exception for phytoplankton as This region represented a highly diverse phy- well. In an aquatic environment nitrogen, sources toplankton population where seasonal succession are mainly available as nitrate and nitrite, was relatively pronounced. Temperature and whereas phosphorus source is available in the salinity gradients were the principle determining form of phosphate. It has long been proposed factors for the seasonal variability in species that marine and estuarine phytoplankton abun- composition, although nutrient concentrations dance is N limited, whereas freshwater phyto- also played an important role. The freshwater plankton is P limited. Relatively high levels of station was more affected due to anthropogenic DIN and DIP were maintained during the entire nutrient loadings, whereas the marine coastal study period at all the stations which suggest that region was least. The estuarine station was a dis- nutrient levels were well above the optimum lev- turbed ecosystem that resulted in less diversifi ca- els and did not act as limiting factors. Cultural tion of phytoplankton population. The marine eutrophication was also an important factor for region was comparatively more stable from an the relatively high DIN and DIP levels in this ecological point of view where different aspects region. At the freshwater station DIN and DIP of population dynamics were more evident as contents were comparatively higher than DSi. compared to the other stations along coastal West On the other hand, DIN and DSi contents were Bengal. higher in the estuarine station and in the marine coastal region. Moreover, during the monsoon 5.4.2.6 Taxonomic Account of Common months, as seasonal precipitation increased, it Phytoplankton Taxa Recorded resulted in a rise in infl ow of nutrient- rich from Indian Coast freshwater from perennial sources and from Division – Cyanophyta other tributaries. This accounted for an increase Class – Cyanophyceae in nutrients especially DIN and dilution of phy- Order – Chroococcales toplankton population. Thus, the DIN-rich habi- Family – Chroococcaceae tat waters allowed the development of 1 . Gloeocapsa punctata Naegeli (Plate 5.5 , cyanobacterial taxa like Gloeocapsa sp., Fig. A) Gleothece sp., Merismopedia spp., Microcystis [Desikachary, 1959 , p. 115, pl. 23, Fig. 2] aeruginosa , Spirulina spp., which are effi cient Plant mass blue green, fl oating, consisting of nitrogen fi xers. Diatoms accounted for a major small aggregated of 8–16 individuals which proportion of the phytoplankton population are spherical and inclosed by thick sheaths; especially during the post-monsoon and winter cells 2 μ in diameter; contents blue–green, months. Diatom production can be limited by the homogenous availability of dissolved silicate (DSi) and DSi 2 . Microcystis aeruginosa Kuetz. emend. Elekin depletion relative to other major nutrients (Plate 5.5 , Fig. B) (Kilham 1971; Schelske and Stoermer 1971 ; [Desikachary, 1959 , p. 93, pl. 17, Figs. 1, 2 & 6, Malone et al. 1980 ). DSi levels were maintained pl. 18, Fig. 10] in optimum conditions throughout the study An irregularly lobed, saccate and clathrate col- area. The comparatively low DSi concentrations ony of numerous spherical cells which are in winter months were primarily due to exces- much crowded within a gelatinous matrix sive growth of planktonic diatom population (several colonies invested by a common which can be inferred from correlation studies as tegument), colonial mucilage hyaline and well. Thus, although salinity and temperature homogenous; cell contents blue green, were the primary regulatory factors in the highly granular; cells 3.5 μ in diameter 142 5 Case Study

Plate 5.5 (A ) Gloeocapsa punctata Naegeli, (B ) Microcystis (Nordst.) Geitler, (I ) Pediastrum simplex (Meyen) aeruginosa Kuetz. emend . Elekin, ( C ) Merismopedia glauca Lemmermann, (J ) Pediastrum simplex var . duodenarium (Ehrenb.) Naegeli, ( D ) Merismopedia minima Beck, ( E ) (Bailey) Rabenhorst, (K ) Pediastrum duplex var. rotundatum Merismopedia punctata Meyen, (F ) Gloeothece rupestris Lucks, ( L ) Pediastrum tetras (Ehrenb.) Ralfs, (M ) (Lyngb.) Bornet in Wittrock & Nordstedt, ( G ) Spirulina Rhizoclonium riparium (Roth) Harvey, (N ) Ankistrodesmus meneghiniana Zanard. ex Gomont, ( H ) Spirulina platensis falcatus (Corda) Ralfs 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 143

3. Merismopedia glauca (Ehrenb.) Naegeli 9. Pediastrum duplex var. rotundatum Lucks (Plate 5.5 , Fig. C) (Plate 5.5 , Fig. K) [Desikachary, 1959 , p. 155, pl. 29, Fig. 5] [Prescott, 1982 , p. 224, Pl. 48, Fig. 8] Colony of 16–64 ovate cells, very regularly Marginal cells with stout lobes which have con- arranged to form quadrangular colonies; 5 μ in vex rather than parallel margins; apices of diameter; 30-celled colony 30 μ wide; cell lobes closer together than in the typical plant contents bright blue green, homogenous 10. Pediastrum simplex (Meyen) Lemmermann 4. Merismopedia minima Beck (Plate 5.5, Fig. D) (Plate 5.5 , Fig. I) [Desikachary, 1959 , p. 154, Pl. 29, Fig 11] [Prescott, 1982 , p. 227, Pl. 50, Fig. 2] Cells four to many in small colonies, 0.498– Colony entire, composed of 16–32–64 smooth- 0.664 μ broad walled cells, inner cells 5- or 6-sided; periph- 5 . Merismopedia punctata Meyen (Plate 5.5 , eral cells with the outer free wall extended to Fig. E) form a single tapering, horn-like process with [Desikachary, 1959 , p. 155, pl. 23, Fig. 5 & pl. concave margins; cells 12–18 μ in diameter 29, Fig. 6] 11. Pediastrum simplex var. duodenarium A rectangular plate of 32–128 ovate cells, usually (Bailey) Rabenhorst (Plate 5.5 , Fig. J) loosely arranged, sometimes in compact [Prescott, 1982 , p. 227, Pl. 50, Figs. 4, 5] groups of 4–8 individuals, the groups widely Colony perforate, composed of 36 cells with their separated within a broad, gelatinous envelope; inner margins concave, the outer margins of cells 3 μ in diameter; cells contents homoge- inner cells forming a long process, peripheral cells nous, blue green forming a stout process; cells 12 μ in diameter, 6. Gloeothece rupestris (Lyngb.) Bornet in 27 μ long; 36-celled colony 135 μ in diameter Wittrock and Nordstedt (Plate 5.5 , Fig. F) 12. Pediastrum tetras (Ehrenb.) Ralfs (Plate 5.5 , [Prescott, 1982 , p. 462, Pl. 103, Figs. 2, 3] Fig. L) Cells ovate, irregularly arranged throughout a [Ralfs, 1844, p. 469] copious colourless or brownish gelatinous Colony entire; inner cells (frequently none) with matrix, in 2′s and 4′s in small families sur- 4–6 straight sides but with one margin deeply rounded by a defi nite sheath; plant mass free incised; peripheral cells crenate with a deep fl oating, cells 4–6–(9) μ in diameter, 15 μ incision in the outer margin, their lateral mar- long gins adjoined along 2 of their length; cells 3 Order – Oscillatoriales 8–12–(16) μ in diameter Family – Oscillatoriaceae Family – Oocystaceae 7. Spirulina platensis (Nordst.) Geitler (Plate 5.5 , 13. Ankistrodesmus falcatus (Corda) Ralfs Fig. H) (Plate 5.5 , Fig. N) Thallus blue green; 6 μ broad, not attenuated at [Prescott, 1982 , p. 253, Pl. 56, Figs. 5, 6] the ends, more or less regularly spirally coiled; Cells somewhat spindle shaped, solitary, not spirals 30 μ broad, distances between the spi- enclosed in a colonial sheath; chloroplast one, rals 45 μ; cells nearly as long as broad,6 μ a parietal plate without pyrenoids; cells 4 μ in long, cross-walls granulated; end cells broadly diameter; 65 μ long, sometimes longer rounded 14. A. falcatus var. stipitatus (Chod) Lemmermann 8. Spirulina meneghiniana Zanard. ex Gomont (Plate 5.6 , Fig. Q) (Plate 5.5 , Fig. G) [Prescott, 1982 , p. 254, Pl. 56, Figs. 14, 15] [Desikachary, 1959 , p. 195, Pl. 36, Fig 8] Cells lunate (rarely almost straight) attached at Trichome 1.99 μ broad, fl exible, irregularly spi- one pole to fi lamentous algae or other sub- rally coiled, forming a thick blue-green thal- merged aquatics; usually gregarious, form- lus, spiral 4.684 μ broad ing clusters of 2–8; cells 3 μ in diameter; Family – Hydrodictyaceae 20 μ long 144 5 Case Study

