Beta-methylamino-L-alanine (BMAA) is a widespread toxin that may contribute to the development of neurodegenerative diseases in humans and wildlife. Because BMAA is produced by cyanobacteria, most research focuses on highly-eutrophic systems with recurring cyanobacteria blooms. However, oligotrophic systems lacking obvious surface blooms are also known to produce BMAA, and predators feeding high in these food chains can accumulate BMAA in relatively high concentrations. Here, we investigate the biomagnification of BMAA as a possible explanation for the accumulation of BMAA in top-predators occupying oligotrophic systems. Although BMAA has been shown to biomagnify in some terrestrial systems, evidence for the biomagnification of BMAA in aquatic systems in limited and inconsistent. These discrepancies may stem from an incomplete understanding of trophic relationships within complex aquatic food webs. By using stable isotope analysis to first establish the trophic structure of the system, we can then determine how BMAA concentrations change with changes in trophic position. This will allow us to quantitatively assess the degree of BMAA accumulation across the food web, which will help us to better asses and predict the risk of BMAA exposure to top predators.
