Marine predators as sentinels for our oceans and human health

“During the course of the 20th century, the planet became and is now chemically different from any previous time”. (1)

Organic and inorganic chemicals occur in greater abundance because of human activity and end up in the ocean. As more humans inhabit coastal regions, question arises about the health of our oceans. Marine vertebrates such as marine fish, turtles, birds and mammals are used to get early warning about negative trends and impact linked to anthropogenic activities. Such organisms are qualified as sentinel species (2). In turn, sentinels will permit us to better characterize and potentially manage negative impacts on human and animal health associated with our oceans. Marine predators including marine mammals and birds can present elevated concentrations of these organic and inorganic chemicals in their tissues, due to their high position in the trophic chain, their life span, and their fat store in which lipophilic chemicals accumulate.
Humans and marine predators share common routes of exposures such as (1) the maternal transfer through placenta and milk and (2) trophic transfer through ingestion of marine fish and shellfish. Furthermore, some human population rely on marine mammal consumption for subsistence. Marine predators offer a snapshot of ocean health that could potentially impact human health. In the hope that this paper will stimulate the research much needed for assessing ocean health in the context of a rapidly changing environment, we provide here a review of (i) levels and trends of contaminants and relationships with biotic and abiotic factors, (ii) toxicological effects and (iii) spatial and geographical trends in tissues of marine predators. We conclude this communication by presenting several necessary perspectives such a more thorough follow of organic and inorganic pollutants in the marine environment including the use of isotopic tracers to assess the local versus global aspects of marine pollution.

(1) Reddy, C. M., Stegeman, J. J. & Hahn, M. E. in Oceans and human Health (eds P.J. Walsh et al.) 121-144 (Academic Press, 2008). (2) Bossart G.D. (2011). Vet. Path. 48:676-690.