Domoic acid (DA), a neurotoxin responsible for Amnesic Shellfish Poisoning (ASP), threatens marine food webs, however, its phenology, magnitude, and ecological routing of DA-producing blooms exhibit obvious regional disparities. The Eastern Pacific frequently suffers catastrophic, high-biomass DA events driven by intense upwelling cycles and marine heatwaves. Conversely, the Asian Pacific, despite hosting high diversity of Pseudo-nitzschia, rarely experiences explosive toxicity of such magnitude. In the Western Pacific, monsoonal mixing and riverine discharge create localized, ephemeral nutrient gradients that foster profound species richness. This extreme biodiversity acts as a natural competitive buffer, likely preventing any toxigenic species from achieving monospecific dominance, with toxic signatures instead emerging from the collective contribution of multiple cryptic lineages. Furthermore, the primary threat in tropical Asia diverges from pelagic pathways, residing in the benthic diatom Nitzschia navis-varingica, isolating the toxin within localized benthic food webs. While pelagic Pseudo-nitzschia utilize a compact dab gene cluster capable of transcriptomic upregulation, this mangrove species utilizes a massively expanded dab biosynthetic gene cluster (>60 kb) to produce unique isodomoic acid chemotypes. Critical knowledge gaps, including cryptic species diversity and the largely unquantified dynamics of dissolved DA, will be addressed. Because toxins are likely to accumulate in benthic systems without visible pelagic blooms, the region faces overlooked implications regarding chronic, low-level DA exposure. Ultimately, integrating these genomic and ecological drivers is critical for region-specific monitoring framework to mitigate the hidden risks of chronic DA exposure across the coastal environments.