CHAPTER 2 LITERATURE REVIEW

2.1 Diversity of algae

Biodiversity is the variety of life forms, it also refers to variation at all levels of biological organization. It can be divided into three groups: genetic diversity, diversity and ecosystem diversity. Genetic diversity refers to the total number of genetic characteristics in the genetic makeup of a species. Whereas, the species diversity refers to the number and distribution of species in one location. It contains the taxonomic difference from individual to species, genera and higher taxonomic level. Ecosystem diversity compasses the scale of physical conditions different from populations to niches and habitats (Gaston and Spicer, 2004). The diversity is influenced by many environmental factors. The most influenced factors are habitat characteristic and ecological complex. High diversity of organisms reflects to complex ecosystem, while the decreased of diversity will obviously affect ecosystem changing (Baimai, 2003). Algae is a highly diverse group of photoautotrophic organisms with chlorophyll-a and unicellular reproductive structures which play very important role in aquatic habitats. There are approximately 8 upto 19 divisions with 26,900 species of algae have been described in the list of species of living organisms in the world (Wilson, 1988). Algae are ranged in size from microscopic single cell to large visible seaweed. They can be separated by their living habitats into 2 groups: floating algae as phytoplankton and benthic algae which are attached to substrate. Algae are usually found in bodies of water and thus are common in terrestrial as well as aquatic environments. However, terrestrial algae are usually rather inconspicuous and far more common in moist, tropical regions. Sometimes they were also found in extreme environments such as in hot spring, snow or high salinity water (John et al., 2002). 5

2.2 Desmids studies

2.2.1 Classification of desmids Desmids are freshwater algae which composed of unicellular and filamentous green algae. Most desmids arje unicellular algae, few are occurred a simple, unbranched, sometimes very fragile filament. Cells ranged in size from very small (7-10 µm) to more than 1 mm. long. Cell wall may be smooth but often shows a distinct pattern of granules, tubercles or spines. Rich cell wall ornamentation, whether or not in combination with deep semi cellular incisions or long processes (Croasdale and Flint, 1986). The shape of the half-cells (semicells) is varied: ranging from globular to disc- or spindle-like. Desmids exhibit a great diversity in their external morphological and show remarkable complex cell symmetry. Particularly a group which is characterized by their conjugation as a way of a sexual reproduction (Ralfs, 1848). The characteristic of cell wall has been used for identifying the desmids into families (Brook, 1981). The desmids are divided into the Placoderm or true desmids and Saccoderm or false desmids. According to the work of Růžička (1977), Placoderm belongs to the order whereas, Saccoderm belongs to order . Most saccoderm desmids are unicellular, with cylindrical or ellipsoidal cells which do not consist of two semicell and possess a one-piece cell wall similar to that of the filamentous Zygnematales (e.g. Spirogyra). The placoderm desmids, cells are generally solitary, but sometimes form colonies or unbranched filaments with their cell wall of two or more pieces. The wall of each cell consists of two symmetry semicell and unique morphology. Round (1973), Brook (1981) and Gerrath (1993) had primarily characterized desmids based on their cell wall structure into 4 families, 43 genera and 3,000 species which could be described as the following;

Division Chlorophyta Class: Conjugatophyceae Order: Zygnematales Family: Zygnemataceae Family: Mesotaeniaceae (Saccoderm desmids)

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Genus: Ancylonema, Cylindrocystis, Geniculus, Mesotaenium, Netrium, Roya, Spirotania Order: Desmidiales (Placoderm desmids) Family: Peniaceae : Genicularia, Gonatozygon, Penium Family: Genus: Closterium, Spinoclosterium Family: Desmidiaceae Genus: Actinotaenium, Allorgeia, Amscottia, Bambusina, Bourrellyodesmus, Cosmarium, Cosmocladium,Desmidium, Docidium, Euastrum, Groenbladia, Haplataenium, Hyalotheca, Ichthyocercus, Ichthyodontium, Micrasterias, Oocardium, Phymatodocis, Pleurotaenium, Prescolliella, Sphaerozosma, Spinocosmarium, Spondylosium, Staurastrum, Staurodesmus, Streptonema, Teillingia, Tetmemorus, Triplastrum, Triploceras, Xanthidium

