Karthik et al., J Mar Biol Oceanogr 2012, 1:2 http://dx.doi.org/10.4172/2324-8661.1000102 Journal of Marine Biology & Oceanography

Research Article a SciTechnol journal

The effects of environmental factors on dynamics has been Phytoplankton Abundance investigated by several authors [3-5]. The influence of various factors on the seasonal growth and abundance of phytoplankton differs and Diversity in the Coastal significantly, with physical (such as temperature and light intensity) and chemical factors (dissolved oxygen, pH, salinity, total hardness, Waters of Port Blair, South electrical conductivity and nutrient level) as primary limiting Andaman Island in Relation to factors reported in many regions of the world [6]. Literatures on the influence of environmental variables on phytoplankton communities Environmental Variables in coastal waters around Andaman Islands are meagre. In view of the importance and scarcity of reports from this area, an investigation Karthik R1*, Arun Kumar M1, Sai Elangovan S1, Siva Sankar R2 was carried out on a monthly interval during Sep 2011 to Mar 2012 in and Padmavati G1 the coastal waters of south Andaman to assess the seasonal variability in phytoplankton community structure and related physicochemical Abstract water quality parameters. The present communication also documents the occurrence of periodic blooms in the coastal The distribution and diversity of phytoplankton was studied in waters of south Andaman. the coastal waters of south Andaman Sea during Sept 2011 to Mar 2012. A total of 227 belonging to 67 genera were Materials and Methods recorded in this study. made larger contribution to the total abundance (68%) followed in order by Cyanophyceae (24%) Phytoplankton sampling and analysis and Dinoflagellates (8%). Silicoflagellates were numerically less (0.4%). Diatoms were represented by 164 species belonging to 46 This phytoplankton study was conducted during Sep 2011 genera, Dinoflagellates were represented by 58 species belonging to Mar 2012 in two distinct areas including: (1) areas with more to 16 genera, Cyanophyceae and Silicoflagellates comprised anthropogenic activity (i.e. fishing harbor, fish landing centre and 2 genera each. Bacteriastrum hyalinum, Coscinodiscus granii, fishing community (Stations 1 and 2); and (2) areas with lower levels of Eucampia zoodiacus, Leptocylindrus danicus, Nitzschia closterium, anthropogenic activity (Stations 3 and 4) (Figure 1). Physicochemical Odentella sinensis, O. mobiliensis, Pleruosigma affine, Rhizosilenia alata, R. imbricata, Prorocentrum micans, Protoperidinium water quality parameters such as seawater temperature, salinity and depressum, Asterionella glacialis, Guinardia striata, Licmophora dissolved oxygen were recorded at each station. Salinity (ppt) was gracilis, Pleurosigma angulatum, Skeletonema costatum and measured with a hand held Refractometer (ATAGO). Dissolved Thalassionema nitzschioides were the most prevalent diatoms oxygen (mg/L) was estimated by the modified Winkler’s method while and dinoflagellates encountered in the samples. The population phytoplankton biomass was estimated as chlorophyll a (µg/L) (90% 5 5 -1 density of phytoplankton ranged from 0.4 × 10 to 4.2 × 10 cells L . acetone method) measured spectrophotometrically in the laboratory Higher population density and chlorophyll a was observed in Sept, Dec and Mar at St. 2 due to the periodic bloom of diatoms such as [7]. Nutrients [nitrate, silicate and phosphate (µmol/L)] were also Coscinodiscus centralis (95000 cells ml-1), Rhizosolenia imbricata measured during the study [7]. For phytoplankton studies, samples (19000 cells ml-1) and R. alata (9500 cells ml-1). Relatively higher were collected in 1 liter labeled plastic containers by filtering 50 L of species diversity (H’= 3.6) and equitability in plankton flora (J=0.9) water, using a phytoplankton net (20 µm) and immediately preserved was observed at St. 4 with lower levels of anthropogenic activity (e.g. Carbyn’s Cove, BOD=2.7mg L-1). Predominance of the red tide species (blue-green algae), Trichodesmium erythraeaeum (27000 cells ml-1) at St. 3 during March lead to an almost monospecific population was observed during the present investigation. Keywords: Phytoplankton; Diatom bloom; Coastal waters; South Andaman sea

Introduction Phytoplanktons are key organisms in aquatic ecosystems. They initiate the marine food chain, by serving as food to primary consumers [1,2]. About 90% of the total production in marine ecosystem is contributed by the phytoplankters that support commercial fisheries.

