Recent studies demonstrate that most cyanobacteria produce the neurotoxin beta-N-methylamino-Lalanine (BMAA) and that it can biomagnify in at least one terrestrial food chain. BMAA has been implicated as a significant environmental risk in the development of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis (ALS). We examined several blooms of cyanobacteria in South Florida, and the BMAA content of resident animals, including species used as human food. A wide range of BMAA concentrations were found, ranging from below assay detection limits to approximately 7000 μg/g, a concentration associated with a potential long-term human health hazard.

Data collected along the southwest coast of Florida between Tampa Bay and Sanibel Island on the abundance of the toxic dinoflagellate Karenia brevis from 1954 to 2002 were examined for spatial and temporal patterns. K. brevis was found to be approximately 20-fold more abundant within 5 km of the shoreline than 20-30 km offshore. Overall, K. brevis was approximately 13-18-fold more abundant in 1994-2002 than in 1954-1963. In 1954-1963, K. brevis occurred primarily in the fall months. In 1994-2002, it was more abundant not only in the fall, but also in the winter and spring months. It is hypothesized that greater nutrient availability in the ecosystem is the most likely cause of this increase in K. brevis biomass, and the large increase in the human population and its activities in South Florida over the past half century is a major factor.

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