Passive sampling and molecular networking for surveillance of lipophilic marine biotoxins along the south coast of Korea

Abstract

Lipophilic marine biotoxins (LMTs) are increasingly reported in coastal ecosystems, posing risks to seafood safety and public health. This study investigated the spatial and seasonal distributions of LMTs along the south coast of Korea in 2022 by integrating phytoplankton and mussel sampling with passive solid-phase adsorption toxin tracking (SPATT) and molecular networking-based high-resolution mass spectrometry. Diatoms dominated the phytoplankton community, but toxin-producing dinoflagellates such as Dinophysis acuminata and Gonyaulax spinifera appeared during seasonal peaks in spring and summer. Four LMTs, including pectenotoxin-2 (PTX2), PTX1, yessotoxin (YTX), and homo-YTX (hYTX), were detected in phytoplankton, whereas mussels accumulated only hYTX, peaking later, consistent with prolonged retention in bivalves. SPATT captured a broader toxin spectrum, including okadaic acid (OA), dinophysistoxin-1 (DTX1), azaspiracid-2 (AZA2), and domoic acid (DA), and often detected toxins earlier than biological samples. The combined application of SPATT and molecular networking further revealed putative PTX-related features based on MS/MS spectral similarity that were not observed in phytoplankton or mussels. Dietary exposure assessment of commercially distributed shellfish based on detected free toxin forms indicated hazard quotients and indices well below regulatory thresholds, suggesting low acute health risk. Repeated detection of LMTs in domestic seafood raises concerns about chronic exposure. Integrating SPATT with molecular networking proved highly effective for early biotoxin surveillance, underscoring the necessity of sustained, multi-matrix monitoring to ensure seafood safety.