Abstrak
Mangrove forests are unique coastal ecosystems found in tropical regions such as Indonesia. Gastropods and bivalves, mollusks with or without shells, are commonly found in mangrove ecosystems, living on or within substrates and attaching to mangrove roots. This study aimed to examine the community structure of mollusks in the Mangrove and Proboscis Monkey Conservation Area (MPMCA) in Tarakan. A quantitative descriptive and survey-based method was used. Fieldwork (in situ) was conducted to identify the composition and abundance of mollusks in the conservation zone. The findings revealed the presence of the Mollusca phylum, consisting of two classes, gastropods with 811 individuals (96.20%) and bivalves with 32 individuals (3.80%). Gastropod abundance was dominated by Nerita sp. (44.0%), followed by Bythinia (25.2%) and Telescopium (23.6%). A single species represented bivalves, Gelonia sp. (kapah clam). The Shannon-Wiener diversity index was very low (H0.1618), indicating low diversity, while the dominance index was high for gastropods (D0.0588) and bivalves (D-0.1582), reflecting an imbalanced mollusk community structure. A rise in gastropod numbers from 749 individuals in 2021 to 811 in 2025 suggests improving the mangrove ecosystem quality in the KKMB Tarakan City.