Dietary preference and digestive physiology of plankti-benthivorous fishes inhabiting mudflats of Indian Sundarban estuaries

In this study, the digestive physiology of 12 plankti-benthivorous species as functional analogues from intertidal mudflats of Indian Sundarbans was carried out in order to find out whether diet or phylogeny played a larger role in influencing digestive enzyme activity. Upon analysis of prey preferences, they were categorized into different trophic subgroups. Two dendrograms, one based on prey diversity and other on digestive enzymes of studied fish species were constructed through cluster analysis. These dendrograms were compared again with the phylogenetic tree constructed on the basis of the taxonomic positions. The specific nature of the enzymes in two plankti-detritivorous fishes appeared to possess a specific feeding behaviour and dietary preference though no clear predominance among digestive enzymes was observed. However, regardless of different feeding habits, four gobiid species showed similarity in their overall digestive enzyme patterns and clustered together. Despite mixed results, it can be concluded that digestive enzymes may serve as effective indicators of the feeding ecology of fishes, but the physiological requirements to live in specific trophic guilds may differ among families and therefore, influence of phylogeny on the digestive physiology could not be avoided without understanding the evolutionary specializations for these feeding modes in fishes.