2.2.2 Ecology and distribution Desmids are freshwater algae. Only few species are known to distribute in brackish water. They are commonly found in lakes and ponds which are widespread throughout the world (Lind and Brook, 1981). Several habitats can be rich in desmids flora such as mire, peat swamp, quark fen and pool (Croasdale, 1994). However, they are being rather rare in lotic environment (Brook, 1981). The acidic (low pH 4-7) and highly colour water also have a large desmids population. Pools in bog or fen are often rich in desmids, which are especially common in aufwuchs around submerged Sphagnum . As shown in Lenzenweger’s study, that found high diversity of desmids, 233 species in low pH level of water in several bog of Austria. (Lenzenweger, 2000)

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Two typical living forms of desmids were revealed that planktonic forms are most recognized in open water. Genus Cosmarium and Staurastrum are commonly found in plankton. Nevertheless, most species of desmids are benthic and live on or between submerged around the margin of water body. The attached species can be derived from the submerged plants to open water. Large and diverse desmid populations were on macrophytes with finely leaves sush as Ceratophylum, Myriophylum and especially Utricularia (Coesel, 2001). Desmids are generally common and diverse in oligotrophic lakes (poor in nitrate and phosphate); low productivity, low conductivity, low bicarbonate alkalinity and low pH (Coesel, 1981). However, they are also found in mesotrophic or eutrophic lakes, most of them belong to the genera Closterium, Cosmarium and Staurastrum (Coesel, 1983). Stamenković and Cvijan (2008) expressed that Closterium spp. were found to be dominated in polluted water in Serbia. Palmer (1970) also pointed that Closterium is a high tolerant species for polluted environments. If desmids are not found in large quantities, they seems to be useful as indicator of oligotrophic conditions of those habitats where they occur (Coesel, 1983). It could be indicated that the presence of desmids assemblages might be revealed a conservation value of aquatic environment (Coesel, 2001). Desmids diversity have been extensive interested for over 150 years. Consequently, there are some 8,000 references relating to these organisms throughout the botanical and limnological literatures. The majority of these papers related to their morphology and since the publication of the first book on identification of British Desmidiaceae by Ralfs in 1848. A succession of keys has been distributed in Europe, Russia, The United States and Japan (Brook, 1981). Therefore, several publications of desmids diversity have been done in many parts of the world. In Europe, most desmids flora were studies intensively for example, a monograph of the British Desmidiaceae. The whole series focused on diversity of desmids encountered in the United Kingdom, applicable to the greater part of Europe (West and West, 1904, 1905, 1908, 1912). The other importance study is work of Krieger (1933, 1939) on all Mesotaeniaceae genera, as well as the Desmidiaceae genera Penium, Closterium, Docidium, Pleurotaenium, Triploceras, Ichthyocercus, Tetmemorus, Euastrum and Micrasterias. This study not only done with European species but also with a fair number

