Thalassiosira species are an important component of phytoplankton populations in pelagic waters around the islands of Helgoland and Sylt in the German North Sea. This taxonomic study revealed the presence of at least 27 species, 21 at Helgoland and 21 at Sylt. Fifteen species had not been recorded previously for Helgoland (T. aestivalis, T. angulata, T. concaviuscula, T. curviseriata, T. delicatula, T. diporocyclus, T. hendeyi, T. kuschirensis, T. minima, T. minuscula, T. oceanica, T. pacifica, T. proschkinae, T. tealata, T. tenera) and 16 for Sylt (T. aestivalis, T. angulata, T. concaviuscula, T. constricta, T. curviseriata, T. delicatula, T. guillardii, T. hendeyi, T. lundiana, T. mediterranea, T. minima, T. pacifica, T. partheneia, T. punctigera, T. tealata, T. tenera). We provide brief descriptions with illustrations and document the seasonal occurrence of these species at the two stations. We also discuss investigation methods used for different levels of species recognition, namely Utermöhl counts, light microscopical observations of living net-samples as well as scanning electron microscopy of net-samples and isolated cultures. Clonal cultures of some species were established to facilitate the taxonomic investigations and 18S ribosomal DNA sequencing was carried out to complement the morphological studies. A perspective for a routine species-level assessment strategy is given.
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Document Type: Research Article
Biologische Anstalt Helgoland, Alfred Wegener Institute for Polar and Marine Research, Kurpromenade, D-27498 Helgoland, Germany
Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, D-27570 Bremerhaven, Germany
Wadden Sea Station Sylt, Alfred Wegener Institute for Polar and Marine Research, Hafenstraße 43, Germany
Publication date: 2007-08-01