The depuration kinetics of the domoic acid from three body parts (i) digestive gland, (ii) adductor mus-cle+gonad+kidney+foot and (iii) gills+mantle of the scallop Pecten maximus was studied over 154 days. The scallops, which had accumulated the toxins during a Pseudo-nitzschia australis outbreak, were obtained from a natural bed and hung from a mussel raft in two locations (front and centre) and at three depths (2, 6 and 10 m). The time course of the depuration of domoic acid (DA), as well as the environmental variables, were monitored throughout the experiment. The whole body depurated the toxin very slowly (ca 0.007 day −1 ) decreasing its concentration from ca. 3200 µg DA g −1 . Its kinetics was driven mostly by the digestive gland, which accounted for ca. 95% of the total toxin burden from the start of the experiment. Suspending the scallops from a raft increased the depuration rate of the whole body and digestive gland (ca. 30%) and of the edible tissues (15%). Increases of the depuration rate of domoic acid seem to be related to the pair of covariating variables temperature-salinity. Food amount does not seem to have a significant effect.

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Surf clams, Mesodesma donacium, were shown to accumulate toxins from Dinophysis acuminata blooms. Only pectenotoxin 2 (PTX2) and some of its derivatives were found, and no toxins from the okadaic acid group were detected. PTX2 seems to be transformed to PTX2 seco-acid (PTX2sa), which was found in concentrations more than ten-fold those of PTX2. The seco-acid was transformed to acyl-derivatives by esterification with different fatty acids. The estimated amount of these derivatives in the mollusks was much higher than that of PTX2. Most esters were originated by even carbon chain fatty acids, but some originated by odd carbon number were also found in noticeable concentrations. Some peaks of toxin in the bivalves did not coincide with those of Dinophysis abundance, suggesting that there were large differences in toxin content per cell among the populations that developed throughout the year. The observed depuration (from the digestive gland) was fast (more than 0.2 day−1), and was faster for PTX2 than for PTX2sa, which in turn was faster than that of esters of PTX2sa. PTX2 and PTX2sa were distributed nearly equally between the digestive gland and the remaining tissues, but less than 5% of the palmytoyl-esters were found outside the digestive gland.

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