Aquatic habitat use by North American moose (Alces alces) and associated richness and biomass of submersed and floating-leaved aquatic vegetation in north-central Minnesota

Abstract

The North American moose (Alces alces) is a species of socio-economic importance that has undergone recent declines in some areas of its range and may be impacted by climate change through effects on physiology or habitat availability. Moose frequently use aquatic habitat during summer but the timing, frequency and reasons for this behaviour are not well understood and appear to vary geographically. My objectives were to: 1) clarify the importance of aquatic habitat to North American moose through a literature review and 2) estimate richness and biomass of submersed and floating-leaved vegetation in lakes and beaver ponds potentially used by moose in north-central Minnesota through a comparative field study. The literature suggests that moose use aquatic habitats to feed and escape biting insects and do not appear to use them to escape predators or ameliorate heat stress, though the latter function may be important at the extreme southern limits of moose range. Richness and biomass of aquatic plants in aquatic areas potentially used by moose in north-central Minnesota was heavily influenced by the presence and damming activity of beaver (Castor canadensis). Beaver ponds contained higher richness and biomass of aquatic vegetation compared to lakes. The creation and maintenance of large (> 1 ha) beaver ponds 6-38 years of age facilitate moose in meeting nutritional demands because they allow growth and reproduction of species less competitive but potentially more palatable than the dominant floating-leaved plant Brasenia schreberi. The maintenance of beaver populations may be important for moose conservation in north-central Minnesota.