The sublittoral distribution of crustose corallines on the Norwegian coast

Abstract

The geographic and depth distributions of crustose corallines, in percent relative abundance, from Oslofjorden coastwise to Varangnfjorden are given. The patterns, coastal and inner fjord, are compared with similar data from Iceland and North America. The existence in the North Atlantic of two major groups of subarctic-boreal crustose corallines, one requiring winter temperatures below 1–4° C, and the other requiring temperatures above that level, is shown. It is hypothesized that temperature control of winter reproduction is involved. The interaction of these two groups in Norwegian waters is discussed.