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Saxitoxin (STX)-producing blooms of the toxic dinoflagellate genus Alexandrium have been responsible for devastating ecosystem-wide impacts in coastal waters of the northeastern USA. In the summer of 2009, a severe Alexandrium bloom in New England coastal waters cooccurred with a shortnose sturgeon Acipenser brevirostrum mortality event in Sagadahoc Bay, Maine, USA. Thirteen individuals of this endangered fish species were found dead on 10 July 2009, and this die-off was associated with extremely high Alexandrium cell densities, recordbreaking toxin burdens (> 80 000 ng g −1) in shellfish, and closures of shellfish beds affecting nearly the entire Maine coastline. STX-like activity was detected in sturgeon (n = 3) stomach contents and liver and gill tissues via neuroblastoma assay and receptor-binding assay at con centrations ranging between 37 and 2300 ng STX-eq. g −1 (STX equivalents per gram sample). Stomach content analyses of the 3 necropsied sturgeon carcasses showed a large number of amethyst gem clams Gemma gemma. Liquid chromatography-mass spectrometry confirmed the presence of STX and related congeners in sturgeon stomach contents, at concentrations between 311 and 743 ng g −1. The present study marks the first reported detection of STXs in shortnose sturgeon, and provides evidence of trophic transfer of Alexandrium toxins as a potential cause of mortality in this event, as well as a threat to the health of this endangered population of fish.

Wintertime toxic blooms of the blue-green alga Anabaena flos-aquae have been documented since 1989 in American Lake, a 446-ha lake near Tacoma, Washington. The toxic episodes were unusual in that algal toxicity occurred during the winter and this lake is considered to be only moderately productive. A year-long study was conducted to determine the environmental factors associated with toxic conditions. Toxic blue-green algal blooms in American Lake were associated with increased nutrient (especially phosphorus) availability following winter turnover. Phosphorus released from lake sediments under conditions of low oxygen during lake stratification fueled winter blooms of algae, including the toxic Anabaena flos-aquae strain. The lake's extremely low iron content was insufficient to completely remove this released phosphorus from the water column during lake turnover.