DIVERSITY AND ABUNDANCE OF GASTROPODS IN THE INTERTIDAL ZONE OF WATUKARUNG, INDONESIA

We present the density, diversity, and environmental conditions of gastropods in the Watukarung intertidal zone ? a coastal region of Pacitan Regency, Indonesia, adjoining the Indian Ocean. Gastropods play an important role in coastal ecosystems. In Watukarung, the local people collect marine organisms, including gastropods during low tide to supplement their income. Baseline information on the presence and abundance of gastropods in Watukarung are not available. Our survey collected 173 individuals of gastropod in the intertidal area of Watukarung that represent 8 families, 9 genera, and 13 species. Gastropod diversity index (H') in the three beaches (Ngalorombo, Pasir Putih, and Kasap) show varying values from the categories of low and medium species diversity. Although the data suggest that there should be a dominant species in the ecosystem (E < 0.5), there are no strong dominance species in the community (C < 0.5). Watukarung coastal waters are still in good condition for marine organisms with salinity > 31‰, DO > 8.1 mg/L, and pH > 8. The substrate is dominated by coarse sand. The total organic matter is relatively low (< 2.6%) due to characteristics of the substrate that is dominated by a rocky and sandy substrate. Based on the results, we suggest that Kasap beach can be established as a core zone considering its high diversity and density of gastropods as well as being distant from any residential area, whereas Ngalorombo and Pasir Putih beaches are suitable as usage zones for surfing tourism. We highlight the need for the local community, government, and private sector need to work together to encourage sustainably tourism while reducing environmental impacts in Watukarung.