species associated with sea ice, which provides a habitat for numerous Arctic species. On land, trees are beginning to encroach on the tundra ecosystem, and a number of plant communities, including species of grasses, sedges, mosses, and lichens, are being replaced by species from more southerly regions7

. I

Populations of certain vertebrates in the Arctic are also declining. The Arctic Species Trend Index (ASTI), which has tracked vertebrate populations in the Arctic over the past 34 years, showed a 10 percent decline in terrestrial vertebrate populations7

. Although the majority

of Arctic species examined in the Arctic Biodiversity Trends 2010 report are stable or increasing, some species of importance to humans are declining. Wild reindeer and caribou, for example, have declined by approximately one- third since their populations peaked in the 1990s and early 2000s7

. II

Other stressors are also impacting Arctic biodiversity. Contaminants can affect Arctic biodiversity, through bioaccumulation in tissues, and can affect the reproduction and mortality of species. Although many so-called “legacy” persistent organic pollutants (POPs) are declining in the Arctic as a result of past bans and restrictions on use and emissions, their concentrations are still high enough to affect biodiversity. Some new POPs, such as polybrominated and perfluorinated compounds, and mercury*

, are not yet

regulated internationally and have the potential to travel and accumulate in Arctic food webs.The Arctic Biodiversity Trends 2010 report also cites habitat fragmentation, industrial development and unsustainable harvest as continuing to have impacts7

. Many Arctic Council reports and other scientific research publications contain a wealth of information on more conventional threats to biodiversity caused by contaminants, resource development pressures, shipping and transportation, and so on. (See Case Studies in Part II for further description of stressors and threats on Arctic biodiversity).

* See reference to the global mercury convention currently under negotiation in Chapter 3.

22 PROTECTING ARCTIC BIODIVERSITY