The Impact of Harmful Algal Blooms in Natural and Human-Modified Systems of Northern Europe

Abstract

The discovery that certain phytoplankton species can render sea foodhighly toxic for humans was made only some 60 years ago. Informationaccumulating since then strongly suggests that harmful algae have had animpact on human diet, customs and also economy over many millennia. Thecurrent rapid advances in knowledge of algal toxins and their occurrenceand role in ecosystems are described and the possible impacts speculatedupon. Thus, we suggest that cyanobacterial toxins in drinking water haveposed a serious threat to human health since the Neolithic and that theunusual drinking habits of the Europeans when compared to those of e.g.the Chinese might be explained in this light. In marine waters, toxinsare transmitted to humans via shellfish that accumulate them by feedingon plankton containing toxic species. Since the toxins are highlypotent, illness and deaths may have occurred often in the past. Regionaldifferences in the acceptance of shellfish as human food might well bedue to incidences of poisoning. Sedimentary records of toxic and relatedspecies suggest that marked fluctuations in abundance and distributionhave occurred during the Holocene that provide additional information onregional climate fluctuation on century and perhaps decadal scales.