Naididae is primarily a freshwater group, but the species included here occur sometimes or exclusively in brackish water. The most comprehensive and still useful review of naidids is Sperber´s (1948) monograph, but for the partly marine genus Paranais, Brinkhurst and Coates (1985) should also be considered.

The marine members of the Tubificidae have been subject to extensive systematic studies in recent years, in particular by C. Erséus, but since the publication of the key to marine and estuarine European species by Brinkhurst (1982), there is no compiled information other than that to be gathered from the primary taxonomical literature (e.g. Brinkhurst 1985, 1986; Erséus 1982, 1983a-b, 1985, 1987a-b and 1992). Some tubificids are restricted to brackishwater, but the majority of species are indeed marine, some species occuring at bathyal or even abyssal depths.

The single megascolecid included, Pontodrilus bermudensis, known from the Mediterranean Sea, is an earthworm (Easton 1984). It is widely distributed in marine beaches throughout the tropics and subtropics of the world, and one of the few, if not the only, earthworm in marine habitats.

The revision and taxonomy of European Enchytraeidae by Nielsen & Christensen (1959, 1961, 1963) provides the basis for the present list of this family, but over 30 European species have been subsequently added and more species await description. Taxonomic difficulties, and the lack of a modern guide to European species, mean that enchytraeids continue to be neglected and are almost never identified, even to genus, in surveys of marine fauna. Faunistic studies have been concentrated in principally the western Baltic, western Scandinavia and continental North Sea coasts, Iceland, Ireland, Wales, and the Atlantic coast of France. There are some records from Svalbard, Barents Sea, Beloye More (White Sea), the eastern Baltic, and Scotland, but few from the coasts of the Iberian Peninsula or the Mediterranean.

Marine enchytraeids are mainly associated with habitats in the upper intertidal, and only the genus Grania is widespread in offshore benthos. Most records are from intertidal deposits, and tidal debris around high water mark where there is some overlap with the terrestrial fauna. The most commonly reported terrestrial species in saltmarshes and tidal debris are included in the list (six spp). The lower salinity limit for most brackishwater species appears to be about 3 ppt, i.e. a-oligohaline according to the Venice System of classification. In the Baltic, some brackishwater enchytraeids have been found to coexist with freshwater and terrestrial species at lower salinities (0.5-3 ppt). However, the salinity of oligohaline waters is rarely recorded by oligochaete specialists and the range of tolerance of the species is unknown. For this reason, four frequently recorded "freshwater" species taken with brackishwater species are included in the list.Many oligochaetes of the Baltic Sea are included in a recently published guide to the Estonian annelids (Timm 1999), including an illustrated key.

References

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