Date of Award

January 2016

Degree Type

Open Access Thesis

Document Type

Master Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

Stephen C. Richter

Department Affiliation

Biological Sciences

Second Advisor

David R. Brown

Department Affiliation

Biological Sciences

Third Advisor

Kelly Watson

Department Affiliation

Geosciences

Abstract

Ephemeral wetlands are a natural feature of the ridge-top ecosystem in the Daniel Boone National Forest (DBNF) in eastern Kentucky, and support a diverse amphibian assemblage characterized by species with short larval periods. However, hundreds of hydrologically permanent ponds have been constructed along the ridge-top system in the last 50 years. The results of previous studies suggest that constructed ponds act as sinks for some historic ridge-top species because they provide habitat for amphibian predators with long larval periods or aquatic adult stages. My objectives were to determine (1) if natural wetlands differ from constructed wetlands in amphibian community composition, (2) the habitat characteristics that predict the presence and abundance of different amphibian species, and (3) if prevalence of either Batrachochytrium dendrobatidis (Bd) or ranavirus differs between natural and constructed wetlands of the London Ranger District, where construction methods, wetland density, and wetland placement differ from those in previous studies conducted in the Cumberland District. Seven natural wetlands, five wetlands constructed for game use, and five wetlands constructed for bat conservation were surveyed for amphibian larvae and habitat characteristics. Natural wetlands had better wetland condition, indicated by higher Kentucky Wetland Rapid Assessment Method scores, and shallower littoral zones than both constructed wetland types. Natural wetlands also had greater canopy closure than bat wetlands. Using an ADONIS procedure, I found that amphibian communities in natural wetlands differed significantly from those in bat wetlands (R2 = 0.22, p = 0.017), and although species richness was similar between natural and game wetlands, the relative species abundances observed between wetland types differed. Ranavirus was detected in large numbers at every wetland; however, there was a higher prevalence in natural wetland types. It is difficult to determine if this was due to the amplifying effect of wood frog larvae or some habitat characteristic present at natural wetland types. Batrachochytrium dendrobatidis (Bd) was not detected at any of the study wetlands. Overall, results suggest that bat wetlands in the London District are not conducive to recruitment and persistence of historical ridge-top species. Some game wetlands appear to be more favorable to historic species, such as wood frogs (Lithobates sylvaticus) and marbled salamanders (Ambystoma opacum); these were game wetlands with shallower littoral zones and more complex basin vegetation that mimicked natural wetland characteristics. However, because none of the constructed wetlands were ephemeral, they did not exactly replicate natural wetland habitat function. Lastly, differences between natural and constructed wetland types in the London District were not as pronounced as those in the Cumberland. This was most likely due to the high densities in which permanent wetlands were constructed in the Cumberland, their placement, and also the size and hydroperiod differences observed between natural wetlands in the two areas. For the DBNF, modifying constructed wetlands to replicate natural features such as hydroperiod, littoral zone depth, and vegetation would likely increase the recruitment and persistence of species characteristic of the ridge-top system.

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