Designing Wetlands for Amphibians: The Importance of Predatory Fish and Shallow Littoral Zones in Structuring of Amphibian Communities

Abstract

Under£401 and£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 understanding of factors that affect the structure wetland faunal communities. We examined the effects of the presence of predatory fish, shallow vegetated littoral zone, emergent vegetation cover, and wetland age and size on amphibian diversity in 42 replacement wetlands located in the Ohio's Eastern Corn Belt Plains ecoregion. We recorded 13 species of pond-breeding amphibians, and the average local species richness (a-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, 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). Amphibian species associated with forested wetlands were either rare (eastern newt, spotted salamander) or not present at all (marbled salamander, wood frog) in replacement wetlands. We surveyed all replacement wetlands constructed under£401 in Ohio during the past decade, 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.

The response of amphibian communities to fish and habitat features in Mediterranean permanent ponds

“…Many authors (Hecnar & M'Closkey 1997;Porej & Hetherington 2005;Hartel et al 2009) found that predator fish reduced the richness of amphibian species. It is important to mention, however, that we found only six amphibian species, one of which (Bufo bufo) is not preyed upon by fish (Smith et al 1999;Kloskowski 2009).…”

“…Previous studies suggest that fish predation affects amphibian communities (Hecnar & M'Closkey 1997;Smith et al 1999;Porej & Hetherington 2005;Indermaur et al 2010). Predators can influence population and community dynamics directly, e.g., by consumption of prey (Menge 1995;Anholt et al 1996) and indirectly, e.g., by consumption of resources that in turn alters the abundance of another species (Carpenter et al 1985;Menge 1995).…”

Design guidelines for integrating amphibian habitat into golf course landscapes

“…Littoral shelves, the shallow zone near the shore of a pond, play a crucial role for amphibians during the aquatic stages of their life cycles (Porej & Hetherington, 2005). A shallow littoral zone provides microhabitats for oviposition, foraging, and refuge for pond-breeding amphibians (Semlitsch, 2002).…”

“…Warnken (2007a, 2007b) found that amphibian abundance and species richness was negatively associated with increasing waterbody bank steepness and turfgrass cover on banks, while there was a positive relationship with floating vegetation. Shallow littoral zones of slopes 15:1 or less promote the growth of sedges and grasses which provide sites for nesting and refuge, while also providing foraging areas and sources of food for larvae (Porej & Hetherington, 2005;Semlitsch, 2002).…”

Habitat relationships and presence of the threatened heath frog Litoria littlejohni (Anura: Hylidae) in central New South Wales, Australia

“…The habitat variables thought to most commonly determine whether a water body will be used by a given species resident within the area include hydroperiod (Lehtinen et al 1999, Beja & Alcazar 2003, Watson et al 2003) and vegetation structure , Homan et al 2004, Porej & Hetherington 2005, Van Buskirk 2005. These important vegetation elements may be found directly in or around the water body or be more distant to it and represent both breeding and nonbreeding requirements (Hartel et al 2007).…”