*Corresponding author: Karthik R, Department of Ocean Studies and Marine Biology, Pondicherry University, Port Blair - 744 112, Andaman, India, E-mail: [email protected]

Received: September 13, 2012 Accepted: December 07, 2012 Published: Figure 1: The study area and location of the sampling sites. December 14, 2012

All articles published in Journal of Marine Biology & Oceanography are the property of SciTechnol, and is protected by International Publisher of Science, copyright laws. “Copyright © 2012, SciTechnol, All Rights Reserved. Technology and Medicine Citation: Karthik R, Arun Kumar M, Sai Elangovan S, Siva Sankar R, Padmavati G (2012) Phytoplankton Abundance and Diversity in the Coastal Waters of Port Blair, South Andaman Island in Relation to Environmental Variables. J Mar Biol Oceanogr 1:2.

doi:http://dx.doi.org/10.4172/2324-8661.1000102 with 4% formalin and fixed with Lugol’s iodine for quantitative occurrence of the diatom bloom of Coscinodiscus centralism. Higher and qualitative analysis. The samples were left to settle for 24hrs dissolved oxygen and lower salinity at St. 1 and St. 3 during Sep and and concentrated to 10 ml by siphoning out the supernatant. In the Nov were due in part to influx of fresh water from precipitation and laboratory, for phytoplankton studies, 1 ml sample was seepage and runoff of fresh water from the land. taken from concentrated sample by using a Sedgwick-Rafter counting Nutrients chamber and examined under the plankton inverted microscope. The total numbers of phytoplankton present in a liter of samples were The concentrations of nitrate (NO3), phosphate (PO4) and silicate calculated according to the following equation: (SiO4) showed pronounced spatial and temporal variation during the n × v present investigation (Table 2). The nitrate content varied between N = ×1000 0.1 umol l-1 in Oct and 5.61 umol l-1 in Sept. Silicate concentrations V Where N is the total number of phytoplankton cells per liter of remained much higher than nitrate and phosphate levels, ranging from 3 umol l-1 in Sept to 14-15 umol l-1 in Dec and Mar. Phosphate water filtered, n is an average number of phytoplankton cells in 1ml -1 -1 of sample, v is the volume of phytoplankton concentrates, V is the fluctuated between 0.1 umol l in Feb and 0.6 µmol l in Sept. The volume of total water filtered. relative amount of nitrate-silicate and nitrate-phosphate ratio was higher during periods of algal blooms. Statistical analysis Chlorophyll a concentrations varied from 0.01-0.16 µg l-1 (Table Statistical analysis was performed by using statistical software 3). Higher values of Chlorophyll a (0.16 µg l-1) was recorded during Primer (Ver. 5). Two-way analysis of variance (ANOVA) was Sep, Dec and Mar at St. 2 due to bloom forming diatoms such as employed and the level of significance was used to define statistically Coscinodiscus centralis, Rhizosolenia alata and Rhizosolenia imbricate significant differences. Biodiversity indices (species richness, diversity followed by 0.14 µg l-1 during Mar which was due to blue-green algae and equitability) were calculated in the phytoplankton population Trichodesmium erythraeum at St. 3. using monthly intervals between samples and cluster analysis to Population density and distribution discern species similarities between different sampling stations. The overall mean phytoplankton abundance was higher (p<0.05) Results at St. 3 compared to other stations in the study area (Figure 2). Physicochemical parameters Minimum densities were recorded at St. 4. Monthly and station wise variations of phytoplankton densities are clearly depicted in table Variations in temperature, salinity and dissolved oxygen among 4. Well marked monthly variations were observed in population stations and sampling dates are shown in table 1. During the study densities of phytoplankton. The lowest densities (215 and 261 cells/ period, water temperature varied from 25-28°C. The high temperature ml) were observed in the month of Nov at Stations 1 and 2, whereas (28°C) was recorded during Oct 2011 at all stations. Salinity ranged the highest population density (95000 cells/ml) was observed during from 30 to 34% and it was highest during Oct and Dec at all stations. Sep at St. 2 due to the dense aggregation of Coscinodiscus centralis cells Both water temperatures and salinities were generally low during the (95000 cells/ml) followed by high densities (27000 cells/ml) during monsoon period during Sept. Dissolved oxygen varied from 3.2 mg/l- Mar at St. 3 due to blue-green algae Trichodesmium erythraeum when 4.5 mg/l throughout the study at all sites. Maximum values (4.5 mg/l) temperature salinity and dissolved oxygen were recorded low and were recorded during Dec 2011 at Stations 1 and 4 and minimum nutrients such as nitrate, silicate and phosphate were high. Population during Sept at St. 2 (3.2 mg/l), which was due in a large part to the density was quite low at St. 4 during the study period.

