Plankton Distribution and Diversity in Selected Freshwater Springs of Kannyakumari, Tamil Nadu, India

Abstract

Freshwater springs are distinctive and sensitive aquatic habitats whose plankton communities remain poorly documented in many mountain regions. This study examined plankton diversity and distribution in six springs of the Kannyakumari District, Tamil Nadu, India, between January and June 2026. Thirty-five plankton species were recorded: one cyanobacterium, 22 protist plankton species, and 12 zooplanktonic fauna. The protist plankton included Chlorophyceae, Bacillariophyceae, Dinophyceae, Chrysophyceae, Cryptophyceae, Xanthophyceae, and Protozoa. Zooplankton belonged to Nematoda and Arthropoda. Station I (Mankuzhy) had the highest richness (16 species), whereas Station VI (North Allanvillai) had the lowest (4 species). Chlorophyceae and Chrysophyceae were the dominant phytoplankton groups, and Arthropoda dominated the zooplankton. Diversity generally peaked during the summer months (April–June). Pollution-indicator taxa such as Microcystis, Spirulina, and Anabaena were absent, suggesting that the spring waters were clean and unpolluted. The results provide baseline information on planktonic community structure in freshwater springs of the Kannyakumari and support the need for conservation of these habitats.