MEPS 176:153-163 (1999)  -  doi:10.3354/meps176153

ABSTRACT: Following an episode of Diarrhetic Shellfish Poisoning (DSP) in mussels Mytilus galloprovincialis from the Ría de Pontevedra (Galicia, NW Spain), produced by organisms of the genus Dinophysis (dinoflagellate), a batch of contaminated mussels was transplanted to several uncontaminated sites having different environmental conditions. The depuration kinetics of okadaic acid (the dominant toxin involved in the episode) in each experimental mussel batch was monitored during a 70 d period, as were the corresponding salinity, temperature, fluorescence, light transmission and mussel body weight. Environmental conditions and body weight were shown to have an effect on depuration rates by principal component and multiple regression analysis. Although most of the variables studied showed a high degree of covariation, fluorescence and light transmission, which serve to measure the availability of solids and phytoplankton for mussels, appeared to have the most prominent effect on depuration. Four different models were tested in order to describe depuration kinetics: 1- and 2-compartment models, each in 2 versions, with and without the inclusion of the effects of the 4 environmental variables studied and body weight. The 1-compartment model without the complementary variables did not give an appropriate description of the kinetics, but when these variables were included, the general fitting was good and a pattern was found in the most important deviations. The simplest of the 2-compartment models fitted also produced an output that adequately described the kinetics observed. However, attempts to estimate the parameters of 2-compartment models including the complementary variables consistently produced a 1-compartment model. The model chosen to describe depuration kinetics substantially influences the estimation of the effect of the environmental variables.

KEY WORDS: Okadaic acid · Depuration · Models · Mussel · Salinity · Temperature · Body weight · Fluorescence · Light transmission