Indian Journal of Marine Science Vol. 39(3), September 2010, pp. 323-333

Bloom of erythraeum (Ehr.) and its impact on water quality and plankton community structure in the coastal waters of southeast coast of India

A K Mohanty 1, K K Satpathy 1, G Sahu 1, K J Hussain 1, M V R Prasad 1 & S K Sarkar 2 1 Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu- 603 102 India 2 Department of Marine Science, University of Calcutta, Kolkata- 700 019 India [Email : [email protected]] Received 14 September 2009; revised 11 January 2010

An intense bloom of was observed in the coastal waters (about 600 m away from the shore) of southeast coast of India during the post-northeast monsoon period. The bloom appeared during a relatively high temperature condition with coastal water salinity > 31 psu. A significant reduction in nitrate concentration was noticed during the bloom period, whereas, relatively high concentration of phosphate and total phosphorous was observed. An abrupt increase in ammonia concentration to the tune of 284.36 µmol l -1 was observed which coincided with the highest Trichodesmium density (2.88 × 10 7 cells l -1). Contribution of Trichodesmium to the total phytoplankton density ranged from 7.79% to 97.01%. A distinct variation in phytoplankton number and phytoplankton diversity indices was noticed. The lowest diversity indices coincided with the observed highest Trichodesmium density. Concentrations of chlorophyll-a (maximum 42.15 mg m -3) and phaeophytin (maximum 46.23 mg m -3) increased abnormally during the bloom.

[Key words : bloom, phytoplankton, tropical, Trichodesmium, oligotrophic, ]

Introduction (> 30 km). This appears to be the second report of Trichodesmium erythraeum, a marine Trichodesmium bloom which was sighted near the cyanobacterium, is an important nitrogen-fixer in the coast similar to the last year report from the same sea. It is one of the common bloom-forming species locality 15 . found in tropical and sub-tropical waters, particularly During a regular coastal water monitoring program, in the eastern tropical Pacific and Arabian Sea, a prominent discoloration of the surface water was contributing > 30% of algal blooms of the world 1. noticed in the coastal waters of Kalpakkam (12 o 33' N Estimated global by Trichodesmium Lat. and 80 o 11' E Long) (Figure 1) on 19 th February bloom (~ 42 Tg N yr -1) and during non-bloom 2008. The bloom was very dense and created conditions (~ 20 Tg N yr -1) suggests that it is likely to yellowish-green coloured streaks (Figure 2a) of about be the dominant organism in the global 4 to 5m width and 10-20m long patches. The entire nitrogen budget 1, 2 . Trichodesmium normally occurs in bloom extended to several kilometers along the coast. macroscopic bundles or colonies and blooms formed The phytoplankton responsible for discolouration was by it are often extremely patchy. The patchy spatial identified as Trichodesmium erythraeum (Figure 2b). distribution of plankton blooms is usually connected Though, bloom of Noctiluca scintillans 16 , Asterionella to the physical variability of the water body 3. glacialis 17 and Trichodesmium erythraeum 15 in the Reports in literature showed frequent occurrence of coastal waters of the Kalpakkam have been reported, Trichodesmium blooms in Indian waters, however, it the present one has many interesting features. has been reported more frequently in the west Although, the data collected during our regular work coast 4, 5, 6-11 as compared to east coast 12, 13-15 . Equipped were not concerned directly with an investigation into with buoyancy regulating gas vesicles and nitrogen the causes of the bloom, the interest stimulated from fixation enzymes, Trichodesmium is regarded as an the studies of various physicochemical and biological organism well adapted to stratified, oligotrophic characteristics of the coastal water justifies the conditions 2. All the available reports on purpose of this paper. The acumen in investigating Trichodesmium bloom from east and west coast of Trichodesmium bloom appearance and distribution India have been observed far away from the coast stems from the recent report about its harmful nature, 324 INDIAN J. MAR. SCI., VOL. 39, No, 3, SEPTEMBER 2010

