Assessing Migration Ability and Behavior of Small Fish in the Everglades

Background/Question/Methods

Small fish are important to the Everglades as a food source for wading birds. Fish migrate to and from wetlands that dry annually, where predation is greatest. It is unclear what factors induce this migration. Our goals are to understand what influences migration, including the fishes’ personality and parasite infection. Our hypotheses test whether personality and parasite load differ among species, by region, or between the dry and wet seasons. We sampled the fish communities at sites that dry annually and sites that do not to identify relative abundances. The most abundant fishes were brought to the lab where we filmed them in artificial habitats to quantify behaviors related to migration and exploration. Fish were dissected to identify parasites. Some parasites may lower fitness, reducing migratory ability. Others alter behavior increasing vulnerability to predators.

Results/Conclusions

Mosquitofish were dominant at all sites, followed by Bluefin killifish. Golden topminnows were more abundant in the long hydroperiod sites. Sailfin mollies were more abundant in short hydroperiod sites that dry annually. Mosquitofish were the boldest and most likely to migrate. They spent the shortest time spent hiding, they swam the greatest distances and explored the greatest proportion of the environment. Golden topminnows were less bold and less willing to explore. This explains their low abundance in sites that dry. During times of the year when water levels fell, Sailfin mollies explored more, likely increasing likelihood of escaping dry-downs in the field. The majority of all species were parasitized, some heavily. Some of the parasites were from groups known to modify host behavior. Our results support our hypotheses that behaviors related to migration vary among species, regions and seasons. This data can assist in Everglades restoration and support species of interest, like wading birds.