Impacts of Invasive Species on Hawaiian Freshwater Fishes

Hawaii is the most remote archipelago on earth but it does harbour a small community of native, mainly endemic, freshwater fauna. As the sole refuge for five fishes, two snails one prawn and one shrimp species, Hawaiian freshwater ecosystems are facing a number of human induced stressors that have caused reductions and local extirpations of the native species. There are records of as many as 63 invasive fishes alone in Hawaii; many of which have been Guppiesreleased from the aquarium trade. Some species reach high densities such as cichlids, guppies and armoured catfishes (see images). The effects of invasive fishes on the native ecosystems vary and include predation of the native species, and competition with native species for food and nutrients.

Our research looks to understand the effects of these invasive species on the native species and the stream ecosystems. We test the effects of removing the established Poecoliid and Loricariid populations Banded Jewel Cichlid Punaluu strin Oahu streams. Ecosystem processes and nutrient flows are measured as well we are looking at changes in native species growth, survival and changes in migratory patterns associated with invasive species removals. This ongoing project will help to inform management decision making for the Hawaiian Department of Aquatic Resources.