Plankton abundance and diversity north of Lembata Island, Indonesia

Plankton is a pivotal organism of marine ecosystems due to its major role in primary productivity and consumer abundance. Given the important role of plankton as a fishery resource, investigating plankton distribution north of Lembata Island is a high priority, as it is a fishing hotspot for pelagic fish. The abundance and diversity of plankton in the region is investigated in this study. 25 plankton samples were collected from 3 different layers: surface layer, thermocline layer, and deep layer, during the OTEC field campaign with the Indonesian RV GEOMARIN III in 2017. Temperature and salinity were measured using Conductivity Temperature Depth (SeaBird 19+). This study found 45 genera of phytoplankton and 25 genera of zooplankton throughout the water column. Phytoplankton from the diatom class was found in all depths, the dominant genera being Chaetoceros and Thalassionema. The zooplankton genera Globigarinella, Nauplius, and Favella are found in all depths, the most abundant genus being Sagena. Furthermore, phytoplankton abundance decreases with depth, with cell abundance of 45500-8517750 cells m-3 observed in the surface, 901875 cells m-3 in the thermocline, and 257125 cells m-3 in deep water. Zooplankton abundance decreased in the thermocline and increased in the surface layer. Our study suggests that water temperature may have played a dominant role in determining plankton abundance north of Lembata Island during the study period. © 2020, BIOFLUX SRL. All rights reserved.