Plate 5.6 Explanation of plates (Camera lucida draw- Lemmermann, ( M ) Rhizoclonium riparium (Roth) ings of phytoplankton genera recorded) (A ) Gloeocapsa Harvey, ( N ) Schroederia judayi G. M. Smith, ( O ) Dictyo- punctata Naegeli, (B ) Merismopedia glauca (Ehrenb.) sphaerium pulchellum Wood, (P ) Ankistrodesmus falca- Naegeli, ( C ) Microcystis aeruginosa Kuetz. emend . tus (Corda) Ralfs, (Q ) Ankistrodesmus falcatus var. Elekin, ( D ) Merismopedia minima Beck, (E ) Spirulina stipitatus (Chod) Lemmermann, (R ) Kirchneriella lunaris meneghiniana Zanard. ex Gomont, (F ) Spirulina platensis (Kirch.) Moebius, ( S ) Scenedesmus dimorphus (Turp.) (Nordst.) Geitler, ( G ) Gloeothece rupestris (Lyngb.) Kuetzing, (T ) Scenedesmus quadricauda (Turp.) de Bornet in Wittrock & Nordstedt, ( H ) Merismopedia punc- Brébisson in de Brébisson & Godey, (U ) Scenedesmus tata Meyen, (I ) Pediastrum tetras (Ehrenb.) Ralfs, bijuga (Turp.) Langerheim, (V ) Crucigenia rectangularis (J ) Pediastrum duplex var. rotundatum Lucks, (A. Braun) Gay, (W ) Crucigenia tetrapedia (Kirch.) West (K ) Pediastrum simplex var. duodenarium ( Bailey) & West, (X ) Tetrastrum staurogeniaeforme (Schröder) Rabenhorst, ( L ) Pediastrum simplex (Meyen) Lemmermann

15. Dictyosphaerium pulchellum Wood (Plate 5.6 , dichotomously branched threads, inclosed in Fig. O) mucilage; cells 3–10 μ in diameter [Prescott, 1982 , p. 238, Pl. 51, Figs. 5–7] 16. Schroederia judayi Smith (Plate 5.6 , Colony spherical composed of as many as 32 Fig. N) spherical cells arranged in series of four [Prescott, 1982 , p. 256, Pl. 57, Figs. 5, 6] 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 145

Cells fusiform, straight, the poles narrowed 22. Crucigenia tetrapedia (Kirch.) West & West and extended into long setae, one of which (Plate 5.6 , Fig. W) terminates into short bifurcations; one [Prescott, 1982 , p. 285, Pl. 65, Fig. 9; Pl. 66, Fig. 1] chloroplast with single pyrenoid; cells 4 μ Colony free fl oating consisting of four triangular in diameter, 55 μ long including the setae cells cruciately arranged about a minute cen- which are 13 μ long tral space; outer free wall and lateral walls 17. Kirchneriella lunaris (Kirch.) Moebius straight, the angles acutely rounded; cells 6 μ (Plate 5.6 , Fig. R) in diameter; frequently forming a rectangular [Prescott, 1982 , p. 258, Pl. 58, Fig. 2] plate of 16 cells (four quartets) Colony composed of numerous cells arranged 23. Tetrastrum staurogeniaeforme (Schröder) in groups of 4–16 within a closed, gelati- Lemmermann (Plate 5.6 , Fig. X) nous envelope; cells fl at, strongly curved [Pl. 66, Fig 3, Pg 286, Prescott] crescents with rather obtuse points; chloro- A colony of 4 triangular cells, cruciately arranged plast covering the convex wall; cells 5 μ in about a small rectangular space; lateral mar- diameter, 10 μ long; colonies 100–250 μ in gins of the cell straight, the outer free walls diameter convex and furnished with hairlike setae; cells Family – Scenedesmaceae 3.81–4.15 μ in diameter, colony 10.74 μ width, 18. Scenedesmus bijuga (Turp.) Langerheim setae 4.15–4.98 μ long (Plate 5.6 , Fig. U) Order – Cladophorales [Prescott, 1982 , p. 276, Pl. 63, Figs. 2, 7] Family – Cladophoraceae Colony composed of 2–8 cells in a single (rarely 24. Rhizoclonium riparium (Roth) Harvey alternate) fl at series; cells ovate, without teeth (Plate 5.6 , Fig. M) or spines; cells 6 μ in diameter, 12 μ long [Krishnamurthy, 2000 , pl. 5, fi g. 2] 19. Scenedesmus dimorphus (Turp.) Kuetzing It forms a membranaceous layer; the algae is soft (Plate 5.6 , Fig. S) and woolly to touch and intricately woven into [Prescott, 1982 , p. 277, Pl. 63, Figs. 8, 9] loosely lying dense mats. The colour of the Colony composed of 4 or 8 fusiform cells algae is bright grass green. The diameter of arranged in a single series; the inner walls the fi lament is 60.35 μ. The length of the cell with straight, sharp apices; the outer cells varies from 89.81 to 97.96 μ. lunate, strongly curved with acute apices; Division – Bacillariophyceae cells 4 μ in diameter; 19 μ long Section – Centricae 20. Scenedesmus quadricauda (Turp.) de Subfamily – Discoidae Brébisson in de Brébisson and Godey Tribe – Coscinodisceae (Plate 5.6 , Fig. T) Subtribe – Melosirinae [Prescott, 1982 , p. 277, Pl. 63, Figs. 8, 9] 25. Aulacoseira granulata var. angustissima Colony consisting of 2-4-8 oblong, cylindrical (Plate 5.7 , Fig. Z) cells usually in one series (sometimes in two [Melosira granulata (Ehr.) Ralfs var. angustis- alternate series); outer cells with a long curved sima Müll, Hustedt, 1930a , Bd VII, Teil 1, pp. spine at each pole; inner cells without spines 250, Fig. 104 d; Venkataraman, 1939, p. 297, or with mere papillae at the apices; cells vari- Fig. 2] able in size, 12 μ in diameter, 20 μ long Filaments long with narrow and long cells, the 21. Crucigenia rectangularis (A. Braun) Gay height of the cells being several times the (Plate 5.6 , Fig. V) diameter, diameter 5 μ, height of half cell [Prescott, 1982 , p. 285, Pl. 65, Figs. 7, 8] 12 μ; number of punctae in the lower cell is 10 Colony free fl oating consisting of ovate cells, in 10 μ very regularly arranged about a rectangular Subtribe – Skeletoneminae central space in two pairs, with the apices 26. Skeletonema costatum (Greville) Cleve adjoining; cells 5.5 μ in diameter, 8 μ long (Plate 5.7 , Fig. X)