Fig. 1  Study area showing the sampling location

Fig. 2a & b  Discolouration of coastal water of Kalpakkam by Trichodesmium erythraeum bloom patches (a); magnif ied view of bundles formed by trichome (b)

sometimes causing damages to coastal fish and shellfish connotations. The impact of bloom on coastal water fauna 18 . Thus, studying the causes that favour the quality and phytoplankton community is reported in this appearance of this bloom has social and economical paper along with the characteristic feature of the bloom. MOHANTY et al .: BLOOM OF TRICHODESMIUM ERYTHRAEUM (Ehr..) AND ITS IMPACT ON WATER QUALITY 325

Materials and Methods Results and discussions Surface water samples were collected twice daily A. Hydrography The values of pH did not show significant (between 9 to 10 AM and 4 to 5 PM during the bloom variations and ranged from 8.0-8.2 during the study period (19 th to 23 rd February), whereas, during pre- period (Figure-3a). It did not show any correlation and post-bloom periods samples were collected with bloom appearance as it remained almost stable weekly only in the morning hours. Samples were during pre-bloom, bloom and post-bloom periods. drawn by lowering a clean plastic bucket from the The surface water temperature during the study period Jetty of Madras Atomic Power Station (MAPS) and analyzed for various physicochemical parameters. ranged from 27.2-32.6 °C (Figure 3b). Comparatively high temperatures were noticed during the afternoon Temperature was measured by a mercury collections. A general increase in water temperate was thermometer with an accuracy of ±0.1 oC. Winkler’s noticed from January to March, which is a general method 19 was followed for the estimation of DO. phenomenon associated with air temperature in this Salinity was estimated by Knudsen’s method 19 . pH locality during this period of the year. Most of the was measured by a pH meter (CyberScan PCD 5500) marine cyanobacteria exhibit substantial growth in the with an accuracy of ±0.1. Dissolved nutrients such as, temperature ranges 25-35 °C11. The present bloom was nitrite, nitrate, ammonia, silicate and phosphate along noticed during relatively high temperature conditions with total nitrogen (TN) and total phosphorous (TP) were estimated following the methods of Grasshoff (28.4-28.7°C in the morning and 31.2-32.6°C in the et al .19 and Parsons et al .20 . Chlorophyll-a and afternoon). Temperature has long been recognized as Trichodesmium phaeophytin were measured spectrophotometrically an important factor that controls abundance 26-27 . Generally bloom of this filamentous (Parsons et al ., 1984. The phytoplankton density was 13 estimated using Utermohl’s sedimentation technique 21 alga occurred during hot weather season , as and counted using Sedgwick Rafter counting chamber cyanobacteria require relatively high temperature for with the aid of binocular research microscope (Nikon its optimum growth compared to other phytoplankton 28-29 . The present study agreed well with Eclipse-50 i). The identification of phytoplankton 4, 13-15, 30 was done by following standard taxonomic earlier reports , which showed similar monographs such as Desikachary 22 for ; temperature conditions with the appearance of 23,24 25 Trichodesmium bloom during early summer and Subramanian for and Fristch 31 for green and blue-green algae (Cyanobacteria). spring in the coastal waters of India. As observed, Three diversity indices such as species richness (R), the bloom was more predominant during afternoon species diversity (D) and evenness (J) were computed period when the temperature was relatively high as to evaluate the variation between phytoplankton compared to morning period. community structure and diversity, using standard The observed salinity ranged from 31.58-33.18 psu. formulae of Gleason (1922), Shannon-Weaver (1963) A gradual increase in salinity was noticed during the and Pielou (1966) respectively. study period (Figure 3b). Stable salinity condition close to typical value of 32 psu and above is known to

