Geology topics

Research about Savannah National Wildlife Refuge

Source-linked reports with geographic coverage including Savannah National Wildlife Refuge.

4 recordsLinked to original sources

USGS2020

Herpetofauna occupancy and community composition along a tidal swamp salinity gradient

Occupancy patterns of herpetofauna in most tidal freshwater swamps are unknown. Tidal freshwater swamps currently face multiple threats, including salinization, which can influence their associated plant and animal communities. The impacts of salinization to herpetofauna communities in tidal freshwater swamps have not been assessed. To improve predictions regarding these herpetofauna, we conducted surveys in tidal freshwater swamps of the Savannah National Wildlife Refuge located in South Carolina, USA, from March to June, 2016 and 2017, using a variety of methods. Goals included inventorying species, determining communities, examining microhabitat associations, and modeling occupancy to predict the impacts of salinity changes. We detected 8 species of amphibians and 12 species of reptiles in our surveys. Community analyses failed to detect patterns related to measured environmental variables. Species richness and diversity declined along the salinity gradient, but the observed patterns did not match our predictions and may instead be related to site-level heterogeneity. Microhabitat associations were detected for two amphibian species via occupancy analyses. Occupancy and regression analyses indicated soil salinity may be a factor affecting nine species’ occurrences. Amphibian detections may be affected by water depth, pH values, and weather conditions. These results expand our understanding of herpetofauna within an understudied, and threatened, wetland type.

South Carolina↗

USGS2017

A survey of the amphibians of Savannah National Wildlife Refuge, South Carolina and Georgia

From 2004 to 2006, we used a variety of sampling techniques to survey the amphibians of Savannah National Wildlife Refuge (SNWR), a large protected area straddling the lower portions of the Savannah River on the border between South Carolina and Georgia. We documented 22 amphibian species—15 frogs and 7 salamanders—with a possible 23rd species present. Species richness was lower than what might be expected from amphibian field guides of species inhabiting the adjacent Coastal Plain, likely due to a lack of specialized habitats, such as temporary ponds and upland pine forest. Amphibians occupied a variety of habitats and appeared tolerant of the mildly acidic and low-oxygen conditions of many of the wetlands. Although additional species may be found at SNWR, this initial survey provides a historic baseline for monitoring amphibian populations as areas adjacent to the refuge are disturbed, the climate changes, and multi-use management objectives are implemented within refuge boundaries.

Georgia, South Carolina↗

USGS2004

Sediment quality in freshwater impoundments at Savannah National Wildlife Refuge

Freshwater impoundments at Savannah National Wildlife Refuge (NWR), South Carolina, provide an important habitat for wildlife species, but degraded sediment quality in the Savannah River downstream of the discharge from two impoundments have caused concern about potential contaminant problems within the impoundments. The quality of sediments from five impoundments (impoundments no. 1, 2, 6, 7, and 17) on the NWR was evaluated using physical and chemical characterization, contaminant concentrations (metals, organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons), and toxicity testing. Survival of Hyalella azteca (freshwater amphipod) exposed for 28 days to solid-phase sediments was not significantly different from controls, but growth was significantly decreased at several sites. Survival in 96-hour exposures to sediment pore water was significantly decreased at most sites. Factors contributing to the toxic responses were low pH (3.7 to 4.1), ammonia (20 mg/L), and increased concentrations of cations in the pore water. The excess of simultaneously extracted metals over the acid volatile sulfides in the sediments was also typical of sites displaying decreased sediment quality. Elemental concentrations in pore water were negatively correlated with pH, and the highest concentrations were observed in impoundment no. 7. The acidic nature of the sediment in this impoundment was exacerbated by recent draining, burning, and disking, which allowed oxidation of the previously anoxic wetland sediment. Sediment disturbance and mixing of vegetation into the sediments by disking may also have contributed to the formation of ammonia caused by microbial decomposition of the fragmented organic matter. Contaminants were not detected in sediments from the impoundments, but releases of acidic water with increased levels of sediment cations from the impoundments may have contributed to the degraded sediment conditions previously observed in the river. The practice of dewatering sediments for vegetation control may exacerbate the acidification of vulnerable sediments within impoundments of this NWR.

Georgia↗

USGS1963

Pre-nesting activity of the purple gallinule near Savannah, Georgia

Observations on the pre-nesting activity of the Purple Gallinule ( Porphyrula martinica ) were made by me at the Savannah National Wildlife Refuge, Jasper County, South Carolina from 9 to 16 April 1960, 12 to 23 April 1961, and 28 to 30 April 1963. Jasper County is in extreme southeastern South Carolina. The Refuge headquarters is approximately 10 miles (16 km) up the Savannah River from the port of Savannah, and about 20 miles from the ocean.

South Carolina↗