Spatial variation in aquatic invertebrate and riparian songbird mercury exposure across a river-reservoir system with a legacy of mercury contamination

Jackson, Allyson K.; Eagles‐Smith, Collin A.; Emery, Colleen

doi:10.1007/s10646-019-02043-z

Cited by 11 publications

(7 citation statements)

References 39 publications

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“…The results of this and other studies in this special issue (e.g., Jackson et al 2020;Shanley et al 2020) suggest that no single landscape or other factor can predict risk of Hg bioaccumulation. The authors urge caution against the automatic assumption that songbirds occupying wetlands will have higher Hg exposure than conspecifics living in other habitats.…”

Section: Landscape and Management Factorsmentioning

confidence: 46%

The impact of mercury on North American songbirds: effects, trends, and predictive factors

Cristol

Evers

2020

Ecotoxicology

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Researchers were asked to contribute new results addressing questions about the exposure and effects of mercury (Hg) in North American songbirds, a rapidly declining group of species that is the subject of enduring interest for millions of birdwatchers, the general public and conservation scientists. Important questions to be answered include: Is Hg causing or exacerbating songbird population declines? Which North American songbirds are at most risk and in which landscapes? Are there aspects of songbird natural history that pre-dispose them to risks of Hg exposure and effects, in particular, their migratory behavior? In all, 61 authors contributed 15 studies addressing aspects of these questions. Articles in this special issue address an array of topics including: (1) three studies on health effects in the laboratory using a domesticated songbird model species, the zebra finch; (2) three studies on changes in songbird exposure to Hg over time spans from less than a decade to more than a century; (3) five studies on landscape characteristics or management practices that cause the oft-noted spatial variation in Hg accumulation by resident songbirds, from the subarctic tundra to high-elevation tropical forests; (4) three papers examining the recently recognized role of migration behavior in predicting risk to songbirds from Hg; and (5) one paper on the potential pitfalls of using feather Hg concentration as a bioindicator for Hg exposure. In summary, although there are many questions still to be answered, it is clear that the effects of Hg are persistent long after exposure, Hg exposure of North American songbirds is not improving, predicting exposure requires a detailed understanding of ecosystem processes beyond simply the amount of Hg present at a site, migration behavior predisposes songbirds to risk of Hg exposure and effects, and carefully selecting appropriate bioindicator sites, species, and tissues is critical to any monitoring efforts.

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Section: Landscape and Management Factorsmentioning

confidence: 46%

The impact of mercury on North American songbirds: effects, trends, and predictive factors

Cristol

Evers

2020

Ecotoxicology

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“…Low oxygen concentrations can also impact aquatic health indirectly by favouring microbial processes that produce methylmercury (MeHg), a biologically available form of mercury (Bigham et al, 2017;Hsu-Kim et al, 2013). Elevated MeHg has been observed in beaver pond water (Ecke et al, 2017;Roy et al, 2009) and in dam structures (Čiuldienė et al, 2020) with other studies demonstrating that MeHg can bioaccumulate in aquatic organisms and spill over to terrestrial food webs (Jackson et al, 2020). Summer hypoxia in beaver ponds can impact salmonids through at least two pathways.…”

Section: Biological Impactsmentioning

confidence: 99%

Dammed water quality—Longitudinal stream responses below beaver ponds in the Umpqua River Basin, Oregon

et al. 2022

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Beaver‐related restoration (BRR) has gained popularity as a means of improving stream ecosystems, but the effects are not fully understood. Studies of dissolved oxygen (DO) and water temperature, key water quality metrics for salmonids, have demonstrated improved conditions in some cases, but warming and decreased DO have been more commonly reported in meta‐analyses. These results point to the contingencies that can influence outcomes from BRR. We examined water quality related to beaver ponds in a diverse coastal watershed (Umpqua River Basin, OR, USA). We monitored water temperature 0–400 m above and below beaver ponds and at pond surfaces and bottoms across seven study sites from June through September of 2019. DO was also recorded at two sites at pond surfaces and pond bottoms. Downstream monthly mean daily maximum temperatures were warmer than upstream reference locations by up to 1.9°C at beaver dam outlets but this heating signal attenuated with downstream distance. Downstream warming was greatest in June and July and best predicted by pond bottom temperatures. DO at pond surfaces and bottoms were hypoxic (≤5 mg/L) for more than half of the 32‐day monitoring period. Water temperatures increased for short distances below monitored beaver ponds and observed oxygen conditions within ponds were largely unsuitable for salmonid fishes. These findings contrast with some commonly stated expectations of BRR, and we recommend that managers consider these expectations prior to implementation. In some cases, project goals may override water quality concerns but in streams where temperature or DO restoration are objectives, managers may consider using BRR techniques with caution.

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“…It also has a history of anthropogenic influences, including Hg contamination (Henny et al, 2005;Hope, 2006;Hope & Rubin, 2005). The Willamette River supports a diversity of subhabitats including backwater alcoves and open channel flowing waters that differ in Hg concentrations (Jackson et al, 2019). To best differentiate aquatic and terrestrial isotope signals, we focused here on the main channel environments.…”

Section: Fieldworkmentioning

confidence: 99%

“…A number of studies have assessed the influence of aquatic factors on the magnitude of emergent aquatic insect and aquatic-derived contaminant flux into the terrestrial ecosystem (Kelly et al, 2019;Walters et al, 2008). Contaminant concentrations in aquatic insects are influenced by aquatic habitat (Jackson et al, 2019), and the biomass of insects that survive to emerge from the aquatic system can be mediated by habitat, water quality, and fish abundance (Jones et al, 2013;Paetzold et al, 2011). For some contaminants, high contaminant loading can reduce invertebrate fecundity and survival, ultimately constraining insect biomass flux and contaminant transfer to riparian food webs (Kraus, 2019;Kraus et al, 2014;Paetzold et al, 2011).…”

mentioning

confidence: 99%

Differential reliance on aquatic prey subsidies influences mercury exposure in riparian arachnids and songbirds

Jackson

Eagles‐Smith

Robinson

2021

Ecology and Evolution

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Spatial variation in aquatic invertebrate and riparian songbird mercury exposure across a river-reservoir system with a legacy of mercury contamination

Cited by 11 publications

References 39 publications

The impact of mercury on North American songbirds: effects, trends, and predictive factors

The impact of mercury on North American songbirds: effects, trends, and predictive factors

Dammed water quality—Longitudinal stream responses below beaver ponds in the Umpqua River Basin, Oregon

Differential reliance on aquatic prey subsidies influences mercury exposure in riparian arachnids and songbirds

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