Population study of freshwater crabs (Crustacea, Decapoda, Brachyura) in Nee Soon Swamp Forest

• Main Author: Tay, Priscilla Shi Yun
• Other Authors: Cai Yixiong
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Science::Biological sciences::Zoology
• Online Access: http://hdl.handle.net/10356/71525
• Institution: Nanyang Technological University

Nee Soon Swamp Forest is the last standing freshwater swamp in Singapore, housing a high diversity of flora and fauna. Parathelphusa maculata, Parathelphusa reticulata and Irmengardia johnsoni are the three primary crab species studied in this research. As the biology of primary freshwater crabs is still poorly understood, an 8- week extensive field survey was carried out at 59 sampling sites to examine the distribution and habitat characterisation of each species. This study noted a 0.21km2 increase in extent of occurrence of P. reticulata, which prefers shaded streams that are narrow and shallow, with a stream bed composing more sand and a thin layer of leaf litter with low dissolved oxygen levels. In contrast, the widespread P. maculata prefers a shallower stream with a high flow rate, acidic water, higher temperatures and low total dissolved solid. While I. johnsoni found only in small pockets inhabits streams with high canopy covers, low pH, width and depth. The difference in sex ratio may be associated with growth, mortality, behavioural etc. Comparison between species found that there would be one crab species more abundant than the other. This study provides a better understanding of the distribution and microhabitat for future studies and conservation efforts.