Observations on Chattonella globosa in Norwegian coastal waters. Are Chattonella globosa and Dictyocha fibula one species?

Summary

Chattonella globosa Y. Hara & Chihara was observed for the first time in Norway in September 2007 where it appeared in eastern Skagerrak and later on at the west coast of Norway, presumably transported there by the Norwegian Coastal Current. The highest density of 15,000 cells/L was observed in inner Oslofjorden at low light conditions in November 2007. It reoccurred in September 2008 in Skagerrak and became the dominant autumn bloom species at our monitoring station in southern Norway (Arendal st.2, E08.8167, N58.3833 (EUREF89-WGS84)), where it constituted 54% of the total algal carbon. As in the previous year, C. globosa spread to the west coast reaching densities of 53,000 cells/L in early November co-occurring with Pseudochattonella sp. and Heterosigma akashiwo. During this bloom 100 tons of caged salmon died. A special observation was made during this blooming event, where cells of C. globosa were observed containing Dictyocha fibula-like skeletons in different stages of development. This observation was confirmed for at least 11 different localities along the west coast. Our findings suggest that C. globosa and D. fibula are related and may be stages in a common life cycle.