14 DAY TRIAL // Pollution has been known to play a role in the deterioration of both dry land and maritime wildlife for quite some time now. But scientists say that seals are most affected by its effects, because their immune systems are virtually destroyed by a form of mercury - Methylmercury (MeHg) – associated with human activities around seal habitats.
Volcanic eruptions can also cause increased quantities of mercury to be spilled in the oceans. However, pollution is identified as the primary cause of mercury build-up in several seal species, a new report indicates. Once inside the animals, the chemical binds with T lymphocytes, a key part of the immune system in both them and humans. The reaction that follows causes the immune cells to stop working, thus rendering the animal's body vulnerable to outside infections.
In fact, the 1998 and 2002 phocine distemper virus outbreaks, which killed thousands of seals, are now attributed to severe pollution. Under normal circumstances, the animals would have been able to protect themselves from the virus, as their immune systems are very strong. But long-term, lasting mercury effects made them unable to adapt and develop a response to the infection. Then, harbor seals were the most affected, with many reported casualties around the globe.
Krishna Das, lead author of the current study and professor at the Université de Liège in Belgium, conducted some tests on blood samples gathered from seals caught in the North Sea and found out that already existing mercury quantities in seals' blood streams were sufficient to cause permanent damage or extended vulnerability to outside infections. She added "Although the in vitro approach utilised in this investigation represents an extreme reductionism relative to the complex situation in the intact organism, it provides an insight into the specific effects of mercury pollution."
The situation could turn out to be very desperate for thousands of seals, especially if pollution levels continue to climb. Coupled with other problems they face, the species could be driven to the brink of extinction very soon. In fact statistics show that most fish species are endangered right now. The only way to stop their disappearance is to limit and reverse pollution in their natural habitats.