Seals As Sentinels: NW Atlantic Coast Research
In 2000, MERI launched a long-term research project, Seals As Sentinels: Assessing the Impacts of Toxic Contaminants in Northwest Atlantic Seals. Seals As Sentinels is an ongoing series of studies examining levels, effects, and trends of toxic environmental contaminants in pinnipeds (primarily harbor seals) and their prey fishes. This landmark project has generated the first extensive, region-wide body of contaminants data in marine mammals and commercially important marine fishes along the northwest Atlantic coast (from Canada to New York) and has earned national and international recognition in the scientific and regulatory communities.
In 2007, MERI received a Citation of Recognition from the the 123rd Maine State Legislature for its Seals As Sentinels research. The finding of brominated flame retardants (BFRs) including the widely used flame retardant Deca-BDE in seal tissues influenced the legislature’s decision to ban Deca as of 2010. The program also received recognition from the Gulf of Maine Council on the Marine Environment representing New England states and Atlantic Canada. Named Gulf of Maine Visionary, MERI’s Director, Dr. Susan Shaw was recognized for creating in MERI a world-class research institute uniquely dedicated to environmental issues affecting the Gulf of Maine and for generating an extensive body of data that places the Gulf ecosystem in a global perspective.
Chemical Contamination: A Cause For Concern
Findings to date indicate that northwest Atlantic harbor seals (Phoca vitulina concolor) are highly contaminated by persistent organic pollutants (POPs) and toxic metals such as mercury. In addition to legacy (banned) compounds such as the polychlorinated biphenyls (PCBs), dioxins, DDTs, and other pesticides, the program targets “novel” halogenated chemicals currently used in consumer products such as the polybrominated diphenyl ethers (PBDEs) and perfluorinated chemicals (PFCs). These contaminants tend to bioaccumulate and are found at high levels in top predators such as seals. For example, our findings have demonstrated that many PBDEs readily biomagnify to high levels in seals from their fish prey.
The oceans are regarded as sinks and final reservoirs for these persistent, bioaccumulative, and toxic chemicals that flow to the sea from sources on land and also travel long distances via atmospheric transport. Many are so persistent that once they enter the ocean environment, they can recycle in the food web for decades.
On a global scale, levels of toxic chemicals in these harbor seals are among the highest in the world. This is a cause for concern, since many of these chemicals are structurally similar and exert a similar array of effects in laboratory animals including endocrine disruption, immune alterations, reproductive impairment, and neurodevelopmental effects. MERI’s findings indicate that at current levels, northwest Atlantic harbor seals are potentially at risk for adverse effects and suggest that toxic chemical stress may be contributing to the recurring disease outbreaks and mortalities affecting the population.