Study of intertidal molluscan diversity of the Dakshina Kannada coast, India using remote sensing and GIS techniques

The intertidal fauna of the Dakshina Kannada coast, Karnataka, India, are facing a threat due to several factors. In the present study, we delineate various changes in the selected intertidal habitats along the coastline of the Dakshina Kannada district, to correlate these changes with the diversity of molluscs in the intertidal zones. The study also aims at understanding the threat faced by molluscs due to various factors. This study was carried out from November 2016 to September 2017. Mapping of the coastline of Dakshina Kannada was done using topographical maps and Indian Remote Sensing Satellite imageries (IRS-Resourcesat 1-LISS-III). Satellite data were processed using ERDAS IMAGINE 9.1 software and various land-use/land-cover classes were analysed using ArcGIS 10.1. The resulting coastal maps were used to estimate the geomorphological changes and shifting of the shoreline position due to erosion and accretion. Shoreline changes were correlated to diversity changes within intertidal mollusc communities. The study revealed the abundance of molluscs at the intertidal zone of Sasihithlu and species richness at Someshwar and Panambur during post-monsoon. Significant correlation was observed between water temperature and diversity of molluscs, indicating that water temperature is the important physico-chemical parameter responsible for the change in molluscan diversity of the Dakshina Kannada coast. The variation in land-use/land-cover during the study period was analysed. The coastline has been threatened by different land-use patterns such as urbanization, industrialization, developmental activities, erosion and accretion. The changes occurring along the coastline during this study due to industrialization and anthropogenic factors have been discussed, which help in the implementation of conservation measures and protect the sensitive habitats of the shelled organisms.