- Research Article
- 10.1016/j.ecolind.2026.115621
Contrasting nutritional proxies and methylmercury exposure in zooplankton delivered by little auks across Greenland and Svalbard
- Oct 01, 2026
- Ecological Indicators
- Kaja Balazy + 15 more +15
Zooplankton forms a key trophic interface in Arctic marine ecosystems, transferring both nutritional resources and contaminants to higher consumers. Yet these dimensions are rarely evaluated together in the prey actually selected and delivered by predators under natural foraging conditions. We used little auks ( Alle alle ) as biological samplers of realized chick-provisioning diets and analysed 138 food loads collected across eight colony-by-year domains at six colonies in Greenland and Svalbard during 2022–2023. We quantified methylmercury (MeHg), total mercury (THg), carotenoids, molar carbon-to‑nitrogen (C:N) ratio, stable carbon and nitrogen isotopes, and taxonomic composition. We also combined standardized carotenoid, molar C:N ratio and MeHg measurements into a dataset-relative Nutrition–Toxicity Trade-off (NTT) score describing their joint configuration within individual diets. Diet chemistry differed markedly among the sampled domains, with particularly pronounced differences in MeHg, molar C:N and stable-isotope values. The component profiles showed that nutritional proxies and MeHg exposure did not necessarily covary: similar relative NTT scores could arise from different combinations of carotenoids, molar C:N and MeHg. Taxon-specific composites further showed that THg did not consistently track either MeHg concentration or the MeHg fraction and that these MeHg characteristics varied among locations within the same prey taxon and developmental stage. An exploratory domain-level analysis further showed a negative association between median dietary MeHg and sea-surface salinity. Where corresponding samples were available, variation in adult blood THg and astaxanthin broadly paralleled patterns observed in chick-provisioning diets. These results show substantial variation in the chemical characteristics of predator-selected zooplankton across contemporary Greenland and Svalbard foraging domains and demonstrate the value of jointly considering nutritional proxies and contaminant exposure when characterizing realized trophic conditions.
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