摘要：Based on extensive data from a variety of sources, including Russian-American Long-term Census of the Arctic expeditions in 2009 and 2012, this paper provides an update on the richness of bryozoans in the Chukchi Sea and evaluates the variation in bryozoan biodiversity along environmental gradients (e.g., depth, bottom water temperature, and bottom sediment composition). Though bryozoans have been studied in only about 77% of the Chukchi Sea, temperature gradients across geographical zones appear to control fauna richness. The inflow of Pacific water through the Bering Strait into the Chukchi Sea strongly influences the distribution of the 204 registered bryozoan species, about 30% of which have a Pacific origin. The greatest similarities between bryozoan fauna in the Chukchi Sea and those occurring further south in the Bering Sea are found in the southern and eastern parts of the Chukchi Sea. The transitional zone between Arctic and Pacific high-boreal biogeographic regions occurs in the western and northern areas of the Chukchi Sea. The dominance of boreal bryozoan species over Arctic species in the southeastern and southern areas of the Chukchi Sea identifies this area as part of a Pacific high-boreal region. The boundary between boreal and northern transitional zones corresponds to a 50:50 ratio of boreal to Arctic species, with the transition extending from Cape Serdtse-Kamen’ in the western Chukchi Sea northward to Point Franklin (68°30'N) in the eastern Chukchi Sea.
