Invasive species in water-dependent ecosystems

Alien invasive species may cause as much havoc in water-dependent ecosystems, such as wetlands, lakes and rivers, as they do in terrestrial systems. In the aquatic medium they are more diffi cult to detect and eradicate or even to control and there needs to be special effort to avoid such invasions from both alien species and genotypes. This paper describes some of the pathways and impacts of alien and other invasive species in aquatic situations and suggests that the intentional introduction of any species to a new environment should be preceded by a rigorous risk assessment process. The proposed introduction of modifi ed Oreochromis niloticus (such as the GIFT strain which is now an alien genotype in Africa) is discussed in this light with examples of the impacts of introductions of this species in other places. It concludes with a plea that risk assessment must be taken extremely seriously for re-introduction in Africa.


Howard, G.W. (2004)
Use of genetically improved and alien species for aquaculture and conservation of aquatic biodiversity in Africa