Beaver-Created Habitat Heterogeneity Influences Aquatic Invertebrate Assemblages in Boreal Canada

Abstract

Habitat heterogeneity and wetland area play important roles in aquatic biodiversity; however, other factors are equally important in the composition and distribution of ecological communities. Over a 3-year period, including a year of drought, we demonstrate how beavers physically altered isolated shallow-water wetlands in Miquelon Lake Provincial Park, Canada, which then influenced aquatic invertebrates diversity and abundance of functional feeding groups and taxa. Digging channels by beavers extended aquatic habitats over 200 m into the upland zone and created unique aquatic habitats, which became hot-spots for predaceous aquatic invertebrates. Some taxa (e.g., Gerridae and Gyrinidae) were found exclusively in beaver ponds, while Culicidae were primarily in wetlands without beavers. Amphipoda were strongly associated with beaver ponds in drought and post-drought years. During extreme drought in 2009, species richness, diversity and abundance declined dramatically, but recovered quickly in 2010. Although species richness was associated with wetland area, increased niche availability through active maintenance of wetlands by beavers played an important role in aquatic invertebrate diversity and distribution. Understanding the role of common, but seldom surveyed within-wetland habitats in boreal wetlands expands our ability to understand aquatic biodiversity, the importance of habitat heterogeneity and the role of other taxa in species assemblages.