An Experimental Test of Novel Ecological Communities of Endangered and Invasive Fish

Translocation is frequently used for the preservation of imperiled aquatic species. Due to the scarcity of suitable refuge sites, managers may need to consider innovative management scenarios such as multi-species refuges as novel ecological communities that may even already include undesirable species. To determine the feasibility of such refuges, we established experimental communities that included allopatric and sympatric communities of three fish species; endangered Pahrump poolfish (Empetrichthys latos), Amargosa pupfish (Cyprinodon nevadensis), and invasive mosquitofish (Gambusia affinis). Mosquitofish larval survival was not significantly affected by the presence of other species. By contrast, pupfish persisted in sympatry with both poolfish and mosquitofish, having higher survival in allopatry (557.0 ± 248.2 (mean ± SE)) and in the presence of poolfish (425.3 ± 35.7) compared to poolfish and mosquitofish (242.3 ± 31.9). Mean poolfish larval survival was high in allopatry (123.2 ± 16.6), but significantly reduced in the presence of pupfish (6.6 ± 1.2), in the presence of mosquitofish (1.0 ± 0.5), and a community of all three species (0.5 ± 0.4). This suggests that translocated pupfish may coexist in refuges containing non-native mosquitofish, but poolfish are not compatible with the other species and management of poolfish in single species refuges is appropriate.