Paralytic shellfish poisoning in southern China

Area of Science:

• Marine Biology
• Ecotoxicology
• Phycology

Background:

• Sporadic paralytic shellfish poisoning (PSP) outbreaks have occurred in China's southern coastal mariculture regions for decades.
• The causative organisms and specific toxin profiles of PSP in Daya Bay remain largely uncharacterized.

Purpose of the Study:

• To compare the high-performance liquid chromatography (HPLC) toxin profiles of shellfish from PSP outbreaks with cultured Alexandrium tamarense from Daya Bay.
• To identify the specific toxins responsible for PSP events and assess the toxicity of local A. tamarense populations.

Main Methods:

• Analysis of toxin composition in three A. tamarense cultures using HPLC.
• Extraction and analysis of toxins from scallop and mussel samples implicated in PSP outbreaks using the AOAC method.
• Comparison of toxin profiles between cultured algae and shellfish samples.

Main Results:

• Cultured A. tamarense predominantly produced low-potency N-sulfocarbamoyl toxins (C1 and C2), exhibiting low overall toxicity.
• Shellfish samples contained a different toxin profile, with dominant gonyautoxins (GTXs) and toxins C1-C4, and significantly higher toxicity.
• The presence of toxins C3 and C4 in shellfish, but not in cultured algae, suggests other PSP-producing organisms were responsible for the outbreaks.

Conclusions:

• The A. tamarense strains cultured from Daya Bay are unlikely to be the sole cause of the observed PSP outbreaks due to their low toxicity and differing toxin profiles.
• Other Alexandrium species or genera may be responsible for the PSP events in Daya Bay.
• Increasing algal blooms due to pollution may enhance the risk of PSP from even low-toxicity algae populations in the future.