Reasons for success Within relatively confined waters of variable salinity it suffers little competition from other serpulids. Many estuaries are characteristically areas of high productivity and so filter-feeders such as Ficopomatus enigmaticus , which are able to stand considerable variations in salinity are well placed to reap the benefit. High fecundity, possibly allied with larval retention within semi-enclosed waters, facilitates a rapid build up of numbers and initially there might be an absence of predators. Its distribution is, however, confined to coastal brackish waters and therefore disjunct. This species is known to be widespread throughout Europe, including Ireland.
More northerly populations survive owing to artificially raised water temperatures.
In addition, successful reproduction is considered to be limited to waters of variable salinity. In Britain, therefore, any future invasions or spread would be expected to be confined to brackish waters on southern coasts. This species favours waters which present some degree of stress to most open-shore marine organisms. Its requirement for variable-salinity water in which to spawn ensures that the major populations do not interfere with most indigenous species. It is a fouling species which affects ships, buoys and harbour structures.