Despite that there are and have been few local source of contaminants, and the Barents Sea is one of the “cleanest” oceans in the world, animals on the top of marine food web such as polar bears and sea birds (e.g glaucous gulls) exhibit high concentration of some hazardous substances.
Contaminants that pose a risk to marine birds and mammals are especially POPs. The lipophilic (dissolves in fat storages in living organisms) nature and persistence of these compounds contribute to their bioaccumulation and biomagnification in marine food webs. These compounds are a particular problem in arctic animals because of their accumulation and subsequent seasonal cycling of lipid stores (which have accumulated high levels of toxins).
Legacy POPs are chemicals that have been banned or restricted (as a part of the Stockholm convention). Reduction in use, have resulted in declining levels that are transported in to the area, but due to their persistence, they remain in the environment. Examples are PCB, HBC and DDT. At high levels, these substances can inhibit immune-system function or cause developmental problems in fetuses or young animals (e.g AMAP, 2009; Gabrielsen, 2007).
A major challenge is to understand the impacts of POPs in the wildlife and to link effects seen in animals to a specific cause, such as load of chemicals. There are always a number of factors that simultaneously affect the health of an animal, like infections, predation, climate change and food scarcity. This makes it difficult to prove cause-effect relationships for one specific stressor. There are however strong indications that contaminants have affected the vitality of the polar bear populations around Svalbard and recent studies of biological effects of POPs have been able to confirm the casual link between POPs and observations of adverse effects in Arctic top predators. These controlled experiments show effects on hormone, immune and reproductive systems. These effects are mainly due to breakdown products from the pollutants, indicating that these may be more important than the original POP compounds (AMAP, 2009).
Levels of contaminants presently found in Brünnich’s guillemots on Bear Island and Levels of contaminants presently found in Brünnich’s guillemots on Bear Island and Kongsfjorden are not considered to affect survival and reproduction of this species, but may have effects under nutritional stress (Gabrielsen, 2007). Studies of the glaucous gulls at Bear Island show correlations of e.g. adult survival, breeding success and high levels of PCB (Bustnes et al., 2006), and even lower levels of contaminants may affect the birds when food availability is low (Helberg et al., 2005; Bustnes et al., 2008). Levels of PCBs and DDEs determined recently in the ivory gull eggs from the northern Barents Sea appeared to be among the highest measured in seabird eggs in the Arctic (Miljeteig et al., 2009). Species at the top of the food chain are most vulnerable to the accumulation of environmental pollutants and many seabirds belong to this group (Gabrielsen, 2007; Letcher et al., 2009).
Other contaminants of concern are radioactive substances that may have harmful effects on population and the ecosystem. For details see pollution-related texts in chapters General background description of the ecosystem; Current and expected state of the ecosystem and Issues of importance for ecosystem based management.