Significance Statement
The biomagnification of BMAA along food chains was synthetically investigated and discussed in the diatom-dominated marine ecosystem. The ubiquity of BAMA, an isomer of BMAA, was confirmed in the phytoplankton samples using the pre-column derivatization method. Results showed that diatoms are the source of BMAA in marine ecosystem because 21 of 56 diatom strains contained this neurotoxin. No BMAA was detected in the isolated bacterial strains from the gut of the typical vector of BMAA,Neverita didyma , which further confirmed that the toxin BMAA was transferred and accumulated along food chains. All these findings improve our understanding for the environmental behavior and risk to human health of the neurotoxin BMAA.