ArcOD is an international collaborative effort to inventory biodiversity in the Arctic's three realms (sea ice, water column and sea floor) from the shallow shelves to the deep basins using a three-step approach: compilation of existing data, taxonomic identification of existing samples, and new collections focusing on taxonomic, regional and other gaps from land based stations, and ice breaker expeditions. The taxonomic scope is wide ranging from microbes to mammals. ArcOD is one of the field projects of the Census of Marine Life (CoML), which is a growing global network of researchers in more than 70 nations engaged in a ten-year (2000-2010) initiative to assess and explain the diversity, distribution, and abundance of marine life in the oceans - past, present, and future. ArcOD will contribute to the Ocean Biogeographic Information System (OBIS) and the Global Biodiversity Information Facility (GBIF). An ArcOD office and a centre have been operating at the University of Alaska Fairbanks and at PP Shirshov Institute in Moscow/Zoological Institute St. Petersburg, respectively, since 2004. Some of the questions ArcOD is faced with include: What is the relationship between species distribution patterns, species richness and environmental conditions and processes in a climate change framework? Is species richness in the Arctic really lower than in lower latitudes - across realms, depth strata and size-classes? What is the distribution of bio-geographic affinities (Atlantic, Pacific, Arctic and cosmopolitan) in all three realms? Are regional differences significant on a molecular level? Can we provide consistent information on biodiversity across scales and model and predict it?
