Mercury bioaccumulation, speciation, and influence on web structure in orb‐weaving spiders from a forested watershed

Wyman, Katherine E.; Rodenhouse, Nicholas L.; Bank, Michael S.

doi:10.1002/etc.572

Cited by 16 publications

(9 citation statements)

References 30 publications

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“…Mean MeHg in spiders from other uncontaminated sites did not exceed 25 ng/g dw. In remote sites from New Hampshire (White Mountain National Forest), MeHg concentrations in spiders were 16 6 4 ng/g (Wyman et al 2011). Similar concentrations were reported in spiders from uncontaminated reference sites in Virginia (24 6 14 ng/g).…”

Section: Discussionsupporting

confidence: 62%

Taking the trophic bypass: aquatic‐terrestrial linkage reduces methylmercury in a terrestrial food web

Bartrons

Gratton

Spiesman

et al. 2015

Ecological Applications

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Abstract. Ecosystems can be linked by the movement of matter and nutrients across habitat boundaries via aquatic insect emergence. Aquatic organisms tend to have higher concentrations of certain toxic contaminants such as methylmercury (MeHg) compared to their terrestrial counterparts. If aquatic organisms come to land, terrestrial organisms that consume them are expected to have elevated MeHg concentrations. But emergent aquatic insects could have other impacts as well, such as altering consumer trophic position or increasing ecosystem productivity as a result of nutrient inputs from insect carcasses. We measure MeHg in terrestrial arthropods at two lakes in northeastern Iceland and use carbon and nitrogen stable isotopes to quantify aquatic reliance and trophic position. Across all terrestrial focal arthropod taxa (Lycosidae, Linyphiidae, Acari, Opiliones), aquatic reliance had significant direct and indirect (via changes in trophic position) effects on terrestrial consumer MeHg. However, contrary to our expectations, terrestrial consumers that consumed aquatic prey had lower MeHg concentrations than consumers that ate mostly terrestrial prey. We hypothesize that this is due to the lower trophic position of consumers feeding directly on midges relative to those that fed mostly on terrestrial prey and that had, on average, higher trophic positions. Thus, direct consumption of aquatic inputs results in a trophic bypass that creates a shorter terrestrial food web and reduced biomagnification of MeHg across the food web. Our finding that MeHg was lower at terrestrial sites with aquatic inputs runs counter to the conventional wisdom that aquatic systems are a source of MeHg contamination to surrounding terrestrial ecosystems.

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Section: Discussionsupporting

confidence: 62%

Taking the trophic bypass: aquatic‐terrestrial linkage reduces methylmercury in a terrestrial food web

Bartrons

Gratton

Spiesman

et al. 2015

Ecological Applications

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“…Recent research has focused on the movement of MeHg from freshwater to terrestrial food webs via aquatic insects (Wyman et al. , Kraus et al. ).…”

Section: Discussionmentioning

confidence: 99%

Dissolved organic carbon modulates mercury concentrations in insect subsidies from streams to terrestrial consumers

Chaves-Ulloa

Taylor

Broadley

et al. 2016

Ecological Applications

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Mercury (Hg) concentrations in aquatic environments have increased globally, exposing consumers of aquatic organisms to high Hg levels. For both aquatic and terrestrial consumers, exposure to Hg depends on their food sources as well as environmental factors influencing Hg bioavailability. The majority of the research on the transfer of methylmercury (MeHg), a toxic and bioaccumulating form of Hg, between aquatic and terrestrial food webs has focused on terrestrial piscivores. However, a gap exists in our understanding of the factors regulating MeHg bioaccumulation by non-piscivorous terrestrial predators, specifically consumers of adult aquatic insects. Because dissolved organic carbon (DOC) binds tightly to MeHg, affecting its transport and availability in aquatic food webs, we hypothesized that DOC affects MeHg transfer from stream food webs to terrestrial predators feeding on emerging adult insects. We tested this hypothesis by collecting data over two years from 10 low-order streams spanning a broad DOC gradient in the Lake Sunapee watershed in New Hampshire. We found that streamwater MeHg concentration increased linearly with DOC concentration. However, streams with the highest DOC concentrations had emerging stream prey and spiders with lower MeHg concentrations than streams with intermediate DOC concentrations; a pattern that is similar to fish and larval aquatic insects. Furthermore, high MeHg concentrations found in spiders show that MeHg transfer in adult aquatic insects is an overlooked but potentially significant pathway of MeHg bioaccumulation in terrestrial food webs. Our results suggest that although MeHg in water increases with DOC, MeHg concentrations in stream and terrestrial consumers did not consistently increase with increases in streamwater MeHg concentrations. In fact, there was a change from a positive to a negative relationship between aqueous exposure and bioaccumulation at streamwater MeHg concentrations associated with DOC above around 5 mg/L. Thus, our study highlights the importance of stream DOC for MeHg dynamics beyond stream boundaries, and shows that factors modulating MeHg bioavailability in aquatic systems can affect the transfer of MeHg to terrestrial predators via aquatic subsidies.

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“…Insects are the important constituent of the ecosystem and provide a significant source of food for wildlife such as spider, birds and some other small mammals. It is reported that some insects accumulate large amount of mercury in their bodies and result in physiological toxicity (Wyman et al, 2011;Townsend et al, 2014). Additionally, mercury would be transported to organisms on the higher position from insects along food chains .…”

Section: Introductionmentioning

confidence: 99%

Mercury in terrestrial forested systems with highly elevated mercury deposition in southwestern China: The risk to insects and potential release from wildfires

Zhou

Wang

Sun

et al. 2016

Environmental Pollution

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a b s t r a c tForests are considered a pool of mercury in the global mercury cycle. However, few studies have investigated the distribution of mercury in the forested systems in China. Tieshanping forest catchment in southwest China was impacted by mercury emissions from industrial activities and coal combustions. Our work studied mercury content in atmosphere, soil, vegetation and insect with a view to estimating the potential for mercury release during forest fires. Results of the present study showed that total gaseous mercury (TGM) was highly elevated and the annual mean concentration was 3.51 ± 1.39 ng m À2 .Of the vegetation tissues, the mercury concentration follows the order of leaf/ needle > root > bark > branch > bole wood for each species. Total ecosystem mercury pool was 103.5 mg m À2 and about 99.4% of the mercury resides in soil layers (0e40 cm). The remaining 0.6% (0.50 mg m À2) of mercury was stored in biomass. The large mercury stocks in the forest ecosystem pose a serious threat for large pluses to the atmospheric mercury during potential wildfires and additional ecological stress to forest insect: dung beetles, cicada and longicorn, with mercury concentration of 1983 ± 446, 49 ± 38 and 7 ± 5 ng g À1 , respectively. Hence, the results obtained in the present study has implications for global estimates of mercury storage in forests, risks to forest insect and potential release to the atmosphere during wildfires.

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Mercury bioaccumulation, speciation, and influence on web structure in orb‐weaving spiders from a forested watershed

Cited by 16 publications

References 30 publications

Taking the trophic bypass: aquatic‐terrestrial linkage reduces methylmercury in a terrestrial food web

Taking the trophic bypass: aquatic‐terrestrial linkage reduces methylmercury in a terrestrial food web

Dissolved organic carbon modulates mercury concentrations in insect subsidies from streams to terrestrial consumers

Mercury in terrestrial forested systems with highly elevated mercury deposition in southwestern China: The risk to insects and potential release from wildfires

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