Plate 5.7 (A ) Nitzschia sigmoidea Ehrenberg, (B ) Pleuro- (N ) Cyclotella meneghiniana Kutzing, (O ) Thalassiothrix sigma normanii Ralfs, (C ) Gyrosigma obtusatum (Sull. & frauenfeldii Grunow, ( P) Nitzschia bilobata var. minor Wormley) Boyer, (D ) Odontella rhombus (Ehrenb.) Grunow, ( Q) Nitzschia pacifi ca n. sp., (R ) Nitzschia deli- Kützing, (E ) Odontella mobiliensis (J. W. Bailey) Grunow, catissima Cleve, (S ) Chaetoceros diversus Cleve, (F ) Biddulphia heteroceros Grunow, ( G) Ditylum bright- (T ) Chaetoceros wighami Brightwell, (U ) Bacteriastrum wellii (West) Grunow, (H ) Eucapmia zoodiacus Ehrenberg, varians Lauder, (V ) Asterionella japonica Cleve, (I ) Thalassionema nitzschoides Grunow, (J ) Chaetoceros (W ) Diploneis weissfl ogii (A. Schmidt) Cleve, (X ) curvisetus Cleve, (K ) Biddulphia alternans (Bailey) van Skeletonema costatum (Greville) Cleve, (Y ) Diploneis Heurck, (L ) Chaetoceros messanensis Castracane, interrupta (Kutzing) Cleve, (Z ) Aulacoseira granulata var. (M ) Surirella fastuosa var. recedens (A. Schmidt) Cleve, angustissima 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 147

[Hustedt, Bd. VII, Teil 1, p. 311, Fig. 149; [Hustedt 1930b , Bd. VII, Teil 1, pp. 388, Fig. Subrahmanyan, 1946 , p. 89, Fig. 7, 8 and 9] 201; Cupp, 1943 , pp. 52, Fig. 14; Frustules weakly silcifi ed, lens shaped with Subrahmanyan, 1946 , p. 93, Figs. 29 and 30] rounded ends forming long slender straight Cells disc shaped., valves almost fl at, narrow mar- chains with the aid of marginal spines which gin, areolae hexagonal, arranged in slightly run parallel to the axis of the chain, space curved, nearly parallel rows, based on arrange- between the cells longer than the cells, ment of seven divisions, central areola with chromatophores two plates which at times seven areolae grouped around it, areolae 7 in dissected, no visible structures on the valve, 10 μ at centre, 9 midway and 10 near margin, diameter of cells 10 μ chromatophores small, numerous, diameter 65 μ 27. Thalassiosira decipiens (Grunow) Jørgensen 32. Coscinodiscus excentricus Ehrenberg var. (Plate 5.8 , Fig. C) fasciculata Hustedt (Plate 5.8 , Fig. E) [Subrahmanyan, 1946 , p. 89, Fig. 19] [Hustedt, 1930b, Bd. VII, Teil 1, p. 390, Fig. 202; Cells disc shaped, valves fl at with minute spines Subrahmanyan, 1946 , p. 93, Figs. 32 and 38] along the border, valve aerolated, areolae in Cells disc shaped, valve aerolated, areolae in sev- three or more systems, their size becoming eral tangential series and because of this smaller towards the border, in the centre, appearing as though in radial bundles, number about 12 in10 μ and towards border 15 in 10 μ; of aerolae in the centre 9 in 10 μ and at the diameter 60 μ border 12 in 10 μ, diameter 65 μ Subtribe – Coscinodiscinae 33. Actinocyclus normanii f. subsala (Juhl.-Dannf.) 28. Cyclotella meneghiniana Kutzing (Plate 5.7 , Hustedt (www.itis.gov) (Plate 5.8 , Fig. D) Fig. N) [ Coscinodiscus radiatus Ehrenberg Cupp, 1943 , [Venkataraman, 1939 , pp. 299, Figs. 11 and 14; pp. 56, Fig. 20] Subrahmanyan, 1946 , p. 92, Figs. 25, 26 and 27] Cells fl at, coin-shaped discs, valves fl at, valve sur- Frustules discoid in valve view, margin well face with coarse areolae, without rosette or defi ned, coarsely striated and the striae wedge central area, areolae nearly same size on whole shaped, striae 8 in10 μ, diameter 15 μ valve,4 in 10 μ, except at margin where they 29. Cyclotella striata (Kutzing) Grunow are smaller, 6 in 10 μ, inner chamber openings (Plate 5.8 , Fig. F) rather indistinct, outer membrane of the areo- [Subrahmanyan, 1946 , p. 92, Fig. 31] lae apparently homogeneous, diameter 50 μ Cells disc shaped, 20 μ in diameter, valves with Suborder – Solenoideae more or less broad evenly striated border, Family – Solenieae striae 10–12 in 10 μ. Central portion with Subfamily – Lauderiineae plexes and coarsely punctuate 34. Leptocylindrus danicus Cleve (Plate 5.8 , 30. Coscinodiscus granii Gough (Plate 5.8 , Fig. G) Fig. B) [Subrahmanyan, 1946 , p. 113, Figs. 109, 110] [Hustedt, 1930b , Bd. VII, Teil 1, pp. 436, Fig. 237; Cells cylindrical, 10 μ in diameter and 50–80 μ in Venkataraman, 1939 , pp. 300, Figs. 16 and 17; length, forming long chains. No structure vis- Cupp, 1943, pp. 56, Fig. 21; Subrahmanyan, ible on the valve. Chromatophores numerous 1946 , p. 96, Figs. 33, 35 and 39] and disc shaped. Cells with excentric arched valves, central are- Subfamily – Biddulphioideae olae in defi nite rosette. Eight aerolae in 10 μ Tribe – Chaetocereae near centre, 10 midway to margin and 11 35. Bacteriastrum delicatulum Cleve (Plate 5.8 , near margin; on edge of valve mantle 13 in Fig. H) 10 μ, chamber openings small, dot-like, [Hustedt, 1930b, Bd. VII, Teil 1, p. 612, Fig. 353; diameter 105 μ. Subrahmanyan, 1946 , p. 125, Figs. 161–163] 31. Coscinodiscus excentricus Ehrenberg Cells longer than broad. Setae eight, perpendicu- (Plate 5.8 , Fig. A) lar to chain axis, basal part long. Apertures

