Volume 27, Issue 80, July - December, 2026

Seasonal Dynamics, Diversity, and Environmental Drivers of Zooplankton Assemblages in the Anicut Dam of a Kangsabati River Ecosystem, Paschim Medinipur, India

Sankar Das¹, Joydev Maity^2♦

¹Department of Fishery Sciences, Vidyasagar University, Midnapore 721102, West Bengal, India
²Associate Professor, Department of Fishery Sciences, Vidyasagar University, Midnapore 721102, West Bengal, India

^♦Corresponding Author
Joydev Maity, Department of Fishery Sciences, Vidyasagar University, Midnapore 721102, West Bengal, India

ABSTRACT

This study was conducted to analyze the composition, diversity, and assemblages of zooplankton, as well as to investigate the environmental influences on them across three seasons at the Anicut dam in Paschim Medinipur. Samples of the zooplanktons were collected during three different seasons from each station, along with the measurements of the environmental factors. Eighteen genera of zooplanktons were noted, including Copepoda (43.88%), Cladocera (30.34%), Rotifera (23.41%), and Amoebozoa (2.35%). Zooplankton density was found to be statistically different (p < 0.05) among the seasons, with the highest value (165.91±10.73 ind.mL-1) recorded in the pre-monsoon and the lowest value (60±3.01 ind.mL-1) in the monsoon seasons. Diversity indices indicated moderate diversity, ecological stability, and habitat suitability, with generally low dominance. Three major clusters were formed from the cluster analysis for the seasons (Pre-monsoon, Monsoon, Post-monsoon), and Major assemblages cluster during post-monsoon and pre-monsoon. In ordination analysis, the results show that pre-monsoon and post-monsoon zooplankton assemblages have similarities compared to monsoon assemblages, which can be seen from their proximal relationship in the ordination plot. Maximum seasonal difference occurred between monsoon and pre- and post-monsoon assemblages. Seasonal fluctuations in flow and turbidity during the monsoon season affected the assemblages of zooplanktons through flushing effect, whereas the steady nature of post-monsoon season helped develop a healthy assemblage of zooplanktons. Examples of zooplanktons that showed strong association with monsoon included Platyias sp., Mytilina sp., Keratella sp., and Chydorus sp. while those showing strong associations with post-monsoon included Daphnia sp., Centropyxis sp., Lecane sp., Asplanchna sp., and Moina sp. On the other hand, Diaptomus sp., Thermocyclops sp., Brachionus sp. and Lepadella sp. were strongly associated with pre-monsoon environmental conditions, hence seasonal differentiation. Environmental variables were statistically different among seasons (p < 0.05).

Keywords: Biodiversity indices, Environmental variables, Seasonal fluctuation.

Species, 2026, 27(80), e19s3297

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Published: 12 August 2026