ScholarWorks@UNO

Behavioral and reproductive effects of invasive juvenile cichlids (Herichthys cyanoguttatus) on a native species, Heterandria formosa.

Behavioral and reproductive effects of invasive juvenile cichlids (Herichthys cyanoguttatus) on a native species, Heterandria formosa / / Manalle Al-Salamah (malsalam @uno.edu), Dr. Tom Lorenz (olorenz@uno.edu), Sierra Riccobono (sriccobo@uno.edu). / / After Hurricane Katrina, small fishes such as the least killifish (Heterandria formosa) declined or even disappeared from parts of City Park in New Orleans. At the same time, Rio Grande cichlids (Herichthys cyanoguttatus) increased in these exact same areas. It is possible that the presence of this invasive species is causing the rapid decline of H. formosa and many other native poeciliids . This could be due to the direct consumption of H. formosa by adult H. cyanoguttatus, or due to stresses imposed on H. formosa by H. cyanoguttatus . To determine this, we observed interactions between juvenile H. cyanoguttatus and adult H. formosa. In addition to H. cyanoguttatus, a native species was also allowed to interact with H. formosa as an alternative form of a control. Heterandria formosa were kept either by themselves, with G.affinis, or with H.cyanoguttatus. Growth, reproduction, and behavioral interactions during feeding were all measured over several weeks. Preliminary analysis of weight in H. formosa shows that there is no significant difference in weight gain of H. formosa between treatments. However, preliminary analysis of the video recordings as well as the number of fry counted in each treatment suggest that H. formosa might be stressed enough to delay the birth of their fry until such a time when the cichlids are no longer a threat. This could have a long term negative effect on recruitment of this species in the presence of H. cyanoguttatus. /