The distribution of chlorophyll 'a' and 'b' in the Arabian Sea along the west coast of India from Cape Comorin to Veraval in the 40-200rn depth contour, in a single cruise of FORV Sagar Sampada (Cruise no. 177) was studied, covering 58 stations duringng the post monsoon period October-November, 1999. Data on nitrates and phosphates were also collected along with chlorophylls. The results indicated that the coastal waters along the south west coast of Inaia are more productive than the waters along the north west coast during the post monsoon period. Earlier observations on chlorophylls and nutrients from eastern Arabian Sea are briefly discussed

Gireesh, R

Gopinathan, C P

Smitha, K S

CMFRI Digital Repository

J. mar. biol. Ass. India, 2001, 43 (1&2) : 21 - 30 Distribution of chlorophyll 'a' a r A  'I-' in the eastern Arabian Sea (west coast of India) in relation during post r ,n IlU V . rients I C.P. Gopinathan, R.Gireesh and K.S. Smitk Central Marine Fisheries Research Institute, Kochi- 682 03 Abstract The distribution of chlorophyll 'a' and 'b' in the Arabian Sea along the west coast of India from Cape Comorin to Veraval in the 40-200rn depth contour, in a single cruise of FORV Sag-- Sampada (Cruise no. 177) was studied, covering 58 st 5ng the post monsoon period October-November, 1999. Data on nitrates and ph were also collected along wi chlorophylls. The results indicated that the coastal waters along the south west coast of Inaia are more productive than the waters along the north west coast during the post monsoc period. Earlier observations on chlorophylls and nutrients from eastern Arabian Sea are a1 briefly discussed. ations dui osphates . . - Introduction It is well known that photosynthetic pigments are the index of primary pro- duction of an area and playing a singnificant role in the ecological charac- teristics of an ecosystem. The biological productivity of the coa d oceanic regions of the Indian se .neral are dependent on the complex pnysico-chemi- cal and biological processes, especially the distribution and abundance of photosyn- thetic pigments in the euphotic zone. While considerable informations are available on the physico-chemical and b 11 characteristic m k Sea along the w ia (~amamirtham and Jayaraman, 1 Y 60; Patil and Ramamirtham, 1963; Sharma, 1966; Radhakrishna, 1969; Qasim, 1977, 1982; Qa zl., 1972 Devassy, Pant, 1' Pillai et ...., ,,30), informarion on me ulatribution of c h l u ~ u ~ ~ ~ y l l  'a' and 'b' during the post monsoon period is lim- ited. Banse (1968) reported some informa- tion on chlorophyll 'a' and nutrients during the south west monsoon period in the coastal waters of Arabian Sea while, Krey and Babernad (1976) and Sumitra Vijayaraghavan and Krishnakumari (1989) have given a general picture of the distribution of chlorophylls along the west coast. Balachandran et a1 (1989, 1997) studied the distribution and profile of chlorophyll 'a' in the inshore waters off Cochin and Laccadive Sea during the mon- soon season. Recently Pillai et al. (2000) gave a comprehensive account on the seasonal variations of the physico- chemi- cal and biological characteristics of the eastern Arabian Sea and Madhupratap et :2001) reviewed es of the Aral reIerence to fisher,,,. tstal anc liologici irabian - :s of th 'est coas e eastel it of Ind --. sim et 1 . 1979; 0 1 . .  7111 I; Bhatta 992; Pi1 . -.~.. - lthiri an lai, 198 ~- - ~- .1 the ocei jian Sei ioc lnograp 3 with hic fea- special 22 C. P. Gopinathan et al. In this account, an attempt is made to study the chlorophyll 'a' and 'b' in rela- tion to nitrates and phosphates in the euphotic zone within the 40-200 m d - zone of the west coast from Cape Corn to Veraval, during the post mons period of October - November 1999. epth lorin boon The authors are thankful to Dr. Mohan Joseph Modayil, Director, CMFRI for his encouragement. Thanks are also due to Dr. V.N. Pillai, former Director, for going through the manuscript critically and offering valuable suggestions and to Shri. A. Nandakumar, Technical Officer for the preparation of figures. The authors are also grateful to the Dept, of Ocean Devel- Delhi, for the facilties rd FORV Sagar Sampai opmer vided ~ t ,  New on boa. Pro- la. l v l a r c r l a l  a d  methods The entire area a101 - --ng the v vest coal .A IT..". SAMPLING 3 " l SAMPADA -177 India between Cape CCIIILVI UI alLu V CA aval, rig. I .  