On the distribution of the intertidal barnacles Chthamalus stellatus, Chthamalus montagui and Euraphia depressa

Abstract

There are three species of chthamalids in Europe. Two of them, Chthamalus stellatus and Chthamalus montagui, overlap extensively in geographic range: they occur together along the whole Atlantic coasts of Britain, Ireland, France, Spain and N. Africa, and both also occur in the Mediterranean Sea. They have almost identical north-eastern limits to their distribution in the English Channel and N. Scotland, but C. stellatus may extend farther south along the W. African coast. These two species also show overlap in their vertical distribution, though C. montagui is usually commoner in the upper barnacle zone while C. stellatus may be dominant lower down. The species are separated by habitat, C. stellatus favouring wave-beaten open coast sites, C. montagui more embayed situations, but there is still extensive overlap. The third European species of chthamalid, Euraphia depressa, has a more restricted vertical distribution and is almost entirely confined to the Mediterranean Sea, where it favours high-intertidal levels in wave-beaten places, and also cryptic habitats.