Domoic acid is a potent neurotoxin made by the microscopic diatom Pseudo-nitzschia. It builds up in shellfish, causing poisoning and fishery closures in California. Risk models call 10,000 cells per liter a bloom, counting every cell alike, though some species make far more toxin. Using weekly pier samples of cells and toxin since 2008, this project tests whether counting only the toxic seriata group, then adding silicate shortage, predicts toxicity better than that flat threshold.