sampilng statlons in the depth zone of 40-200 m in the coastal and oceanic regions were covered lowed. Quantitative and qualitative stud- in a single cruise of FORV sap,. sampada ies on ~hytoplankton were also made. (Cruise no. 177) during the post monsoon I period of October-November 1999 (Fig. Chlorophyn .a. : 1). The samples for the estimation of chlorophylls and nutrients were collected Figs. 2-7 ind: e distribution of from 58 stations; 37 stations in the south chlorophyll 'a' b stern Arabian Sea eastern and 21 stations in the north east- at various dept' m ern Arabian Sea. Data on chlorophylls 2 n, 50m i iic and nutrients were collected at every sta- 2 icate th n the ea! h regio: 3nd 75rr ns (sud 1) of the face, 10 ! euphol surface 'a' vah 8 ,.m - waters, res of t - the hig 3.28 mg . -. tion (representing one degree square) from o- surface to maximum depth of 75 m using r as chlorophylls and nutrients such as nitrates N and long. 76"42.7zfE. Higher values ~ and phosphates, the methodology of (5.60 mg/m3) were also observed off Goa Strickland and Parsons (1972) was fol- (lat. 15" 24.94'~ and long. 73" 39' 09'E). Distribution of chlorophyll 'a' and 'b' in the eastern Arabian Sea 23 wtion of LORE :hlaophyl l '! (SURFACE 1 Fig. 2. Distribution y cnruruphyll 'a' ur surTuce 16' 14.- 120- lO0- 8. Moderate values of more than 2.0 mg/m3 were noticed in the coastal waters south and north of Ca] 1 Mumbai (Fig.2). A very high value of 15.72mg/m3 of chlorophyll 'a' was noted at 10 m depth off Cape Comorin at lat.8O27.58'N and long. 76'42.72'E. Further at the Wadge Bank area (lat. 9'57.02'N and long. 76O00.01'E) a high value of 8.01 mg/m3 was noticed. Again pockets of high values were observed off Karwar (7.47 mg/m3), off Wadge Bank (5.87 mg/m3) and o - -  Cape Comorin (5.07 mg/m3). Modera to high values of more than 3mg/m3 we1 observed at stations off Goa and Mumbai. (Fig.3). - 0 - 6&10 ;V 4' 76' At 20m-depth zone, the highest chlo- rophyll 'a' value of 21.36 mg/m3 was observed off Karwar (11°28.12'N and 75O21.47'E) and next highest values of 15.22 mg/m3), was again off Karwar. Pockets of high values were observed off Karwar (15.22 mg/m3). Cape Comorin (11.48 mg/m3); Goa (6.67 mg/m3) and moderate value of 3-4 mg/m3 of chloro- phyll 'a' recorded off Cape Comorin and off Ratnagiri (Fig.4). At 30m-depth zone, high values of 9.6 mg/m3 and 8.81 mg/m3 of chlorophyll 'a' were observed off Cape Comorin and Goa respectively. Moderate to high values of 3-4.5 mg/m3 of chlorophyll 'a' were re- OROPHYLL ( I O m )  HORIZONTAL DISTRIBUTION OF CHL I I I 1 I Fig. 3. Distribution of chlorophyll 'a ' at 24 C. P. Gopinathan et al. LNGALORE \ tl.0 As regards the column production of chlorophyll 'a' (Fig.8) an exceptionally high value (423.5 mg/m2) wa led off Cape Comorin (8" 27.58'; 76" 42.72'E) and high to moderate values of 127 mg/m2 anc /m2 were observed off Goa and K ~espectively . IS recort N and .-.I - Chlorophyll 'b ': Though chlorophyll 'b' is considered to be an accessory pigment of chlorophyll 'a', pockets of high values exceeding 1.5 mg/m3 were observed at surface off Cape Comorin (B02'N and 77"20'E), off Cohin (lat. 9"N and long. 76O23'E) and south of Marmagoa (lat. 15O25'N and long. 73'30'E). Low values were observed in Fig. 4 Distribution of chlorophyll 'a' at 20m corded off Veraval, off Karwar and off Ratnagiri regions (Fig.5). At 50 m-depth zone, moderate to high values were ob- served only at few stations. An apprecia- bly good value of 2.93 m g / d  was ob- served at lat.16°41.08' N and long. 73" 03. 