Integrative Studies of Florida Spring Ecosystems

Science Center Objects

Florida's springs are a source of cultural, recreational, and ecological importance. But land-use changes and increased demands for groundwater due to the state's growing population have led to widespread impairment of these unique ecosystems. 

Integrative Studies of Florida Spring Ecosystems
A variety of tools were used to collect baseline data. 

PROJECT COMPLETED

The Science Issue and Relevance: Florida is famous for its large number of artesian springs and spring-fed rivers of intrinsic natural allure and beauty. These unique ecosystems have significant cultural, recreational, and ecological value. Increasingly, there is widespread impairment of Florida’s springs and spring-fed rivers resulting from land-use changes and increased demand for groundwater resources as the human population of Florida expands. Many springs have experienced substantially decreased discharge in recent years, and nutrients (principally nitrate) and other groundwater contaminants contribute to extensive eutrophication, algal blooms, and greatly diminished water quality. Furthermore, non-native aquatic invasive species are becoming increasingly prevalent in many of Florida’s springs and rivers. Impairment of these fragile ecosystems has shifted them away from historical conditions and threatens their long-term ecological integrity. WARC investigators collaborate with other USGS scientists, Florida state agencies (e.g., St. Johns and Suwannee Water Management Districts, Florida Department of Environmental Protection, Florida Park Service), environmental consultants, and university colleagues to conduct relevant ecological research on Florida springs, spring runs, and spring-fed rivers. Components of this research are to compile baseline biological and hydrologic data to better understand how changes in water quantity and quality affect aquatic communities. Under legislative mandate, the Water Management Districts are required to establish Minimum Flows and Levels (MFL’s); baseline research conducted by WARC scientists and collaborators provide data directly to resource managers as they consider ecological criteria and targets for planning and implementing MFL’s. Further, state agencies conduct Water Resource Value Assessments (WRVA’s) for long-term monitoring and to evaluate the efficacy of MFL benchmarks. Thus, basic ecological data are required in order to understand deviation from historical conditions and to forecast possible community alterations or responses under different management or water-resource use scenarios.

Methodology for Addressing the Issue: Baseline ecological data are obtained by a variety of methods appropriate to faunal groups under study as well as to specific project goals. Additionally, many of Florida’s springs have complex geomorphology and may present unique challenges to studying their faunas. Fishes are typically studied by visual surveys and/or with electrofishing gear, and secondarily using seines or dip nets. Benthic macroinvertebrates are sampled both qualitatively (e.g., 0.5 m D-frame dip net) and quantitatively (e.g. petite ponar grab). Typical community metrics are used to characterize communities (e.g., Shannon-Wiener Diversity Index, Pielou’s Evenness). Multivariate methods (e.g., Principal Components Analysis, Nonmetric Multidimensional Scaling) are applied to data representing multiple combinations of spring communities to understand general patterns of assemblage composition, and associations between species occurrences and abundance, distribution, hydrology, and water-chemistry.

Integrative Studies of Florida Spring Ecosystems
Florida is well-known for its unique springs ecosystems.

Future Steps: Many springs in Florida have received very little ecological study, and basic surveys and characterization of aquatic communities would provide valuable information about current conditions. Even for springs that have received extensive study, there are many unanswered questions about ecological processes and limited understanding about species or community responses to further alterations in hydrology or water quality. For example, it has been demonstrated that shifts from macrophyte-dominated systems to algae-dominated systems have profound impacts to benthic macroinvertebrate communities, but the mechanisms underlying these community-level shifts are inadequately understood. Another example is that, although lethal effects of nitrates on various organisms (e.g., insects, amphibians) have been examined, very little is known about sublethal effects (e.g., physiological condition, reproduction, growth).