Fig. 3a 326 INDIAN J. MAR. SCI., VOL. 39, No, 3, SEPTEMBER 2010

support the growth and abundance of Trichodesmium . near bloom area is common to post-bloom era and It is well known that the cyanobacterium is a indicative of decayed phase of the bloom. stenohaline form with optimum growth at > 33 psu and can’t survive in low salinities 11-14 . DO B. Nutrients concentration ranged from 6.2-8.1 mg l -1 Nitrate concentrations ranged from 0.17–6.79 (Figure 3a). The lowest and the highest DO µmol l -1, the highest value being observed during the concentration was observed during the post-bloom pre-bloom period and the lowest during the bloom and bloom period respectively. Marginally high DO (Figure 3c). Relatively low nitrate levels, continuous was noticed during the bloom compared to the pre- patches with yellowish green colour and increased and post-bloom period. However, concentrations of primary production (as reflected in chlorophyll-a DO during pre-bloom period were relatively high as values) coinciding with peak bloom period compared to post-bloom period. This could be due to sufficiently indicated that the bloom was in growth photosynthetic release of oxygen by the dense algal phase. A significant reduction in nitrate concentration biomass. Similar increase of DO content during was noticed during the bloom as compared to pre- and Trichodesmium bloom has also been reported post-bloom periods. Similar reduction of nitrate earlier 2,15 . As expected relatively low DO contents concentration during Trichodesmium bloom has also were observed during the post-peak bloom period, been reported by others 12,14-15 . Insignificant variation indicating that some of the cells are in decayed stage. in concentration of nitrite was noticed during the This phenomenon of observation of low DO values period of study. On the contrary, ammonia values

Fig. 3b

Fig. 3c MOHANTY et al .: BLOOM OF TRICHODESMIUM ERYTHRAEUM (Ehr..) AND ITS IMPACT ON WATER QUALITY 327

were significantly high during the bloom, especially production of offensive smell, increase in ammonia on the day of the highest cell density, compared to the content and fish mortality in coastal waters due to pre- and post-bloom observations (Figure 3d), which Trichodesmium bloom 11 . During the present ranged from 0.22-284.36 µmol l -1. This could be observation, in spite of prevalence of very high ascribed to the diazotrophic nature of Trichodesmium , ammonia content, there was however, no fish which has the ability to produce ammonium through mortality and thus social and economical implications the process of nitrogen fixation 32 . As a result of the were minimal. Considering the fact that, ammonia above process, the observed TN concentration was concentration >0.1 mg l -1 is toxic for the fish 18 also relatively high (392.80 µmol l -1) on the peak community , the bloom could have a significant bloom day (Figure 3d). Surprisingly, perusal of a adverse effect on the biota of the coastal waters had it plethora of literature available from Indian coasts continued for a longer period. No report of fish revealed that ammonia concentration during mortality or any such nuisance incidence during the Trichodesmium bloom has rarely been estimated or present study could be attributed to factors like reported 4, 8, 33 . A comparison of the present ammonia shorter period of bloom persistence and its drifting concentration with that of earlier reported value away along with the pole-ward water current. -1 (126.72 µmol l -1) during Trichodesmium bloom from Phosphate levels ranged from 0.09 µmol l during the same locality 15 showed a two fold increase. the pre-bloom to 1.51 µmol l -1 during the bloom Many reports have indicated discolouration of water, (Figure 3e). The peak coincided with the day of the

Fig. 3d

Fig. 3a-e  Variations in physico-chemical properties of the coastal waters of Kalpakkam during appearance of Trichodesmium erythraeum bloom. 328 INDIAN J. MAR. SCI., VOL. 39, No, 3, SEPTEMBER 2010

