TEMPORAL VARIATION AND TISSUE LOCALIZATION OF PARALYTIC SHELLFISH TOXINS IN THE NEW-ZEALAND TUATUA (SURFCLAM), PAPHIES SUBTRIANGULATA

Changes in the paralytic shellfish poison (PSP)-toxin profiles in popu lations of Tuatua (Paphies subtriangulata) inhabiting beaches in the B ay of Plenty were analyzed by high-performance liquid chromatography d uring the contamination phase caused by a bloom of Alexandrium minutum in January 1993 and over a 6-mo period 1 yr later, when low-level tox in residues persisted within these shellfish. During the peak of toxic ity (less than or equal to 412 mu g of saxitoxin [STX] equivalents/100 g), the toxin profiles consisted of various proportions of the carbam ate (gonyautoxin) derivatives GTX(1), GTX(2), GTX(3), GTX(4), and neoS TX, and STX, with some traces of the decarbamoyl derivative dc-STX. Th ese profiles resembled those produced by the toxic dinoflagellate itse lf. One year later, when the toxicity had declined to a stable level o f about 40 mu g/100 g, only traces of derivatives other than STX remai ned and almost all of this toxin was sequestered within the siphons. T he considerable length of time that toxin residues are retained, the t issue localization, and change with time in the spectrum of toxin deri vatives in tuatua are very similar to those observed in other surfclam species elsewhere in the world. Analysis of toxin profiles in these s hellfish provides a means of determining whether the observed PSP toxi city is the result of recent or long-past contamination episodes.