polar bears Essay

Submitted By Jessica-Rong
Words: 577
Pages: 3

Polar bears in the Arctic are tremendously affected by pollution now. As global warming progresses, wind and water currents carry pollutants, most of which come from industrial sources in different parts of the world, and cause them to travel to the Arctic because of the ‘conveyor belt’ nature of the atmosphere and ocean (Yarim 2013). These chemicals accumulate in the fat of many animals, mainly through the food chain, which are then eaten by top predators such as polar bears. Thus, polar bears inevitably have severe health problems and risk death.
When consumed at high levels, the pollutants can have a dramatic and potentially fatal impact, which affects the polar bear population in the Arctic severely. The most prevalent chemicals found in the Arctic are “Persistent Organic pollutants (POPs)”, such as the pesticide DDT, the industrial chemical polychlorinated biphenyls (PCBs), which can biomagnify up the food chain. Other pollutants may include acid rain, heavy metals and radioactive isotopes (Yarim 2013). According to studies, bears with high levels of some POPs have low levels of vitamin A, thyroid hormones, and some antibodies (WWF Global 2009). The pollutants load of polar bears in the Arctic are negatively affecting the immune system, hormone regulation, growth patterns, reproduction, and survival rates of polar bears. The studies have suggested that the immune system is weaker in some polar bears with higher levels of PCBs. A weakened immune system means that these polar bears are more susceptible to disease or parasites and even death in some cases (IUCN/SSC PBSG 2009).
Additionally, the polar bear population in the Arctic is also heavily influenced by the effect of pollution on its fertility and reproduction. The male bears that have higher level of pesticides in their body have the smaller size and weight of their testicles, not to mention that the ovary size and weight in female bears also decrease as pollutant levels rise (Ned Haluzan 2011). Even if the female and male succeed in breeding, the embryo or fetus is more vulnerable to the effects of pollution through endocrine (hormone) disruption due to the delayed implantation of the blastocyst in polar bears. Further, because female polar bears are fasting during gestation, the pollution loads of their fetuses increase because they are using their fat stores for energy…