highest Trichodesmium cell density. It did not show a during the present study. Except for the enhanced clear trend during the study. Phosphate constitutes the concentration levels of silicate during pre-bloom most important inorganic nutrient that can limit the period, its concentration remained almost stable phytoplankton production in tropical coastal marine during the bloom and post-bloom period. ecosystems 34 and thereby the overall ecological Observations similar to this have also been reported processes. Usually seawater serves as the main source by several authors during the appearance of non- of phosphate in estuarine and coastal waters except blooms 16,37-38 , where silicate remains those receives fresh water contaminated with unutilized. phosphate. Apart from the physical and chemical processes, phosphate concentration in coastal waters C. Phytoplankton community structure mainly depends upon phytoplankton uptake and Trichodesmium is considered as an organism well replenishment by microbial decomposition of organic used to stratified, oligotrophic environment. Thus, its matter. In the present study, an abrupt increase in abundance should be high in the boundary currents and phosphate content was encountered on the day of decrease towards the coast wherein the availability of highest cell density compared to other observations. nitrogenous nutrients is more. There has not been any This increase in phosphate could be due to the report of T. erythraeum bloom in the coastal zone right extracellular release 35 and decomposition of plankton. near the coast (within 600 m from the shore). Results Moreover, bacterial liberation of phosphate from dead showed that the bloom constituted both individual organisms has also been reported to be responsible for trichomes and colonial forms although the later enhanced levels of phosphate during blooms 36 . Many dominated to the extent of 80-90%. Generally the other authors have also reported similar increase of trichome length varied from 300-1200 µm. Unlike the phosphate content during the occurrence of bloom of west coast of India wherein phytoplankton bloom is Trichodesmium 14-15,35 , Noctiluca 37-39 and generally observed during the beginning of SW Asterionella 17 . The irregular trend observed in monsoon period (May-September), the present bloom phosphate concentration during the study could be was observed during the end of NE monsoon period. due to its rapid uptake as well as replenishment The present observation coincided with the transition processes taking place in the coastal waters. Total period during which the coastal water current was phosphorous concentration showed a trend similar to about to change from southerly to northerly direction. that of phosphate and ranged from 0.14-2.83 µmol l -1 This is the lull period during which the lowest (Figure 3e). magnitude of current is observed at this location. Blooms have been reported to be conspicuous in calm Silicate values ranged from 7.58-16.28 µmol l -1 with conditions. These calm conditions assist the trichomes lowest and highest values being observed during bloom to form dense rafts on the surface of the sea as has and post-bloom periods respectively (Figure 3c). Pre- been observed during this study. bloom concentrations of silicate were marginally high as compared to that of bloom and post-bloom periods. Phytoplankton community showed a distinct Silicate, utilized for the formation of the siliceous variation in its qualitative as well as quantitative frustules of diatoms, constitutes one of the most aspects during the study. In total 69 species of important nutrients regulating the phytoplankton phytoplankton were identified which comprised of growth and proliferation and ultimately to its 62 diatoms, 5 dinoflagellates, one silicoflagellatte and blooming. Relatively high values of silicate observed the cyanobacterium Trichodesmium erythraeum . The during the pre-bloom period could be ascribed to the population density of phytoplankters ranged from silicate rich freshwater input into the coastal water 1.23 × 10 5 and 2.94 × 10 7 cells l -1 (Figure 4) showing during the post-monsoon period. Also, during post- more than two order increase during the peak bloom monsoon period, the environmental conditions were period. The lowest cell density was observed during unfavorable for phytoplankton growth, and thus post-bloom period. Surprisingly, Trichodesmium was silicate uptake was negligible leading to enhanced found only during the bloom period from 19.02.08- level of silicate in the coastal waters. Gradually, with 23.02.08 and was totally absent during the pre- and onset of favourable conditions for phytoplankton post-bloom observations. Contribution of Tricho- growth, silicate uptake increased leading to decrease desmium to the total cell count ranged from 7.79 % in its concentration in the coastal waters as observed (1.10 × 10 4 cells l -1) to 97.01 % (2.88 × 10 7 cells l -1). MOHANTY et al .: BLOOM OF TRICHODESMIUM ERYTHRAEUM (Ehr..) AND ITS IMPACT ON WATER QUALITY 329

It is well known that Trichodesmium is more abundant collections on all the occasions as compared to the in subsurface layers (20-30 m) as compared to surface morning collections. This again emphasized that water 36 . Though, the present bloom was observed in certain phytoplankton such as Trichodesmium coastal waters with much lower depth erythraeum , which can tolerate relatively high amount (~ 8 m), in order to examine the presence of of irradiance in the surface water during afternoon as Trichodesmium in the subsurface layers, bottom compared to morning period 1-3,32 . However, species samples were collected, and found to be absent. The not tolerant to irradiance, evading the surface water observed density of Trichodesmium was found to be leading to low species diversity. Based on the significantly higher than the earlier reported value of numerical abundance, 30 species were considered as 3.38 × 10 6 cells l -1 by Ramamurthy et al .13 and important contributing 74.19-99.70% of the 4.80 × 10 6 cells l -1 by Krishnan et al .11 . Scrutiny of population density (Table 1). Out of these published literature showed that, the present observed Asterionella glacialis , Nitzschia longissima , density of Trichodesmium is the highest, reported to Thalassionema nitzschioides , Thalassiosira decipiens date from Indian waters, and surpassed by a factor of and Thalassiothrix longissima were present almost 1.75 times from that of earlier reported highest value throughout the study period. Species such as (1.75 × 10 7 cells l -1) by Santhanam et al .14 from Biddulphia heteroceros , Cocconeis distans and Tuticorin Bay. Leptocylindrus minimum were found only during the Community structure of phytoplankton showed that pre-bloom period and totally absent during bloom and the number of species on a single observation varied post-bloom periods. On the contrary, two species of between 7 species (on the day of highest cell count) Biddulphia (B. aurita and B. rhombous ) were found and 24 during the post-bloom period. As expected only during the post-bloom period. This clearly relatively less number of species were found during indicated that presence of Trichodesmium erythraeum the bloom as compared to pre- and post-bloom favours growth of a selected group of diatoms during periods. Similar results have also been reported 40 the post-bloom period. during Asterionella bloom. Interestingly, number of Distinct variations in all the three diversity indices species were relatively less during the afternoon were noticed during the study period (Figure-5).

