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opined that limited mixing. high organic production. sinking and decomposition of large amount of organic matter were the reasons for this oxygen depletion in higher latitudes. Ivanenko and Rozanov (1961) have reported the presence of H 2S in the oxygen deficient zones of AS and BOB. Nejman (1961) observed sinking of high saline. high temperature. oxygen poor water in the Persian Gulf and Gulf of Aden and spread into the subsurface layers which may have its influence on the low oxygen and high saline water observed in the northern transects. Rao and Jayaraman (1970) suggested that the oxygen minimum is because of near stagnant conditions in the north and central parts of the AS. According to Wyrtki (1973) the oxygen minimum layer is due to the isolation and stagnation of the intennediate water. limited horizontal advection and high primary productivity. The distribution of DO in the northern Indian Ocean is different from most of the other open ocean areas in that the surface layer is well mixed down to the thennocline and oxygen maximum could occasionally be observed within this layer, especially during pre-monsoon season. The intensity of the incident solar radiation is very high during this period. which causes maximum primary production to occur a few meters below the sea surface (Qasim. 1977). This together with high vertical stability may result in the observed oxygen maximum in the shallow depths. The strong density gradient prevent any significant exchange of DO from the euphotic zone to layers below the thennocline. and the horizontal advection is poor due to the semi enclosed nature of the region. These features in conjunction with a high rate of supply of organic matter from the surface result in a severe depletion of DO below the thermocline throughout the northern Indian Ocean. a feature recognjzed by several workers (Nejman. 1961, Wyrtki, 1971. 1973. Gupta et al .• 1976a, 1976b, Naqwi et al .• 1982). 45
3.4. References Bhattathiri, P. M. A., Aditi Pant, Surekha Sawant, Gauns, M., Matondkar, S. G. P., Mohanraju, R., 1996. Phytoplankton production and chlorophyll distribution in the eastern and central Arabian Sea in 1994-1995. Curr. Sci. 71(11), 857-862. Darbyshire, M., 1967. The surface waters off the coast of Kerala. Deep Sea Res. 14,295-320. Fincham, A. A., 1984. Basic Marine Biology, Cambridge University Press, London. Gupta, Sen R., Sankaranarayanan V. N., De Sousa S. N., Fondekar, S. P., 1976a. Chemical Oceanography of the Arabian Sea: Part 111- Studies on nutrient fraction and Stoichiometric relationships in the northern and eastern basins. Indian J. Mar. Sci. 5, 58-71. Gupa, Sen R., Rajagopal, M. D., Qasim, S. Z., 1976b. Relationships between dissolved oxygen and nutrients in the north-westtern Indian Ocean. Indian J. Mar. Sci. 5, 201-211. Gupta, Sen R., Analia Braganca, Noronha, R. J., Singbal, S. Y. S., 1980. Indian J. Mar. Sci. 9, 240-245. Ivanenkov, V. N., Rozanov, A. G., 1961. Hydrogen sulphide contamination of the intennediate water layers of the Arabian Sea and the Bay of Bengal. Okeanologiia 1,443-449 (in Russian). Joydas, T.V., 2002. Macrobenthos of the shelf waters of the west coast of India. Ph.D. Thesis, Cochin University of Science and Technology. Kumar, Hareesh, P. V., Basil Mathew, 1997. Salinity distribution in the Arabian Sea. Indian J. Mar. Sci. 26, 271-277. Kumar, Prasanna, S., Prasad, T. G., 1996. Winter cooling in the northern Arabian Sea. Curr. Sci. 71 (11), 834-841. Levinton S. Jeffrey, 1982. In: Marine Ecology. Prentice-Hall Inc., Englewood Cliffs, New Jersey. 46
Page 2 and 3: Certificate I hereby certify that t
Page 4 and 5: Contents Page No. Chapter 1. Introd
Page 6: the bottom. Ekman (1935) described
Page 9 and 10: wonns are the most abundant group a
Page 11 and 12: leadership of Sir James Clark Ross,
Page 13 and 14: Ansari et al., (1977b) carried out
Page 15 and 16: Gopalakrishnan and Nair (1998) cond
Page 17 and 18: Major objectives:- 1. To understand
Page 19 and 20: CMFRI (Central Marine Fisheries Res
Page 21 and 22: Joydas, T.V., Damodaran, R., 2001.
Page 23 and 24: monitoring committee (Atlantic Mari
Page 25 and 26: Vizakat Lathika, I-Iarkantra, S. N.
