Extension of the range of the Bryozoans <i>Tricellaria inopinata</i> and <i>Bugula simplex</i> in the north-east Atlantic ocean (Bryozoa: Cheilostomatida)

A survey of the bryozoan fauna of harbours and marinas in the Netherlands, Belgium and France revealed two interesting bryozoans. The invasive Tricellaria inopinata originates from the North Pacific Ocean. It has probably been introduced by man in southern Australia, New Zealand, the western part of the Pacific and in Venice. In recent years it has expanded its range in the lagoon of Venice and colonized the Atlantic coast of Europe. It has now been found for the first time in France, Belgium and the Netherlands. Bugula simplex was first described in 1886 from the Adriatic Sea. Its occurrence mainly in ports and harbours in the North-East Atlantic suggests introduction by man. At the end of the twentieth century the species was introduced to Australia and New Zealand and it is also known from the Atlantic coast of Norh America. It has now been found for the first time in the Netherlands and Belgium. Expected future developments in the distribution of both species in Belgium and the Netherlands are discussed