Differential okadaic acid accumulation and detoxification by oysters and mussels during natural and simulated Dinophysis blooms
2015
Mafra, Luiz Laureno Jr | Ribas, Tatiany | Alves, Thiago Pereira | Proença, Luís Antonio Oliveira | Schramm, Mathias Alberto | Uchida, Hajime | Suzuki, Toshiyuki
A bloom of D. acuminata complex was detected in early March 2008 in the shellfish farming area of Baía Sul, southern Brazil. Cell density reached up to 4.7 × 10⁴ cells/L at the surface by March 31st, quickly decreasing (<4.0 × 10³ cells/L) 1–2 weeks later as salinity increased (>32) in all sampling stations. On average, commercial-sized mussels, Perna perna, accumulated 11-fold higher okadaic acid (OA) levels in the digestive glands (DG) (maximum 2422 ng/g) compared to those of oysters, Crassostrea gigas (maximum 271 ng/g). Moreover, 50 % of the mussel DG extracts tested (n = 42) produced acute toxic effects as assessed by mouse bioassay, whereas all oyster samples produced negative results (n = 17). In parallel, juvenile oysters, Crassostrea brasiliana and C. gigas, and juvenile mussels, P. perna, exposed to a laboratory-simulated D. acuminata complex bloom (1350–13,750 cells/L) accumulated 7.5, 23.4, and 51.1 ng OA/g in whole bodies (22.7, 66.1, and 183.3 ng OA/g in visceral tissues), respectively. Toxin levels in the whole bodies dropped to similarly low average levels in all bivalve species (3.6, 3.7, and 1.3 ng/g, respectively) after 168 h of depuration. Mussels, therefore, detoxified OA at faster rates (0.023/h) than oysters C. gigas (0.010/h) and C. brasiliana (0.004/h).
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