Page 28 and 29: analysed after acidification by tit
Page 30: used as stain prior to sorting and
Page 33 and 34: space. Therefore, it is very essent
Page 36 and 37: Fig. I - Station locations 32
Page 39 and 40: affected at high temperature. Most
Page 41 and 42: layers exhibit different oceanograp
Page 43: Transect wise variation in temperat
Page 46 and 47: 3.2.2.3. Dissolved oxygen (DO) Dist
Page 48 and 49: monsoon temperature initially incre
Page 52 and 53: Naqvi, S. W. A., Noronha, R. J., Re
Page 56: orr Mormugao orr Vernal 35.36 35.32
Page 62 and 63: The continental shelf and its adjoi
Page 64: sediments (4 stations). Silty sand
Page 68 and 69: fine sediments with comparatively h
Page 70 and 71: Narayana, 1991 ). Limited input of
Page 73 and 74: In general. two ditlerent patterns
Page 75 and 76: et al., (1980) reported values in t
Page 77 and 78: organisms living in the water and t
Page 79 and 80: Hashimi, N. H., Kidwai, R. M., Nair
Page 81 and 82: Postma, H., 1967. In Estuaries, Lau
Page 85: Depths Sand Silt Clay Organic matte
Page 90: • PRE'MONSOON SOUTHERN'TRANSECTS
Page 96 and 97: as the best indicators of the envir
Page 99 and 100: showed that northern transects have
Page 101 and 102:
decreased from shallow to deeper de
Page 103:
different depth zones showed that a
Page 106 and 107:
cm 2 with a dominance of nematodes.
Page 108 and 109:
and 6.08 g/m 2 were recorded during
Page 110 and 111:
were located in the nearshore water
Page 112 and 113:
changes in the hydrographical and t
Page 114 and 115:
factor for such a large difference
Page 116 and 117:
Belegvad, H., 1932. Investigations
Page 118 and 119:
Parulekar, A. H., Harkantra, S. N.,
Page 120:
Savich, M. S., 1972. Quantitative d
Page 123 and 124:
Traosects Polychaetes Crustaceans M
Page 125:
Miscellaneous Transects Nematodes C
Page 128 and 129:
Depths Nematodes Cope pods Foramini
Page 136 and 137:
Wagh, 1975; Parulekar et ai, 1976;
Page 138 and 139:
ones and 17 were included in the 'r
Page 140 and 141:
Nephtydae (2%). Among the 20 sedent
Page 143 and 144:
At 75 m zone, 31 groups/species wer
Page 145 and 146:
Porbandar. At 50 m depth zone, fluc
Page 148 and 149:
otTMumbai and Ratnagiri and low eve
Page 150 and 151:
species richness at each depth zone
Page 153 and 154:
E2.2.2.!. Richness (Margalef's inde
Page 155:
I ):.2.2.2.4. Dominance (Pie/ou's i
Page 172 and 173:
Tablc 17. Contd .. - Sternaspidae 0
Page 176:
Table 20. contd .. G. alba 20 25 20
Page 179:
150 Taxa 30m 50m 75m lOOm 150 m m D
Page 186:
9% 1% o poIychaete • crustacea o
Page 203 and 204:
a) c) e) g) Plate 5 a) Prinospio sp
Page 205 and 206:
a) c) e) Plate 7 a) Cardium sp. d)
Page 207 and 208:
7/. /ntroduct ion 7.2. Hydrography
Page 211 and 212:
also showed a similar pattern with
Page 213 and 214:
y most of the organisms. It was als
Page 215 and 216:
with sand of which total density (r
Page 217 and 218:
muddy bottom of the west coast of I
Page 219 and 220:
crustaceans and miscellaneous group
Page 221:
the organic rich environment with h
Page 225 and 226:
Icvci (p
Page 227 and 228:
mcioHmna serve primarily as rapid m
Page 229 and 230:
surface chlorophyll a was 0.36mg I
Page 231 and 232:
Devassy, V. P., Achuthankutty, C. T
Page 233 and 234:
Longhrust, A. R., Pauly, D., 1987.
Page 235 and 236:
Sikora, W. B., 1977. The ecology of
Page 237:
Faunal groups Silty Clayey Mixed Sa
Page 257:
Mannagoa to Porbandar located betwe
Page 260 and 261:
against gastropods during pre- mons
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