Table 1: Variations in physico-chemical water quality parameters during September 2011 to March 2012 in the study area. Temperature (ºC) Salinity (%) Dissolved oxygen (ml/l) Month Intervals S1 S2 S3 S4 S1 S2 S3 S4 S1 S2 S3 S4 Sep’11 28 25 25 27 31 32 31 30 3.6 3.2 4.2 4.4 Oct 27 28 28 28 33 34 32 32 4.0 3.5 4.3 4.3 Nov 25 28 25 26 31 32 30 32 4.3 3.9 4.1 4.1 Dec 26 25 27 26 33 34 32 32 4.5 3.9 3.9 4.5 Jan 28 28 26 25 32 32 32 30 4.4 4.1 4.2 3.7 Feb 25 26 27 25.5 32 31 30 30 4.6 4.5 3.5 4.5 Mar’12 26 26 26.7 26 31 33 31 30 4.1 4.2 3.8 3.7

Table 2: Variations in nutrient concentration during September 2011 to March 2012 in the study area. Nitrate (μmol l-1) Silicate (μmol l-1) Phosphate (μmol l-1) Month Intervals S1 S2 S3 S4 S1 S2 S3 S4 S1 S2 S3 S4 Sep’11 0.5 5.6 0.2 0.2 11 13 3 4 0.3 0.6 0.3 0.3 Oct 0.3 0.2 0.1 0.1 4 4 4 4 0.5 0.5 0.4 0.3 Nov 0.8 0.9 0.1 0.8 4 5 5 4 0.3 0.5 0.4 0.4 Dec 3.4 3.8 0.4 0.4 14 14 4 4 0.3 0.6 0.1 0.2 Jan 1.0 1.1 0.8 0.9 7 6 6 6 0.3 0.4 0.2 0.3 Feb 1.2 1.2 0.2 1.1 6 6 5 6 0.0 0.1 0.0 0.1 Mar’12 3.7 4.3 4.1 0.8 10 14 15 5 0.3 0.4 0.4 0.1

Volume 1 • Issue 2 • 1000102 • Page 2 of 6 • Citation: Karthik R, Arun Kumar M, Sai Elangovan S, Siva Sankar R, Padmavati G (2012) Phytoplankton Abundance and Diversity in the Coastal Waters of Port Blair, South Andaman Island in Relation to Environmental Variables. J Mar Biol Oceanogr 1:2.

doi:http://dx.doi.org/10.4172/2324-8661.1000102

S3 Species composition S1 S3

Cyanophyceae Diatom 1% Silicoflagelates Silicoflagellates 0% 7% Dinoflagellates Phytoplankton identified at all stations comprised a total of 225 Dinoflagellates 1% 1% 4% species (161 Diatoms, 58 Dinoflagellates, 4 Cyanobacteria and 2 Silicoflagellates species (Table 5). Diatoms formed the most dominant taxa and contributed to the total population at almost all the stations (Figure 3). The massive bloom ofCoscinodiscus centralis at St. 2 (95000 Diatom Cyanophyceae cells/ml) during Sept was found to be the most abundant species in the 94% 92%

S2 S4 study area. It caused blooms with high relative abundances (99.9%) Dinoflagellates Cyanophyceae 0% Cyanophyceae Silicoflagelates 0% Silicoflagelates 2% 0% 1% which lead to a monospecific population at some sites. Blue green Dinoflagellates 24% algae Trichodesmium erythraeaeum was predominant at St. 3 during Mar and contributed 92% of the total population. Dinoflagellates were generally more dominant only at St. 4 and St. 1 and contributed 24% and 4% of the population, respectively. Silicoflagellates occurred

