Population study on the freshwater shrimps in Nee Soon swamp forest, Singapore.

Abstract

As the only freshwater swamp left in Singapore, Nee Soon Swamp Forest (NSSF) houses a rich biodiversity of the remaining fauna left in Singapore. Using freshwater shrimps as a biological indicator to study ecological changes, Hand Sampling and Trap Sampling were carried out over an 8-week period (February 2013 to March 2013) to survey the biodiversity in the area. First, among the other determining environmental and biological factors present, distribution pattern and diversity scores obtained suggest presence of strong microhabitat preferences in certain shrimp species. Second, changes in rainfall levels might account for the changes in shrimp abundance observed. Third, length-frequency profiles of the shrimps showed a consistent pattern across four cycles, implying absence of short-term seasonal trend. Fourth, male-biased sex ratio of 4.6: 1 obtained for Macrobrachium malayanum suggest that higher fitness in males could be due to competition for females. Lastly, Macrobrachium idae, Macrobrachium neglectum and Caridina gracilirostris are proposed to be locally extinct in NSSF. Hence, by complementing previous studies, this study aims to update the current status of freshwater shrimps in NSSF and to better understand the factors influencing biodiversity of freshwater shrimps. Results obtained may potentially contribute to future conservation efforts in this area.