Assessing Migration Ability and Behavior of Small Fish in the Everglades

Grant Winners

Dean

Abstract

The Everglades is a seasonal wetland divided into regions of short and long hydroperiod. In the dry season short hydroperiod regions may dry completely, leaving water only in the deeper long hydroperiod regions. Large, diverse communities of minnow-sized fish live in the short hydroperiod regions during the wet season. These fish actively migrate there, but there is variation in terms of migratory behavior. Some fish undertake active, directed migrations to rapidly exploit new habitat. Others show less ability to migrate efficiently and slowly trickle in to short hydroperiod regions. The first hypothesis that we will test is whether swimming performance differs between good and poor migrators. Morphological, behavioral and physiological adaptations may allow some fish to more quickly exploit temporary wetlands. We will compare fin morphology (using geometric morphometrics) and endurance (via swimming trials in a flume) to determine which traits best equip a fish for long distance migrations. Next, we will perform behavioral assays in a maze to test the hypothesis that bold fish are more likely to explore new habitats. Finally, we will compare the condition (size, health, parasite load) of fish that have undertaken long-distance migrations to short hydroperiod wetlands and compare them with members of the same species that have not made that journey. We expect only the healthiest individuals to have the ability to complete such a migration. This information will be valuable to organizations like South Florida Water Management District because they are responsible for managing water levels across the landscape. Water level is critically important to the establishment of fish communities in short-hydroperiod regions. These fish provide an important food source for wading birds (a major conservation target) and thus, understanding their migration behaviors is fundamental to Everglades protection.