Chen W.-Y.CHUNG-MIN LIAOJu Y.-R.Singh S.Jou L.-J.Chen B.-C.Tsai J.-W.2020-01-142020-01-1420120963-9292https://scholars.lib.ntu.edu.tw/handle/123456789/448845It has been proposed that irreversible responses of organisms exposed to contaminants are due to a systemslevel feedback. Here we tested this hypothesis by reanalyzing the published data on toxicokinetics and survival probability based on a systems-level threshold damage model (TDM) incorporating with a positive damage feedback to explore the steady-state response and dynamic behavior of damage for tilapia and freshwater clam exposed to waterborne arsenic (As). We found that ultrasensitivity appeared in As-tilapia and freshwater clam systems with Hill coefficient n C 4, indicating that the positive damage feedback mechanism has been triggered. We confirmed that damage can trigger a positive feedback loop that together with As stressor increases irreversibility. This study also showed that TDM with positive feedback gave a much better predictability than that of TDM at As concentrations ranging from 100 to 500 mg l-1 for freshwater clam, whereas for tilapia, two models had nearly same performance on predictability. We suggested that mortality-time profile derived Hill coefficient could be used as a new risk indicator to assess the survival probability for species exposed to waterborne metals. We anticipated that the proposed toxicokinetics/toxicodynamics with a positive damage feedback may facilitate our understanding and manipulation of complex mechanisms of metal susceptibility among species and improve current risk assessment strategies. © 2011 Springer Science+Business Media, LLC.Arsenic; Damage feedback; Ecotoxicology; Freshwater Clam; Tilapia; Toxicodynamics; Toxicokinetics[SDGs]SDG15arsenic; fresh water; organoarsenic derivative; arsenic; ecotoxicology; feedback mechanism; fish; freshwater ecosystem; mollusc; numerical model; risk assessment; article; clam; concentration (parameters); mortality; positive feedback; priority journal; risk assessment; sensitivity analysis; statistical model; survival prediction; Tilapia; toxicodynamics; toxicokinetics; toxicology; animal; aquaculture; bivalve; differential threshold; drug effect; feedback system; longevity; physiology; predictive value; Bivalvia; Tilapia; Animals; Aquaculture; Arsenicals; Bivalvia; Differential Threshold; Feedback, Physiological; Fresh Water; Longevity; Predictive Value of Tests; Risk Assessment; Tilapiajournal article10.1007/s10646-011-0810-22-s2.0-84861660608https://www2.scopus.com/inward/record.uri?eid=2-s2.0-84861660608&doi=10.1007%2fs10646-011-0810-2&partnerID=40&md5=6f85734cd2f5a7d0cdeacba378fc80bc