Legacy contaminants in waterbird eggs: divergent temporal and spatial trends in the St. Lawrence River, Canada.

Most legacy contaminants declined over five decades in waterbird eggs from the St. Lawrence River, except mercury, which remained stable in both species.

• Why it matters: Understanding long-term contaminant trends in aquatic ecosystems is crucial for assessing ecological recovery and guiding environmental management strategies.
• What they did: The study analyzed levels of mercury, HCB, DDE, dieldrin, Mirex, and PCBs in eggs of American Herring Gulls and Great Blue Herons collected from 1972 to 2022, using generalized additive models to identify temporal and spatial patterns.
• The result: Findings indicate a gradual ecological recovery in the river, with species-specific differences in contaminant accumulation reflecting variations in contaminant pathways and availability across sectors.