Study of Molluscs Diversity as Ecosystem Engineer from Beach of Sungai Bakau Village, Tanah Laut, South Kalimantan

Abstract

Molluscs are engineered biota that play an important role in changing the structure and function of ecosystems, including coastal and mangroves. This study aims to record the diversity of molluscs as a group of engineers in coastal areas in Sungai Bakau Village, Tanah Laut, South Kalimantan. Purposive random sampling method was used to obtain mollusc data at three observation stations (Station 1 : sandy beaches, Station 2 : rocky beaches, and Station 3 : river estuaries). Only one type of bivalve was found (Meretirix meretrix) and 13 types of gastropods (Nassarius Sp., Turricula javana, Cerithidea alata, Polygona angulate, Distorsio decipiens, Latirus pictus, Bursa granularis, Latirus sp., Littorina undulate, Naticarius hebraeus, Murex. elenensis, Neverita didyma, and Turritella terebra). The highest diversity index (1.95) was found at station 1. While the evenness index is 0.755. Similarity index was 92.85% (stations 1-2 and stations 1-3) while at stations 2-3 was 85.71%. The highest density of Cerithidea alata is reached 2,996,700 ind/Ha and the least was Turritella terebra (20,000 ind/Ha). Water parameters between observation stations were close to each other : pH ± 7.6 - 7.7, temperature ± 29.3 - 29.7 0C, and salinity ± 34.9 - 35.4 ppt. The difference between research stations can be seen from sediment content. Station 1 has the highest sand content (96.2%). Station 2 consists of 64.7% sand dust and 20.6% clay. Station 3 has the highest dust content, reaching 84.6%. The types and presence of mollusks (bivalves and gastropods) at each research station is vary in value.