Spiders as sentinels of mercury contamination in high arctic lentic systems and potential risk to arachnivorous birds
Strang, Benjamin
Strang, Benjamin
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2024-12-02
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Abstract
Due to global atmospheric circulation of mercury, polar food webs are contaminated with detectable levels of mercury despite their remoteness. In aquatic systems, inorganic forms of mercury are methylated into the bioavailable and toxic form, methylmercury. The Arctic has an estimated 1.4x106 km2 of freshwater lakes and ponds, making monitoring efforts of where wildlife may be at risk of mercury exposure difficult. Common sentinels of aquatic Hg contamination in monitoring studies include dragonflies, fish, and spiders. However, only spiders are found consistently and at high abundance in Arctic ecosystems. Spiders are also consumed by nestling songbirds and therefore can also provide insight into the potential health risk mercury poses to arachnivorous birds. The objectives of the present study were to 1) determine if spiders are sentinels of freshwater Hg contamination in six Arctic lentic systems located in northwest Greenland and 2) to determine if Hg-contaminated spiders pose a health risk to arachnivorous birds. The average (± 1 SE) concentration of MeHg of P. glacialis from all lentic systems was 424.0 (± 28.4) ng/g (range: 212.9 to 897.9) dry weight (dw). We detected a significant main effect of leg length on spider tissue MeHg concentration (p = ≤ 0.001); spider tissue MeHg concentration was positively correlated with leg length at each site. We detected a significant leg length × site interaction effect (GLM, F5,21 = 4.4, p = 0.007) and we observed a significant positive relationship between riparian spider and aquatic insect tissue MeHg (linear regression, R2 = 0.75, p = 0.04). The results of this study suggest that shoreline spiders are sentinels of aquatic mercury contamination, providing evidence for their future use as sentinels of other aquatic systems in the Arctic. We also suggest that arachnivorous birds are at varying levels of risk from MeHg toxicity at six lentic systems in Northwest Greenland.
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Subject
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Biology
Arachnivorous birds
Mercury poisoning
Spiders
Arachnivorous birds
Mercury poisoning
Spiders
Research Projects
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Biology