Fig. 4 Total phytoplankton density, density of Trichodesmium erythraeum and number of species observed during the bloom 330 INDIAN J. MAR. SCI., VOL. 39, No, 3, SEPTEMBER 2010

Table  1 Percentage contribution of dominant phytoplankton species, total cell density and number of species encountered during the Trichodesmium erythraeum bloom in the coastal waters of Kalpakkam 14.02.08 19.02.08 19.02.08 20.02.08 20.02.08 21.02.08 21.02.08 22.02.08 22.02.08 23.02.08 28.02.0 M E M E M E M E M 8 M Asterionella 21.98 16.48 1.14 3.75 14.40 20.66 5.59 21.52 30.43 24.68 12.90 glacialis Biddulphia 4.84 aurita Biddulphia 1.10 heteroceros Biddulphia longicuris 0.06 2.42 Biddulphia mobiliensis 2.42 Biddulphia rhombus 1.30 4.03 Chaetoceros 0.42 2.25 2.42 lorenzianus Chaetoceros sp 0.19 1.13 1.38 1.61 Cocconeis distans 1.10 Coscinidiscus sp 1.10 0.19 2.42 Cyclotella sp 1.30 Dictyocha sp 2.60 Guinardia flaccida 1.61 Leptocylindrus 0.90 minimum Licmophora gracilis 2.20 Melosira sulcata 2.20 0.33 6.49 Melosira sp 16.81 Nitzschia longissima 3.30 1.48 0.98 3.19 16.00 5.36 1.97 6.33 14.49 2.60 1.61 Nitzschia sigma 2.20 0.60 1.43 2.53 Nitzschia stagnorum 1.10 1.27 Pinnularia interrupta 1.32 Pleurosigma sp 1.27 Pseudonitzschia 0.59 5.07 delicatissima Pseudonitzschia 1.13 pungens Thalasiossira 12.09 0.26 0.09 0.80 0.25 8.86 8.70 6.49 8.87 decipiens Thalasiossira sp 12.09 0.53 0.04 0.19 2.40 1.74 0.66 1.27 4.35 7.79 10.48 Thalassionema 24.18 4.69 0.34 2.06 16.00 15.05 8.88 17.72 21.74 24.68 13.71 nitzschioides Thalassiothrix 4.40 0.45 0.09 1.13 1.06 0.99 1.27 5.19 2.42 frauenfeldii Thalassiothrix 0.41 0.94 2.40 2.04 2.53 1.30 2.42 longissima Trichodesmium 0.00 44.04 97.01 75.80 33.60 43.43 74.67 17.72 13.04 7.79 0.00 erythraeum % contribution of 89.01 88.19 99.70 96.81 85.60 92.47 94.08 82.28 92.75 92.21 74.19 above sp. Total cell density 1.29 13.91 294.05 6.89 1.46 8.28 5.63 1.29 1.23 1.37 2.02 (X 10 5) Total No. species in 16 19 7 18 9 16 13 12 8 13 24 the sample

M= morning collection, E= evening collection MOHANTY et al .: BLOOM OF TRICHODESMIUM ERYTHRAEUM (Ehr..) AND ITS IMPACT ON WATER QUALITY 331

