Impact of invasive fish species

One of the world’s most invasive species is the eastern mosquitofish (Gambusia holbrooki), which is known to displace native amphibian and fish species. Mosquitofish were originally introduced into southern Europe in the 1920s to control mosquito populations.

The project 'The effects of invasive fish on native species' (INVASIVE FISH) investigated the interaction between mosquitofish and the native Iberian species Aphanus iberus. In particular, the factors that influence these interactions and the wider ecological effects were investigated.

This information can be used by conservationists to highlight which individuals of an invasive species should be targeted in management and conservation programmes. It can also be used to identify which individuals of endemic species are in greatest need of protection. Furthermore, these findings add to the growing body of knowledge available to managers and policymakers dealing with the effects of, and potential for, environmental alterations.

INVASIVE FISH also showed that the behaviour of invasive species is affected by exposure to arsenic, and aquatic algae which was thought to reduce the harmful effects of arsenic by absorbing it, may in fact be aggravating the problem. Eutrophication, whereby bodies of water receive excess nutrients, may be influenced by increased aquatic ammonia from fish metabolism. Multidisciplinary, cross-taxon research is thus vital for understanding the impacts of arsenic toxicity, and the differing potential for eutrophication by native and invasive fish species and possible chemical interactions may also be significant.

The INVASIVE FISH project will help elucidate the wider environmental effects of invasive species such as mosquitofish. Data from the initiative will help scientists and policymakers develop effective conservation strategies.