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PW08 Aquatic Ecotoxicology II
(PW131) Variability of CBRs in landlocked salmon (Salmo salar m. sebago): a direct calorimetry study.
Penttinen, O.-P.1, Kukkonen, J.2, 1 University of Helsinki, Lahti, Finland2 University of Joensuu, Joensuu, Finland
ABSTRACT- Questions of organism-specific factors, toxicity end-points, and their relation to mode-of-action are all related to consistency and applicability of critical body residue approach (CBR). To address this issue, the body residues were used as a dose metric for sublethal responses. Direct calorimetry was used to evaluate metabolic responses of alevins of landlocked salmon to pentachlorophenol (PCP) exposure ranging from 0 to 1.04 M for 24-h or for 24, 48 and 72-h (0, 0.26 and 0.55 M). The salmon alevins accumulated PCP from 0.01 to 0.4 mol g-1 wet mass and the amount of chemical accumulated was directly related to the exposure concentration. The wet mass of landlocked salmon varied from 72.4 to 140 mg but fortunately within the treatments, body size and bioaccumulation were not correlated. On the other hand, body size, rapid ontogenetic development and exposure to specific pollutant were all heat output-modifying factors. The highest mass-specific heat output value of 0.47 W mg-1 was measured in small (84.2 mg) alevin exposed to PCP (0.2 M) over period of 72-h whereas the lowest value (0.088W mg) was measured in large (119 mg) unexposed and freshly hatch individual. In unexposed organisms metabolic heat output varied from 0.08 to 0.21 W mg-1 partly for reason that the increment of metabolic rate was 5.6 % per day during the experimental period. Consequently, the older alevins also had significantly higher BCF-values. The acute exposure (24-72 h) to PCP leads to dose dependent heat output-enhancing effect. Within the treatments, body size/level of metabolic rate and magnitude of physiological response were not correlated, thus the alevins with higher mass-specific metabolic rate were not more sensitive to PCP. The observed increase in heat output was directly related to internal concentration of PCP in the range from 0.01 to 0.15mol g-1. Primarily, increasing metabolic rate during post-hatch development controls PCP toxicity only by affecting bioaccumulation kinetics, not the toxic potency of chemical. A new information of a relationship between observed natural variation in measured physiological trait of landlocked salmon and PCP-induced response and its body-residue based level is of ecotoxicological importance.
Key words: calorimetry, salmon, CBR, pentachlorophenol
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