Diatom in very low abundances and contributed <1% to the total population. 100% Diatom 73%

The diatom flora comprised of 53 centrales and 53 pennales. Figure 3: Percentage composition of phytoplankton in the study area. Between the two groups of diatoms, centrics were predominated pennates during the entire study period. Among the centrales, 4 families Licmophoraceae, Naviculaceae and Fragilariaceae dominated the such as, Coscinodiscaceae, Leptocylindraceae, , diatom community. Among diatoms Coscinodiscus centralis, C. and Rhizosoleniaceae were found floristically richer than the others granii, Pleurosigma affine, Leptocylindrus danicus, Bacteriastrum while in the case of pennales, 4 families, such as Pleurosigmataceae, furcatum, B. hyalinum, Rhizosoleniaalata, R. imbricate, Guinardia steriata, G. flaccid, decipiens were found to be dominant. Table 3: Variations in chlorophyll a concentration during September 2011 to Similarly, the dinoflagellate community was dominated by Ceratium March 2012 in the study area. furca, Prorocentrum micans and Protoperidinium depressum (Table Chlorophyll a (μgl-1) Month Intervals 6). S1 S2 S3 S4 Species diversity Sep’11 0.5 5.6 0.2 0.2 Oct 0.3 0.2 0.1 0.1 The number of species (S) and range of diversity indices in the Nov 0.8 0.9 0.1 0.8 study area are shown in table 7. Marked seasonal variation was noticed Dec 3.4 3.8 0.4 0.4 in species diversity in the present investigation. The maximum Jan 1.0 1.1 0.8 0.9 number of species (68) was observed at stations St. 1, followed by 51 Feb 1.2 1.2 0.2 1.1 at St. 4 in Mar while minimum numbers were observed at stations 1 Mar’12 3.7 4.3 4.1 0.8 (15) and 3 (18) during Nov. The lowest species diversity (H’=0.01 to 0.09) and evenness (J=0.01 to 0.04) values were observed during Sept, Table 4: Variations in population density during September 2011 to March 2012 Dec and Mar at St. 2 and during Mar at St. 3. in the study. Phytoplankton density (No.l-1) Two separate assemblages of species were observed (Figure 4). Month Intervals The bloom-forming species at Stations 2 and 3 formed one cluster S1 S2 S3 S4 and species in Stations 1 and 4 formed a separate cluster, where Sep’11 635 9512 643 552 dinoflagellates were more dominant. Oct 408 450 254 278 Nov 549 630 215 261 Discussion Dec 8862 9633 301 302 Jan 550 610 341 330 Population density and chlorophyll a did not show any significant Feb 663 716 412 348 correlation at St. 2 and St. 3 (p>0.05) whereas, chlorophyll a and Mar’12 963 1911 27111 852 nutrients discerned a positive correlation (p<0.05) at almost all the station. During the bloom period (diatoms & blue-green algae) both temperature and salinity were low and concentrations of nutrients 4500 (nitrate, silicate and phosphate) were high. This nutrient rich water 4000 could be due to the precipitation during monsoon (September), the 3500 cyclone “Thane” (Dec 2011) and the run-off of urban and domestic

1 -

l 3000 . wastes from land into the coastal waters might that may have 3 10

s 2500 influenced the abundance of phytoplankton in this area. Nutrient ll ce

l 2000 levels, particularly of silicate and nitrate reduced to minimum levels a o t

T 1500 that coincided with the decline of Coscinodiscus centralis, R. imbricate 1000 and Rhizosolenia alata cell densities. The low phytoplankton growth 500 at Stations 1 and 3 during Nov could be due to low temperature, 0 salinity and poor nutrient levels which were not optimal for growth. S1 S2 S3 S4 The overall mean phytoplankton abundance was higher at St. 3 and Figure 2: Mean abundance of phytoplankton during September, 2011 to minimum at St. 4 may be due in part to the grazing pressure by January, 2012 in the study area. zooplankton.

