Coastal waters of the United States (U.S.) are subject to many of the major harmful algal bloom (HAB) poisoning syndromes and impacts. These include paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NSP), amnesic shellfish poisoning (ASP), ciguatera fish poisoning (CFP) and various other HAB phenomena such as fish kills, loss of submerged vegetation, shellfish mortalities, and widespread marine mammal mortalities. Here, the occurrences of selected HABs in a selected set of regions are described in terms of their relationship to eutrophication, illustrating a range of responses. Evidence suggestive of changes in the frequency, extent or magnitude of HABs in these areas is explored in the context of the nutrient sources underlying those blooms, both natural and anthropogenic. In some regions of the U.S., the linkages between HABs and eutrophication are clear and well documented, whereas in others, information is limited, thereby highlighting important areas for further research.

A B S T R A C TAlong the Pacific coast of North America, from Alaska to Mexico, harmful algal blooms (HABs) have caused losses to natural resources and coastal economies, and have resulted in human sicknesses and deaths for decades. Recent reports indicate a possible increase in their prevalence and impacts of these events on living resources over the last 10-15 years. Two types of HABs pose the most significant threat to coastal ecosystems in this ''west coast'' region: dinoflagellates of the genera Alexandrium, Gymnodinium, and Pyrodinium that cause paralytic shellfish poisoning (PSP) and diatoms of the genus Pseudo-nitzschia that produce domoic acid (DA), the cause of amnesic shellfish poisoning (ASP) in humans. These species extend throughout the region, while problems from other HABs (e.g., fish kills linked to raphidophytes or Cochlodinium, macroalgal blooms related to invasive species, sea bird deaths caused by surfactant-like proteins produced by Akashiwo sanguinea, hepatotoxins from Microcystis, diarrhetic shellfish poisoning from Dinophysis, and dinoflagellate-produced yessotoxins) are less prevalent but potentially expanding. This paper presents the stateof-knowledge on HABs along the west coast as a step toward meeting the need for integration of HAB outreach, research, and management efforts.Published by Elsevier B.V.

No abstract

Blooms of the marine flagellate Heterosigma carterae have been associated with catastrophic fish kills at mariculture facilities around the world. The precise cause(s) of the sudden appearance and disappearance of Heterosigma surface blooms has not been completely described or understood. Environmental data from prior studies of blooms indicate the presence of vertical stratification of the water column that is often induced by freshwater runoff. We report the relatively rapid concentration of Heterosigma cells at the surface of tubes shortly after the addition of distilled water to the surface. This phenomenon of cell concentration in surface waters may partially explain the sudden appearance of Heterosigma cells near the surface and subsequent disappearance when vertical stratification is lost due to turbulence or mixing. The results may lead to bloom mitigation techniques for net pen aquaculture.Résumé : Des poussées de flagellés marins (Heterosigma carterae) ont été associées à de catastrophiques mortalités massives de poissons dans des installations de mariculture à divers endroits du monde. Les causes exactes de l'apparition et de la disparition soudaines des efflorescences d'Heterosigma en surface n'ont pas encore été clairement définies, ni bien comprises. Des données environnementales provenant d'études antérieures révèlent la présence d'une stratification verticale de la colonne d'eau, souvent liée à un apport d'eau douce. Nous avons enregistré une augmentation relativement rapide de la concentration de cellules d'Heterosigma à la surface des éprouvettes peu après l'ajout d'eau distillée à la surface. Ce phénomène de concentration de cellules dans les eaux superficielles pourrait expliquer en partie l'apparition soudaine de cellules d'Heterosigma près de la surface, puis leur disparition lorsque la stratification verticale s'efface en raison de la turbulence ou du brassage. Les résultats de l'étude pourraient servir à élaborer des techniques d'atténuation des efflorescences qui seraient utiles à l'aquaculture en parcs de filet. [Traduit par la Rédaction]

No abstract