Plate 5.8 ( A) Coscinodiscus excentricus Ehrenberg, fortianum Hust., ( M) Gyrosigma acuminatum (Kütz.) (B ) Coscinodiscus granii Gough, (C ) Thalassiosira decipi- Rabenh., (N ) Pleurosigma salinarum Grunow, ( O) Navicula ens (Grunow) Jørgensen, (D ) Actinocyclus normanii f. sub- minima Grunow, (P ) Navicula mutica Kutz. fo. cohni (Hilse.) sala (Juhl.-Dannf.) Hustedt, (E ) Coscinodiscus excentricus Grunow, (Q ) Navicula peregrina (Ehrenberg) Kutzing, Ehrenberg var. fasciculata Hustedt, (F ) Cyclotella striata (R ) Navicula quadripartita Hustedt, (S ) Amphiprora gigan- (Kutzing) Grunow, (G ) Leptocylindrus danicus Cleve, tea Grunow, ( T) Cymbella naviculiformis Allerswald, (H ) Bacteriastrum delicatulum Cleve, ( I) Odontella (U ) Bacillaria paxillifer (O. F. Müller) Hendy, (V ) Nitzschia aurita(Lyngb.) C. Agardh, (J ) Biddulphia dubia (Brightwell) amphibia Grunow, (W ) Nitzschia ignorata Kresske, Cleve, (K ) Cocconeis dirupta Greg., (L ) Gyrosigma beau- (X ) Nitzschia obtusa Smith, (Y ) Nitzschia punctata W. Smith 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 149

large. Terminal setae bent over the chain. chain axis; end setae more or less parallel to Diameter of cell 11 μ the chain axis, chromatophore platelike 36. Bacteriastrum varians Lauder (Plate 5.7 , Tribe – Biddulphieae Fig. U) Subtribe – Eucampiinae [Subrahmanyan, 1946, p. 127, Figs. 170–172 41. Eucapmia zoodiacus Ehrenberg (Plate 5.7 , and 175] Fig. H) Cells cylindrical, setae 19, bifurcated at about mid- [Cupp, 1943 , pp. 145, Fig. 103; Subrahmanyan dle and extended up to the tip, at right angles to 1946 , p. 145, Figs. 248, 250–253] the chain axis, terminal setae with fi ne spines Cells fl attened, elliptical–linear in valve view, arranged in spiral rows, 12 μ in diameter united in chains by two blunt processes, length 37. Chaetoceros curvisetus Cleve (Plate 5.7, Fig. J) of cell along apical axis 25 μ, chains spirally [Hustedt, 1930b , Bd. VII, Teil 1, pp. 737, Fig. curved, with relatively narrow lanceolate or 426; Cupp, 1943, pp. 137, Fig. 93 (pp. 138); elliptical apertures, apertures variable in size Subrahmanyan, 1946 , p. 143, Figs. 238, and shape, valves distinctly sculptured, chro- 244–246] matophores small, numerous Chains spirally curved. No distinct end cell. Apical Subtribe – Triceratiinae axis of cell measuring 12 μ. Cells in broad girdle 42. Ditylum brightwellii (West) Grunow view oblong, setae starting from the corners. (Plate 5.7 , Fig. G) Aperture somewhat broadly elliptical. Setae all [Cupp, 1943 , pp. 148, Fig. 107A, 107B; directed towards one side of the chain. Subrahmanyan, 1946 , p. 147, Figs. 263 and 264] Chromatophores a single plate with pyrenoid Cells prism shaped with strongly rounded angles 38. Chaetoceros diversus Cleve (Plate 5.7 , Fig. S) to nearly cylindrical, usually 3–5 times as long [Hustedt, 1930b, Bd. VII, Teil 1, pp. 716, Fig. as broad, valves triangular to circular with a 409; Subrahmanyan, 1946 , p. 142, Figs. 235, central hollow spine, valve rim strengthened 241–243] by small parallel ribs, girdle zone very long, Cells with apical axis measuring 5 μ in length, chromatophores small, numerous, nucleus forming straight chains which are usually central, diameter 74 μ short, apertures very small, setae, some hair- Subtribe – Biddulphiinae like; others thicker, tubular and spinous 43. Biddulphia alternans (Bailey) van Heurck. 39. Chaetoceros messanensis Castracane (Plate 5.7 , Fig. K) (Plate 5.7 , Fig. L) [Cupp, 1943 , p. 166, Fig. 115; Subrahmanyan, [Hustedt, 1930b , Bd. VII, Teil 1, pp. 718, Fig. 410; 1946 , pp. 153, Figs. 277 and 282 (Triceratium Subrahmanyan, 1946 , p. 142, Figs. 236, 237 alternans )] and 240] Valves quadrangular, with straight or somewhat Cells forming long straight chains, apical axis unevenly concave sides. Corners slightly ele- 12.5 μ in length, the corners of adjacent cells vated, rounded, separated from the central part touching each other, apertures elliptical, bris- by costae or ribs. Only a slight constriction tles thin, chromatophore a single plate between valve and girdle zones. Irregular ribs 40. Chaetoceros wighami Brightwell (Plate 5.7 , on both valve and girdle. Fine areolae (slime Fig. T) pores) on corners, 17 in 10 μ. Areolae 9 in [Hustedt, 1930b , Bd. VII, Teil 1, pp. 724, Fig. 414; 10 μ in centre of valve. Length along side of Cupp, 1943 , pp. 136, Fig. 91; Subrahmanyan, valve 30 μ 1946 , p. 142, Fig. 247] 44. Odontella aurita (Lyngb.) C. Agardh Cells somewhat tender forming chains, apical (Plate 5.8 , Fig. I) axis measuring 10 μ, cells in broad girdle view [ Biddulphia aurita (Lyngbye) Brébisson and oblong with sharp corners, the corners of Godey, Cupp, 1943 , p. 161, Fig. 112-A (1), neighbouring cells touching each other and 112-A (2), 112-A (3)] enclosing a narrow slitlike aperture, setae thin Valves elliptical–lanceolate, with obtuse pro- and fragile, inner ones perpendicular to the cesses infl ated at the base. Centre part of valve 150 5 Case Study