Volume 1 • Issue 2 • 1000102 • Page 3 of 6 • Citation: Karthik R, Arun Kumar M, Sai Elangovan S, Siva Sankar R, Padmavati G (2012) Phytoplankton Abundance and Diversity in the Coastal Waters of Port Blair, South Andaman Island in Relation to Environmental Variables. J Mar Biol Oceanogr 1:2.

doi:http://dx.doi.org/10.4172/2324-8661.1000102

Table 5: List of phytoplankton species recorded at each station. Rhizosolenia cochlea Stephanopyxis turris Bacillariophyceae (Diatoms) Rhizosolenia hyaline Striatella unipunctata Amphaora salina Cymbella cistula Navicula follis Rhizosolenia imbricate Surirella ovalis Amphiphora paludosa Cymbella sp Navicula granulate Cylindrotheca gracilis Navicula elegans Amphora acuta Dactyliosolen fragilissima Navicula inornata Dinophyceae (Dinoflagellates) Amphora ostrearia Dactyliosolen phuketensis Navicula lata Alexandrium catenella Dinophysis rotundata Amphora ovalis Diploneis crabro Navicula lawissima Alexandrium minutum Dinophysis tripos Amphora plicata Ditylum brightwellii Navicula lridis Alexandrium tamarense Gonyaulax conjuncta Amphora robusta Eucampia antarctica Navicula lyra Ceratium candelabrum Gonyaulax polygramma Ceratium declinatum Gonyaulax spinifera Asterionella formosa Eucampia cornuta Navicula pungens Ceratium dens Gymnodinium catenatum Asterionellopsis glacialis Eucampia zoodiacus Navicula serians Ceratium extensum Lingulodinium polyedrum Bacillaria paradoxa Guinardia blavyanus Navicula solaris Ceratium furca Noctiluca scintillans Bacillaria paxillifera Guinardia delicatula Navicula splendida Ceratium fusus Ornithocercus magnificus Bacteriastrum comosum Guinardia flaccida Nitrschia pungens Ceratium horridum Oxtoxum scolopax Bacteriastrum delicatulum Guinardia striata Nitzachia vitrea Ceratium lineatum Peridinium leonis Bacteriastrum furcatum Gyrosigma balticum Nitzschia acicularis Ceratium lunula Podolampas palmipes Bacteriastrum hyalinum Gyrosigma diminutum Nitzschia angustata Ceratium macroceros Prorocentrum balticum Biddulphia alternans Gyrosigma fasciola Nitzschia apiculata Ceratium massiliense Prorocentrum lima Chaetoceros aequatorialis Hemialu shauckii Nitzschia closterium Ceratium trichoceros Prorocentrum micans Chaetoceros atlanticus Hemialus membranaceus Nitzschia frustulum Ceratium tripos Prorocentrum obtusum Chaetoceros coarctatus Hemialus sinensis Nitzschia gracilis Cochlodinium polykrikoides Protoperidinium balticum Chaetoceros constrictus Hemiaulus indicus Nitzschia longissima Cochlodinium sp Protoperidinium brevipes Chaetoceros curvisetus Hemidiscus cuneiformis Nitzschia panduriformis Dinophysis acuta Protoperidinium claudicans Chaetoceros decipiens Hemidiscus hardmannianus Nitzschia paradoxa Dinophysis caudate Protoperidinium conicoides Chaetoceros didymus Leptocylindrus danicus Nitzschia rectilonga Dinophysis dens Protoperidinium conicum Chaetoceros diversus Leptocylindrus minimus Nitzschia sigma Dinophysis nules Protoperidinium denticulatum Chaetoceros eibenii Licmophora communis Nitzschia spathulata Dinophysis ovum Protoperidinium