Population genetic structure and spatial scaling are critical parameters for management of animal and plant populations. Population structure is largely the result of dispersal and migration, and is very susceptible to alteration by environmental change. Analysis of genetic markers provides a cost-effective approach to examine landscape-level patterns of animal movement. Population genetic structure reflects patterns of movement, breeding, and genetic interchange by individuals integrated over a number of past generations. Population genetic structure of three aquatic species provide an indication of the effects of water management on animal movement. Species studied (mosquitofish, spotted sunfish, and grass shrimp) were chosen because of ubiquity and having potentially different population responses to hydrological variation.

In small aquatic animals, migration rate and pattern are not easily revealed by direct measures, so indirect techniques must be employed. Direct methods generally involve following the movements of marked individuals. Indirect methods include examination of patterns of genetic diversity and patterns of stable-isotopic markers. Most Everglades aquatic animals are small and mobile, such that direct observation of marked individuals has limited application. Data have been gathered to permit hypothesis testing hypothesis about the effects of levees and canals on animal movement, and on the role of long hydroperiod marshes as aquatic refugia and as a source of colonists for nearby short hydroperiod marshes. Both protein electrophoresis and DNA microsatellite analysis in these studies, as appropriate. Dry conditions in 1999 were used to advantage to sample extensively from animals crowded in dry-season refugia. Research in the remaining project period will focus on larger-bodied species in alligator ponds.

The fact that mosquitofish populations in Water Conservation Area (WCA) 3B were genetically isolated was used in analysis of the Comprehensive Everglades Restoration Plan (CERP) affecting that area. General information on sink/source areas and about fish movements with relation to levees and canals is useful to other CERP related projects such as MODWATERS, C-111 and Everglades Expansion Area work.

This project addresses a number of items identified by the Science Information Needs Report (1996) including: (1) the need to look at the effect of hydropattern on trophic structure and energy flow; (2) the role of compartmentalization of the once-continuous Everglades system; (3) collection of genetic and demographic data to provide estimates of migration rates for parameterizing the Across Trophic Level Systems Simulation (ATLSS) model; and (4) the quantification and modeling of the dynamics of productivity and composition of fish communities across the landscape.

Additionally, this project includes analysis of population migration between short and long hydroperiod marshes indicating the ecological linkage of these habitats. This affects planning of water-management structures and their operation and development of performance measures for habitat connectivity. Future needs include estimates of migration rates and population structure for more types of aquatic organisms, including the direct marking and radio-tagging of larger-bodied fish species. Finally, the Everglades Conceptual models for the Ridge and Slough and Marl Prairie habitats use fishes as key indicators, and we anticipate that they will be selected as a group to be monitored to gauge the progress and success of the CERP.

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(This abstract was taken from the Greater Everglades Ecosystem Restoration (GEER) Open File Report (PDF, 8.7 MB))

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