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 food highly toxic for humans was made only some 60 years ago. Information accumulating since then strongly suggests that harmful algae have had an impact on human diet, customs and also economy over many millennia. The current rapid advances in knowledge of algal toxins and their occurrence and role in ecosystems are described and the possible impacts speculated upon. Thus, we suggest that cyanobacterial toxins in drinking water have posed a serious threat to human health since the Neolithic and that the unusual drinking habits of the Europeans when compared to those of e.g. the Chinese might be explained in this light. In marine waters, toxins are transmitted to humans via shellfish that accumulate them by feeding on plankton containing toxic species. Since the toxins are highly potent, illness and deaths may have occurred often in the past. Regional differences in the acceptance of shellfish as human food might well be due to incidences of poisoning. Sedimentary records of toxic and related species suggest that marked fluctuations in abundance and distribution have occurred during the Holocene that provide additional information on regional climate fluctuation on century and perhaps decadal scales.