8 of many tropical desmids. Similarly to the work of Förster (1982) which is focused on planktonic desmids of selected taxa from all over the world. Thus, there are but few really euplanktonic species among the desmids. This selection was composed of some tychoplanktonic species (the great majority in the desmids). Ruzicka flora in 1981 deals with the genera Gonatozygon, Genicularia, Penium, Closterium, Docidium, Pleurotaenium, Triploceras, Triplastrum, Actinotaenium, Tetmemorus, Euastrum and Micrasterias in central European area. Similarly, Lenzenweger’s flora (1996, 1997, 1999, and 2003a) revealed the desmids flora of Austria where approximately 600 species of temperate climatic or alpine regions area were presented. The latest flora represented all desmids taxa known from the Netherlands and lowland areas. Over 28 genera, 500 species and 150 additional varieties are dealt with (Coesel, 2007). The other valuable desmids flora are from North America in which nearly 1,000 species of Placoderm and Saccoderm desmids were descript (Prescott et al., 1972, 1975,1977,1981,1982 and 1983). Moreover, the investigation of 30 genera, 117 taxa of desmids from New Zealand were shown as rich desmids diversity. At least 17% of them occur only in New Zealand (Croasdale et al., 1994). However, the floras mentioned above were all from temperate zone. In other regions, the desmids diversity mostly report in some specific publications. The tropical region is wildly known for its high diversity of organisms. In the same way as the desmids diversity was high. The characteristic of the biogeography of desmids was declared as Indo-Malaysian and North Australian Region following West and West (1902) that recognized this regions compose with the Indian subcontinent, Sri Lanka, Tropical Southeast Asia and North Australia which were confirmed by Krieger (1932) who defined more nine phycogeographical in the world, based on the composition of desmids flora. This region was investigated in the early period by many desmidiologists particularly Myanmar and Indonesia (Bonea, Java and Sumatra). Joshua (1886), West and West (1907) and Skuja (1949, 1964) studied the biodiversity of desmids in Myanmar in which 186 and 147 species were reported, and many species are new to science. Indonesia is an interesting location in this region in search for a tropical species of desmids because of diverse types of freshwater habitat. Krieger (1932) reported 23 genera and 380 species of desmids from Indonesia. Scott and Prescott (1961) also reported 24 genera and 525 species from Indonesia including South Borneo.

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Lenzenweger (1974) also collected the planktonic sample from West-Boneo. In addition, about 500 desmid of Papua New Guine were revealed by Bando et al. (1982), Yamagishi and Kanetsuna (1990), Vyverman (1991) and Gontcharov et al.(1999, 2001). The most extensive list of species including 427 taxa was presented by Vyvermann’s study, which covered wide range of habitats and provides valuable information about desmid diversity in this part of the world. In addition, nine taxa were described as a new species from about 200 species collected from Malaysia and Singapore (Prowse, 1969). The desmid studies on Indochinese Peninsula are fewer than other regions. The major report was by Hirano (1992) on 27 genera, 663 species from Thailand and Malaysia. In Malaysia, Williamson (1998) also reported 82 taxa from Tasek Bera and 14 genera, 104 taxa from Kuala Lumper, Salawak (Yamacishi and Kanetsuna, 1991). The tropical area in Northern part of Australia appears to be rich in desmids taxa, with approximately 2,060 taxa, an equivalent to 50% of whole list of Australia (Coesel, 1996). Previous desmids collections made in this area were done by Borge (1896), Scott and Prescott (1958), Thommasson (1971, 1986), Croasdale and Scott (1976), Dingley (2001) and Coesel and Dingley (2005). Many desmids species from this part showed a phycogeographical relationship with the neighboring countries (Ling and Tyler , 2000). Indian subcontinent and Sri Lanka have many desmid publications in the region. One third of all publications in Vyvermann (1996) were from India such as Agarker and Agarkar (1977) , Agarkar et al. (1979), Prasad and Misra (1984), Hegde (1986a, 1986b), Bongale and Kaulapur (1989), Bongal (1989) and Bharati and Hegde (1982). Including neighboring area in Pakistan (Islam, 1970), Bangladesh (Islam and Haroon,1980) and Srilanka (Rott and Lenzenweger, 1994). The algal flora in this region, Indo-Malaysian North Australian Region was reviewed by Vyverman (1996). It was found that more than 4,700 taxa of algae have been recorded, with more than 2,680 desmids were presented as the highest number in this area (57% of all taxa). 800 have never been found elsewhere. Coesel (1996) suggested that desmids flora from Indo- Malaysia and Northern Australia has a high degree of resemble. The characteristic species of this region are Triploceras splendens, Euastrum aspertum, E. moebii, Micrasterias anomala, M. ceratofera, Staurastrum freemanii, S. tauphorum and Streptonema trilobatum. A comparison of the number of

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desmid species reported from these two geographical areas in Southwest Asia seems to be interesting for diversity and distribution of desmids in Thailand. Because the comparison of species distribution in Indonesia and Thailand showed similar genera and species (more than 35% of species) (Hirano, 1992). Moreover, the geographic distribution of desmids in this region seems to be restricted to temperature limits, both along latitudinal and altitudinal gradients. However, more knowledge of species diversity, taxonomy and ecology to fulfill the gap of tropical freshwater algae distribution are very much needed (Vyverman, 1996).

