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FFFeeebbbrrruuuaaarrryyy 222666,,, 222000111000 Final Report AAAnnn EEEcccooosssyyysssttteeemmm---LLLeeevvveeelll SSStttuuudddyyy ooofff FFFlllooorrriidddaaa’’’sss SSSppprrriiinnngggsss FWC Project Agreement No. 08010 Prepared for Florida Fish and Wildlife Conservation Commission St. Johns River Water Management District Southwest Florida Water Management District Florida Park Service Florida Springs Initiative Three Rivers Trust, Inc. Prepared by Wetland Solutions, Inc. February 26, 2010 WETLAND SOLUTIONS, INC. This report is funded in part by the Florida Fish and Wildlife Conservation Commission (FWC) through FWC Agreement Number 08010. The views expressed herein are those of the authors and do not necessarily reflect the views of the State of Florida, Fish and Wildlife Conservation Commission. WETLAND SOLUTIONS, INC. ES-1 Executive Summary The Florida Fish and Wildlife Conservation Commission (FWC), with support from the Florida Department of Environmental Protection (FDEP), the St. Johns River Water Management District (SJRWMD), the Southwest Florida Water Management District (SWFWMD), and Three Rivers Trust, Inc. sponsored this synoptic ecosystem study of twelve of Florida’s artesian springs. Wetland Solutions, Inc. (WSI) was selected to conduct this work. The twelve springs selected for this state-wide comparison include three in each of four water management districts: Jackson Blue (Jackson Co.), Ponce de Leon (Holmes Co.), and Wakulla (Wakulla County) in the Northwest Florida Water Management District (NWFWMD); De Leon (Volusia Co.), Silver (Marion Co.), and Silver Glen (Marion Co.) in the SJRWMD; Madison Blue (Madison Co.), Ichetucknee (Columbia Co.), and Manatee (Levy Co.) in the Suwannee River Water Management District (SRWMD); and Homosassa (Citrus Co.), Rainbow (Marion Co.), and Weeki Wachee (Hernando Co.) in the SWFWMD. All field work for this project was completed during 2008 and 2009, including: receipt of permits to sample state (10), federal (1), and county (1) managed springs; reconnaissance trips to each of the springs, and synoptic sampling and data analysis of a broad range of ecological indices at the twelve springs. Syntheses of new data and previously published information for the twelve springs are provided in this final report. Selected parameters measured at the 12 springs during 2008-2009 are summarized in Table ES-1. Findings described in this report indicate that while specific springs display remarkable consistency over various temporal periods, there may be large differences between individual springs in their physical, chemical, and biological properties. Artesian springs vary greatly in their physical dimensions and in the quantity of the water they discharge. The spring boils of the twelve study springs ranged in size from about 1,700 m3 (2,220 cubic yards) at Ponce de Leon to 50,000 m3 (65,000 cubic yards) for Wakulla Springs. The volume of the spring pool is in part a function of the existing and historical spring discharge, with smaller spring pools resulting from lower discharge rates (e.g., Ponce de Leon with a pool of about 1,700 m3 [2,220 cubic yards] and a measured flow of 0.33 m3/s [12 cfs]) and larger boils such Wakulla Springs associated with higher discharge rates (measured in this study following locally high rainfall at 30.8 m3/s [1,086 cfs]). Large spring size and high flows are in turn the basis for high levels of primary productivity and food- chain support for wildlife. WETLAND SOLUTIONS, INC. ES-2 TABLE ES-1 Selected spring ecosystem parameters (average pool station values unless noted) measured during 2008-2009. Gross Water Specific Dissolved Maximum Net Primary Community Spring Pool Discharge NO -N NH -N PO Primary Spring pH x 4 4 Productivity Respiration Photosynthetic Management 3 3 Conductance Oxygen Horizontal (County) Volume (m ) (m /s) (SU) (mg/L) (mg/L) (mg/L) Productivity 2 2 Efficiency (%) District (µS/cm) (mg/L) Secchi (m)* 2 (gO2/m /d) (gO2/m /d) (gO2/m /d) Blue NWFWMD (Jackson) 4,081 3.42 262 6.8 7.55 3.32 0.05 0.02 64 2.88 -0.16 3.04 1.30 Ponce de Leon (Holmes) 1,708 0.33 218 3.6 7.62 0.28 0.08 0.02 33 2.67 2.46 0.21 0.80 Wakulla (Wakulla) a 49,607 30.78 b 282 2.1 7.32 0.48 0.03 0.03 3 2.71 1.82 0.89 8.55 De Leon SJRWMD (Volusia) 4,898 0.84 945 0.7 7.44 0.78 