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The effects of chronological age and size on toxicity of zinc to juvenile brown trout
Citation:
Diedrich, D., R. Sofield, J. Ranville, D. Hoff, D. Wall, AND S. Brinkman. The effects of chronological age and size on toxicity of zinc to juvenile brown trout. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY. Springer, New York, NY, 69(1):123-131, (2015).
Impact/Purpose:
These results indicate that fish size or some related characteristic is a significant determinant of susceptibility and should be considered in acute zinc toxicity tests, with specific attention paid to the expected exposure scenario in the field. This work also supports that consideration of climate related variables is appropriate for field relevance, as climate may influence organism development, field exposure scenarios, and toxicity.
Description:
A series of toxicity tests were conducted to investigate the role of chronological age and organism weight on zinc tolerance in juvenile brown trout (Salmo trutta). Four different incubation temperatures were used to control the maturation of the juveniles prior to zinc exposures. These 165 hr exposures used flow-through conditions and four chronological ages of fish, with weights ranging from 0.12 to 1.43 g. Time-to-death (TTD) data were collected throughout the exposure, as well as the final mortality. The results indicate that chronological age does not play a predictable role in zinc tolerance for juvenile brown trout. However, size was shown to be an important factor in zinc toxicity at this developmental stage. Smaller fish (0.15 - 0.45 g) were shown to be less sensitive than larger fish (0.61-1.4 g) with LC50s of 965 and 405 µg Zn/L, respectively. Parametric estimation of survival functions supported the LC50 results by showing that smaller fish were more tolerant over the duration of the exposures with a longer median TTD than larger juvenile fish. These results indicate that fish size or some related characteristic is a significant determinant of susceptibility and should be considered in acute zinc toxicity tests, with specific attention paid to the expected exposure scenario in the field. This work also supports that consideration of climate related variables is appropriate for field relevance, as climate may influence organism development, field exposure scenarios, and toxicity.
