Inventory and Monitoring Activities: St Marks National Wildlife Refuge

Background

       Located in Florida's panhandle approximately 25 km south of Tallahassee (Fig. 1), St. Marks National Wildlife Refuge (SMNWR) encompasses 27,500 hectares of diverse upland and wetland habitats (Fig. 1). Established in 1931 to provide wintering habitat for migratory birds, SMNWR extends along the Gulf coast in Taylor, Jefferson, and Wakulla Counties (Fig. 2A). For management purposes the refuge is divided into three major units.  The easternmost of these, the St. Marks Unit, is generally bounded by the Aucilla River to the east and by the Wakulla and St. Marks Rivers to the west.  The Wakulla Unit runs west from the Wakulla and St. Marks Rivers to Spring Creek Hwy (CR 365). The westernmost section, the Panacea Unit, extends west from Spring Creek Hwy to the Ochlockonee River and Ochlockonee Bay.

       SMNWR has a diversity of upland and wetland habitats which potentially support 40 species of amphibians (21 frogs and 19 salamanders) and 68 species of reptiles (13 lizards, 34 snakes, 20 turtles, and one crocodilian).  The Flatwoods Salamander (Ambystoma cingulatum), a federally threatened species, has been documented from many sites on SMNWR.  In the late 1970's, data on presence of amphibians and reptiles were collected by the USFWS during a study which quantified the relationships among forestry management practices and diversity and abundance of non-game wildlife (USFWS, 1980).  This previous study included 14 upland drift fence arrays which were monitored for 2 years, although some of the arrays were not as extensively monitored during the second year.  SEARMI research at SMNWR began in May 2002.

Effort in 2005

       ARMI made three visits to SMNWR in 2005: 14-21 Feb, 2-8 Jun, and 24-30 Aug (Table 2). We visited a total of 40 wetland sites (Tables 3, 4, 5). Our Water Resources Division collaborator, Brian Hughes (USGS WRD), collected water samples during our Aug visit to SMNWR.

Results

       We have detected a total of 80 species of amphibians and reptiles at SMNWR through Dec 2005 (Tables 4, 5). This includes captures and observations made with all of the methods used, including incidental observations of animals on roads. The 31 species of amphibians were comprised of 20 frog and 11 salamander species.  The 48 species of reptiles were comprised of 10 lizard, 27 snake, one crocodilian, and 11 turtle species (Table 4). Our detection rate of species previously unrecorded in our sampling has decreased, indicating we have probably recorded most species for this refuge we are likely to capture using our sampling techniques (Figs. 3, 4). We detected 17 frog and four salamander species among the 40 wetlands sampled during 2005 (Table 5). The most commonly encountered species were Acris gryllus, Hyla femoralis, and Rana sphenocephala. 

Water Quality Data

       In Aug 2005 we assisted USGS WRD personnel in the collection and field processing of water samples from 16 sites. Sampling was concentrated in the Panacea Unit and was co-located with amphibian monitoring sites (Table 3). Field parameters (pH, conductance, dissolved oxygen, temperature), major ions, nutrients, trace metals (including mercury), and suspended/particulate organic carbon were analyzed from all sites. To view WRD water quality data for this refuge from 2005, please see the USGS NWISWeb Data site, which can be found at the USGS Water Resources home page (http://waterdata.usgs.gov/fl/nwis/qw). For more information on WRD water quality results contact Brian Hughes, Southeast Regional Hydrologic Research Coordinator for ARMI (US Geological Survey, 3039 Amwiler Road, Atlanta, GA 30360; Phone: 770-903-9162; E-mail: wbhughes@usgs.gov).

       We collected water-quality field parameters (pH, conductance, dissolved oxygen, temperature) at 39 ponds sampled in 2005 (Table 6). We measured these parameters at 17 of the ponds more than once.  These wetland sites varied from small isolated wetlands to large lakes. Several sites were overwashed by storm surge during Hurricane Dennis.  Values for pH were acidic, with a mean among all samples of 4.46 and range from 3.51 to 7.39. Conductivity was generally low, only exceeding 1.06 mS/cm at six sites which were apparently subjected to hurricane overwash. Dissolved oxygen (DO, mg/l) and % DO varied considerably, ranging from 0.23 mg/l and 2 % to 13.1 mg/l and 131%. Water temperatures ranged from 9 ºC to 35 ºC (Table 6).

Disease monitoring

       During our survey activities at SMNWR we looked for diseased or malformed amphibians (Table 7). One Oak Toad (Bufo quercicus) was collected which appeared to have an abnormal patch of skin on its dorsum. No other animals exhibiting malformations or obvious disease symptoms were observed during 2005.  In Jun and Aug of 2005, we submitted apparently healthy amphibian larvae for disease screening from Perkinsus Pond, a site in which a previous tadpole die-off was observed in 2002.  The results of the analysis of these specimens are still pending. During 2005 SMNWR personnel and volunteers participated in a USFWS survey of amphibian disease and malformation.  We assisted in this survey when possible by providing information on collection sites and species identification.

Future Plans

       ARMI has received a USGS Bureau Venture Capital Fund grant to study the effects of saltwater overwash from hurricane storm surge at SMNWR.  We plan to visit at least 30 sites approximately every six weeks to collect amphibian and water chemistry data. Our goal for this study is to determine what effects the salt water overwash of Hurricane Dennis had on amphibian species richness and abundance, to evaluate the change in salinity of wetlands over time, and to monitor the potential recovery of amphibians at sites affected by overwash.  In addition, we will begin repeated collections of tadpoles for disease analysis from at least five sites (including Perkinsus Pond) during at least three visits each year to lead to a establish more complete dataset on the dynamics of disease occurrence on this refuge. 

       SMNWR supports a relatively large population (at least 44 breeding sites) of the federally threatened Flatwoods Salamander (Ambystoma cingulatum). Management recommendations for A. cingulatum include burning of uplands with growing season fires and increasing the herbaceous edge vegetation around breeding ponds.  Beginning in 2006 ARMI will assist managers at SMNWR in evaluating the effects of management activities on A. cingulatum populations. ARMI will begin by evaluating larval habitat use in ponds to determine the extent to which A. cingulatum larvae use the sawgrass interior of ponds relative to the herbaceous edge area.  Potential future research includes evaluation of upland habitat use by juvenile and adult A. cingulatum. 

       Our drift fence arrays will be left in place but will remain closed during completion of the analysis collected thus far. Long-term drift fence data is valuable, but funding and personnel constraints prevent ARMI from adequately sampling these fences every year. Thus the drift fences may be monitored on a 5-7 year cycle to build a long-term dataset without having to monitor the fences every year.

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