Are beluga whales victims of PAHs?
The principal suspects in the development of intestinal cancer in beluga whales are the PAHs produced by aluminum smelters in the Saguenay area. However, scientific proof of this connection has yet to be established. The presence of PAHs in the sediment and organisms of the Saguenay and St. Lawrence is alarming and deserves a special attention. The trophic transfer of carcinogenic PAHs is a process that is practically unknown in natural ecosystems, and even less so in a system as vast as the St. Lawrence.
To go through the looking glass
In 2000, PAHs (26 different molecules) from 5 sediment cores taken at different stations in the Saguenay Fjord were analyzed. In 2001 and 2002, benthic and pelagic organisms were sampled all along the Saguenay Fjord, as well as at two stations in the St. Lawrence Estuary, near the mouth of the Fjord. During these cruises, organisms were taken from all trophic levels, including annelids, gastropods, echinoderms, bivalves, crustaceans (crab, shrimp and krill) and several species of fish. The analysis of all of these animals began in May 2003 and will take more than a year to be completed. The purpose of these analyses is to determine not only PAH concentrations, but also levels of metabolites produced by several species as a defence mechanism against contamination. Another sampling cruise was done in the spring of 2003 and has encompassed the entire length of the St. Lawrence between Orleans Island and Anticosti Island. The goal of this mission is to evaluate the contribution of PAHs from the St. Lawrence River to habitats used by belugas and other marine mammals living in the Estuary.
These data will be used to determine if PAHs are, or are not, present in beluga food. If they are present, we will follow their movement through the St. Lawrence food web and determine what threat these compounds could pose to the environmental health of the St. Lawrence.
Émilien Pelletier Institut des sciences de la mer de Rimouski (ISMER), Université du Québec à Rimouski
The Saguenay–St. Lawrence Marine Park, Natural Sciences and Engineering Research Council of Canada (NSERC), Fonds québécois de recherche sur la nature et les technologies (FQRNT) and Alcan Ltd.
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