Throughout the world, freshwater ecosystems are considered to be among the most vulnerable systems. In the isolated Pacific islands there are a relatively small number of native freshwater species, which are mainly endemic to these locations (found nowhere else in the world). These species are characterized by an amphidromous lifecycle; reproducing in the stream, with larvae drifting to the ocean and eventually returning to a stream as juveniles and spending the remainder of their lifecycle there. Throughout the region, native flora and fauna face significant threats from species...