Steve L. Morton

Occurrence of Cyanobacterial Harmful Algal Blooms Workgroup report.

Appreciation is given to all those whose efforts made the production of this book possible. Thanks are due to the editors, Anthony Fristachi, US Environmental Protection Agency, Office of Research and Development, Cincinnati, Ohio and Jim Sinclair, PhD, US Environmental Protection Agency. Thanks are also due to Dr. Jeffrey Johansen of John Carroll University for his review and revisions to the Section 4 discussion of the current status of taxonomy of cyanobacteria. Special thanks to the workshop co–chairs: Jim Sinclair, PhD, US Environmental Protection Agency, Office Water, Cincinnati, Ohio and Sherwood Hall, PhD, Food and Drug Administration, CFSAN, Laurel, Maryland, who co–managed the process of preparing the manuscript.

A second species of ichthyotoxic Pfiesteria (Dinamoebales, Dinophyceae)

Abstract A second toxic species within the family Pfiesteriaceae, Pfiesteria shumwayae Glasgow & Burkholder sp. nov., is described from the New River Estuary and the Neuse Estuary of the Albemarle-Pamlico Estuarine Ecosystem, USA. The species is polymorphic and multiphasic, with flagellated, amoeboid and cyst stages. The flagellated zoospores (diameter 8–24 μm) have permanently condensed chromosomes (mesokaryotic nucleus); a chrysophyte-like cyst (diameter 6–25 μm)with organic scales and bracts; and thin thecal plates arranged in a Kofoidian series of Po, cp, X, 4′, la, 6″, 6c, 4s, 5″′, 2″″. The benthic filopodial (filose), lobopodia1 (lobose) and rhizopodial amoeboid stages (5–250 μm) have an outer covering that ranges from rough to smooth in texture, depending on the stage of origin and the prey source. Pfiesteria shumwayae amoebae have a normal eukaryote nucleus and cysts of multiple sizes (diameter 4–25 μm) with a reticulate outer covering. Toxic strains of the two Pfiesteria species have overlapping distributions in the mid-Atlantic and southeastern United States and Scandinavia, with toxic P. shumwayae also having been verified from New Zealand. Pfiesteria shumwayae is similar to P. piscicida in its complex life cycle, general nutrition, attraction to live fish prey, and ichthyotoxic activity that is stimulated by the presence of live fish or their fresh tissues and excreta. However, it can be distinguished from P. piscicida morphologically by having six precingular plates and a four-sided la plate, as well as genetically, on the basis of its ISS ribosomal DNA sequence.

Morphology and toxicology of Prorocentrum arabianum sp. nov., (dinophyceae) a toxic planktonic dinoflagellate from the Gulf of Oman, Arabian Sea ☆

Abstract A new species of planktonic dinoflagellate, Prorocentrum arabianum isolated from the Gulf of Oman, is described using both scanning electron microscopy (SEM) and light microscopy. This clonal isolate has the following morphological characteristics: (1) cell shape is asymmetric; (2) thecal surface is rugose, covered with small poroids; (3) periflagellar area is unornamented, and (4) intercalary band is horizontally striated. Analysis of P. arabianum confirms the production of one cytotoxic compound and one ichthyotoxic compound. P. arabianum is the second known toxic planktonic Prorocentroid dinoflagellate.

Nitrogenous Nutrients Promote the Growth and Toxicity of Dinophysis acuminata during Estuarine Bloom Events

Diarrhetic Shellfish Poisoning (DSP) is a globally significant human health syndrome most commonly caused by dinoflagellates within the genus Dinophysis. While blooms of harmful algae have frequently been linked to excessive nutrient loading, Dinophysis is a mixotrophic alga whose growth is typically associated with prey availability. Consequently, field studies of Dinophysis and nutrients have been rare. Here, the temporal dynamics of Dinophysis acuminata blooms, DSP toxins, and nutrients (nitrate, ammonium, phosphate, silicate, organic compounds) were examined over four years within two New York estuaries (Meetinghouse Creek and Northport Bay). Further, changes in the abundance and toxicity of D. acuminata were assessed during a series of nutrient amendment experiments performed over a three year period. During the study, Dinophysis acuminata blooms exceeding one million cells L-1 were observed in both estuaries. Highly significant (p<0.001) forward stepwise multivariate regression models of ecosystem observations demonstrated that D. acuminata abundances were positively dependent on multiple environmental parameters including ammonium (p = 0.007) while cellular toxin content was positively dependent on ammonium (p = 0.002) but negatively dependent on nitrate (p<0.001). Nitrogen- (N) and phosphorus- (P) containing inorganic and organic nutrients significantly enhanced D. acuminata densities in nearly all (13 of 14) experiments performed. Ammonium significantly increased cell densities in 10 of 11 experiments, while glutamine significantly enhanced cellular DSP content in 4 of 5 experiments examining this compound. Nutrients may have directly or indirectly enhanced D. acuminata abundances as densities of this mixotroph during experiments were significantly correlated with multiple members of the planktonic community (phytoflagellates and Mesodinium). Collectively, this study demonstrates that nutrient loading and more specifically N-loading promotes the growth and toxicity of D. acuminata populations in coastal zones.