5'E off Goa. However, moderate to low values of chlorophyll 'a' was found in the regions off Ratnagiri, Mumbai and Veraval waters in the depth zone of 50m (Fig.6). As expected, the distribution of chloro- phyll 'a' in the 75m-depth zone were scarce and very low throughout the pe- ' riod of observation. The only high value (2.67 mg/m3) was recorded at 9'46.24'N and 75" 41'E in the Wadge Bank area. (Fig.7). Fig. 5. Distribution of chlorophyll 'a' at 30m Horlzontol distribution of ALORE Distribution of  chlorophyll 'a' and 'b' in the eastern Arabian Sea 25 IZONTAL DIS CHLOROPk ( B O W  -Nutrients: . The high and low concent of nitrates and phosphates in the sournern and northern regions are presented in Table 1 and 2. In the southern region, high values of nitrates (1.3 and 1.5pg atN/ 1) were observed off Karwar and Calicut and low values were noted at Cape Comorin and Wadge Bank area (0.2-0.8 pg at./l). Similarly, high phosphate val- ues were observed at Calicut - Kannur region (1.77-2.62 pg at. P/1) and low values off Quilon and Cape Comorin (0.7- 0.8 pg at P/1). In the north, high values of nitrates were noted off Goa and Mumbai (0.56 - 0.6 pg at. N/1) and low values were re- LNGAWRE \ Fig. 6. Distribution of chlorophyll 'a' at 50m the northern region when compared to southern region. Chlorophyll 'b' concen- trations at lorn, 20m, 30m, 50m and 75m depths ranged from 0.1 - 1.4; 0.04-1.5; 0.05-1.2; 0.04-1.05; 0.07-1.2 mg/m3 respec- tively. Moderately high values were ob- served (0.5-1.0 mg/m3) in the area be- tween Marmagoa and Veraval. 1 'b' 'NAGIRI IG0* rations - ---.<I-. LORE Column production of chlorophyl (Fig 9) indicated high values in the south- ern region; off Calicut and Marmagoa (>90 mg/m2) when compared to the northern region (>70mg/m2). Moderate values (25- 45 mg/m2) were noted frequently in the south and moderate to low values (20-25 mg/m2) in the north. Fig. 7. Distribution of chlorophyll 'a' at 75m C. P: Gopinuthan et al. 00 GOA Fig. 8. Column production of chlorophyll 'a' Coscinodiscus, Thalassiosira, Nitzschia and Eucampia along with other commonly oc- curring forms like Planktoniella sol, Asterionella japonica and Thalassiothrix fraunfeldii. In the north, the diatoms showed the dominance over dinoflagellates. Samples of Goa, Ratnagiri and Mumbai revealed that species of Biddulphia, Coscinodiscus, Nitzschia, Rhizosolenia, Thalassiosira and Eucampia were abundant in these areas. The region from Ratnagiri to Goa indi- cated a mixture of almost equal represen- tation of diatoms and dinoflagellate spe- cies such as Dinophysis, Pyrophacus, Ceratium, Peridinium and Ceratocorrys. corded at Ratnagiri (0.-0.13pg at. N/1). While the phosphate values were found to be high off Goa, Ratnagiri and Mumbai regions (1.18-1.48 pg at P/1) and low values were observed off Veraval(0.19 pg at. P/1). Qualitative studies on phytoplankton The qualitative studies on phytoplank- ton obtained from 58 stations, collected by 1/2m nets (bolting silk, 40 p) indicated . that in the south there is an abundance of dinoflagellates, dominated by the spe- cies of Ceratium, Peridinium, Dinophysis, Pyrophacus and Diplopsalis in the order of - abundance. Diatoms were represented in lesser numbers, comprising of species of Fig. 9. Column production of chlorophyll 'b' IRI Distribution of chlorophyll 'a' and 'b' in the eastern Arabian Sea 27 Table 1. Values of nitrate and phosphate in the south eastern Arabian Sea Area Latitude F Karwar igh value F Calicut f Calicut 1.2 O.! 3w values 20 59' 1" 40 02' 'O 21 59' 5 (PO.) i0 04 35' Lo 14 78' 1" 06 59' ! Cape ! Calicut tdge Bank Of i Ofi Wa Off Calicut Off Kannur off Kannur )w values ~dge Bank ' Cape ~dge Bank n Arabian I Sea Table 2 : Values of nitrate and phosphate in the nl orth eastn - '0-30 m average) - Location Latitude Longitude High values (NO,) rea 20'42 72 69'16 46 20°34 42 70041 95 16'38 18 72 16'41 33 73 Low values (NO,) 18'49 75 70 20°26 66 70 20'57 50 6 0 ~ ~  wi High values (PO,) 16'43 53 73'12 42 Katnagiri Off Gc Ratna~ Off Gc Off Ratnagiri Off Miumbai N w Mumbal NW Goa NW Goa Off Ratnagiri NW Mumbai n n A r  I #---1--2 Off Gc - w values .- -,, "59 59 Off Veraval 28 C. P.  