Journal of the Marine Biological Association of India

Spatiotemporal variation in intertidal isopod diversity along the southern Kerala coast: Indicators of coastal ecosystem health under environmental changes

Volume 68 Issue 1

Arya Unni, R. S. Balamurali, A. S. Shibina and S. S. Amrutha

doi:10.6024/jmbai.2026.68.1.SPL.03-07

Abstract

Diverse benthic communities that are essential to coastal resilience are supported by intertidal zones, which are among the most dynamic and climate-sensitive ecosystems. Over the course of two years (2018–2020), this study examines the spatiotemporal diversity and abundance of four intertidal isopod species (Ligia dentipes, Alloniscus perconvexus, Dynamenella lauticauda, and Cirolana bovina) at three coastal sites on the southern Kerala coast: Kovalam, Thirumullavaram, and Varkala. Tidal gradients (high, mid, and low tide) and seasonal intervals (pre-monsoon, monsoon, and post-monsoon) were sampled using stratified quadrats. Community structure was assessed using diversity indices, such as Shannon-Wiener, Simpson’s, Fisher’s Alpha, and Berger-Parker Dominance. With low species richness and strong dominance, Varkala demonstrated biotic impoverishment, whereas Kovalam displayed the greatest diversity and ecological stability. Seasonal trends showed that the best conditions for isopod proliferation occurred after the monsoon, perhaps as a result of better moisture regimes and organic detritus input. These patterns show how sensitive isopod assemblages are to changes in the environment, making them useful bioindicators of the health of intertidal ecosystems. With implications for SDG 14 (Life Below Water) and wetland conservation policies, the findings support climate-responsive biodiversity monitoring. The significance of baseline faunal evaluations in predicting and controlling ecological change along India’s sensitive coastal habitats is highlighted by this study. 

Keywords

Marine isopods, intertidal diversity, bioindicators, climate variability, Kerala coast, ecosystem health

Date : 29-05-2026