In January 2003, the US Environmental Protection Agency sponsored a "roundtable discussion" to develop a consensus on the relationship between eutrophication and harmful algal blooms (HABs), specifically targeting those relationships for which management actions may be appropriate. Academic, federal, and state agency representatives were in attendance. The following seven statements were unanimously adopted by attendees based on review and analysis of current as well as pertinent previous data: 1) Degraded water quality from increased nutrient pollution promotes the development and persistence of many HABs and is one of the reasons for their expansion in the U.S. and the world; 2) The composition -not just the total quantity -of the nutrient pool impacts HABs; 3) High biomass blooms must have exogenous nutrients to be sustained; 4) Both chronic and episodic nutrient delivery promote HAB development; 5) Recently developed tools and techniques are already improving the detection of some HABs, and emerging technologies are rapidly advancing toward operational status for the prediction of HABs and their toxins; 6) Experimental studies are critical to further the understanding of the role of nutrients in HAB expression, and will strengthen prediction and mitigation of HABs; and 7) Management of nutrient inputs to the watershed can lead to significant reduction in HABs. Supporting evidence and pertinent examples for each consensus statement is provided herein.

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The ichthyotoxic dinoflagellate Pfiesteria piscicida Steidinger et Burkholder has a complex life cycle with several heterotrophic flagellated and amoeboid stages. A prevalent flagellated form, the nontoxic zoospore stage, has a proficient grazing ability, especially on cryptophyte prey. Although P. piscicida zoospores lack the genetic capability to synthesize chloroplasts, they can obtain functional chloroplasts from algal prey (i.e. kleptoplastidy), as demonstrated here with a cryptophyte prey. Zoospores grown with Rhodomonas sp. Karsten CCMP757 (Cryptophyceae) grazed the cryptophyte population to minimal densities. After placing the cultures in near darkness where cryptophyte recovery was restricted and further prey ingestion did not occur, the time‐course patterns in growth, prey chloroplast content·zoospore−1, and prey nucleus content·zoospore−1 were followed. Ingested chloroplasts were selectively retained in the dinoflagellate, as indicated by the decline and, ultimately, near absence of cryptophyte nuclei in plastid‐containing zoospores. Chloroplasts retained inside P. piscicida cells for at least a week were photosynthetically active, as indicated by starch accumulation and microscope‐autoradiographic measurements of bicarbonate uptake. Recognition that P. piscicida can function as a phototroph broadens our perspective of the physiological ecology of the dinoflagellate because it suggests that, at least during part of its life cycle, P. piscicida’s growth and survival might be affected by photoregulation and nutritional control of photosynthesis.

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.

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Toxicity and its detection in the dinoflagellate fish predatorsPfiesteria piscicida and Pfiesteria shumwayae depend on the strain and the use of reliable assays. Two assays, standardized fish bioassays (SFBs) with juvenile fish and fish microassays (FMAs) with larval fish, were compared for their utility to detect toxic Pfiesteria. The comparison included strains with confirmed toxicity, negative controls (noninducible Pfiesteria strains and a related nontoxic cryptoperidiniopsoid dinoflagellate), and P. shumwayae strain CCMP2089, which previously had been reported as nontoxic. SFBs, standardized by using toxic Pfiesteria (coupled with tests confirming Pfiesteria toxin) and conditions conducive to toxicity expression, reliably detected actively toxic Pfiesteria, but FMAs did not. Pfiesteria toxin was found in fish-and algae-fed clonal Pfiesteria cultures, including CCMP2089, but not in controls. In contrast, noninducible Pfiesteria and cryptoperidiniopsoids caused no juvenile fish mortality in SFBs even at high densities, and low larval fish mortality by physical attack in FMAs. Filtrate from toxic strains of Pfiesteria spp. in bacteria-free media was cytotoxic. Toxicity was enhanced by bacteria and other prey, especially live fish. Purified Pfiesteria toxin extract adversely affected mammalian cells as well as fish, and it caused fish death at environmentally relevant cell densities. These data show the importance of testing multiple strains when assessing the potential for toxicity at the genus or species level, using appropriate culturing techniques and assays.toxigenic dinoflagellates ͉ Pfiesteria piscicida ͉ Pfiesteria shumwayae

Species within the class Raphidophyceae were associated with fish kill events in Japanese, European, Canadian, and U.S. coastal waters. Fish mortality was attributable to gill damage with exposure to reactive oxygen species (peroxide, superoxide, and hydroxide radicals), neurotoxins, physical clogging, and hemolytic substances. Morphological identification of these organisms in environmental water samples is difficult, particularly when fixatives are used. Because of this difficulty and the continued global emergence of these species in coastal estuarine waters, we initiated the development and validation of a suite of real-time polymerase chain reaction (PCR) assays. Sequencing was used to generate complete data sets for nuclear encoded small-subunit ribosomal RNA (SSU rRNA; 18S); internal transcribed spacers 1 and 2, 5.8S; and plastid encoded SSU rRNA (16S) for confirmed raphidophyte cultures from various geographic locations. Sequences for several Chattonella species (C. antiqua, C. marina, C. ovata, C. subsalsa, and C. verruculosa), Heterosigma akashiwo, and Fibrocapsa japonica were generated and used to design rapid and specific PCR assays for several species including C. verruculosa Hara et Chihara, C. subsalsa Biecheler, the complex comprised of C. comprehensive data set, we were also able to perform phylogenetic analyses to determine the relationship between these species.

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