Gopinafhan et al. Discussion tion of chlorophyll 'a was noted off Cape It is well known that abundance of chlorophylls and nutrients in the water column are of paramount importance for determining the biological productivity and potential resources. Light penetra- tion decides the depth of the euphotic zone while the nutrients especially the nitrates and phosphates indicate the fer- tility of the water to promote productivity and the availability of photosynthetic pigments reveal the production at the primary level. It is quite interesting to note that there is a positive correlation between chloro- phyll 'a and 'b noticed in most of the regions of the present study. High values of chlorophyll 'b' observed at Calicut and Wadge Bank area of the south west coast and off Goa and Mumbai coincided with high concentrations of chlorophyll 'a'. Though chlorophyll 'b' is considered to be an accessory photosynthetic pigment of chlorophyll 'a', its concentration in these regions are significant for assessing the fertility of the area. The availability of nitrates and phos- phates in the surface to 75m in the eastern Arabian Sea is largely due to upwelling and river run off and also drainage from the land. Very often, these nutrients avail- able in the water column are not fully utilized by the phytoplankton and high concentrations are detected in the surface and column regions (Table 1 and 2). A negative correlation between chlorophyll 'a concentration and nutrient distribution is observed in the south. High concentra- and Wadge Bank area and low values of nitrates and phosphates were recorded from these areas during the post monsoon period. In the north a close positive cor- relation existed between chlorophylls and nutrients. The high values of chlorophyll 'a noted in the coastal waters off Goa and Mumbai and high to moderate value of nutrient concentrations observed in these areas clearly revealed the positive corre- lation. These observations have indicated that in the south, the nutrients were fully utilized by the phytoplankton for its growth and development while in the north the nutrients were partially utilized by the planktonic algae. The negative correlation especially with the phosphates in the south indicated that phytoplankton is able tomeet the requirements for growth and multiplication through inorganic phosphate sources. A positive correlation between chlorophyll 'a' and phosphates has been reported by Balachandran et al (1989) from the inshore waters of Cochin while negative correlation was reported between these parameters from the Laccadive Sea during the south west monsoon season (Balachandran et al. 1997) In the present investigation, the high- est values of phosphates (1.77 to 2.62 pg at P/1) recorded off Calicut and Kannur, coincided with the low to moderate val- ues of chlorophyll 'a' observed from these regions. The integrated values for column production (0-30m) of chlorohyll 'a' indi- cated that the pigments are localized in pockets between 10-30m depth contours. Distribution of chlorophyll 'a' and 'b' in the eastern Arabian Sea 29 o obsen ntal she1 shore w India. aters alc the ?a,. there is a zone or nign cnloropnyll 'a' productivity (423 mg/m2) which could probably be due to localized phytoplank- ton abundance, a common phenomen found during the post monsoon in 1 south eastern Arabian Sea. It was observed that the .regic .gh concentrations of chlorophyll d drt: the coastal north Comorin area in me ---,-.. Inregrat--. red that .f, in the < . .  at the E Wadge . .. !dge of i Bank an . .. >ng the r south w est coast es n. V.K., M . -. Referenc Balachandra .S. Rajagq 1, 1989. Chlorophyll 'a' and pheopigment as in- dices of biological productvity in the inshore surface waters off Cochin.Indian J. Fish. 36(3) : 227-237. palan and . . V.K. Pillai . . Lon the ---C.P.Gop: K.K. Val inathan, 1 lsala and 1 Y.K. Pillai vI.S., Rajal dakumar. 997. Chlo waters c and W - ---- hff Goa a 'adge 1 1 ._ ~ 1 -  ~ n d  Mur Bank a sol1 th. nbai in 1 ~ n d  Ca 1- 1- __- 1 the Pe .edrophyll Laccadi1 1990. Ibi profile c ve Sea du 'd, 44(1):2! )f the eu] ring the I 9-43. photic za Monsoon lne in thc Season o of the AI 1 and effe " --.