2.2.3 Study of desmids in Thailand The first record on desmids flora of Thailand was given by West and West (1901) in “Flora of Koh Chang”, based on the sample from Koh Chang, Trad, a small island in the Gulf of Thailand. The samples were investigated by Dennish expeditions to Thailand from 1899 to 1900. The 11 genera and 84 species of desmids were reported. Then, from 1961 to 1962, the material collected by the joint Thai-Japanese Biological Experdition to South East Asia was identified by Hirano (1967). The collection consisted of gathering from lowland districts, ranging from Chiang Mai, northeastern and southern part of Thailand. 11 genera, 171 species of desmids were found in this study with 86 species desmids, or one half of the total number was collected from Chiang Mai area. The present of desmid species revealed the relations of distributions with desmid flora of Southern part of Asia, Eastern Africa and even northern Australia. The following noteworthy species were suggested by Hirano (1967): Pleurotaenium bulbosum, Cosmarium freemanii, C. maculatiforme var. major, C. medioscrobiculatum var. egranulatum, C. perpastum, C. proteiforme, C. triordinatum, C. tjibenongense, C. treubii, C. westii, Staurodesmus curvatus, Xanthidium antilopaeum f. javanica, X. superb, Euastrum ansatum var. javanicum, E. ceylanicum, E. didelta var. bengalicum, E. dubium var. tropicum. E. mobil, E. serratum, Micrasterias apiculata var. lacerata, M. ceratofera, M. cumningtonii, M. radians, Staurastrum cerastes var. coronatum f. inflatum, St. diptilum, St. javanicum, St. sexangulare var. bidentatum. Boraphet lake, the biggest lake in Thailand was examined by Hirano (1975) and Yamagishi and Kanetsuna (1987). The former investigated the phytoplankton community of the lake, whereas 91 planktonic desmid species were recorded while the dominant species was cyanophycean algae, Microcystis

