Comparison of Freshwater Mollusc Assemblages between Dry and Rainy Season in Situ Gede System, Bogor, Indonesia

Abstract

Anthropogenic activities, which reduced and damaged natural situ (freshwater ponds), also reduced fauna diversity in its aquatic ecosystem. Freshwater molluscs in the situ, one of the largest numbers of animals group with documented extinction, may also be impacted. The aims of this study were to record and to compare the abundance and species composition of freshwater molluscs between dry and rainy season in three situ. The freshwater molluscs were determined by twelve sampling points in Situ Gede (SG), Situ Panjang (SP) and Situ Burung (SB). Samplings were conducted once during dry season (August 2015) and rainy season (February 2016). Total abundance of molluscs encountered was 4321 individuals, which was comprised of 76 bivalve individuals (1.75 %) and 4245 gastropods individuals (98.44%). The abundance of molluscs were generally higher in rainy season than in dry season in all situ, while species richness showed the contrary. The species composition was significantly different between dry and rainy season in SP and SB but no significant differences was found in SG. From eight dominant species, there were six dominant species such as Filopaludina javanica, Melanoides tuberculata, Thiara scabra, Sermyla requeti, Pila scutata (gastropods) and Pilsbryoconcha exilis (bivalve) which were found in high numbers during dry season while two gastropod species (Pomacea canaliculata and Wattebledia crosseana) was numbered higher in rainy season than dry season.