THE STATUS AND IMPACT OF INTRODUCED FRESH-WATER ANIMALS IN SINGAPORE

Singapore's location at the centre of major air and shipping routes ha s resulted in the introduction of numerous species of freshwater anima ls from various parts of the world. To date, some 37 introduced freshw ater fishes, turtles, molluscs and prawns have become established here . Studies show that the introduced species have not significantly affe cted the fauna in pristine forested streams. This is probably because much of the native freshwater fauna includes acid-water species, where as introduced ones prefer more neutral and harder waters. Of the 54 na tive Singapore freshwater fishes, the greater majority (over 80%) are forest species adapted to living in acid waters. These species have su ffered mainly because of forest clearance and more than 50% of this fa una is now exctinct. A similar situation occurs for freshwater prawns. The conservation of the native freshwater fauna in Singapore should t hus centre on the preservation of their natural forest habitat. There is a potential danger posed by imported fishes which originate from so ft, acid waters in Africa, South America or other parts of Southeast A sia. Thus far, only one or two species have managed to establish thems elves in Singapore. Legislation and appropriate quarantine measures wi ll be needed to ensure that alien tropical acid water species do not b ecome established here.