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The dinoflagellate genus Chytriodinium, an ectoparasite of copepod eggs, is reported for the first time in the North and South Atlantic Oceans. We provide the first large subunit rDNA (LSU rDNA) and Internal Transcribed Spacer 1 (ITS1) sequences, which were identical in both hemispheres for the Atlantic Chytriodinium sp. The first complete small subunit ribosomal DNA (SSU rDNA) of the Atlantic Chytriodinium sp. suggests that the specimens belong to an undescribed species. This is the first evidence of the split of the Gymnodinium clade: one for the parasitic forms of Chytriodiniaceae ( Chytriodinium, Dissodinium), and other clade for the free-living species. [ABSTRACT FROM AUTHOR]

Abstract: The composition of the micro-phytoplankton was investigated at two fixed stations in the northeastern English Channel from November 1997 to December 2005. In late summer-autumn 2005, proliferations of the centric diatoms Proboscia indica and Rhizosolenia hebetata f. semispina were recorded for the first time in this area. The weather in 2005 was abnormal: a cold winter and early arrival of summer conditions that extended to late autumn. This resulted in an unusually long, sustained calm and warm period. We suggest that the reduction in mixing may have allowed diatoms of more-stratified waters to be competitive in the normally highly mixed northeastern English Channel in summer-autumn 2005. In 2003 and in 2005, two warm-water diatom species were recorded for the first time. A colony of Eucampia cornuta was observed after an exceptional heat wave in September of 2003, and again in September 2005. Simultaneously at both fixed stations, Chaetoceros peruvianus was recorded in the warm October of 2005. The climatic events are associated with the northward spreading of thermophilic diatoms such as E. cornuta and Ch. peruvianus in the European Atlantic waters, and the proliferation of diatoms of stratified environments such as P. indica and R. hebetata f. semispina in the usually highly turbulent waters of the northeastern English Channel. [Copyright &y& Elsevier]

In this paper we present microplankton distribution patterns in the Strait of Gibraltar obtained during a cruise carried out in September 1997. Chlorophyll, microplankton abundance and biovolume increase from southwest to northeast, a tendency that coincides with a gradual elevation of the interface depth in the same direction. The vertical distribution of biomass at the different stations shows deep maxima associated with the pycnoclines. The generation of internal waves and eventual intrusion of deep water on the sill can be decisive in the enrichment of surface water and plankton dynamics. The taxonomic structure agrees with the expected pattern, with a predominance of diatoms in the richer Mediterranean stations (especially in the north) and a predominance of dinoflagellates and microzooplankton at the Atlantic side. Phytoplankton distribution and salinity values found in the Strait of Gibraltar can be explained by a preliminary model that assumes a coupling between diatom life cycles and hydrodynamic features. Thus, the cells in the surface waters of the eastern side of the Strait would aggregate and sink below the interface, moving westwards and returning to the surface waters coupled with the rising and mixing of deep Mediterranean water at the sill. [ABSTRACT FROM PUBLISHER]