convex, more or less fl attened at the top from 48. Odontella rhombus (Ehrenb.) Kützing [ www. which long spines project. Girdle zone sharply itis.gov ] (Plate 5.7 , Fig. D) differentiated from the valve zone by a clear [ Biddulphia rhombus Ehrenberg, Hustedt, 1930b , depression. Cell wall strongly siliceous, areo- Bd. VII, Teil 1, p. 842, Fig. 496, 497; Cupp, lated punctuated. Areolae 8–10 in 10 μ, on the 1943 , p. 163, Fig. 113] valve in radial rows. On the girdle band in per- Valves rhombic–elliptical, cells thick walled, valvar rows, 7–10 rows in 10 μ, with 8–14 strongly sculptured, processes small, short and punctae obtuse, length of apical axis 35 μ, surface of 45. Biddulphia dubia (Brightwell) Cleve valve convex, beset with small spines over entire (Plate 5.8 , Fig. J) surface, valve zone and girdle zone divided by [Cupp, 1943, p. 164, Fig. 114; Triceratium deep groove, areolae on valve 9 in 10 μ, irregu- dubium Brightwell, Subrahmanyan, 1946 , lar at centre, then more or less regular radiating, p. 151, Figs. 274–276 and 278] girdle band more delicately sculptured 12 aero- Valves rhombic–lanceolate. Processes obtuse. lae in 10 μ in regular prevalvar rows Centre part of valve convex. Valve with Section – Pennatae numerous small spines and a larger one near Subsection – Araphideae base of each process. Valve zone and girdle Subfamily – Fragilariodeae zone divided by a deep groove. Valves distinctly Tribe – Fragilarieae punctate, 9 puncta in 10 μ. Length of apical Subtribe – Fragilariinae axis 54 μ 49. Thalassionema nitzschoides Grunow 46. Biddulphia heteroceros Grunow (Plate 5.7 , (Plate 5.7 , Fig. I) Fig. F) [Cupp, 1943, pp. 182, Fig. 133; Subrahmanyan, [Subrahmanyan, 1946 , p. 155, Figs. 288, 298 1946 , pp. 167, fi gs. 344–346] and 303] Frustules united into zigzag chains. Cells in girdle Cells box-shaped without a sharp constriction view linear–rectangular, in valve view linear– between valve and girdle in girdle view. Horns lanceolate, poles alike, 50 μ long, 3 μ broad from each pole of apical axis well developed, 50. Thalassiothrix frauenfeldii Grunow directed slightly away from pervalvar axis. Two (Plate 5.7 , Fig. O) strong spines on each valve a short distance [Cupp, 1943, pp. 184, Fig. 135; Subrahmanyan, from the horns. Valve between spines slightly 1946 , pp. 169, fi gs. 349, 351, 354–357 and higher that between spines and horns somewhat 360] fl at. Areolation almost the same size on valve Cells united into star-shaped colonies. In girdle and girdle, in regular rows, 9 in 10 μ view linear. Valves very narrow, linear, ends 47. Odontella mobiliensis (J. W. Bailey) Grunow distinct, one-end blunt rounded, near the other [ www.itis.gov ] (Plate 5.7 , Fig. E) end usually widened then decreased to form a [Biddulphia mobiliensis Bailey, Hustedt, 1930b , wedge-shaped point. Valves 53 μ long, 7 μ Bd. VII, Teil 1, p. 840, Fig. 495; Subrahmanyan, wide. Valves structure less 1946 , p. 155, Figs. 286, 287, 291–296 and 51. Asterionella japonica Cleve (Plate 5.7 , 299, Pl. II, Figs. 1 and 2] Fig. V) Cells single, length of apical axis 60 μ, valves [Venkataraman, 1939 , pp. 309, Fig. 34; Cupp, elliptical–lanceolate, convex, with a fl at or 1943 , pp. 188, Fig. 138; Subrahmanyan, 1946 , nearly fl at central part, valve processes slen- pp. 170, fi gs. 361 and 371] der, directed diagonally outward, two long Cells united into starlike spiral colonies. In gir- spines placed far apart but about equally far dle view, very narrow linear with parallel from the processes, directed obliquely out- sides, with greatly enlarged three-cornered ward, straight, cells relatively thin walled, region at the base. Cells united at the corners without a sharp constriction between valve of enlarged region. Valves very narrow, then and girdle zone, sculpturing fi ne, reticulate, 15 with a widened knob-like region at the base. areolae in 10 μ on valve and valve mantle. Length of valve 85 μ; length of enlarged 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 151

