Beaver Loggers: Beaver Herbivory Alters Forest Structure

Johnston, Carol A.

doi:10.1007/978-3-319-61533-2_4

Cited by 2 publications

(1 citation statement)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Beaver ponds create temporary wetlands, which have long been thought of as ideal environments for Hg methylation (Chen et al 2012, Tjerngren et al 2012 due to (a) the flooding of labile organic carbon (Hall et al 2005), (b) the subsequent anoxic conditions (St. Louis et al 1994, Driscoll et al 1998 and (c) the higher and more stable water temperature (Collen and Gibson 2000, Sun et al 2023, all favouring microbial activity. Beavers also continually add fresh organic matter to the inundated area via direct delivery for food and dam construction (Johnston 2017) as well as by creating foraging canals around the pond that facilitate additional transport of upland material (Grudzinski et (Mangal et al 2022). However, as these processes occur on a small scale when compared to overall watershed factors, the overall downstream increase in MeHg is small.…”

Section: Upstream In-pond and Downstream Water Chemistrymentioning

confidence: 99%

Landscape characteristics govern the impacts of beaver ponds on surface water methylmercury concentrations in boreal watersheds

Lam,

Mackereth,

Mitchell

2024

Environ. Res.: Ecology

View full text Add to dashboard Cite

Studies in boreal regions concerning the bioaccumulative neurotoxin methylmercury (MeHg) in natural wetlands and experimental reservoirs have shown that these waterbodies contribute to high MeHg levels in underlying sediments, inundated vegetation, and aquatic organisms. Beaver ponds are natural reservoirs that are ubiquitous in the Canadian boreal region and have been reported to increase downstream MeHg concentrations. However, the reported impacts of beaver ponds on stream MeHg vary widely across a limited number of studies, and factors influencing this variation are not well understood. To quantify the effect of beaver ponds on stream mercury concentrations, water samples were taken upstream and downstream of 10 in-channel beaver impoundments in northwestern Ontario, Canada. The downstream:upstream MeHg concentration ratios were related to pond and landscape characteristics to examine potential factors that play a role in determining the effect of beaver ponds on stream MeHg concentrations. Overall, MeHg concentrations were 1.6 times greater downstream of the beaver ponds, though this increase was not consistent; downstream concentrations up to 12 times greater and up to 5 times less were also observed. Landscape characteristics that can be readily obtained from existing spatial datasets or quantified using remote sensing techniques emerged as better predictors of downstream:upstream MeHg concentrations than site-specific stream chemistry parameters or pond characteristics that are more difficult to ascertain, with drier landscapes indicative of lower background MeHg export being more likely to exhibit greater increases in MeHg downstream of a beaver pond. These results suggest that the effects of beaver ponds on surface water MeHg concentrations are generally small but highly variable, and that the magnitude of the pond’s influence on stream MeHg are lessened in landscapes already conducive to higher MeHg concentrations.

show abstract