Aquatic Invasive Species

The second most farmed fish in the world, the Nile tilapia has posed a serious threat to the environments in which it has invaded.  Because of its widespread aquaculture, the Nile tilapia can be found worldwide.  Nile tilapia are extremely difficult to manage due to the fact that there are currently no effective biological or chemical methods to controlling this rampant species.  They are known to feed at the base of the food web, which may indirectly force a cascading effect by altering food types at upper food web levels.

Nathaniel Berger of Duke University has proposed a research to determine if Nile tilapia are able to outcompete a certain native species in degraded habitats.  Recent studies have shown that there exists a higher percentage of Nile tilapia in degraded habitats than in pristine habitats.  These observations have prompted scientists to begin studying the effects of the environment on the Nile tilapia population growth.  This has led to the idea that habitat conservation and restoration may be the solution to the Nile tilapia invasion.

Based on a Brazilian study, Berger’s study will involve comparing the Nile tilapia population to the pearl cichlid (Geophagus brasiliensis) population in the Black Creek Cooling Pond.  This location was chosen “because of its significant Nile tilapia population as well as its strong population of cichlids.”  Adults of each species will be marked to establish an easy method of differentiating between the fish.  Using pollution records and ecological assessments of the pond, different locations of the pond will be rated on a scale from one to ten (numbers close to one mean “well preserved” and numbers close to ten mean “highly damaged”).  After this rating process, five distinct locations will be chosen throughout the pond; a 1-2 rated area, a 3-4 rated area, a 5 rated area, a 6-7 rated area, and a 9-10 rated area.  Berger will then compare the Nile tilapia with the competing cichlid species of the area by determining the percentage of the pearl cichlid population to the Nile tilapia population.

According to Berger, this research is important because understanding “Nile tilapia and the environmental characteristics that enable them to outcompete native species” can help prevent future spreads.  Through this research, Berger hopes that future research into the causes of environmental degradation and how it can be prevented will be conducted.  His research will influence habitat conservation and restoration policies and projects to manage this growing Nila tilapia problem.