depressum Chaetoceros lorenzianus Licmophora ehrenbergii Odentella sinensis Protoperidinium divergens Protoperidinium obtusum Protoperidinium excentricum Protoperidinium ovum Chaetoceros messanensis Licmophora gracilis Odontella mobiliensis Protoperidinium grande Protoperidinium pellucidum Chaetoceros neglectus Licmophora nebecula Pleurosigma acapense Protoperidinium leonis Protoperidinium pentagonum Chaetoceros orientalis Licmophora paradoxa Pleurosigma affine Protoperidiniumpyriforme Chaetoceros peruvianus Licmophora remulus Pleurosigma spencerii Pyrodiniumbahamense Chaetoceros pseudocurvisetus Licmopho ratincta Pleurosigma angulatum Pyrophacushorologium Chaetoceros wighamii Mastogloia apiculata Pleurosigma attenuatum Pyrophacusstinii Climacosphenia elongata Mastogloia erythraea Pleurosigma cuspidatum Cyanophyceae (Blue-greens) Cocconeiss cutellum Mastogloia smithii Pleurosigma directum Lyngbyasp Oscillatorriasp Coscinodiscus asteromphalus Melosira cf.spaerica Pleurosigma distortum Trichodesmiumerythraeum Coscinodiscus centralis Melosira dubia Pleurosigma elongatum Synechococcussp Coscinodiscus granii Melosira nummuloides Pleurosigma fasciola Dictyochophyceae (silicoflagellates) Coscinodiscus stellaris Meuniera membranacea Pleurosigma formosum Dictyocha fibula Coscinodiscus thorii Navicula crucicula Pleurosigma hippocsmpus Dictyochastaurodon Cylindrotheca closterium Navicula delicatula Pleurosigma macrum Cylindrotheca gigas Rhizosolenia polydactyla Synedra barbatula The results of the present study shows almost a two fold increase Pleurosigma obscurum Rhizosolenia shrubsolei Synedra gallionii in the species composition of phytoplankton taxa compared to an Pleurosigma speciosum Rhizosolenia sigma Synedra pulchella earlier report [8] from the oceanic region of this area. This earlier investigation [8] reported 143 phytoplankton species from Andaman Proboscia alata Rhizosolienia robusta Tabellaria flocculosa and Nicobar region of the Bay of Bengal. Similarly, Siva Sankar Pseudo-nitzschia australis Rhizosolienia setigera Thalasiossira anguste-lineata and Padmavati [9] reported only 65 species from this region with Pseudo-nitzschia pungens Rhizosolienia styliformis Thalasiossira decipiens phytoplankton levels that were low in comparison with the species Pseudosolenia calcar Rizosolenia calcar Thalassionem anitzschioides number measured in this study. Geetha and Kondalarao [10] have Rhizosolenia alata Rizosolenia striata Thalassiosira eccentria similarly reported 249 species from coastal waters of Bay of Bengal, Rhizosolenia hebetata Schroederella delicatula Thalassiothrix frauenfeldii which is higher than this study and ascertained their oceanic preference. This kind of variations could be attributed to differences Rhizosolenia bergonii Skeletonema costatum Thallasiothrix longissima in ecological distribution in the types of organisms as well as climatic, Rhizosolenia castracanei Stephanopyxis palmeriana Triceratium reticulatum geographic and temporal differences between these two studies.

