Identification Guide to the Planktonic Polychaete Larvae Around the Island of Helgoland (German Bight)
HELGOL.~NDER MEERESUNTERSUCHUNGEN Helgol/inder Meeresunters. 48, 1-58 (1994) Identification guide to the planktonic polychaete larvae around the island of Helgoland (German Bight) S. Plate* & E. Husemann* * Biologische Anstalt Helgoland (Meeresstation); D-27483 Helgoland, Federal Republic of Germany ABSTRACT: The purpose of this work is to provide the means of identifying the planktonic larvae of the polychaete species appearing in the plankton around the island of Helgoland (North Sea). During a three-year survey in this area, the larvae of 54 species out of 24 families belonging to the orders Orbiniida, Spionida, Capitelhda, Phyllodocida, Oweniida, Terebelhda, Sabelhda and the former Archiannelida have been recorded. Illustrated keys to the families, genera and species are presented. To facilitate the identification, additional descriptions and information about the seasonal appearance of the species are given. INTRODUCTION More than 13 000 species of polychaetous annelids take part in the marine benthos communities worldwide. Their distribution, species composition and population density are monitored within various benthos surveys. For the North Sea, especially the German Bight and the Wadden Sea, much information about the benthic polychaete fauna is available (Caspers, 1950; Stripp, 1969; DSrjes, 1977; Rachor & Gerlach, 1978; Gillandt, 1979; Salzwedel et al., 1985; Rachor, 1990; Bosselmann, 1991; Kr6ncke, 1991). In contrast, the holoplanktonic polychaete species and the meroplanktonic polychaete larvae, which are only part of the plankton during a more or less expanded phase of their ontogenesis, have never received much attention. Meroplanktonic polychaete larvae are seldomly recorded during studies monitoring the North Sea plankton (Smidt, 1951; Giere, 1968; Fransz, 1981; Bosselmann, 1989; Belgrano et al., 1990).
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