Surveillance of algal toxins in shellfish from Scottish waters

Abstract

Shellfish samples were collected from coastal and offshore aquaculture sites and harvesting areas in Scottish waters between March 2003 and September 2004. Samples were analysed for the presence of algal toxins using traditional mouse bioassays for the detection of paralytic shellfish poisoning (PSP) toxins and diarrhetic shellfish poisoning (DSP) toxins; immuno-lateral flow chromatography for the detection of PSP toxins in the form of the Jellett Rapid Test; high-performance liquid chromatography (HPLC) with UV diode-array for the detection of amnesic shellfish poisoning (ASP) toxins; and liquid chromatography with mass spectrometry (LC-MS) for the detection of multiple lipophilic shellfish toxins (LSTs) including pectenotoxins (PTXs), yessotoxins (YTXs), azaspiracids (AZAs) and toxins from the 'traditional' DSP toxin group, okadaic acid (OA) and dinophysistoxins (DTXs). In order to investigate the presence of OA esters, alkaline hydrolysis was performed. All toxin groups were detected with a geographically widespread distribution. ASP toxins were the most prevalent occurring in 69% of samples. Using the PSP mouse bioassay, PSP toxins were detected in 5% of shellfish samples from coastal waters around the islands and the east coast. The Jellett Rapid Test for PSP toxins revealed a wider distribution (24% of samples) including the west coast of Scotland. Toxins from the 'traditional' DSP toxin group (OA/DTXs) and/or other LST groups (PTXs, YTXs and AZAs) were detected by LC-MS in 63% of the shellfish analysed. PSP, ASP toxins and LSTs occurred concurrently in a limited sample set, highlighting the importance of using methods capable of detecting multiple algal toxin groups in Scottish shellfish monitoring programmes.