ABSTRACT Quick and cheap biomarkers to evaluate water quality are urgently needed to accommodate remote and low-budget laboratories. Recently, three simple and cheap biomarkers were proposed for water quality assessments using two morphological biomarkers (condition factor-CF and growth index-GI) and a tolerance test to air emersion. A multiple regression model was used to find predictors of air survival in wild bivalve populations. The data revealed that the air lethal time (LT) was negatively related with weight loss (WL) at the 7th day of exposure to air. This suggests that WL >25% at the 7th day predicts LT below the natural variation range. The relationship was significant with the CF, GI and air temperature indicating that larger animals with sustained growth and in warmer air temperature resist less time to air exposure. Moreover, the relationship was also significantly related to oxidative stress (lipid peroxidation) and decreased temperature dependence of mitochondria activity. For intertidal Mya arenaria clams, a temperature of 28.4 ºC could harm clams between tides (LT=0.5 day) which is in agreement to the reported maximal temperature (28.7 ºC) of the southern limit of clam distribution in North America coast. This relationship was statistically stronger at polluted sites than in pristine sites. In conclusion, this study permits to determine the critical range of air exposure time and temperature range during drought and strong temperature changes caused by global warming at contaminated sites.
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