Fig. 5  Variations in phytoplankton diversity indices during the bloom period

Fig. 6 Chlorophyll-a and phaeophytin fluctuations during the appearance of bloom Relatively high values of all the indices during the periods and the peak values of these two pigments pre- and post-bloom periods showed that the were about 20 times higher than the normal values. phytoplankton community was floristically rich Interestingly, concentrations of these pigments were during these periods. A significant decrease in relatively high during the post-bloom period as diversity indices was noticed on the day of the highest compared to the pre-bloom period. This affirmed the Trichodesmium density. This could be attributed to fact that phytoplankton growth gradually increased the dominance of Trichodesmium and the presence of from post-monsoon to summer in this part of Bay of very less number of other phytoplankton species. Bengal 10-11 . Similar observations of unusually high pigment concentrations have been reported by E. Photosynthetic pigments Ramamurthy et al .13 , Pant & Devassy 35 and Satpathy Photosynthetic pigments such as chlorophyll-a and et al .15 during Trichodesmium bloom and Mishra phaeophytin showed wide variations which ranged et al .40 and Mishra & Panigrahy 41 during Asterionella from 1.21-42.15 mg m -3 and 0.78-46.23 mg m -3 bloom. respectively (Figure 6). The highest concentration was encountered during the bloom which coincided with Conclusion highest cell density. In general, concentration of Relatively high temperature, low current chlorophyll-a and phaeopigments remained high magnitude, stable salinity (~ 33 psu) and low nitrate during bloom as compared to pre- and post-bloom concentration were observed during the bloom of 332 INDIAN J. MAR. SCI., VOL. 39, No, 3, SEPTEMBER 2010

cyanobacterium T. erythraeum in the coastal waters of 11 Krishnan, A.A., Krishnakumar, P.K. and Rajagopalan, M., Kalpakkam. Abnormally high concentration of Trichodesmium erythraeum (EHR) bloom along the sothwest coast of India (Arabian Sea) and its impact on trace metal ammonia observed during the bloom period was a concentrations in seawater, Estuar . Coast. Shelf. Sci ., 71 concern. The cell density was found to surpass all the (2007) 641-646 earlier reported densities from east and west coast of 12 Jyothibabu, R., Madhu, N.V., Murukesh, N., Haridas, P.C., India. Appearance of T. erythraeum in coastal waters Nair, K.K.C. and Venugopal, P., Intense blooms of of east coast of India during two successive years Trichodesmium erythraeum (Cyanophyta) in the open waters along east coat of India, Indian J. Mar. Sci., 32 (2003)165-167 necessitates the need for continuous monitoring of 13 Ramamurthy, V. D., R. Selva Kumar, A. and Bhargava, R. physico-chemical parameters on a long-term basis, M. S., Studies on the blooms of Trichodesmium erythraeum which would help in comprehending its cause and its (EHR) in the waters of the Central west coast of India, Curr. ecological significance. Sci ., 41 (1972) 803-805 14 Santhanam, R., Srinivasan, A., Ramadhas, V. and Devaraj, M., Impact of Trichodesmium bloom on the plankton and Acknowledgement productivity in the Tuticorin Bay, Southeast coast of India, Authors are grateful to Director, Indira Gandhi Indian J. Mar. Sci ., 23 (1994) 27-30 Centre for Atomic Research and Director, Safety 15 Satpathy, K.K., Mohanty, A.K., Gouri Sahu, Usha Natesan, Group for their encouragement and support. Help Venkatesan, R. and Prasad, M.V.R., On the occurrence of Trichodesminum erythraeum (Ehr.) bloom in the coastal rendered by Shri. S. Bhaskar of Environmental and waters of Kalpakkam, east coast of India, Indian J. Sci. Industrial Safety Section is also duly acknowledged. Tech. , 1 (2007) 1-11 16 Sargunam, C.A., Rao, V.N.R. and Nair, K.V.K., Occurrence References of Noctiluca bloom in Kalpakkam coastal waters, east coast of India, Indian J. Mar. Sci., 18 (1989) 289-290 1 Westberry, T.K. and Siegel, D.A., Spatial and temporal distribution of Trichodesmium in the world’s , Global 17 Satpathy, K.K. and Nair, K.V.K., Occurrence of Biogeochemical Cycles , 20 (2006) GB4016 phytoplankton bloom and its effect on coastal water quality. 2 Capone, D.G., Zehr, J.P., Paerl, H.W., Bergman, B. and Indian J. Mar. Sci ., 25 (1996) 145-147