Volume 1 • Issue 2 • 1000102 • Page 4 of 6 • Citation: Karthik R, Arun Kumar M, Sai Elangovan S, Siva Sankar R, Padmavati G (2012) Phytoplankton Abundance and Diversity in the Coastal Waters of Port Blair, South Andaman Island in Relation to Environmental Variables. J Mar Biol Oceanogr 1:2.

doi:http://dx.doi.org/10.4172/2324-8661.1000102

Table 6: List of dominant species of phytoplankton within the coastal waters of their rate of sinking. Thus, to overcome this problem, diatom always South Andaman. prefers to inhabit and dominates the phytoplankton community in No. of Month Area Station Dominant Species shallow coastal region [16]. Species September'11 MAA S1 257 Coscinodiscus centralis Bacteriastrum hyalinum, Coscinodiscus granii, Eucampia MAA S2 9500 Coscinodiscus centralis* zoodiacus, Leptocylindrus danicus, Nitzschia closterium, Odentella LAA S3 173 Pleurosigma affine sinensis, O. mobiliensis, Pleruosigma affine, Rhizosilenia alata, LAA S4 158 Leptocylindrus danicus R. imbricata, Prorocentrum micans, Protoperidinium depressum, October MAA S1 75 Coscinodiscus granii Asterionella glacialis, Guinardia striata, Licmophora gracilis, MAA S2 136 Coscinodiscus granii Pleurosigma angulatum, Skeletonema costatum and Thalassionema LAA S3 65 Licmophora ehrenbergii nitzschioides were common during the present observation. Similar LAA S4 37 Licmophora ehrenbergii observations have been made from different locations of east coast November MAA S1 165 Bacteriastrum furcatum of India [8,15]. MAA S2 157 Bacteriastrum hyalinum Devassy and Bhattathiri reported that dinoflagellates as largest LAA S3 36 Nitzschia sigma group followed by diatoms from little Andaman Island but this was LAA S4 34 Pleurosigma angulatum not observed in this study [12]. Dinoflagellates were represented by December MAA S1 8700 Rhizosolenia alata 58 species belong to 16 genera which is low compared to an earlier MAA S2 9500 Rhizosolenia alata* report from the oceanic region in this area [17] but are higher LAA S3 42 Licmophora gracilis than other studies from this region [9]. These findings suggest that LAA S4 42 Coscinodiscus granii these organisms might not be able to withstand the fluctuations in January MAA S1 174 Guinardia steriata the environmental conditions and possibly have a lower chance MAA S2 152 Guinardia flaccida of survival. They are able to thrive successfully in oligotrophic LAA S3 28 Nitzschia gracilis tropical waters unlike diatoms [12]. Most of the dinoflagellates are LAA S4 96 Chaetoceros decipiens mixotrophic or heterotrophic and gain their nutrition through a Febrauary MAA S1 147 Guinardia steriata combination of photosynthesis and uptake of dissolved or particulate MAA S2 249 Leptocylindrus danicus organic material or phagotrophy on ciliates [18,19]. In this study LAA S3 52 Asterionella glacialis maximum population density of dinoflagellates was recorded during LAA S4 25 Guinardia steriata Mar at Stations 4 and 1 when both minimal salinity and temperature March'12 MAA S1 197 Rhizosolenia imbricata values were observed. MAA S2 19000 Rhizosolenia imbricata Further, absence of some genera of dinoflagellates viz., LAA S3 27000 Trichodesmium erythraeum* Pyrocycystis, Exuviaella, Achnanthes, Amphitholus, Asteromphalus, LAA S4 87 Proboscia alata Gossleriella, Gloedinium, Fragilaria, Phalacroma, Plantoniella, MAA: More Anthropogenic Activity (St. 1 and St. 2); LAA: Less Anthropogenic Activity (St. 3 and St. 4) Rabdosphaera, Thracosphaeraand Oxytoxum, Amphidinium, *bloom forming diatoms and blue green algae Amphisolenia, Heterolaucus, and Ceratocorys [8,17] in the present study could be due to their adoption to different depths within Moreover, phytoplankton species numbers of this region were oceanic regions. strongly associated with its local environmental variables in this and other studies [11]. The blue green algal population was composed of Oscillatoria sp, Lyngbya sp and Trichodesmium erythraeum. Only one of these High population density during Sep, Dec and Mar might be due species, Trichodesmium erythraeum, appeared throughout the study to the predominance of diatoms Coscinodiscus centralis, Rhizosolenia and caused blooms with considerable cell densities 27000 cells ml-1 at imbricate and R. alata and blue-green algae such as Trichodesmium St. 3 during Mar. Formation of Trichodesmium blooms as observed in erythraeaeum. During the study period, phytoplanktons were this study have been reported earlier from the Arabian Sea [20] and abundant when the coastal waters were enriched with nutrients. Bay of Bengal [10]. Nutrients, more importantly the nitrate and silicate, have emerged as the key factors controlling the phytoplankton growth in this area. The toxic dinoflagellates such as Alexandrium tamarense, A. The coastal waters where nutrient levels are higher sustaining a richer catenella, Lingulodinium polyedrum, Goniaulax conjuncta, Noctiluca diatom population [12]. The low phytoplankton growth during Jan scintillans and Gonyaulax polygramma were observed with low and Feb could be due to lower nutrient levels in this area. Chlorophyll cell densities. Among them, Noctiluca scintillans, Lingulodinium a and nutrients showed a significant (p<0.05) positive correlation polyedrum, Gonyaulax polygramma and Alexandrium catenella were at Stations 2 and 3 (p<0.05), indicating the influence of nitrate and recorded at almost all stations during Sep and Mar. silicate on phytoplankton growth at this area. Bloom forming diatom Species diversity (H’=0.6 to 0.8) and equitability (J=0.1 to 0.2) species require silicon as a major nutrient and the ratio of nitrate and indices showed minimum values at Stations 2 and 3 which co-occurred silicate influence the composition of phytoplankton as observed in with bloom forming diatoms. The evenness index approached zero this study has been reported earlier [13-15]. when a single species becomes very abundant. The diatom blooms Predominance of diatoms in phytoplankton assemblage and at stations Stations 2 and 3 led to low evenness and diversity indices. dominance of centrics over pennates with respect to species number There were two major clusters were observed. The bloom-forming are common phenomena in coastal waters. Diatoms are larger in species at Stations 2 and 3 formed one cluster. Species in Stations 1 size as compared to other phytoplanktonic components, increasing and 4 formed a separate cluster where dinoflagellates were dominant.

