Organic pollutants in plankton have mostly been investigated near the research stations and their sewage systems. The results are therefore not especially representative for plankton in Antarctica. Studies of contaminants in krill, a key species in the Antarctic ecosystem, have shown that HCB? is the most dominant contaminant. The studies have so far not found any biomagnification? from plankton to krill.
Fish which live on the shelf, such as emerald rockcod, contain contaminants like DDT?, PCBs and PAHs in levels corresponding to those in their most important food item, krill. The levels are lower than in fish in other waters. Bottom-living fish species have somewhat higher levels of contaminants because they feed on other nutrient sources than krill.
Marine mammals in Antarctic waters have far lower levels of contaminants than those in the Arctic. However, it has been found that levels of some herbicides rose in 1984-1994 in species living in the south, whereas they fell in the north. This means that the herbicides were still being used in the Southern Hemisphere, whereas they were banned in the north. Weddell seals at George V Land have the lowest values in the world of DDT and PCBs in their blubber, and they are also lower than in seals elsewhere in Antarctica. This shows that the variations may be great within Antarctica, too.
Emperor and Adélie penguins are good indicator species for the marine food chain because they breed on the continent itself. Adélie penguins have a low transfer rate for PCBs and DDT from mother to chick, only 4 %. In general, the concentrations of organic pollutants in penguins are lower than known threshold values for toxicological effects. However, as no research has been performed on threshold values for penguins, no conclusions can be drawn about this. Studies from Palmer Station show that levels of DDE (a breakdown product of the herbicide, DDT) have not changed in Adélie penguins on the Antarctic Peninsula for 30 years, in contrast to DDT levels, which fell significantly in 1975-2003 in seabird eggs in Antarctica as a whole.
A baseline survey carried out in 1997 on the Antarctic Peninsula focused on levels of heavy metals in Antarctic organisms (34 species of algae, filtering animals, invertebrates and vertebrates). Mercury was only found in elephant seals and seabirds in low levels, whereas cadmium was found in low levels in the majority of organisms, except fish. Some invertebrates had very high contents of zinc, whereas the highest copper levels were found in a snail.