The effects of the protist parasite Dermomycoides Sp., on the Dusky Gopher Frog (Rana Sevosa) and the Southern Leopard Frog (Rana Sphenocephala)

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Matthew Scot Atkinson (Creator)
Western Carolina University (WCU )
Web Site:
Joseph Pechmann

Abstract: This research addressed whether characteristics of translocation ponds, Gosner (developmental) stage at exposure, stress caused by density, and perceived presence of predators have an effect on the susceptibly of frog tadpoles to the protozoan parasite Dermomycoides sp. In 2014, Dusky Gopher Frog tadpoles were headstarted in tanks and translocated to Pony Ranch Pond (N = 1168). Additional tadpoles were marked and returned to nine tanks (N = 180) or translocated to 18 screen cages (N = 62) in Pony Ranch Pond. In 2015, five Dusky Gopher Frog tadpoles were placed into each of 12 cages in each of three ponds, or into each of 10 cages in tanks used as controls. Survival to metamorphosis in 2014 was 0.09-0.26% for free-swimming translocated tadpoles, 0.12-0.18% for three natural clutches, and 15.7% for caged tadpoles. Survival to metamorphosis in 2015 was 0.03% for 18 natural-egg clutches, and for translocated, caged larvae it was 1.67% in Pony Ranch, 11.67% in TNC1 Pond, 0% in New Pond, and 22% in the control tanks. Individuals headstarted for 2 months also survived better than individuals only headstarted for 1 month. Necropsies of caged tadpoles suggest that survival of translocated and natural larvae was significantly decreased by Dermomycoides sp. I examined if developmental stage affected the survival of tadpoles exposed to Dermomycoides sp. Southern Leopard Frog tadpoles were exposed to the parasite at different Gosner stages (replicates = 6). Survival to metamorphosis was 63% for exposure at Gosner Stage 25, 61% for Stage 30, 71% for Stage 35, 84% for Stage 40, and 80% for the control. No significant difference among treatments was found (p = 0.19), but mortality was higher in tadpoles exposed early in development than that in those exposed late in development. I examined whether stress from high population density or the odor of a predator (Red-spotted Newt) affected the survival or length of larval period of tadpoles exposed to Dermomycoides sp. Survival to metamorphosis was 62% for high density and predator odor present, 83% for low density and predator odor present, 76% for high density and predator odor absent, and 85% for low density and no predator odor. No statistical differences among the different environmental stress levels in survival or length of larval period were found (p > 0.32). However, mortality from infections occurred more often at higher densities than in those groups housed at low density. Dermomycoides sp. plays an important role in the ecology of ephemeral ponds in southern Mississippi, and it may be a hurdle to deal with as we attempt to augment the population of the Dusky Gopher Frog.

Additional Information

Language: English
Date: 2016
Dermomycoides sp., Disease Ecology, Dusky Gopher Frog, Wildlife Management
Tadpoles -- Parasites -- Mississippi
Protozoan diseases -- Environmental aspects -- Mississippi
Tadpoles -- Development -- Mississippi
Frogs -- Ecology -- Mississippi
Protozoa, Pathogenic -- Mississippi

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