Diversity and distribution of arrow worms, zooplankton along the Mangaluru and Udupi Coast, Karnataka

Abstract

The present study was done to understand the abundance and species diversity of arrow worms, zooplankton in relation with hydrographical parameters and the spatial and temporal variations for a period of 16 months from October 2020 to March 2022. Monthly sampling was carried out at selected stations of coastal waters with average depth of 8m. The qualitative analyses revealed the presence of seventeen different groups of zooplankton. copepods, cladocerans are dominant group in zooplankton followed by chaetognaths, during the study period seven species of chaetognaths recorded viz, Sagitta enflata, Sagitta robusta, Sagitta bedotii, Sagitta bipunctata, Sagitta ferox, Sagitta planktonis, and Sagitta elegans. Among them, Sagitta enflata was the dominant species followed by S.bedotii and S. robusta. The richness, evenness and diversity of chaetognaths varied in the different stations and the maximum and minimum values also varied between stations, but in the most of the stations the minimum values were observed in the post-monsoon season and the highest values ranged between January to March. On comparison of the present abundance of chaetognaths with previous study, it was observed that the density of chaetognaths decreased compared to previous studies.