Pelagic coelenterates and eutrophication: a review

Although eutrophication is a widespread problem in marine waters, its effects are often difficult to separate from normal fluctuations of pelagic coelenterate populations and from other anthropogenic changes due to industrial pollution, construction, introductions, global warming and overfishing. The least complex situations are in small coastal water bodies such as the Caribbean lagoons and Scandinavian fjords. Typically, the diversity of pelagic coelenterates decreases, but the biomass of a small number of species (such as the hydromedusae Aglantha digitale and Rathkea octopunctata and the scyphomedusae Aurelia aurita and Cassiopea spp.) may increase. Adaptations that may allow these species to survive under eutrophic conditions are discussed.