Spatio-temporal variation in mangrove crab diversity in five estuaries of Kerala, India

The present study investigated the community structure and faunal composition of mangrove crab assemblage of five estuaries in Kerala. Mangrove crabs were collected from different estuaries namely Puthuvype, Ayiramthengu, Dhalavapuram, Pullichira and Kottaramthuruth from January 2015 to December 2015. The numerical abundance was directly enumerated by handpicking crabs from the estuarial mangrove region from 100×100 cm quadrats from the estuarine mangrove regions. Thirteen brachyuran crab species were identified across the five estuaries, along with environmental and sedimentological parameters. Various diversity indices were calculated for spatial temporal comparisons. The study revealed that four of the estuaries exhibited similar crab species diversity, while Pullichira differed, displaying the lowest diversity due to habitat characteristics such as small islands or sand dunes and shallow depth. The calculated indices for species diversity, richness, dominance, evenness, taxonomic and phylogenetic relationships provide insights into the spatio-temporal variations of mangrove crab diversity. This study serves as a benchmark reference for future studies in these estuaries, and further monitoring and assessment of mangrove ecosystem health could support the development of ecosystem-based management strategies for deteriorating mangrove ecosystems.