Louisiana crayfish (Procambarus clarkii) (Crustacea: Cambaridae) in Kenyan ponds: non-target effects of a potential biological control agent for schistosomiasis.

摘要

The Louisiana crayfish (Procambarus clarkii) has been proposed as a biological control agent for the intermediate snail hosts (Bulinus and Biomphalaria spp.) of human schistosomes (Schistosoma haematobium and S. mansoni) in Kenya. Using laboratory and field experiments, the potential non-target effects of Louisiana crayfish introductions on the native aquatic biota of Kenya were investigated. In an 8-week (March-May 1999) laboratory mesocosm experiment, crayfish decreased water clarity and reduced populations of slow-moving, benthic invertebrates including non-target snails, chironomid larvae and oligochaetes. Similar declines in invertebrates occurred in an unreplicated 35-day whole-pond experiment. In addition, water lilies disappeared from the pond into which crayfish were introduced, while water lilies remained abundant in the pond without crayfish. Given the large impacts of crayfish on native invertebrate and macrophyte communities in these experiments, the promotion of this crayfish as a biological control agent should not proceed without additional assessment of the risks posed to native biota, including fishes (which were not addressed in these experiments). If crayfish colonized the large natural lakes of East Africa, globally important freshwater biodiversity resources might be at risk..