Depuration of Domoic Acid from Live Blue Mussels (Mytilus edulis)

Abstract

Industrial depuration may provide a means of removing domoic acid toxin from blue mussels (Mytilus edulis). Mussels containing up to 50 μg domoic acid∙g−1 were transported from a Prince Edward Island estuary into controlled laboratory conditions to test the effects of temperature, salinity, mussel size, and feeding upon depuration. Fifty percent of toxin was eliminated within 24 h. After 72 h, mussels were either clean or contained, on average, only residual levels of toxin (< 5 μg∙g−1), regardless of conditions. Exponential depuration curves were fitted to the domoic acid concentration data. To evaluate differences in rate of depuration under various conditions, statistical comparisons were made between slopes of the clearance curves. Rates of depuration were faster in small (45–55 mm) than in large mussels (60–70 mm) and more rapid at 11 than at 6 °C. There was no significant difference in depuration rate at 18‰ salinity as opposed to 28‰ or in starved versus fed mussels. Because of their relatively large digestive glands, meats of small mussels contained more toxin per unit weight than meats of large mussels. The bulk of domoic acid appeared to reside in the gut lumen. However, the presence of small amounts of domoic acid in intracellular compartments cannot be ruled out.

Domoic acid uptake and elimination kinetics in oysters and mussels in relation to body size and anatomical distribution of toxin

“…Domoic acid elimination rates in whole tissues ranged from 0.25 to 0.88 d −1 in oysters and from 1.4 to 1.6 d −1 in mussels in the present study. These rates are comparable to those measured for the fastest DA-detoxifying bivalves, such as the mussels Mytilus californianus [0.3-0.5 d −1 (Novaczek et al, 1992); 2.0 d −1 (Krogstad et al, 2009 with data from Wohlgeschaffen et al, 1992)]. …”

“…The influence of bivalve body size on DA uptake and elimination, however, remains controversial. Novaczek et al (1992) measured higher elimination rates in smaller mussels in the laboratory, and Bogan et al (2007) found that smaller scallops exhibited faster toxin uptake and depuration in the field. Other studies reported no relationship between body size and DA concentration in various invertebrates, such as P. maximus (Arévalo et al, 1998), the sand crab Emerita analoga (Powell et al, 2002) and the cuttlefish Sepia officianalis (Costa et al, 2005).…”

“…In the first category, DA elimination occurs at a constant decay rate, which leads to exponentially decreasing toxin concentrations over the entire depuration period, as indicated for M. edulis and Pecten spp. (Novaczek et al, 1992;Wohlgeschaffen et al, 1992;Blanco et al, 2002a). In this case, toxin elimination can be described by a single-compartment kinetics model.…”

“…The second category is associated with an initial phase of rapid DA elimination followed by a period of slower toxin loss. As a result, residual DA concentrations may be retained for prolonged periods, as observed in 10% of the mussels (M. edulis) exposed to toxic P. multiseries in the laboratory by Novaczek et al (1992),a s well as in S. patula (Drum et al, 1993;Horner et al, 1993) and the mussels Volsella modiolus (Gilgan et al, 1990) and Mytilus galloprovincialis (Blanco et al, 2002b). A two-compartment model, with a different elimination rate for each compartment and transfer of toxin from the faster-to the slower-detoxifying compartment, more adequately describes DA elimination kinetics in these cases.…”

“…Domoic acid elimination has been more extensively studied in mussels (Novaczek et al, 1992;MacKenzie et al, 1993;Whyte et al, 1995;Blanco et al, 2002b), but inter-species comparisons are made difficult by the inconsistent toxin exposure conditions used in different studies. The present study examines DA uptake and elimination kinetics in oysters and mussels simultaneously exposed to toxic P. multiseries cells under "common-garden", controlled laboratory conditions.…”