Benthic biodiversity assessment in epipelic and epissamic habitats of Tapi Estuary, Surat, Gujarat

Epipelic and epipsammic benthic habitats play a critical role in estuarine ecosystem functioning by regulating nutrient cycling, stabilizing sediments, and supporting primary production. However, these habitats remain poorly studied in Indian estuaries, particularly in the Tapi Estuary, despite increasing anthropogenic pressures. The present study aimed to evaluate the benthic biodiversity of epipelic and epipsammic habitats in the Tapi Estuary and to assess their ecological significance in relation to environmental and seasonal variations. Quarterly sampling was conducted at selected reference and impacted locations within the Tapi Estuary during post-monsoon, winter, and summer seasons. Sediment samples were analyzed for biological parameters, focusing on algal communities and meio- to macrofaunal assemblages. Habitat characteristics and species–environment relationships were examined to identify key regulatory factors influencing community structure. The study revealed distinct spatial and seasonal variations in benthic assemblages. Periphyton density ranged from [89–6336 units/m2 in Epipelic region and 96 – 2458 units/m2 in Epissamic region, while meiofaunal (Zoobenthic) abundance varied between 52 – 550 Number/m2 in Epipelic region and 25 – 284 Number/m2 in Epissamic region across seasons. Impacted locations exhibited reduced diversity and dominance of pollution-tolerant taxa, indicating stress from industrial and domestic effluents. This study represents one of the first integrated assessments of epipelic and epipsammic biodiversity in the Tapi Estuary. The findings highlight the potential of benthic communities as sensitive indicators of water quality and ecosystem health, providing valuable baseline data for estuarine monitoring, management, and conservation under escalating anthropogenic influence.