Growth of Non-Native Rio Grande Cichlids (Herichthys cyanoguftatus) at Different Salinities and in the Presence of Native Bluegill (Lepomis macrochirus)

ABSTRACT

The Rio Grande cichlid (Herichthys cyanoguttatus) is a non-native fish that has become established in the greater New Orleans metropolitan area. We conducted laboratory experiments to determine if H. cyanoguttatus growth was impacted either by salinity or the presence of bluegill (Lepomis macrochirus), a native fish. There was no significant difference in growth of H. cyanoguttatus held at three different salinities (0, 8, and 16 psu) for 14 d. When H. cyanoguttatm and L. macrochirus were held at 0 psu for 28 d both with and without the other species present (n = 6 per trial), there was a significant difference in growth between species. Lepomis macrochirus held on their own grew faster than H. cyanoguttatus on their own and faster than H. cyanoguttatus held with L. macrochirus (p < 0.005). Also, L. macrochirus housed with H. cyanoguttatus grew faster than H. cyanoguttatus on their own and faster than H. cyanoguttatus with L. macrochirus (p < 0.001). A second 28 d trial compared growth of individual H. cyanogutatus and L. macrochirus held together with different relative sizes (half with a largerH. cyanoguttatus as invader [n=7]; half with a smaller H. cyanoguttatus as invader [n=7]). This experiment showed no significant difference in growth between the species (p = 0.064). These results indicate that salinity levels will not limit H. cyanoguttatus dispersal in southeastern Louisiana, while biotic resistance in the form of native L. macrochirus may or may not impact growth of this non-native species.