DIVERSITY OF ISOPODS (CRUSTACEA) - NEW DATA FROM THE ARCTIC AND ATLANTIC OCEANS

New data on the diversity pattern of isopods (Crustacea) from the nort hern most part of the North Atlantic and the Arctic Oceans is presente d. The pattern of diversity with depth is similar at depths < 1000 m, but differs considerably below about 1000 m. In the Arctic the diversi ty of isopods (expressed both as numbers of species per sled and expec ted number of species) increased with increased depth to a maximum at depths of about 320 to 1100 m, but then declined towards deeper waters . There was a significant increase in numbers per sled and in the expe cted number of species with increased depth in the northernmost part o f the North Atlantic Ocean. Additionally, changes occurred in the rela tive composition of the shallow and deep water fauna, with asellote is opods being relatively larger part of the isopod fauna in the Arctic t han in the northern most part of the North Atlantic. This indicates ma jor faunistic changes occurring at the Greenland-Iceland-Faeroe Ridge, possibly caused by rapid changes in the temperature. Furthermore, tha t the low diversity of the Arctic deep-sea is a regional phenomenon, a nd not a part of a large scale latitudinal pattern in the North Atlant ic.