PS 19-78 - Quantifying the movement and habitat use of native sunfishes in response to seasonal hydrological variation in the Everglades

Tuesday, August 9, 2011
Exhibit Hall 3, Austin Convention Center
Amartya K. Saha , Earth and Environment, Southeastern Environmental Research Center, Florida International University, Miami, FL
M. Brett Gallagher , Environmental Studies, Florida International University, Miami, FL
Amy Narducci , Earth and Environment, Florida International University, Miami, FL
Mac Kobza , South Florida Water Management District
Mark Cook , South Florida Water Management District
Jennifer S. Rehage , Environmental Studies, Florida International University, Miami, FL
Background/Question/Methods

Understanding animal habitat selection and inter-habitat movements plays an important role in population and community ecology. Yet, obtaining a sufficiently high spatiotemporal resolution of the movement paths of organisms remains a major challenge in movement ecology. In this study, we use a combination of tagging and enclosure techniques to gain this high spatiotemporal resolution and examined the movement and habitat use of native centrarchid fishes (warmouth, bluegill, and spotted sunfish), in relation to seasonal variation in environmental conditions, notably hydrology.  We conducted our experiment in an experimental wetland facility at Loxahatchee National Wildlife Refuge in the Everglades. Low frequency Radio Frequency Identification (RFID) technology was used to track the movement and habitat use of fishes individually tagged with 21 mm Passive Integrated Transponder (PIT) tags.  To overcome the sparse recapture rate inherent in tagging studies, we use six replicate 12m by 4 m field in situ enclosures, equipped with an antenna array. Each enclosure spans three key Everglades habitat types: ridge, slough and alligator holes, along an increasing water depth gradient.

Results/Conclusions

Preliminary data from the wet season (July-August) show significant differences amongst species in diurnal patterns of inter-habitat movement and activity levels. Spotted sunfish exhibited the most frequent movements amidst all three species between shallow and deep water habitats. Spotted sunfish activity was predominantly in the daytime, while at the other extreme, warmouth showed more activity during crepuscular hours.  Bluegill activity was intermediate between that of spotted sunfish and warmouth. We found no evidence of a preference for a particular habitat or depth zone, at least in the wet season. These data suggest a degree of temporal partitioning in habitat usage, that may relate to foraging and may differentially influence the susceptibility of these species to avian predation.

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