region 15 μ, width of enlarged part 6 μ. Valves linear lanceolate, slightly sigmoid. Raphe Chromatophores ½ small plates, in basal central. Central nodule elongated. Length enlarged part only 120 μ, breadth 17 μ Suborder – Monoraphidineae 58. Diploneis weissfl ogii (A. Schmidt) Cleve Family – Achnanthaceae (Plate 5.7 , Fig. W) Subfamily – Cocconeoideae [Subrahmanyan, 1946 , pp. 177, fi g. 397] 52. Cocconeis dirupta Greg. (Plate 5.8 , Fig. K) Valves strongly constricted, with sub-elliptical [Gregory, 1857 , pp. 491, pl. 9, fi g. 25] ends, 28 μ long and 12.5 μ broad, at the con- Cells broadly elliptic, about 40 μ long and 30 μ striction 8 μ broad. Central nodule with broad, striae 21 in 10 μ. Raphe sigmoid. approximate horns. Axial area narrow, dilating into a very small 59. Diploneis interrupta (Kutzing) Cleve central area (Plate 5.7 , Fig. Y) Subsection – Biraphideae [Hustedt, 1930b , Heft 10, pp. 252, Fig. 400; Subfamily – Naviculoideae Venkataraman, 1939 , pp. 323, fi g. 82] Tribe – Naviculeae Valves deeply constricted, the segments elliptical, 53. Gyrosigma beaufortianum Hust. (Plate 5.8 , rounded at the ends. Central nodule elongated, Fig. L) quadrate with parallel horns. Furrow linear, [Foged, 1978, p. 73, 21: 8] narrow. Costae strong usually interrupted in Valves slightly sigmoid with acute ends. Raphe the middle of the valve. Length of the valve central, sigmoid, central area small, rhombic, 35 μ, breadth in the middle 10 μ length 55.025 μ and breadth 6 μ 60. Navicula minima Grunow (Plate 5.8 , Fig. O) 54. Gyrosigma acuminatum (Kütz.) Rabenh. [Hustedt 1930b , pp. 272, fi g. 441] (Plate 5.8 , Fig. M) Valves are lanceolate in shape, with tapering [Gyrosigma spencerii (Quekett) Cleve, Cupp, ends. Striations are very fi ne. Length 13.96 μ, 1943 , p. 194, Fig. 144] breadth 3.49 μ Valves sigmoid, lanceolate, with obtuse ends. 61. Navicula mutica Kutz. fo. cohni (Hilse.) Raphe central. Central nodule elliptical. Grunow (Plate 5.8 , Fig. P) Transverse striae 18 in 10 μ; longitudinal [Foged 1978, pp. 93, pl. XXVIII, fi g. 10] striae 25 in 10 μ. Length of valves 185 μ Valves are elliptic lanceolate in shape, with 55. Gyrosigma obtusatum (Sull. & Wormley) rounded ends. Striations fi ne and delicate. Boyer (Plate 5.7 , Fig. C) Length 13.96 μ, breadth 6.98 μ [ Gyrosigma scalproides (Rabh.) Hustedt, 1930b , 62. Navicula peregrina (Ehrenberg) Kutzing Heft 10, pp. 226, Fig. 339; Venkataraman, (Plate 5.8 , Fig. Q) 1939 , pp. 319, fi g. 76] [Hustedt, 1930b , Heft 10, p. 300; Venkataraman, Valves linear with parallel sides and obliquely 1939 , p. 326, fi g. 85] rounded ends. Raphe straight, nearly central, Valves lanceolate with obtuse ends. Axial area slightly sigmoid at the ends. Longitudinal distinct, narrow, central area broadened, ellip- striae very faint. Length of valve along apical tical, length 62.12 μ and breadth 14.9 μ axis 76 μ and breadth 8 μ 63. Navicula quadripartita Hustedt (Plate 5.8 , 56. Pleurosigma normanii Ralfs (Plate 5.7 , Fig. B) Fig. R) [Cupp, 1943 , pp. 196, Fig. 148; Subrahmanyan, [Foged, 1979 , pl. XXIX, Fig. 18] 1946 , pp. 175, fi gs. 378, 379, 385 and 387] Valves elliptical with broadly rounded ends. Valves broadly lanceolate, slightly sigmoid, with Central area widened, striations radial; the subacute ends. Raphe nearly central, sigmoid. number of striae in 10 μ is 14, length 17.92 μ, Length of valve 115 μ breadth 5.31 μ 57. Pleurosigma salinarum Grunow (Plate 5.8 , Subfamily – Amphiproroideae Fig. N) 64. Amphiprora gigantea Grunow (Plate 5.8 , [Hustedt, 1930b, Heft 10, p. 228, Fig. 344; Fig. S) Venkataraman, 1939 , p. 320, fi g. 78] [Subranmanyan, 1946 , p. 184, Figs. 410 and 413] 152 5 Case Study

Cells strongly constricted. Keel with hyaline Frustules broad, linear with ends obliquely margin. Junction line curved like a bow. truncate. Striations punctate, punctae very fi ne Cells 75 μ long. Keel punctae forming and linear, number of striations 10 in 10 μ. obliquely decussating rows, 15 rows in 10 μ. Length 44 μ, breadth 4.5 μ Connecting zone with numerous longitudi- 70. Nitzschia obtusa Smith (Plate 5.8 , Fig. X) nal divisions [Hustedt, 1930b , Heft 10, p. 422, Fig. 817; Subfamily – Gomphocymbelloideae Venkataraman, 1939 , p. 354, Fig. 147] 65. Cymbella naviculiformis Allerswald (Plate 5.8 , Frustules broad, linear with ends obliquely Fig. T) truncate. Striations punctate, punctae fi ne and [Hustedt, 1930b, Heft 10, p. 356, Fig. 653; linear. Length 98 μ and breadth 10 μ Venkataraman, 1939 , p. 346, Fig. 119] 71. Nitzschia punctata W. Smith (Plate 5.8 , Valve elliptic lanceolate with capitate ends. Axial Fig. Y) area narrow, linear, suddenly dialated in mid- [Foged 1979 , p. 209, pl. XL, Fig. 16] dle. Striations radial. Length 30.04 μ, breadth Valves linear with slightly concave margins. 10.12 μ, number of striations 13 in 10 μ Ends wedge shaped and rounded. Striae clear, Subfamily – Nitzschioideae 10 in 10 μ. Length 22.908 μ, breadth 5.312 μ Tribe – Nitzschieae 72. Nitzschia sigmoidea Ehrenberg (Plate 5.7 , 66. Bacillaria paxillifer (O. F. Müller) Hendy Fig. A) (Plate 5.8 , Fig. U) [Hustedt, 1952, p. 147] [Bacillaria paradoxa Gmelin, Subrahmanyan, Cells solitary. Frustules isopolar, straight in valve 1946 , p. 187, Figs. 417, 421 and 427] view but sigmoid in girdle view; bilaterally Cells in girdle view linear and rectangular, united symmetrical valves linear lanceolate, straight. by their valves to form a mat-like colony, indi- The sigmoid shape of the frustule is entirely vidual cells of which exhibit gliding move- due to the form of the valve margin and girdle. ment in the living condition. Valves linear, Two chloroplasts per cell. Length of valve spindle shaped in outline, 150 μ long, 8 μ 172.5 μ broad. Keel punctae 7 in 10 μ. Transapical 73. Nitzschia delicatissima Cleve (Plate 5.7 , striae fi ne, 21 in 10 μ Fig. R) 67. Nitzschia amphibia Grunow (Plate 5.8 , [Cupp, 1943 , p. 204, Fig. 158 (p. 206)] Fig. V) Valve narrow, linear, acute. Cells united into [Hustedt, 1930b, Heft 10, p. 414, Fig. 793; stiff hairlike chains by the overlapping tips of Venkataraman, 1939 , p. 353, Fig. 149] the cells. Chains usually short, motile. Valves linear to linear lanceolate with the ends Length of valve 80 μ; width 3 μ. Keel puncta slightly produced and sometimes rounded. 20 in 10 μ. No striae visible. Chromatophores Striations coarse. Length 17.45 μ, breadth two per cell 3.49 μ, striae 15 in 10 μ 74. Nitzschia pacifi ca n. sp. (Plate 5.8 , Fig. Q) 68. Nitzschia bilobata var. minor Grunow [Cupp, 1943 , p. 204, Fig. 157] (Plate 5.7 , Fig. P) Cells spindle shaped with more or less pointed [Cupp, 1943 , p. 200, Fig. 152] ends. United into stiff chains by the overlap- Valves linear lanceolate, constricted in the mid- ping points of the cells. Chains motile as a dle, apiculate at the ends. Keel puncta 12 in whole. Length of valve 94 μ, width 6 μ. Keel 10 μ. Striae 25 in 10 μ. Cells broad, oblong, puncta distinct, 14 in 10 μ. Chromatophores truncate, constricted in the middle. Length of two per cell the valve 55 μ, width of widest point 6 μ Subfamily – Surirelloideae 69. Nitzschia ignorata Kresske (Plate 5.8 , Tribe – Surirelleae Fig. W) 75. Surirella fastuosa var. recedens (A. Schmidt) [Foged, 1979 , p. 215, Pl. XLII, Fig. 6] Cleve (Plate 5.7 , Fig. M) 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 153

