The status and impact of introduced freshwater animals in Singapore

Abstract

Singapore's location at the centre of major air and shipping routes has resulted in the introduction of numerous species of freshwater animals from various parts of the world. To date, some 37 introduced freshwater fishes, turtles, molluscs and prawns have become established here. Studies show that the introduced species have not significantly affected the fauna in pristine forested streams. This is probably because much of the native freshwater fauna includes acid-water species, whereas introduced ones prefer more neutral and harder waters. Of the 54 native Singapore freshwater fishes, the greater majority (over 80%) are forest species adapted to living in acid waters. These species have suffered mainly because of forest clearance and more than 50% of this fauna is now extinct. A similar situation occurs for freshwater prawns. The conservation of the native freshwater fauna in Singapore should thus centre on the preservation of their natural forest habitat. There is a potential danger posed by imported fishes which originate from soft, acid waters in Africa, South America or other parts of Southeast Asia. Thus far, only one or two species have managed to establish themselves in Singapore. Legislation and appropriate quarantine measures will be needed to ensure that alien tropical acid water species do not become established here. © 1993.