11 and Anabaena. The latter found that 14 genera, 62 species of desmids were presented as abundant group. In 1992, the valuable desmids study was published by Hirano (1992). A total of 27 genera and 663 taxa of desmids have been identified in samples examined of Thailand and Malaysia. These samples were collected from 52 sites in Thailand and 2 sites from Malay Peninsula. The collections from Thailand samples included 16 new taxa, 8 species (Pleurotaenium annuloides , Cosmarium amoeboides, C. ellipticum, C. thailandicum, Arthrodesmus thailandicus, Xanthidium multispinum, Staurastrum pachyrhynchiforme), 7 varieties (P. trabecula var. Thailandicum, Tetmemorus brebissonii var. ansatiformis, Euastrum ansatum var. undulatum, E. bilobum var. Thailandicum, E. exile var. latum, E. intermedium var. rotundatum, Micrasterias radians var. siamense, M. rotata var. curvata, Staurastrum archeri var. curvatum, St. praenii var. major) and 1 form (P. ehrenbergii f. distinctum). Moreover, the following 99 taxa detected in Hirano (1992) from Thailand and Malaysia are tropical species according to Krieger's (1932), proposed lists of the characteristic desmid flora in the tropical zone of Southeast Asia and Australia, i.e., the "Indo-Malay and Northern-Australian area". They are as follows: Pleurotaenium granuliferum, Ichthycercus longispinus, I. angolense, Cosmarium cuneatum C. javanicum, C. askenasyi var. latum, C. bengalense, C. otus var. ornatum, C. perpastum, Euastrum didelta var. bengalicum, E. exile, E. exile var. latum, E. serratux, E. horikawae, E. indicum var. capitatum, E. longicolle var. capitatum, Micrasterias anomall, M. cunningtoni, M. rotata var. curvata, M. lux, M. suboblonga var. tecta, M. moebii var. burmense, Xanthidium burkillii var. alternans, X. spinosum, X. sexmamillatum var. pulneyense, X. multispinosum, Arthrodesmus spiculatus, A. convergens var. curtun, A. curvatus var. borgei, A. curvatus var. kalimantanus, A. curvatus var. latus, A. gibberulus, A. suchlanai, A. sumatranus, Staurastrum asterias, S. gibbum, S. burkillii, S. calyxoides var. orientale, S. cerastes var. coronatum, S. cerates var. pulchrum, S. ceylanicum, S. clepsydra var. obtusum, S. columbetoides, S. contectum, S. corniculatum var. variabile, S. leptopus var. variabile, S. leptodermum var. ikapoae, S. indentatum var. minus, S. inconspicuum var. crassum, S. javanicum var. apiculiferum, S. horametrum, S. hexacerum f. pentagona, S. heimerianum var. sumatranum, S. gracile var. ornatum, S. gracile f. kriegeri, S. gracile var. elongatux, S. freemanii var. triquetrum, S. fremanii var. nudiceps, S. ensiferum, S. dentatum, S.

12 pygmaeum var. obtusum, S. saltans var. polycerax, S. saltans var. sumatratum, S. sebaldi var. ventriverrucosum, S. sexangulare var. asperum, S. sexangulare var. attenuatum, S. sexangulare var. bidentatum, S. sexangulare var. productum, S. sexangulare var. subglabrum, S. smithii, S. striolatum var. divergens, S. megacanthum var. orientale, S. modestum, S. perundulatum, S. pinnatum var. hydea, S. pinnatum var. subpinnatum, S. pinnatumn var. robustum, S. praenii var. major, S. protectum var. rangoonense, S. pseudozonatum var. sumatranum, S. punctulatum var. ellipticum, S. tauphorum, S. thienemanii var. calvum, S. thienemanii var. triradiatum, S. tohopekaligense f. minus, S. tohopekaligense var. insigne, S. tripyrenoideum, S. trissacanthum, S. unguiferum var. inerme, S. wildemanii var. majus, S. xanthium, S. zahlbrucknei var. mamillatum, S. zonatum var. ceylanicum, S. zonatum var. majus, Spondylosium javanicum, S.. nitens var. triangulare, Desminium aptogonum var. tetragonum, D. suboccidentale. After that, few documents on desmids study in Thailand were reported. The study of desmids diversity in the Songkram River and its tributaries found 78 species of 15 genera which Hyalotheca dissiliense was the most common and abundance species (Saenudom, 1993). Later, Ruangrit (2000) investigated the desmid diversity from 13 freshwater resources in northern Thailand. It was found that some species, Staurastrum manfeldtii var. fluminense from Chiang Sean Lake, Cosmarium moniliforme from Mae Ngud Dam and Closterium ehrenbgergii from Mae Sa Stream, can be used as indicator for oligotrophic status of water. Some more new desmids species of Thailand were reported by Coesel (2000) and Kanetsuna (2002). The first author investigated sample from Thale Noi Lake, Phattalung that 28 species of non-cosmapolitian taxa were appeared in high portion. Thus, the 3 new taxa, Euastrum siamense, Cosmarium siamense and C. javanucum var. williamsonii, were listed as a new species in Thailand. The latter published some rare and interesting desmids from several material collected from Thailand, Cambodia, Malaysia and Japan. 21 new taxa were listed included 3 new varieties, 2 new forms and 1 rare species i.e. Euastrum fissum var. yasukaae, E. Pseudojenneri var. glabrum, E. gemmatum var. tenuous f. porosum, Xanthidium fasciculatum var. siamense, X. superbum var. centriconis and Staratrum trissacanthum var. dissacanthum f. longispinum. Besides, Lenzenweger (2003b) had listed many desmid species collected