Carpenter, E.J., Trichodesmium , a globally significant marine 18 Bhat, S.R. and Verlencar, X.N., Some enigmatic aspects of , Science , 276 (1997)1221-1229 marine cyanobacterial , Trichodesmium . Curr. Sci., 91 3 Kononen K & Leppänen J M, Patchiness, scales and (2006) 18-19

controlling mechanisms of cyanobacterial blooms in the 19 Grasshoff K, Ehrhardt M & Kremling K, Methods of Baltic Sea: application of a multi-scale research strategy, in: seawater analysis , (Wiley- VCH, New York) 1983, pp. 786

Monitoring Algal Blooms: New Techniques for Detecting 20 Parsons T R, Maita Y & Lalli C M, A manual of chemical Large-Scale Environmental Change , edited by M. Kahru and and biological methods for Seawater analysis , (Pergamon Ch.W. Brown, (Landes Biosience, Austin, TX, USA,) 1997, Press, New York) 1984, pp. 173

pp. 63–84 21 A manual on methods for measuring primary production in 4 Qasim S., Z., Some characteristic of a Trichodesmium bloom aquatic environments , IBP hand book no 12, Blackwell in the Laccadives, Deep Sea. Res. , 17 (1970) 655-660 scientific publication, London, 1974, pp. 225 5 Sarangi, R.K., Prakash, C. and Nayak, S.R., Detection and 22 Desikachary T V, Atlas of diatoms III & IV , (Madras Science monitoring of Trichodesmium bloom in the coastal waters of Foundation, Madras) 1987, pp.239 Sourashtra coast, India using IRS P4 OCM data, Curr. Sci ., 23 Subramanian R, The Dinophycaes of Indian Seas Part-I. 86 (2004) 1636-1841 Genus Ceratium, (Marine Biological Association of India) 6 Prabhu M.S., Ramamurthy, S., Kuthalingam, M.D.K. and 1968, pp. 129 Dhulkheid. M.H., On an unusual swarming of the planktonic 24 Subramanian R, The Dinophycaes of Indian Seas Part-II. blue green algae Trichodesmium Spp. off Mangalore. Curr. Peridiniaceae , (Marine Biological Association of India) Sci ., 34 ( 1965) 95 1971, pp. 134 7 Devassy, V.P., Bhatrarhiri, P.M.A. and Qasim, S.Z., 25 Fristch F E, The Structure and Reproduction of Algae, Vol. Trichodesmium Phenomenon. Indian J. Mar. Sci ., 73 ( 1978) II , (Cambridge Univ. Press, London) 1935, pp. 263 168-186 26 Marumo, R. and Nagasawa, S., Seasonal variation of the 8 Devassy V P, Trichodesmium red tides in the Arabian Sea, standing crop of a pelagic blue-green alga, Trichodesmium in the in: Contributions in Marine Sciences : A Special Volume to Kuroshio water, Bull. Plankton Soc. Japan , 23 ( 1976) 19-25 Felicitate Dr. S. Z. Qasim Sastyabdapurtl on His Sixtieth 27 Carpenter, E.J., Physiology and ecology of the marine Birthday , edited by T.S.S. Rao, (National Institute of plankton Oscillatoria ( Trichodesmium ), Mar. Biol. Lett ., 4 Oceanography, Dona Paula, India) 1987, pp. 61–66 (1983) 69-85 9 Shetty H P C, Gupta T R C and Kattai R J, Green water 28 Suvapepant S, Trichodesmium blooms in gulf of Thailand, phenomena in the Arabian Sea off Mangalore, in: Proceedings in: Marine pelagic cyanobacteria: Trichodesmium and other of the first India fisheries forum , 1988, pp 339-346 , edited by E.J. Carpenter, (Kluwer Academic 10 Koya, K.P.S. and Kaladharan, P., Trichodesmium bloom and Press) 1992, pp. 343-348 mortality of Canthigaster margaritatus in the Lakshadweep 29 Sellner, K.G., Physiology, ecology and toxic properties of marine Sea, Mar. Fish. Inf. Serv. Tech. Ext. Ser., 147 (1997) 14 cyanobacteria blooms, Limnol. Oceanogr ., 42 (1997) 1089-1104 MOHANTY et al .: BLOOM OF TRICHODESMIUM ERYTHRAEUM (Ehr..) AND ITS IMPACT ON WATER QUALITY 333

