A review ofPseudo-nitzschia, with special reference to the Skagerrak, North Atlantic, and adjacent waters
© Biologische Anstalt Helgoland 1996
ThePseudo-nitzschia flora of the Skagerrak, North Atlantic, and adjacent waters, comprisingP. pungens, P. multiseries, P. seriata, P. fraudulenta, P. heimii, P. delicatissima, andP. pseudodelicatissima, has been examined. Except forP. australis, allPseudo-nitzschia species shown to produce the toxin domoic acid are present in the area although an outbreak of amnesic shellfish poisoning has never been reported. For comparison of morphological and taxonomic characters,Pseudo-nitzschia seriata f.obtusa, P. australis, P. subfraudulenta, P. subpacifica, P. lineola, P. inflatula, andP. cuspidata have been included in this investigation. Fine details of band structure and poroid occlusions, previously ignored or unresolved, have proven to add to the morphological distinction betweenP. pungens andP. multiseries, P. seriata andP. fraudulenta, P. seriata andP. australis, andP. delicatissima andP. pseudodelicatissima. Additional information on the structure of the proximal mantle compared to that of the valve face has revealed similarities in most of the species but differences betweenP. pungens andP. multiseries. The species seasonal and long-term distributional patterns during the sampling period (October 1978 through September 1993) in the Skagerrak area are outlined. The greatest abundances ofP. seriata, a cold-water species most likely restricted to the northern hemisphere, occurred in the spring, and those of the presumably cosmopolitan diatomsP. pungens, P. multiseries andP. pseudodelicatissima, in the autumn. WhereasP. multiseries seems to have decreased in abundance in the 1990s,P. pseudodelicatissima has apparently increased.