13 form Chiang Mai and Sakolnakhon that are tropical, Indo-Malaysian North Australian characteristic species. In 1995, the checklist of algae in Thailand was published by Lewmanomont et al. This checklist compiled from 53 publications, listing 161 genera, 1,001 species, 287 varieties and 63 forms. The checklist of desmids recorded in division Cholrophyta, class Zygnematales, revealed by Wongrat (1995). A total of 22 genera, 296 species were reviewed from paper published by foreign scientists, except a report of Hirano (1992). The present state of desmid diversity in Thailand consisted 28 genera and 703 species.

2.2.4 The factors that influence the distribution of desmids Desmids are cosmopolitan microorganisms of tropical to arctic water bodies (Brook and Williamson 1983). They occur as euplankton, tychoplankton, and periphyton. Coesel (1992). There are several environmental conditions that influence the growth of desmids. The planktonic desmids are mostly occurring in the open water. Parts of lakes with good water circulation also showed a grater diversity of planktonic desmids than less active or poor circulations lakes (Brook, 1981). Microhabitat also influenced attached desmids. The changes of temperature affect the growth of algae. Some group of algae requires high temperature for growth while some does not. However, temperature changes are limited to the succession of algae in some ecosystems (Dillard, 1966). Most of the studies in northern hemisphere lakes indicated that they are most abundant during summer and autumn (Brook 1981). Not only the shade can decrease light intensity but turbidity is also a very important factor. Turbidity values are dependent on suspended particles in water-bodies and obstruct the light throughout the water-body. High turbidity will result in low light through the water and is a limited factor for some groups of algae (Kochasaney, 1993). In the lotic ecosystem, a high velocity of water induces high turbidity in the water-body. The strong and fast flowing currents help more particles to dissolve in different forms than the standing water of reservoirs and dams (Hynes, 1970). Most desmids are found in waters with near neutral pH or slightly acidic (pH 4-7) (Brook, 1981). Weltering et al. (1975) reported that diversity of desmids

14 appears to be correlated with low conductivity, calcium and alkalinity levels and pH values of 5.1–7.0. The presences of 624 taxa showing high diversity of desmids in 12 bog lake in Hungary were reported (Borics, 2003). However, Ngearnpat (2001), found high growth of desmids species in alkaline lake (pH 8-9) in Nonghan. This finding suggested many desmids may grow well in alkaline lake. The narrow range of pH gradient caused limited distribution of Closterium and Cosmarium species as occurred in 2 similar conditions of subalpine peat bog in Czech Republic. pH is a limited factor between oligotrophic and eutrophic desmid species. However, there was no difference at the minimum tolerance level, pH 4.0 for most species. Oligotrophic species did not show tolerance at the high level of pH of 8.0-8.5, whereas most of eutrophic exhibited good growth at approximately pH 9 (Coesel, 1983). The role of the pH show indirect relation with the carbon dioxide- bicarbonated system on algal growth. Desmids as a group are world-wide in distribution with probably about two-thirds of the species being cosmopolitan, although to a limited degree. The reference can be made to geographical floras (Prescott, 1948). Distribution in limited areas is more restricted, however, and their occurrence is determined by local ecological factors and water chemistry. More specifically desmids generally are a cacophonic group and occur more abundantly in waters with a high Na-K/Ca-Mg ratio (Pearsall, 1922). The pH of such waters is usually below 7.0.

