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Abstract:
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Food and feeding habits of fourteen demersal finfishes exploited off the
Karnataka coast were studied to investigate trophic interactions within the
marine food web. Index of Relative Importance (lRI),Ontogenetic, seasonal (pre-monsoon,
monsoon and post-monsoon) variation in feeding and prey-predator
relationship studies were conducted.The results of prey-predator trophic interaction studies identified four
major trophic guilds based on the predators feeding similarity.Trophic guild I is 'copepod and detritus fceders'with an average
group similarity of 61.4%. The second trophic guild, 'prawn and crab
feeders'with an average similarity of 52.7%. 'Acetes feeders', the largest trophic
guild with an average group similarity of 62.5%, composed of six
demersal finfish species.The guild 'piscivores' is
constituted by C. limba/us and P. arsius with an average similarity of
45%.For each predator, ontogenetic diet shift
is common and is characterized by prey of low to high trophic level.Strong
selection of certain prey types was observed in some predators while most
of them avoided abundant prey.In addition to Acetes spp, strong
predation impact was observed for penaeid prawns, epibenthic crabs and
detritus.This information on trophic guilds and prey-predator interactions can be
used to construct trophic model on the benthic ecosystem off Karnataka
and to investigate fishery induced changes as well as predation impact of
different animals on commercially important demersals |