Occurrence and distribution of lipophilic phycotoxins in a subtropical bay of the South China Sea. 
Lipophilic phycotoxins (LPs) pose significant threats to the health of marine mammals, birds, and human beings.  The distribution and components of lipophilic phycotoxins contamination in subtropical area in the South China Sea are rarely known.  This study systematically assessed the composition, concentration, and distribution of typical LPs in a typical subtropical bay, Daya Bay located in the South China Sea.  Phytoplankton, seawater, suspended particulate matter, sediments, and shellfish samples were simultaneously collected from Daya Bay, and analyzed using liquid chromatography with tandem mass spectrometry.  Okadaic acid, dinophysistoxins-1, pectenotoxins-2, yessotoxin and its derivate homo-yessotoxin, azaspiracid-2, 13-desmethyl spirolide C and gymnodimine were widely spread in multiple media in Daya Bay.  Pectenotoxins-2 was the most widely distributed and highly concentrated toxin in the marine environments of Daya Bay.  Toxin homo-yessotoxin was only detected in sediments and shellfish samples, and none of yessotoxin group components were found in phytoplankton and seawater, indicating that sediments were the major source of yessotoxin in shellfish.  The study strongly demonstrated the lipophilic phycotoxins accumulated in shellfish are multisource, not only derived from toxigenic algae, but also from other marine media containing lipophilic phycotoxins.  This study systematically distinguished multi-pathways of bioaccumulation of LPs in the marine shellfish.