The diatoms Odontella sinensis, Coscinodiscus wailesii and Thalassiosira punctigera in the European Atlantic: recent introductions or overlooked in the past?
Gómez, F.; Souissi, S. (2010). The diatoms Odontella sinensis, Coscinodiscus wailesii and Thalassiosira punctigera in the European Atlantic: recent introductions or overlooked in the past? Fresenius Envir. Bull. 19(8): 1424-1433
In: Fresenius Enviromental Bulletin. Birkhäuser: Basel, more
The diatoms Odontella sinensis, Coscinodiscus wailesii and Thalassiosira punctigera are the most common examples of non-indigenous phytoplankton species in the European Seas. We investigated their seasonal and interannual distributions at two fixed stations in the northeast English Channel (1998-2005). The climate conditions along our 8-y time series and those during the first historical outbreaks in Europe were reconstructed. Odontella sinensis was preferentially found in late summer and early autumn, especially after 2003. A change in the climate in 1903 may have favoured the development of O. sinensis that until then had gone unnoticed due to the low sample coverage. Coscinodiscus wailesii was preferentially found in winter and early spring, with a maximum in April 2001 (720 cells L-1). This coincided with exceptionally high precipitation rates, river discharges and a cold winter (negative phase of the North Atlantic Oscillation). Thalassiosira punctigera was sporadically found between autumn and early spring, with a peak in mid-December 2005 after abnormal autumn weather. The blooms of C. wailesii and T. punctigera in 1977-79 coincided with the arrival of the ‘Great Salinity Anomaly’ into the English Channel, negative NAO phase and higher river discharges. In addition to an introduction from sub-arctic waters, these two diatom species may remain as residual populations under ‘normal’ hydroclimatic conditions, misidentified, overlooked in the past and favoured after atypical climate periods. The consideration for these diatoms being labelled as introduced or non-native species is questionable.
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