Exploring Bivalve Community on the Southern Beaches of Bangkalan Madura Regency, Indonesia

The southern beaches of Bangkalan Madura Regency are located in the Madura Strait, near the harbour of Surabaya. The areas have various substrates and mangrove vegetation, rich in invertebrates’ diversity such as bivalve. This study aimed to identify the species, to analyse the diversity, and the importance value index of bivalve, as well as to describe the ecological characteristics on the southern beaches of Bangkalan Madura Regency, Indonesia. The sampling was conducted in the intertidal zone of the southern beaches of Bangkalan, namely Rongkang Beach, Kwanyar Beach, and Modung Beach. The quadrant transect method was applied for the sampling process using 270 plots of 1 x 1 m2, located at upper intertidal, middle intertidal, and lower intertidal of beaches. Furthermore, samples were identified based on morphological characters and diversity was analysed using the Shannon-Wiener diversity index. The importance value index of each species was calculated and the ecological characteristics of the habitat were analysed by using Principal Component Analysis (PCA). The results showed that the South Beach of Bangkalan Madura Regency had 19 bivalve species from 10 families and 7 orders. Bivalve in this area were diverse, with a diversity index of 2.16. The highest importance value index was Solen sp. at 58.87 % followed by Tegillarca granosa at 30.34 %. Additionally, the PCA results showed that substrate pH, water pH, salinity, temperature, sand of substrate, and clay of substrate affected bivalve community. This showed that the southern beaches of Bangkalan were favourable for bivalve habitat.