[Cupp, 1943 , p. 208, Fig. 160] lanceolate. Marginal striae distinct, 18 in Cells wedge shaped, rounded at the angles. 10 μ. Striae in central fi eld 17 in 10 μ. Valves ovate. Costae or ribs about 2.5 in 10 μ, Length of valve 60 μ, width 35 μ (Plate 5.13 , robust, dialated at the margin. Central space Fig. N)

Plate 5.9 (A ) Ankistrodesmus falcatus var. stipitatus quadricauda (Turp.) de Brébisson in de Brébisson & (Chod) Lemmermann, ( B ) Dictyosphaerium pulchellum Godey, ( G ) Schroederia judayi G. M. Smith, ( H ) Cruci- Wood, ( C ) Scenedesmus bijuga (Turp.) Langerheim, genia tetrapedia (Kirch.) West &West, (I) Crucigenia ( D ) Scenedesmus dimorphus (Turp.) Kuetzing, ( E ) Kirch - rectangularis (A. Braun) Gay, (J ) Tetrastrum staurogeni- neriella lunaris (Kirch.) Moebius, (F ) Scenedesmus aeforme (Schröder) Lemmermann 154 5 Case Study

Plate 5.10 (A ) Coscinodiscus granii Gough, ( B ) alternans (Bailey) van Heurck, (I ) Chaetoceros massenensis Coscinodiscus excentricus Ehrenberg, (C ) Actinocyclus Castracane, ( J ) Bacteriastrum varians Lauder, (K ) Chae- normanii f. subsala (Juhl.-Dannf.) Hustedt, (D ) Thala- toceros diversus Cleve, (L ) Chaetoceros wighamii ssiosira decipiens (Grunow) Jørgensen, (E ) Cyclotella Brightwell, ( M ) Odontella mobiliensis (J. W. Bailey) meneghiniana Kutzing, (F ) Chaetoceros curvisetus Cleve, Grunow ( G ) Odontella rhombus (Ehrenb.) Kützing, ( H ) Biddulphia 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 155

Plate 5.11 (A ) Odontella aurita (Lyngbye) Brébisson tum (Greville) Cleve, (H ) Aulacoseira granulata (Ehr.) and Godey, (B ) Biddulphia dubia (Brightwell) Cleve, Ralfs var. Angustissima , ( I) Cyclotella striata (Kutzing) (C ) Biddulphia heteroceros Grunow, (D ) Ditylum bright- Grunow, (J ) Coscinodiscus excentricus Ehrenberg var. fas- welli (West) Grunow, (E ) Eucapmia zoodiacus Ehrenberg, ciculata Hustedt, (K ) Thalassiothrix frauenfeldii Grunow, ( F) Leptocylindrus danicus Cleve, (G ) Skeletonema costa- ( L) Thalassionema nitzschoides Grunow 156 5 Case Study

Plate 5.12 ( A ) Asterionella japonica Cleve, (B ) Gyrosigma beautifortianum Hust., (G ) Amphiprora gigantea Grunow, obtusatum (Sull. & Wormley) Boyer, (C ) Gyrosigma acumi- ( H ) Nitzschia delicatissima Cleve, (I ) Nitzschia sigmoidea natum (Kütz.) Rabenh., (D ) Pleurosigma salinarum Ehrenberg, (J ) Navicula peregrina (Ehrenberg) Kutzing Grunow, (E ) Pleurosigma normanii Ralfs, (F ) Gyrosigma 5.4 Case Study III: Phytoplankton Dynamics of Eastern Indian Coast 157

Plate 5.13 ( A ) Diploneis weissfl ogii (A. Schmidt) Cleve, ( I ) Cymbella naviculiformis Allerswald, (J ) Navicula (B ) Diploneis interrupta (Kutzing) Cleve, ( C ) Cocconeis mutica Kutz. fo. Cohni , (K ) Nitzschia bilobata var. minor dirupta Greg., (D ) Surirella fastuosa var. recedens Grunow, ( L ) Nitzschia obtusa Smith, (M ) Nitzschia punc- (A. Schmidt) Cleve, ( E ) Navicula quadripartita Hustedt, tata W. Smith, (N ) Bacillaria paxillifer (O. F. Müller) ( F ) Navicula minima Grunow, (G ) Bacteriastrum deli- Hendy, ( O ) Nitzschia amphibia Grunow, ( P ) Nitzschia catulum Cleve (top view ), ( H ) Nitzschia ignorata Kresske, pacifi ca n. sp 158 5 Case Study

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Algae Algae are polyphyletic group of simple, Chlorophyll Fat-soluble, green, porphyrin-type oxygenic photosynthetic organisms that have pigment. chlorophyll as their main photosynthetic pig- Chloroplast Plastid with chlorophyll. ment and lack sterile covering of cells around Chloroplast endoplasmic reticulum or chlo- the reproductive cells. roplast ER One or two membranes surround- Algal bloom Dense population of planktonic ing the chloroplast envelope; ribosomes are algae or cyanobacteria that distinctly colours usually attached to the outside of the outer the water and may form scum on the surface. membrane. Algal trophic index Quantitative expression Chromatic adaptation Change in the propor- of algal species counts, providing a measure tion of different photosynthetic pigments of the trophic (nutrient) status of the aquatic enabling optimum absorption of the available environment. wavelengths of light. Allochthonous Materials (usually organic) pro- Circadian rhythm Repeated sequence of duced within a water body. metabolic activities that occur at about 24 h Apochlorotic Colourless or without chlorophyll. intervals. Organism capable of synthesizing Coccoid Spherical structure. organic matter by means of photosynthesis. Coccolith Calcifi ed scale in a coccolithophorid Bathyal zone Ocean water over continental (Prymnesiophyceae). slope. Coenobium Spherical colony of algal cells Biofi lm Community of microorganisms occur- with central hollow and number that is fi xed ring at a physical (e.g. water/solid) interface at the time of origin and is not subsequently that is typically present within a layer of extra- augmented. cellular polysaccharide that is secreted by the Compensation depth Depth of water at which community. suffi cient light is penetrated so that photo- Bioluminescence Emission of light by a living synthesis equals respiration over a 24 h organism. period. Biovolume Volume of single algae and algal Compensation point Particular light intensity populations in a particular population. It may at which respiration equals photosynthesis be measured either for a single genus or for a over a 24 h period of a specifi c area. mixed population (volume of individual taxa Coralline Calcifi ed algae. should be measured). Cryptomonads Group of unicellular motile Brackish Saline water with a salinity less than eukaryote algae of the division Cryptophyta.

that of seawater (33 0/00 ) . Cyanelle Endosymbiotic blue-green alga that Calcifi cation Deposition of calcium carbonate, gave rise to chloroplast. usually in association with smaller amounts of Cyanome Host cell containing a cyanelle that other carbonate. gave rise to eukaryotic algae. Carotenoid Yellow, orange or red hydrocarbon Cyanophage Virus that infects the cells of the or fat-soluble pigment. Cyanophyceae.