0.11 0.06 14 4.32 -5.45 9.78 1.85 Silver (Marion) 11,969 12.04 447 2.1 7.25 1.11 0.01 0.04 76 24.89 6.02 18.88 6.62 Silver Glen (Marion) 1,875 2.21 1,810 3.1 7.86 0.05 0.02 0.02 70 11.10 c 9.26 c 1.84 c 4.56 c Blue SRWMD (Madison) 2,457 3.50 280 1.4 7.60 1.45 0.09 0.05 19 2.82 c -1.74 c 4.56 c 4.43 c Ichetucknee (Columbia) d 5,644 2.31 312 3.6 7.48 0.66 0.03 0.03 32 9.09 5.01 4.08 2.26 Manatee (Levy) 3,683 2.57 499 1.1 7.07 2.00 0.005 0.03 31 14.92 7.72 7.20 4.05 Homosassa SWFWMD (Citrus) 5,578 2.04 4,755 3.7 7.90 0.55 0.03 0.02 11 1.26 -0.23 1.48 1.03 Rainbow (Marion) 8,245 3.87 179 6.9 8.01 1.75 0.15 0.03 59 18.58 -0.15 18.73 4.42 Weeki Wachee (Hernando) 5,867 2.53 328 1.6 7.51 0.74 0.10 0.01 87 6.98 2.15 4.83 2.76 * horizontal Secchi visibility exceeded maximum dimensions of Jackson Blue and Silver spring pool; Wakulla Spring pool was flooded and tannin stained when surveyed a includes clear and tannin stained water periods b discharge made at SR61 overpass of Wakulla River c values from pool and run combined d values from upper sonde station (24 m below confluence of Blue Spring and Ichetucknee River) WETLAND SOLUTIONS, INC. ES-3 The twelve study springs illustrated the normal range of electrical conductivities (due to dissolved cations and anions), ranging from a low specific conductance of 125 µS/cm at Madison Blue Spring in the Central Highlands of north Florida to a high of 4,755 µS/cm at Homosassa Springs in Citrus County, adjacent to the Gulf Coast. While artesian springs have long been categorized by their quantity and quality of salts and other inorganic ions, the importance of dissolved oxygen concentration variability with respect to their aquatic ecology has not been widely appreciated. The spring pool average dissolved oxygen concentrations recorded in this study ranged from a high of 6.9 mg/L at Rainbow Springs in Marion County to a low of 0.7 mg/L at De Leon Springs in Volusia County, with a relatively even distribution of values between these two extremes. Nitrate nitrogen concentrations which are primarily the result of anthropogenic pollution ranged from a low of 0.05 mg/L at Silver Glen Spring in the Ocala National Forest in Marion County to a high of 3.32 mg/L at Jackson Blue Spring located in an area of intensive row crop agriculture. Measured concentrations of total phosphorus among the twelve study springs ranged between 0.01 to 0.06 mg/L. A variety of biological data were collected during this study, including observations of the percent cover and dominance of submerged aquatic macrophytes and benthic and attached algae, populations and occurrence of snails, turtles, aquatic insects, and manatees (primary and secondary consumers of plants and algae), and fish, bird, and reptile species at higher trophic levels. Monitoring also included detailed observations of human use at each spring. In addition to these population-level study methods, this project quantified the overall functioning of these spring ecosystems as a response to their chemical and physical forcing functions. These top-down study methods included the estimation of overall assimilation of nutrients; system export of organic and inorganic matter; light attenuation due to suspended matter, turbidity, and dissolved color; and community or ecosystem metabolism (primary productivity, respiration, and photosynthetic efficiency. Table ES-1 indicates that these springs have a relatively wide range of community-wide metabolic rates with gross primary productivity (GPP) ranging from a low of about 1.26 g 2 2 O2/m /d at Homosassa Springs to a high of about 25 g O2/m /d at Silver Springs. GPP is the best available measure of a natural ecosystem’s “gross domestic product” or the total amount of organic carbon fixed by photosynthesis within that system and available to meet the respiratory requirements of all plants, microbes, invertebrates, and vertebrates living in that ecosystem. GPP magnitude reflects the overall ability of a natural ecosystem to support life. Overall community respiration (CR) was also estimated for these twelve springs and ranged 2 2 from about 0.21 g O2/m /d at Ponce de Leon to a high of about 18.8 g O2/m /d at Silver Springs. CR is an independent estimate of the size and function of the biological community and is analogous to the caloric metabolic rate of a human or other animal.