Abstract

Understanding of shellfish detoxification dynamics is a useful tool forresources management and ecological comprehension. Data collected from 19 selected sites at the Magellan region (48°-55°S), since 1994 to 2015 allowed a comparison of temporal and spatial PSP variability and detoxification rates in two species, ribbed mussel (Aulacomya atra) and blue mussel (Mytilus chilensis). The detoxification natural rate was assessed following PSP temporal variation from data estimated by mouse bioassay. Selected series considered as dependent variable the toxin concentration. A decreasing exponential model was adjusted to time series by minimun least squares analysis. Comparisons of detoxification rates and mean toxin values between sampling sites were performed (ANCOVA). If significant differences were found Scheffé test was applied. Toxicity levels for A. atra were between 25,128–30 μg STX eq. 100g-1 and for M. chilensis between 50,760 –30 μg STX eq. 100g-1. Detoxification rates varied from -0.0081 to -0.0792 and -0.0048 to -0.0892 μg STX eq. 100g-1day-1 for a. atra and M. chilensis, respectively. Spring and Summer were the periods with higher probabilities to reach high PSP values; the lapse to reach the minimum level detected by mouse bioassay differ from 594 to 28days for the entire region, for both species. M. chilensis presents higher records and longer detoxification periods than A. atra, determined by greater PSP levels. Detoxification rates for M. chilensis, are influenced by the PSP level, being lower at higher PSP levels, and the latitude of the sampling site, being lower at higher latitude.