Designing Wetlands for Amphibians: The Importance of Predatory Fish and Shallow Littoral Zones in Structuring of Amphibian Communities |
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Authors: | Email author" target="_blank">Deni?PorejEmail author Thomas E?Hetherington |
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Institution: | (1) The Nature Conservancy, 6375 Riverside Drive, Suite 50, Dublin, OH 43207, USA;(2) Department of Evolution, Ecology and Organismal Biology, The Ohio State University, 1735 Neil Avenue, Columbus, OH 43210, USA |
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Abstract: | Under section 401 and section 404 of the Clean Water Act, permission to degrade existing natural wetlands in the USA may be
conditional on restoring or creating ‘replacement’ wetlands. Success of wetland mitigation efforts in adequately replacing
lost wildlife habitats depends on our good understanding of key ecological attributes that affect the structure of wetland
faunal communities. We examined the effects of the presence of predatory fish, shallow vegetated littoral zone, emergent vegetation
cover, wetland age and size on amphibian diversity in 42 replacement wetlands located in the Ohio’s North Central Tillplain
ecoregion. We recorded 13 species of pond-breeding amphibians, and the average local species richness (α-richness) was 4.2 ± 1.7 species per site (range 1–7). There is strong evidence for the positive association between amphibian
species richness and presence of a shallow littoral zone, and the negative association with presence of predatory fish. There
was no evidence for the association between species richness and age, size, amount of forest cover within 200 m, nor the amount
of emergent vegetation cover at the study sites. It is estimated that local species richness in wetlands with shallows was
1.76 species higher on average than in wetlands without shallows (95% CI from 0.75 to 2.76). The presence of predatory fish
was associated with an average reduction in species richness by an estimated 1.21 species (95% CI from 0.29 to 2.11). Replacement
wetlands were placed in areas with little or no existing forest cover, and amphibian species associated with forested wetlands
were either rare (eastern newt, spotted salamander) or not present at all (marbled salamander, wood frog). In addition, we
surveyed all replacement wetlands constructed under section 401 in Ohio since 1990, and found that predatory fish were present
in 52.4% of the sites and that shallows were absent from 42.7% of the sites. Our results indicate that current wetland replacement
practices could have a negative effect on the amphibian diversity within our region. |
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Keywords: | Ambystoma American bullfrog amphibian community colonization green frog habitat restoration leopard frog Ohio predation small-mouthed salamander wetland mitigation |
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