Date of Award
Wetlands in dune landscapes provide important breeding habitat for amphibians along the Lake Michigan Coast. Unfortunately, these unique habitats and the corresponding amphibian metapopulations are understudied and threatened. We assessed amphibian species richness and terrestrial habitat type in 16 permanent and ephemeral wetlands along the coast of Lake Michigan in Grand Haven, MI. Wetland area, terrestrial habitat type, depth, hydroperiod, shade, and degree of isolation were measured from April to September of 2017. Nine species of amphibian were found; Green Frog (Rana clamitans melanota) and Spring Peepers (Pseudacris crucifer crucifer) were most abundant and Fowlers Toad (Anaxyrus fowleri) was rarest. Non-metric multidimensional scaling (NMDS) revealed that wetlands in open dunes and great lake barrens were more likely to contain American Toad (Anaxyrus americanus), and Leopard Frog (Rana pipiens) while forested wetlands were more likely to contain Wood Frog (Rana sylvatica), and Gray Tree Frog (Hyla versicolor). Least cost modeling (LCM) was used to determine the shortest path through navigable habitat between wetlands and provided an associated isolation score for each wetland ranging from 243—least isolated, to 928—most isolated. Isolation was significantly negatively correlated with species richness (r = -0.29), p = 0.02). There was also a positive correlation between hydroperiod, area, and depth (PCA, scaling =2). Non-parametric correlation testing showed a strong positive correlation between species richness and area (r = 0.6, p = 0.014) and hydroperiod (r = 0.86, p < 0.001). However, some small temporary wetlands situated in the open dunes harbored rare species not found in other wetlands. These findings highlight the importance of protecting all of these habitats from land development, fragmentation and degradation in order to conserve multiple species, as well as overall landscape connectivity of the system.
Jouney, Alex H., "Environmental factors influencing amphibian community assemblage in dune wetlands on the Lake Michigan coast" (2018). Masters Theses. 907.
Available for download on Wednesday, September 23, 2020