Dynamic features of ecophysiological response of freshwater clam to arsenic revealed by BLM-based toxicological model.

The objective of this study was to use a quantitative process-based damage assessment model (DAM) associated with biotic ligand model (BLM) to examine the ecophysiological responses of freshwater clam Corbicula fluminea to waterborne arsenic. We carried out a 14-day exposure experiment to obtain bioaccumulation parameters and a 7-day acute toxicity bioassay to obtain survival data. To investigate the survival dynamics, we examined 2 key parameters characterizing bioaccumulation and damage regulation: capacity to eliminate body arsenic burden and reversible ability to recover the damage. Results show that uptake rate constant of 2.075 + or - 0.442 (mean + or - SE) ml g(-1) d(-1) during uptake phase and elimination rate constant was estimated to be 0.1995 + or - 0.022 d(-1). The derived bioconcentration factor of 10.401 ml g(-1) suggests that arsenic has a high potential for bioaccumulation in C. fluminea. Our results show that a negative association between bioaccumulation and the fraction of arsenic binding in biotic ligand at 50% mortality, indicating that C. fluminea with higher arsenic binding in gill biotic ligand at 50% mortality level gives a lower capacity to accumulate bioavailable arsenic. We found a linearly positive correlation between elimination rate and recovery rate constants. Yet, a potential tradeoff between ability to eliminate arsenic and ability to recover the damage is not found. We showed that an ecophysiological significance of C. fluminea exposed to arsenic can be revealed by the elimination-recovery regime. This research may also provide mechanistic insights into the development of biomonitoring organism such as C. fluminea mimicking metal bioaccumulation in a real situation.