
This study provides the drivers of variation in mercury concentrations in seabirds and, further, the first biologically based estimate of oceanic mercury distribution, analyzing blood mercury levels in more than 11,215 seabirds from 108 species, including 659 newly collected samples and over 10,556 from prior research. (THg: total mercury) Credit: Jumpei Okado (modified from Okado et al. 2026
(CC BY 4.0)
Scientific Frontline: Extended "At a Glance" Summary: Biologically Derived Oceanic Mercury Distribution
The Core Concept: This research provides the first biologically based estimate of global oceanic mercury distribution by analyzing blood mercury concentrations in more than 11,000 seabirds across 108 species.
Key Distinction/Mechanism: Unlike traditional approaches that rely heavily on marine biogeochemical simulation models, this methodology utilizes empirical measurements from marine organisms. Because mercury bioaccumulates as it moves up the food chain, seabird blood accurately reflects short-term dietary mercury intake, capturing the physical realities of marine toxicity across diverse geographic regions and foraging depths.
Major Frameworks/Components:
- Trophic Bioaccumulation: Mercury concentrations are measurably higher in seabirds with larger body mass, those positioned at higher trophic levels, and species foraging at mesopelagic depths between 200 and 1,000 meters.
- Regional Stratification: Statistical mapping identified heightened mercury levels in the North Atlantic, North Pacific, and zones of low primary productivity, contrasting with significantly lower levels in the South Atlantic and Southern Oceans.
- Sentinel Species Viability: The utilization of seabird blood collected during breeding acts as an effective, low-harm indicator of localized ocean health, specifically reflecting mercury intake over the two months prior to sampling.

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