Diversity of zooplankton along the northern part of Vembanad lake, Kerala, India

Abstract

Zooplankton samples collected from six stations, along the Kollam Kottappuram waterway (National Waterway 3) on the northern part of Lake Vembanad on monthly intervals during October 2018 to September 2019 formed the basis of this study. The samples were analysed both qualitatively and quantitatively by adopting standard methods. 23 groups of zooplankton were recorded from the study area. Out of these, a maximum of 18 groups were recorded from station 1 (Cochin bar mouth) and a minimum of 9 groups from station 6 (Kottappuram). Overall average density of zooplankton in the study area was 3044 numbers per 100 m3 . Station-wise studies indicated that the average zooplankton density was maximum (4882 per 100 m3 ) at station 2 (Kadamakudy) and minimum (1649 per 100 m3 ) at station 5 (Azhikode bar mouth). Among the different groups of zooplankton in the study area, a maximum of 79% was contributed by copepods, 14% by rotifers while the remaining groups contributed less than 2% each. Month-wise analysis indicated the maximum density during September and the minimum during January. Biodiversity analyses were carried out by Primer v. 6 software. From the cluster analysis and Bray-Curtis similarity matrix, July and August months showed the maximum similarity of species composition compared to all other months.