Volume 1 • Issue 2 • 1000102 • Page 5 of 6 • Citation: Karthik R, Arun Kumar M, Sai Elangovan S, Siva Sankar R, Padmavati G (2012) Phytoplankton Abundance and Diversity in the Coastal Waters of Port Blair, South Andaman Island in Relation to Environmental Variables. J Mar Biol Oceanogr 1:2.

doi:http://dx.doi.org/10.4172/2324-8661.1000102

Table 7: Number of phytoplankton species (S), diversity indices (H’) and equitability (J) during September 2011 to March 2012 in the study area. No. of. Species Species diversity H’ Evenness Month Intervals S1 S2 S3 S4 S1 S2 S3 S4 S1 S2 S3 S4 Sep’11 33 27 28 29 2.49 0.01 2.8 2.84 0.71 0.04 0.84 0.84 Oct 30 22 27 21 2.83 2.45 2.51 2.58 0.83 0.79 0.76 0.76 Nov 37 30 18 19 2.49 2.71 2.49 2.62 0.69 0.79 0.86 0.86 Dec 15 24 30 22 0.13 0.09 2.99 2.85 0.04 0.03 0.87 0.87 Jan 42 39 45 37 2.46 2.85 3.41 2.82 0.66 0.78 0.89 0.89 Feb 42 37 46 42 3.21 2.76 3.3 3.32 0.86 0.76 0.86 0.86 Mar’12 68 31 29 51 3.55 0.05 0.03 3.61 0.84 0.01 0.01 0.01

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14. Mani P, Krishnamurthy K, Palaniappan R (1986) Ecology of phytoplankton blooms in the Vellar estuary, east coast of India. Indian J Mar Sci 15: 24-28.

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16. Stowe K (1996) Exploring Ocean Science. John Wiley and Sons, France. Figure 4: Dendogram of the cluster analysis showing affinities of the species 17. Jyothibabu R, Madhu NV, Maheshwaran PA, Nair KKC, Venugopal P, et al. and formation of similar taxanomic groups. (2003) Dominance of dinoflagellates in microzooplankton community in the oceanic regions of the Bay of Bengal and the Andaman Sea. Curr Sci 84: It is well recognized that the abundance of each species may be highly 1247-1253. variable and, on the basis of its relationship with other species, this 18. Bockstahler KR, Coats DW (1993) Grazing of the mixotrophic dinoflagellate may affect the patterns of assembling or grouping are established at Gymnodinium sanguineum on ciliate populations of Chesapeake Bay. Mar locations throughout the region [21]. Biol 116: 477-487. 19. Bockstahler KR, Coats DW (1993) Spatial and Temporal aspects of Acknowledgement Mixotrophy in Chesapeake Bay Dinoflagellates. J Eukaryot Microbiol 40: 49- Authors are thankful to the Head of the Department, Ocean Studies and 60. Marine Biology, Pondicherry University, Port Blair for providing facilities. 20. Devassy VP (1987) Trichodesmium: Red tides in the Arabian Sea. Rao TSS References et al. (ed) Contributions in Marine Sciences: A Special Volume to Felicitate Dr. S.Z. Qasim Sastyabdapurti on His Sixtieth Birthday. National Institute of 1. Ananthan GA, Sampathkumar P, Soundarapandian P, Kannan L (2004) Oceanography, Dona Paula, India: 61-66. Observation on environmental characteristics of Ariyankuppam estuary and Verampattinam coast of Pondicherry, India. J Aqua Biol 19: 67-72. 21. Paul JT, Ramaiah N, Gauns M, Fernandes V (2007) Preponderance of a few diatom species among the highly diverse microphytoplankton assemblages 2. Tas B, Gonulol A (2007) An ecologic and taxonomic study on phytoplankton in the Bay of Bengal. Mar Biol 152: 63-75. of a shallow lake, Turkey. J Environ Biol 28: 439-445.

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