30 Desa, E., Suresh, T., Matondakar, S.G.P., Desa, E., Goes, J., 36 Subba Rao, S.D.V., Asterionella japonica bloom and Mascarenhas, A., Parab, S.G., Shaikh, N. and Fernandes, discolouration off Waltair, Bay of Bengal, Limnol. C.E.G., Detection of Trichodesmium bloom patches along Oceanogr. , 14 (1969) 632-634 the eastern Arabian Sea by IRS-P4/OCM ocean colour sensor 37 Raghuprasad, R. and Jayaraman, R., Preliminary studies on and by in-situ measurements, Indian J. Mar. Sci. , 34 (2005) certain changes in the plankton and hydrological conditions 374-386 associated with the swarming of Noctiluca , Proc. Ind. Acad. 31 Madhu, N.V., Jyothibabu, R., Maheswaran, P.A., Gerson, Sci., 40 (1954) 49-57 V.J., Gopalakrishnan, T.C. and Nair, K.K.C. Lack of 38 Dharani, G., Abdul Nazar, A.K., Kanagu, L., seasonality in phytoplankton standing stock (chlorophyll-a) Venkateshwaran, P., Kumar, T.S., Ratnam,K., Venkatesan, and production in western Bay of Bengal, Continent. Shelf R. and Ravindran, M., On the reoccurrence of Noctiluca Res. , 26 (2006) 1868-1883 scintillans bloom in Minnie Bay, Port Blair: Impact on water 32 Chang, J., Chiang, K.P. and Gong, G.C., Seasonal variation quality and bioactivity of extracts, Curr. Sci., 87 (2004) and cross-shelf distribution of the nitrogen-fixing 990-994 cyanobacterium, Trichodesmium , in the southern East China 39 Sahayak, S., Jyothibabu,R., Jayalakshmi, K.J., Sea. Continent. Shelf Res. , 20 (2000) 479-492 Habeebrehman, H., Sabu, P., Prabhakaran, M.P., Jasmine, P., 33 Nair V E, Devassy V P & Madhupratap M, Blooms of Shaiju, P., Rejomon, G., Thresiamma, J. and Nair, K.K.C., phytoplankton along the coast of India associated with Red tide of Noctiluca miliaris off south of nutrient enrichment and the response of zooplankton, in: Thiruvananthapuram subsequent to be “Stench event” at the Marine coastal eutrophication. Science of the Total south Kerala coast, Curr. Sci ., 89 (2005) 1472-1473 Environment , edited by R.A. Vollenweiden, (Elsevier) 1992, 40 Mishra, S., Sahu, G., Mohanty, A. K., Singh, S.K. and pp. 819-828 Panigrahy, R.C., Impact of the diatom Asterionella 34 Cole C V & Sanford R L, Biological aspects of the glacialis (Castracane) bloom on the water quality and Phosphorus cycle, paper presented at Symposium on phytoplankton community structure in coastal waters of Phosphorous Requirements for Sustainable Agriculture in Gopalpur sea, Bay of Bengal, Asian J. Water, Env. Poll., 3 Asia and Oceania , SCOPE/UNEP, 1989, 6-10. (2006) 71-77 35 Pant. A. and Devassy, V. P., Release of extracellular matter 41 Misra, S. and Panigraphy, R.C., Occurrence of diatom during by a Trichodesmium bloom, Curr. blooms in Bahuda estuary, East Coast of India, Indian J. Sci ., 45 (1976) 487-489 Mar. Sci. , 24 (1995) 99-101