-..- #. . rabian Sei r ts  on de 15 : 45-79 - values of chlorophyll 'a' (0-75m) indicated that much of the photosynthetic pigments occur below the surface in the southern region. Comparatively higher concentra- tions of chlorophyll 'a' and 'b' were found to exist between 10 to 30m. Column pro- duction of chlorophyll 'a' and 'b' in the entire eastern Arabian Sea during the post monsoon period indicated that the sou em region has higher production than 1 northern region. Recent findings of Pillai et al. (2000) also revealed this fact. The findings of Madhupratap et al .  (2001) further revealed that there is a clear ten- dency for carnivorous fishes to dominate the Northern region and planktonivorous forms in the southern region. However, according to Radhakrishna et al. (1978)' the average production in the north east- em Arabian Sea is higher than region is by and large more fertile than the south- em region. Recent studies by Balachandran et al. (1989, 1997) in the inshore waters of Cochin and Laccadive Sea pointed out the role of photosynthetic pigments as indices of biological productivity in the Banse, K., 1968. Hydi shelf of India anc mersal fisheries. ueep sea nesearcn. Bhattathiri, P.M.A. and V.P. Devassy, 1979. Biologi- cal characteristics of the Laccadive Sea (Lakshadweep). Indian J. Mar.Sci., 8 : 225-226. Krey, J and B.Babernad, 1976. Phytoplankton pro- duction. Atlas of the International Indian Ocean Expedition. (KielIIOC-UNESCO) : 70. th- adhupratap, M., K.N.V. Nair, T.C. Gopalakrishnan, P.Haridas, K.K.C.Nair, P.Venugoplan,. and Mangal Gauns, 2001. Ara- bian Sea Oceanography and fisheries of the West cost of India. Curr. Sci., 81 (4) 355-361. Pant, A., 1992. Primary productivity of the Arabian Sea. Tropical Ecosystems: Ecology and Man- agement. (Eds.) K.P. Singh and J.S. Singh. Wiley Eastern Ltd., New Delhi : 255-267. Patil, M.R. and C.P Ramamirtham, 1963. Hydrog- raphy of the Laccadives offshore waters - A study of the Winter condition. J. mar. biol. Ass.lndia., 5 (2) : 159-169. Pillai,V.N.,1983.Physical characteristics of the coastal waters along the Kerala coast with an attempt to study possible correlation with oil sardine,mackerel and anchovy fisheries. Ph.D.Thesis. Cochin University of Science& Technology. 30 C. P.  Gopinathan et al. ------ , V.K.Pillai, C.P.Gopine - and ----.V.P.Devasy,P.M.A. Bhattathiri and R.M.S. A.Nandakumar,2000. Seasonal va t the Bhargava,l978.Primary productivity in the physicochemical and biological i stics Northeastern Arabian Sea. lndian J.Mar.Sci., of the Eastern Arabian Sea./.mar.biol.Ass.l 420 &2):1-20 3- . Primary adives. Ini ,obiology Qasim,S.Z., P.M.A.Bhattathiri and C.V.ti.Kec r product ha t iona  ion of ar 1 Revenue I attol in der qestal -.1977. Biological productivity of the Indian O( Indian J.Mar.Sci.6:122-137. ndia imamirthi graphic . - :features of the continental shelf waters the offCochin during the years 1958 and 1959. nten ' J.mar.biol.Ass.lndia, 2(2):199-207. Sharma.G.S.1966. Thermocline as an indicator of *. . l(1) : 8-19 ng. Ibid, l -.1982.0ceanography of the northern Arabian =a. Deep Sea Research. 29:1041-1068 t of Indii .Mar.Biol. I during 4:174-181. the +st rickland, J I--- >I-- nanaw Bd. Can 1.D.H and -1. -c - un or seawarer analvsls. ourl. Fish. Res. ada, 167:3 10. Ivan and , L. Krish Radhakrishna,K.1969.Primary produc dies Su jayaragha i, ;- Ye shelf waters off Alleppey,south west 1989. Primary production in the southeastern I of Arabian Sea during Southv I- dian 1. Mar. Sci., 18 : 30-32. vest ma msoon. h 

Distribution of chlorophyll 'a' and 'b' in the eastern Arabian Sea (west coast of India) in relation to nutrients during post monsoon

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Distribution of chlorophyll 'a' and 'b' in the eastern Arabian Sea (west coast of India) in relation to nutrients during post monsoon

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