Monitoring of shellfish poison of ark shell and Japanese cockle in Osaka Bay using a simple testing kit for paralytic shellfish toxins

Abstract

　A lateral flow immunoassay kit was experimentally introduced to monitor paralytic shellfish toxins (PSTs) in two species of bivalves, ark shell and Japanese cockle, in Osaka Bay. The regression equation between the Test-line/Control-line ratio and the toxicities in mouse bioassay was used to estimate the toxicities of other samples. Specimens of ark shell and Japanese cockle were collected in the eastern part of Osaka Bay after the density of toxic dinoflagellate Alexandrium catenella fell below the warning level set in Osaka prefecture in 2019. The toxicity of Japanese cockles was estimated to be below the regulatory level of 4 MU g⁻¹ by the lateral flow immunoassay kit on June 25 and the samples collected thereafter were tested by the official testing method, mouse bioassay (MBA) for PSTs. Japanese cockles were determined to be below the regulatory level for three consecutive weeks, which is the minimum period to resume harvesting of shellfish. Because the MBA was replaced by the PSTs testing kit, the number of MBA in 2019 was largely reduced in this experimental monitoring for Japanese cockle. The result indicates that this kit is useful for reducing the cost of PST monitoring.