A reassessment of Northern Atlantic seaweed biogeography

Abstract

Abstract On the basis of 25 seaweed floras of both the North Atlantic Ocean and the Mediterranean Sea mutual similarity dendrograms have been obtained for whole floras as well as for major taxonomic groups. Nine biogeographical regions were recognized: Tropical Western Atlantic Region, Warm Western Atlantic Region, Cold Western Atlantic Region, Arctic Atlantic Region, Cold Eastern Atlantic Region, Warm Eastern Atlantic Region, Subtropical Eastern Atlantic Region, Tropical Eastern Atlantic Region, Mediterranean Region. With some minor differences the pattern in the various taxonomic groups is very similar. Statistical relationships have been sought between species numbers and several geographical features (latitude, longitude, average February seawater temperature, average August seawater temperature, tidal height and coastal length). For the whole flora (including the Rhodophyta), tidal height appears to be inversely related to species numbers, and average seawater temperature in August and February is di...