Marine mammals integrate exposure across food webs and throughout their lifespans, establishing them as powerful sentinel species for assessing ocean ecosystem health and early warning indicators of seafood-borne metal risks to humans. Based on this premise, this study employed the Web of Science (WOS) Core Collection and a science mapping workflow via CiteSpace to analyze the knowledge structure and temporal dynamics of research on heavy metals in marine mammal organs/tissues (1990–2025, 588 publications). Analytical techniques included co-authorship and country-collaboration networks, keyword co-occurrence, cluster labeling, and timeline visualizations.
The literature reveals sustained growth and a multi-hub collaborative network prominent nodes in the United States, France, and China.. Research fronts have consolidated around four primary domains: "bioindicator role," "heavy metal toxicity effects," "tissue distribution and accumulation characteristics," and "pollution monitoring and risk assessment." These fronts are anchored in well-established biological mechanisms: mercury (Hg) and cadmium (Cd) are the principal priority metals, with burdens typically highest in the liver (Hg) and kidney (Cd), while lead (Pb) partitions predominantly to bone. Key detoxification pathways involve selenium-mediated mercury sequestration and metal-binding proteins. Cross-scale drivers—including diet/trophic level, age, sex, geographic region, and physiological state—govern accumulation patterns and subsequent health effects. Maternal transfer, occurring primarily via the placenta and to a lesser extent through lactation, links adult exposure to developmental risks in offspring.
Timeline analyses chart a progression from baseline surveys to organ- and species-specific mechanisms, and, more recently, a field-wide pivot: from static description to predictive frameworks that embed climate change; from single-substance to mixture assessments (metals with persistent organic pollutants); from status reporting to quantitative ecological and human-health risk (dose–response and thresholds); and from conventional chemistry to integrated multi-omics for early biomarkers and mechanism-resolved warning.
By synthesizing these findings with relevant policy frameworks (e.g., the Minamata Convention) and the Sustainable Development Goals (notably SDG 14 with co-benefits for SDG 3), this science mapping exercise identifies actionable research priorities. These include establishing organ-resolved toxicity thresholds relevant to management, elucidating cross-life-stage and transgenerational effects, developing standardized non-lethal monitoring pipelines, and generating decision-ready evidence that explicitly links biodiversity conservation with seafood safety and the One Health paradigm.
 

Marine mammals; Heavy metals; Bibliometrics; Health risk; Bioindicator