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Cyanobacteria are the most common toxigenic algae in inland waters. Their toxins can affect the health of aquatic and terrestrial organisms, including humans. Other algal groups, such as haptophytes (e.g., Prymnesium parvum) and euglenoids (e.g., Euglena sanguinea), can also form harmful algal blooms (HABs) whose toxins cause injury to aquatic biota but currently have no known effects on human health. Prymnesium parvum, however, is responsible for some of the worst HAB-related ecological disasters recorded in inland waters. Here, we provide an overview of the primary toxigenic algae found in U.S. inland waters: cyanobacteria (planktonic forms), P. parvum, and E. sanguinea with the objective of describing their similarities and differences in the areas of HAB ecology, algal toxins, and the potential for future range expansion of HABs. A detailed account of bloom habitats and their known associations with land cover and use is provided from the perspective of water quality. This review revealed that salinity may have an influence on inland cyanobacterial blooms and cyanotoxins that had not been fully recognized previously. [ABSTRACT FROM AUTHOR]

The smallest known eukaryote, Ostreococcus tauri Courties et Chrétiennot-Dinet, was first reported as the dominant picoplankter in a French lagoon known for its diverse phytoplankton community and high oyster productivity. Long-term seasonal blooms of this picoeukaryote were observed in association with stable plankton communities. On 5 June 2001, a distinctive monotypic picoplankton bloom was detected by flow cytometry as part of an ongoing study of “brown tide” (Aureococcus anophagefferens ) bloom initiation in Long Island bays. The bloom reached a concentration of 5 × 10[sup 5] cells·mL[sup -1] in West Neck Bay and lasted less than 2 weeks. Epifluorescence microscopy and TEM indicated that the bloom organism was an Ostreococcus -like picoalga, the first ever observed in a Long Island bay. Many cells of this alga contained numerous virus-like particles. The Ostreococcus -like picoalga, which resembles O. tauri , was rare in samples collected the following week. Instead, a substantial increase in the Synechococcus population was observed. Such rapid population changes have not previously been reported for Ostreococcus . Viral lysis and grazing by heterotrophic nanoflagellates may have contributed to the rapid decline of the Ostreococcus -like cells in West Neck Bay. [ABSTRACT FROM AUTHOR]