Effect of habitat attributes on the abundance of Sargassum’s epifauna and the feeding habit of an amphipod epifauna from the coast of Western India

The Sargassum bed along the rocky intertidal region is highly productive and serves as a habitat for numerous associated species. In this study, the effect of habitat attributes (algal morphology) on the abundance and diversity of epifauna in Sargassum tenerrimum was investigated. Qualitative and quantitative analysis showed that the overall species diversity was high, and Hyale nuda, Gammaropsis sp. and Modiolus adriaticus were the most abundant epifaunal species observed. The abundance of epifauna varied significantly with time. Compared to pre-monsoon months (February to May), post-monsoon (October to January) had a greater diversity of S. tenerrimum associated epifauna. The diversity was particularly high in the month of November. Epifauna showed a positive correlation with the characteristic of algal morphology, indicating its influence on abundance and diversity. Hyale nuda being the most ubiquitous and abundant epifauna observed, the biotic interaction between S. tenerrimum and H. nuda was studied further. Close examination of the gut contents of H. nuda revealed that they graze and consume the epiphytic microalgae of S. tenerrimum, instead of the macroalgal fronds. This suggests that through this relationship, epibiosis in Sargassum may remain in control, while the amphipod derives food, shelter and protection from the predators.