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OFR 2006-1107


Prepared in cooperation with
St. Johns River Water Management District

2006


Characterization of the Hydrology, Water Chemistry, and Aquatic Communities of Selected Springs in the St. Johns River Water Management District, Florida, 2004

G.G. Phelps, S.J. Walsh, R.M. Gerwig, and W.B. Tate



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CONTENTS
Abstract
Introduction
      Purpose and Scope
      Previous Studies
      Acknowledgments
      Site-Numbering System
      Environmental Setting
Methods
      Hydrologic and Water-Chemistry Data
      Aquatic Community Data
Characterization of Springs
      Silver Springs
            Hydrology and Water Chemistry
            Aquatic Communities
      De Leon Spring
            Hydrology and Water Chemistry
            Aquatic Communities
      Gemini Springs
            Hydrology and Water Chemistry
            Aquatic Communities
      Green Spring
            Hydrology and Water Chemistry
            Aquatic Communities
Comparisons among Springs
      Hydrology and Water Chemistry
     Aquatic Communities
Summary
Selected References
Appendix A. Water-Chemistry Data, 2004
Appendix B. Compounds Commonly Detected in Wastewater
Appendix C. Pesticides Analyzed
Appendix D. Macroinvertebrate Taxa Reported in this Study
Appendix E. Scientific Names, Authorities and Dates of Original Descriptions,
  and Common Names of Fishes Reported in this Study

Abstract

   The hydrology, water chemistry, and aquatic communities of Silver Springs, De Leon Spring, Gemini Springs, and Green Spring in the St. Johns River Water Management District, Florida, were studied in 2004 to provide a better understanding of each spring and to compile data of potential use in future water-management decisions. Ground water that discharges from these and other north-central Florida springs originates from the Upper Floridan aquifer of the Floridan aquifer system, a karstic limestone aquifer that extends throughout most of the State’s peninsula. This report summarizes data about flow, water chemistry, and aquatic communities, including benthic invertebrates, fishes, algae, and aquatic macrophytes collected by the U.S. Geological Survey, the St. Johns River Water Management District, and the Florida Department of Environmental Protection during 2004, as well as some previously collected data.

   Differences in water chemistry among these springs reflect local differences in water chemistry in the Upper Floridan aquifer. The three major springs sampled at the Silver Springs group (the Main Spring, Blue Grotto, and the Abyss) have similar proportions of cations and anions but vary in nitrate and dissolved oxygen concentrations. Water from Gemini Springs and Green Spring has higher proportions of sodium and chloride than the Silver Springs group. Water from De Leon Spring also has higher proportions of sodium and chloride than the Silver Springs group but lower proportions of calcium and bicarbonate. Nitrate concentrations have increased over the period of record at all of the springs except Green Spring. Compounds commonly found in wastewater were found in all the springs sampled. The most commonly detected compound was the insect repellant N,N’-diethyl-methyl-toluamide (DEET), which was found in all the springs sampled except De Leon Spring. The pesticide atrazine and its degradate 2-chloro-4-isopropylamino-6-amino-s-triazine (CIAT) were detected in water from the Silver Springs group and in both boils at Gemini Springs. No pesticides were detected in water samples from De Leon Spring and Green Spring. Evidence of denitrification was indicated by the presence of excess nitrogen gas in water samples from most of the springs.

   Aquatic communities varied among the springs. Large floating mats of cyanobacteria (blue-green algae), identified as Lyngbya wollei, were observed in De Leon Spring during all sampling events in 2004. At Gemini Springs, the dominant periphyton was Rhizoclonium sp. Of the three springs sampled for benthic invertebrates, De Leon Spring had the highest overall species richness and most disturbance intolerant species (Florida Index = 4). Green Spring had the lowest species richness of the springs sampled. Based on qualitative comparisons, overall macroinvertebrate species richness seemed to be negatively related to magnesium, potassium, sodium, and specific conductance. Invertebrate abundance was greatest when dissolved oxygen and nitrate were high but phosphorus and potassium concentrations were low. Dipteran abundance seemed to be positively associated with specific conductance and total organic carbon but negatively associated with nitrate-N. Amphipods were the numerically dominant group collected in most (six of nine) collections. Shifts in amphipod abundance of the two species collected (Gammarus sp. and Hyalella azteca) varied by season among the three springs, but there were no trends evident in the variation. Fish populations were relatively species-rich at the Silver Springs group, De Leon Spring, and Gemini Springs, but not at Green Spring. Nonindigenous fish species were observed at all springs except Green Spring.


Suggested Citation:

Phelps, G.G., Walsh, S.J., Gerwig, R.M., and Tate, W.B., 2006, Characterization of the Hydrology, Water Chemistry, and Aquatic Communities of Selected Springs in the St. Johns River Water Management District, Florida, 2004: U.S. Geological Survey Open-File Report 2006-1107, 51 p.

For additional information, contact:

U.S. Department of the Interior
U.S. Geological Survey
12703 Research Parkway
Orlando, FL 32826
407-803-5531

kroening@usgs.gov

swalsh@usgs.gov



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