Douding Lu1 and Jeanette Göbel2, 1Second Institute of Oceanography, SOA, Hangzhou 310012 China, 2 Landesamt für Natur und Umwelt des Landes Schleswig-Holstein, Hamburger Chaussee 25, 24220 Flintbek, Germany
Abstract
Several extensive blooms caused by potentially toxic raphidophytes, Chattonella sp. cells, occurred from the German Bight to the almost north Skagen between late March and first half of May of 1998, 2000 and 2001 and caused fish killing. The extension and process of the bloom in the sea surface could be possibly observed by a series of remote sensing pictures in the near real-time situation. However, the peak concentration of the bloom might be situated at subsurface of seawater especially in the sunny weather condition and not visible from the satellite data. This organism has shown strong phototactic behavior.
Cells are 12 - 30 µm in length. Shape is very variable. From elongated ovoid to irregularly ovoid, looks unlikely Chattonella verruculosa. The cell contains numerous chloroplasts and it has mucocysts. Living cells are very sensitive. They can be dead in a few minutes under light microscope.
The pigment profiles of both species show that they contain large amounts of 19'-butanoyloxy-ucoxanthin as previously described in only one genus of Raphidophytes-Haramonas. In addition to 19'-butanoyloxyfucoxanthin, the Chattonella sp. in the North Sea contains three unidentified carotenoids which Chattonella verruculosa does not have.
The observations from microscopy and pigment profile from HPLC suggest that Chattonella sp. in the German Bight should be a new HAB species.
The history of Chattonella in the North Sea is not long. Because the cells are so small, fragile and difficult to preserve, they might be overlooked if cell density is low. On the other hand, raphidophytes species were never found in such high cell concentrations and formed large blooms in this area before 1998. It seems that they have established their ecological niche and potentiality of recurrence to form spring blooms in the North Sea. Does this phenomenon indicate some kind of environmental change?