Inventory and Monitoring Activities: Lower Suwannee National Wildlife Refuge

Background

       Located along Florida's Big Bend region on the Gulf of Mexico, approximately 80 km WSW of Gainesville (Fig. 1), Lower Suwannee National Wildlife Refuge (LSNWR) encompasses approximately 21,425 hectares of upland and wetland habitats (Fig. 2B). Established in 1979 to preserve unique coastal, flood plain, and upland ecosystems at the lower reach of the Suwannee River, the refuge stretches 42 km north to south in Levy and Dixie Counties. The refuge includes lands along both banks of the Suwannee River from Yellow Jacket landing southwest to the Gulf of Mexico.  The Dixie Co. portion extends north along the coast to Shired Island. The main Levy Co. portion runs south along the coast almost to the mouth of Ericson Creek. The Shell Mound Unit of LSNWR is just south of Ericson Creek and adjacent to Cedar Keys National Wildlife Refuge (administered and managed by LSNWR staff). Cedar Keys NWR is a complex of 13 islands (approx. 310 hectares) around the municipality of Cedar Key and was established in 1929 as a refuge for colonial wading birds.

       LSNWR protects a diversity of aquatic and upland habitats including floodplain forest, salt marsh, hardwood swamp, cypress swamp, cabbage palm hammock, sandhill, scrub, and pine flatwoods. This refuge potentially supports 37 species of amphibians (21 frogs and 16 salamanders) and 66 species of reptiles (one crocodilian, one amphisbaenid, 15 lizards, 34 snakes, and 15 freshwater turtles).  Historical information on the herpetofauna of the refuge is scant. Florida Museum of Natural History records included voucher specimens for only 18 species (three amphibians and 15 reptiles) from the refuge proper, most of which dated from the 1970's or earlier. SEARMI research began at LSNWR in May 2002.

Effort in 2005

       ARMI made three visits to Lower Suwannee NWR in 2005: 31 Jan-4 Feb, 25-29 Apr, and 8-12 Aug (Table 2). We visited a total of 30 wetland sites (Tables 3, 4, 5).

Results

       We have detected a total of 61 species of amphibians and reptiles at LSNWR through Dec 2005.  This includes captures and observations made with all of the methods used.  The 23 species of amphibian were comprised of 19 frog and four salamander species.  The 38 species of reptiles were comprised of eight lizard, 18 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 12 frog species and three salamander species among the 30 wetlands sampled during 2005 (Table 5). The most commonly detected species were Rana sphenocephala, R. clamitans, and Acris gryllus.

Water Quality Data

       We collected water-quality field parameters (pH, conductance, dissolved oxygen, temperature) at 30 ponds sampled in 2005 (Table 6). We measured these parameters at 6 ponds on two visits.  Values for pH were less acidic than at SMNWR, with a range from 3.38 to 7.42 and a mean among all samples of 5.91. Conductivity was generally low, less than 0.57 mS/cm at all sites. Dissolved oxygen (DO, mg/l) and % DO varied considerably, ranging from 0.64 mg/l and 7.5% to 8.4 mg/l and 93.1%. Water temperatures ranged from 16.9 ºC to 26.1 ºC (Table 7).

Future Plans

       ARMI will continue to monitor amphibians at LSNWR with the goal of continuing to expand into more wetland sites. Our drift fence arrays will be left in place but will remain closed during completion of the analysis of the data 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 these fences may be monitored on a 5-7 year cycle to build a long-term dataset without having to monitor the fences every year. Our treefrog PVC arrays will be removed in 2005-2006.

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