R. Pal and A.K. Choudhury, An Introduction to Phytoplanktons: Diversity and Ecology, 163 DOI 10.1007/978-81-322-1838-8, © Springer India 2014 164 Glossary

Cyanophycin granule Polypeptide storage Intertidal Occurring between the low and high granules within the cells of Cyanophyceae. tide marks. Diatom indices Use of diatom species counts to Iridescence The play of colours caused by assess the trophic status of a water body. refraction and interference of light waves at Dystrophic Brown or yellow coloured waters the surface. rich in organic matter where the rate of decay K-selected species (K-strategist ) Organisms of that organic matter is slow having a low pH. adapted to high levels of competition in a Ecosystem Self-regulating biological commu- crowded environment where they survive, nity living in a defi ned habitat. grow and reproduce. Environmental stress factor External change Lentic Related to a pond or lake habitat. that impairs biological function at the level of Limnology Study of aquatic systems in relation individual organisms and molecular systems to physicochemical and biotic factors. of an ecosystem. Littoral zone Peripheral shoreline at the edge of Epilithic Organisms living on rock surfaces. lakes and rivers. Epipelic Organisms growing on mud. Lotic Related to rivers or stream habitat. Epiphyte One plant living on other plant. Macroplankton Planktons larger than 75 μm in Epontic Organisms living on the bottom of ice. diameter. Also called net plankton. Estuary The junction of a river and ocean where Meroplanktonic Algae with only a limited tidal effects are evident and where freshwater planktonic existence in the water column. and seawater mix. Most of the annual cycle is spent on sediments Euphotic or photic zone Regions of water body as a resting stage. above the compensation depth. Mesotrophic Water body with moderate levels Eurysaline (euryhaline ) Organisms tolerant of of inorganic nutrients and moderate primary a wide salinity range. productivity – intermediate state between Eutrophic A body of water that receives large oligotrophic and eutrophic condition. amounts of nutrients, usually resulting in a Microplankton Unicellular and multicellular large growth of algae. planktonic organisms in the size range of Eutrophication An increase in the concentra- 20–200 μm. tion of soluble inorganic nutrients such as Mixotrophy Organisms having the ability to phosphates and nitrates in aquatic ecosystem. combine both autotrophic (using inorganic Gas vacuole Gas-fi lled vacuum found in some carbon sources) and heterotrophic (organic car- aquatic blue-green algae and bacteria that bon sources including phagotrophy) nutrition. increases buoyancy. It is composed of gas Nannoplankton or nanoplankton Plankton vesicles which are made of protein. smaller than 75 μm but larger than 2 μm. Habitat The living place of an organism or com- Nephelometer Submerged instrument used to munity, characterized by its physicochemical measure the particulate concentration (tur- and biotic properties. bidity) of water by collecting light scattering Holoplanktonic Aquatic organisms which are from suspended matter. present in the water column over most of the Oligotrophic Water body with less dissolved annual cycle. inorganic nutrients (particularly nitrogen and Hydrology All aspects of water fl ow connected phosphorous) resulting in low levels of bio- with an aquatic system, including infl ow and logical productivity. outfl ow of water. Organotroph (osmotrophy, saprotrophy) Hypertrophic Water body with extremely high Organisms that either use reduced organic levels of dissolved inorganic nutrients, also compounds as its sources of electrons or carry called hypereutrophic. out organotrophy. Hypolimnion Region of water body beneath the Pelagic All organisms normally present in the thermocline in thermally stratifi ed water bodies water column of water bodies like plankton with low light intensity. and nekton. Glossary 165

Pelagic zone The central main part of a lake. Secchi depth A particular depth of a water Periphyton Plantlike organisms present in a column at which a suspended sectored plate community mainly on underwater substrata – (Secchi disc) can no longer just be seen including algae, bacteria and fungi. indicating the measure of water turbidity and Photic zone Upper part of water column phytoplankton biomass. on aquatic ecosystem in which net photo- Sedgwick rafter cell counter A grooved slide synthesis can occur (also known as the eupho- with counting chamber commonly used for tic zone). phytoplankton samples. Phototroph Organisms that use solar energy to Stratifi cation Vertical structuring of static or fi x inorganic carbon to organic compounds by very slow moving water bodies into three dis- photosynthesis. tinct layers – epilimnion, metalimnion and Phragmoplast Wall formation by the coales- hypolimnion. Determined by temperature and cence of Golgi vesicles between spindle circulatory differences with the water column. microtubules. Sublittoral zone In the freshwater region, the Phytoplankton Free-fl oating plants that fl oat zone from the end of rooted vegetation (about aimlessly or swim too feebly to maintain a 6 m) to the compensation depth and in the constant position against water current. marine ecosystem the zone from the lowest Picoplankton Plankton with a diameter of low tide mark to 200 m depth. 0.2–2 μm. Succession Temporal sequence of organism that Plankton Organisms that fl oat aimlessly or swim occurs in a developing community such as too feebly to maintain a constant position biofi lm or lake pelagic community. against water current. Supralittoral zone In marine ecosystem the zone Plankton sedimentation Gravitational force- above the high tide mark in the ocean and in induced sinking of nonmotile plankton in the freshwater region above the standing water mark, water column. which receives splash during windy periods. Primary production Synthesis of biomass by Trophic The term ‘trophic’ is used to describe photosynthetic organisms – higher plants, the inorganic nutrient status of different water algae and photosynthetic bacteria. bodies (oligotrophic to eutrophic) and the Productivity The rate of increase in biomass feeding relationships (trophic interactions) of (growth rate) in a population of organism. Can freshwater biota. 2 be expressed as mgC/m /day. Turbidity Opacity of water caused by sus- r-selected species (r-strategist) Organism pended particulate matter used as measure of adapted to an uncrowded environment, with phytoplankton biomass. low competition. Tychoplankton Organisms circumstantially Saline lakes Lakes with highly concentrated carried into the plankton often from plant or salts often resulting in white salt ‘crusts’ rock surfaces. Also referred to as ‘accidental round their margins where evaporation from plankton’ or ‘’. the surface greatly exceeds the inputs. Water bloom See algal bloom. Saprobic pollution High concentration of solu- Zooplankton Assemblage of invertebrate ble organic nutrients. planktonic organism. Bibliography

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R. Pal and A.K. Choudhury, An Introduction to Phytoplanktons: Diversity and Ecology, 167 DOI 10.1007/978-81-322-1838-8, © Springer India 2014