The fiddler crabs, being a dominant intertidal macrobenthic faunal components’ contribute significantly to ecosystem functioning by their repeated burrowing and re-burrowing activities which enhance the aeration of soil, reshuffle textural components of different layers of sediments and promote nutrient recycling. These biogenic processes collectively termed as ‘bioturbation’, is the disturbance of sediment layers, act as major modulators of microbial activities and accelerate biogeochemical processes in the land-water interface. The present paper has attempted to study the structural diversity of different biogenic structures formed by 3 species of fiddler crabs in the temporal and spatial scales and also to assess their functional roles towards bio-geo-physico-chemical cycling in the ecosystem by virtue of their survival strategies vis-à-vis feeding, territory protection, aggression, female attraction, courtship signaling etc. in the coastal belts of Midnapore (East), WestBengal, India. The fiddler crab species, the Uca acuta acuta exhibited maximum bioturbatory activities followed by U. lactea annulipes and U. triangularis bengali mostly during premonsoon at high-tide-level. Statistical analyses such as ANOVA, Duncan Tests have been computed to establish the level of significance of variabilities among different tidal levels in the studied intertidal belts in different seasons of two consecutive years.

Biogenic structure, nutrient cycling, survival strategy, fiddler crabs, coastal belt.