2.2.5 Desmids as bioindicator Ecological indicators have widespread appeal to science, environmental management, and general public. Indicators have long been used to detect changes in nature. Scientific detection have been developed for the past 40 years in many countries and worldwide. Currently, bioindicators are mainly used to assess environmental conditions, as early warning signals of ecological changing (Niemi and Mcdonald, 2004). In aquatic ecosystems, algae have long been used to assess environmental conditions throughout the world. Such application was based on the environment sensitivities and tolerances of individual taxa and species composition of assemblages. As nutrient uptake of algal growth was a part of problem in eutrophication of lake, the trophic status was able to characterize by amount of algae (Vollenweider,1976). In many aquatic habitats,

15 algae are the most diverse assemblage of organisms that can easily be sampled and readily identified to species particularly diatoms and desmids (Stevenson and Smol, 2003) Peerapornpisal (2007) proposed the method for assess the water quality, which based on the 35 limnology researches in Thailand (Peerapornpisal, 2005). This water quality assessment is called “AARL- PP Score”. It is composed of 2 parts scoring system. The first part is the standard score of water quality base on trophic status. The water quality was categorized into 6 status using 1-10 scores. Each status was divided by former research experience, i.e. clean (oligotrophic status), clean to moderate (oligotrophic-mesotrophic status), moderate (mesotrophic status), moderate to polluted (mesotrophic-eutrophic status), polluted (eutrophic status), and very polluted (hypereutrophic status). In the second part, the dominant genera of phytoplankton from different water quality resources were given 1-10 scores. The lower scores indicated clean water whereas the higher scores indicated polluted water. The physical and chemical properties of water were used in combination to evaluate the water quality (Lorraine and Vollenweider, 1981; Peerapornpisal et al., 2004). Desmids are widely studied in lakes and reservoirs in many parts of the world. Several studies reported the relation of desmid occurrence with water chemistry in several habitats such as lakes, reservoirs, ponds, bogs and streams. It was show that are characteristic of low nutrient contents and low pH , conductivity, calcium and alkalinity level (Woelkerling and Gough, 1976; Burkholder and Sheath, 1984). Characteristics of the epiphytic communities can also be used in environmental assessment (John et al., 2002). Sensitive properties of desmids in oligotrophic environment were practically applied in many works. Though, thier use as bioindicators for environmental conditions were limited as the knowledge on ecology, distribution and the taxonomic accuracy of desmids are not well documented (Coesel, 1975). Lake water quality was evaluated by the phytoplankton association, while the diatoms were popular for an assessment in rivers and streams. Most desmids are known as periphyton. The water-plant type there was also considered as periphyton (Brook, 1981). In case of monitoring river in Hungarian when the filamentous algae are over grown the diatoms. The epiphytic desmids that form on plants or leaves of water plants were useful in such condition (Fehér, 2007). However, numerous experiments have been described on the use of

16 desmids as indicator for classifying the trophic status of water. The group of desmids was suitable in many type of environments (Krasznai et al., 2008). Coesel (2001) proposed the new method for assessing the nature conservation value of the aquatic habitats, based on the occurrence of desmids from many desmids investigations in the Netherland where the study area were well documented (Coesel:1975, 1978, 1982, 1983, 1998). This method has been elaborated from desmids occurrence which classified by three principle criteria: biodiversity (as a measure of niche and habitat differentiation), rare taxa (indicating specific abiotic conditions) and the presence of species that may be associated with ecosystem maturity. This method has been applied in many areas of European countries. It was applied to investigate 15 South-Hungarian water-bodies. The results showed that 6 of them have a high natural conservation value according to their desmid flora and useable method for Hungarian water type. Moreover, there was some modification factors for the indicator value based on the desmid taxa in Hungary (Fehér, 2007). A modified rarity values recently proposed by Fehér were compared with the Coesel’s value. No significant effect to natural conservation value was observed. The usefulness of this method depended on the sampling location (open water or macrophytic region) (Krasznai et al., 2008). Coesel (2001) suggested that the method of quantifying conservation value in freshwater habitats based on the use of desmids as bioindicator may be a useful tool for aquatic management in both euplanktonic environments and very small water bodies and habitats with fine-scale gradients. However, an improvement, such as a transformation of data into decimal scale for primary data evaluation was under consideration.