Change in Paralytic Shellfish Toxins in the MusselMytilus galloprovincialisDepending on Dynamics of HarmfulAlexandrium catenella(Group I) in the Geoje Coast (South Korea) during Bloom Season

Paralytic shellfish toxins (PSTs) produced byAlexandriumcatenella(formerlyA. tamarense) in Korean coastal waters caused the deaths of four people (in 1986 and 1996) who consumed contaminated mussels (Mytilus edulis). This led to more detailed consideration of the risks of PST outbreaks and incidents in Korea, including the introduction of shellfish collection bans. In this study, we investigated the relationships betweenA. catenellapopulation dynamics and PST accumulation in the musselM. galloprovincialis.Discharges from the Nakdong River affect the environmental conditions along the Geoje coast, resulting in low salinity and high nutrient levels that trigger blooms ofA. catenella. At the toxin peak on 24 April 2017, the toxins detected inA. catenellacells were C1, gonyautoxin (GTX)1 and GTX2, whereas the concentrations of PSTs inM. galloprovincialiswere high and in the order of GTX4 > GTX1 > GTX3 > saxitoxin (STX) > GTX2 > neoSTX > decarbamoylgonyautoxin (dcGTX)2 > dc GTX3. The PST level in mussels was also high. At 15 degrees C, the PSTs are constantly found to be higher (10-fold higher in 2017 and 30-fold higher in 2018) than safe levels for human consumption (80 mu g STX diHCl equivalents 100 g(-1)).