Distribution of meiofauna in the sublittoral sediments of the tropical island ecosystem, off Port Blair, Andaman Sea

Abstract

Meiofaunal studies from offshore sediments of the Andaman Sea were conducted during the South-West Monsoon Season (SWMS), North-East Monsoon Season (NEMS) and Non-Rainy Season (NRS) of the year 2019. The study focussed on identifying the meiofauna and its distribution from the sub-littoral sediments of South Andaman Islands. Altogether ten meiofaunal groups viz., foraminifera, nematodes, copepods, pteropods, diatoms, polychaetes, kinorhyncha, ostracods, halacarids and gastrotricha were reported in the present study. Foraminifera dominated throughout the study period (24 %), followed by nematodes (22 %), while gastrotrichs (0.94 %) were found to be the least abundant group. NEMS was observed to have the highest meiofaunal density among all three seasons. Cluster analysis represented foraminifera and nematodes as a single cluster with the highest similarity percentage (97 %). Shannon-Weiner diversity index was highest in North Bay during Non-Rainy Season (NBNRS) and lowest in Corbyn’s Cove during South-West Monsoon Season (CCSWMS). Principal Component Analysis (PCA) results indicated that sediment composition, Dissolved Oxygen (DO) and Organic Carbon (OC) content were the most important factors influencing the meiofaunal distribution in these areas. The study revealed marked differences in the meiofaunal population dynamics compared to the mainland India and have also reported additional meiofaunal groups from the studied regions.