A long-term perspective on the Chrysochromulina bloom on the Norwegian Skagerrak coast 1988: a catastrophe or an innocent incident?

The long-term effects of the 1988 algal bloom (Chrysochromulina polylepis Manton et) along the Norwegian Skagerrak coast are evaluated and discussed on the basis of several programmes. Effects on individual growth and survival of coastal cod and its population are analysed. Cod suffered a high mortality from June until November, and the 1988 yearclass strongly reduced. Growth was only slightly affected. Furthermore, the effects at the community are evaluated for the coastal fish community and the benthic communities. These communities strongly affected on a short time scale, but recovered surprisingly fast. Populations of organisms had recovered within months, and after 1 yr few traces of the toxic bloom could be; after 4 to 5 yr all communities had essentially recovered. As part of the review we also discuss what extent harmful blooms are likely to reoccur, and conclude that blooms have reoccurred will continue to do so. However, nothing can be concluded about the toxicity of such blooms. We that even large perturbations are unlikely to leave any profound long-lasting effects. The of the 1988 bloom are discussed within a theoretical framework including stability, resilience inertia. In conclusion we emphasise the importance of long-term monitoring data; without such the analyses reported in this paper would have been impossible.