Carp (Cyprinus carpio) Ecosystem Impacts: Carp (Cyprinus carpio) Invasion and Impacts acrossFreshwater Landscapes: An Australian Perspective

Carp (Cyprinus carpio) are alien fish typically associated with degraded freshwater ecosystems. This study explored local impacts of carp and landscape patterns in carp distribution to develop conceptual models of ecological impact by carp. Field experimentation showed that carp impacts are more carp size-dependent than previously described (eg in determining total algal biomass). Additionally, patterns of carp distribution, biomass density and recruitment were explored among the rivers of New South Wales (Australia) in relation to their physical habitat. The populations with a size structure and biomass density most likely to cause ecological degradation occurred at altitudes from 200 to 500 m. Furthermore, the regulation of river flows does not always favour carp recruitment, especially during drought. Nevertheless, invasion by alien carp in Australia and elsewhere in the world is most successful in streams with formerly highly variable flows that are now subject to flow regulation. Furthermore, carp often enhance their advantage in these waters through habitat modification.