Diversity and Distribution of Molluscs in the Intertidal Zone of Nglambor Beach, Gunung Kidul, Yogyakarta

The intertidal zone is the area between the highest and lowest tides, which represents the transition from ocean conditions to land conditions. This study aimed to determine the diversity and distribution of mollusks that exist along the intertidal zone of Nglambor Beach, between August and November 2020. Observations of all molluscs were carried out at two random stations using 10 plots measuring 1 x 1 m 2 with 5 meters. A total of two classes of Mollusca (Gastropod and Bivalvia) belonging to twelve families and 19 species were found from upper to lower an intertidal zone. The upper intertidal zone was recorded to have the highest diversity and an evenness index (Shannon-Wiener diversity index: H ’= 2.524 and Pielou evenness index: J’ = 0.932) compared to the middle and lower zones. It can be concluding that the diversity index in the study location is categorized as medium and its evenness is high. Thais hippocastanum is the most dominant species found in the upper and middle zones, while Thais tissoti dominates in the lower zone. This research contributed to a preliminary checklist on molluscs, which will support a baseline study on the intertidal in future