| dc.description.abstract | Diatom communities are influenced by environmental perturbations, such as the monsoon system that impact the niche opportunities of species. To discern the influence of the monsoon system on diatom community structure, we sampled during two consecutive post-monsoons (2001 and 2002) and the intervening pre-monsoon at Mumbai and Jawaharlal Nehru ports along the central west coast of India. Characteristic temporal shifts in diatom community structure were observed across the sampling periods; these were mainly driven by temperature, salinity and dissolved oxygen saturation. The nutrient-poor pre-monsoon period supported low abundance yet high species richness and diversity of diatoms. Coscinodiscus, Cyclotella, Thalassiosira, Triceratium, Pleurosigma, Skeletonema and Surirella were the most dominant genera. Both the post-monsoon periods, following dissimilar monsoon events, were dominated by Skeletonema costatum, but differed in some of the residual species. Thalassiosira and Thalassionema spp. dominated mostly during post-monsoon 1st whereas Triceratium and Pleurosigma spp. dominated during post-monsoon 2nd. To understand the underlying ecological mechanisms involved in such dynamics, we focus on the dominant diatom species in post-monsoon periods, S. costatum, that contributes upto 60% to total diatom cellnumbers. This research is relevant in light of the fluctuating monsoon regimes over the Asian continent, the confounding effects of anthropogenic eutrophication and the resulting cascading effects on trophic web dynamics | |
