Burrower Gastropod (Gastropoda: Mollusca) and Sediment Grain Size in Intertidal Zone of Alas Purwo National Park, East Java

Abstract The diversity of burrower Gastropod could correlate with its specific niche, including the grain size of sediment. We have investigated the burrower Gastropod population in 9 sites of Alas Purwo National Park, East Java to analyse these Gastropods and the sediment grain size. The plot squares were on 40 cm 2 and 10 cm depth in the line transect were carried out at low tide. Diversity index was determined based on the Shannon’s and Simpson’s indexes by PAST 3.22, redundancy analysis for environment factors and population cluster similarity that analysed by Canoco software for windows 4.5. Granulometry analysis used sieve mesh method on dry sediment. The Gastropod habit of burying oneself begins to simply be covered in sand or mud to a depth of 10 cm. The highest diversity indexes was on Slenggrong beach. We found 11 species and shown 1.8 of Shannon’s index and 5.25 of Simpson’s index. Some species: Conus coronatus , Cypraea annulus and Nerita chamaeleon were found to be still in juvenile. The highest number of species was refer to Nassariidae, which is 12 species. The grain size of sediments between 2.190 - 4.231 phi (fine sand to coarse silt); the sand is overgrown by seagrass ( Cymodocea rotundata ) or not vegetated, especially at sandy beach, muddy beach and the bottom of the estuarine.