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live at or near the bottom. Many Benthic organisms have the power to swim and can change their position, while some livc wholly or partially buried in the sediment and have limited ability to move around. They collectively form benthos or bottom communities. Benthos (both moving and sessile forms) represents a major component of the marine ecosystem and plays a vital role in the transfer of energy through food chain in the sea. Demersal fishes, crustaceans, molluscs, worms, echinoderms etc. are the larger forms coming under first category (moving forms). Sessile organisms are those, which stay at one place either fixed to the substrata or anchored at a suitable site. Corals, barnacles, encrusting sponges, anemones and seaweeds are sedentary in nature and belong to this group. However it must be noted that the distinction between pelagic and benthic is purely ecological and arbitrary as certain molluscs and crustaceans, living close to the bottom can adopt temporarily a pclagic mode of life. Larval forms of these organisms spent part of their life in the pelagic realm and are referred to as meroplankton. Three functional groups of benthos could be recognized namely the infauna, epibenthic fauna and hyper benthic fauna i.e., organisms living within the substratum, on the surface of the substratum and just above it, respectively (Pohle and Thomas, 2001). The infauna is much more restricted than the epifauna and only one-fourth as rich in species as the epifauna. The epifauna is represented by a maximum number of species in the tropical regions and they show decrease in number of species towards the poles. Based on the habitat, benthic organisms could be divided into two major groups namely soft-bottom benthos, and hard-bottom benthos. Depending upon the size, all large organisms retained by O.5mm (500J.l) sieve are generally referred to as macrobenthos; organisms which pass through a sieve of O.5mm but retained by 63J.l sieve are known as meiobenthos and those which pass through 63 J.l sieve are known as microbenthos. The dominant groups of organisms that constitute the macrobenthos are the sublittoral soft bottom inhabitants belonging to 4 major taxonomic groups polychaetes, crustaceans, molluscs and echinodenns. Among these, polychaete
wonns are the most abundant group and represented by numerous tube dwelling and burrowing species. Among meiobenthos, nematodes and foraminifers are the predominant ones. Other meiobenthic t'onns include harpacticoid copepods, ostracods, isopods, cumaceans, coelenterates, turbellarians and juveniles of larger invertebrates, gastrotrichs, kinorhynchs and tardigrades. The microbenthos include bacteria, protozoa, yeasts, fungi, diatoms, dinoflagellates, blue-green algae, euglenoids, crypomonads etc. (Mare, 1942). This distinction of benthos into three size categories is rather arbitrary and it has no biological significance and varies according to the researchers and also on the pore size of the sieve used. Demersal fishes, which browse and burry themselves in the sediment surface, are grouped as megafauna. All feeding types from selective feeders to carnivores and omnivores are represented in this group. Based on their trophic status benthos are classified as phytobenthos which are represented by plants and algae seen on the sea floor and zoobenthos which include all consumers. Of all the marine animals, a great many live on finn substrate, good numbers occur on sandy or muddy bottoms and a small percentage remains planktonic throughout their life. Benthic f'onns develop chitinous exoskeleton, calcareous shells and several other adaptations in the fonn of appendages and body musculature, enable them to live, move and propagate into the sediments or substrata they select to live. Animal representatives of most of the phyla are generally found in benthos, but a particular habitat is characterised by a few dominant species. 1.3. Importance of benthos Estimation of benthic abundance is necessary for the assessment of demersal fishery resources, as the benthos fonn an important source of food for demersal fishes (Longhrust, 1958, Harkantra et al., 1980). According to Spark (1935) the average weight and number of benthic organisms have a correlation with primary production in the water column, climatic factors and also with demersal fish
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 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 50 and 51: opined that limited mixing. high or
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
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a) c) e) g) Plate 5 a) Prinospio sp
Page 205 and 206:
a) c) e) Plate 7 a) Cardium sp. d)
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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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