Planktonic Communities and Trophic Interactions in the Kavaratti Waters, Lakshadweep Archipelago, India

Abstract

The complex relationships among marine planktonic trophic levels are not yet well understood, despite the importance of the plankton community in the global carbon cycle and its role as a food source for commercial fisheries. In this study, phytoplankton and zooplankton samples were collected and identified from the oligotrophic Kavaratti waters. Within the phytoplankton community, siliceous diatoms and dinoflagellates responded differently with environmental variations. Differential responses by different trophic interactions were also found with both phyto- and zooplankton com- munities. Low abundance of microzooplankton and along with the concomitant occurrence of low mesozooplankton in the Lakshadweep suggests that there could be a general lack of planktonic grazers. This would result in a weak transfer of pri- mary and bacterial carbon to higher trophic levels, eventually leaving behind much unconsumed basic food in the stations like light house and helipad. Tracking changes in planktonic biodiversity and their trophic interactions over time will help for the assessment of potential fisheries. The study provides baseline information on the productivity, pigment concentration and plankton community structure and their trophic state with respect to marine food web, which could give new insight to the future ecological assessment of Kavaratti waters.