The Effects of Chronological Age and Size on Toxicity of Zinc to Juvenile Brown Trout

Abstract

A series of toxicity tests were conducted to investigate the role of chronological age on zinc tolerance in juvenile brown trout (Salmo trutta). Four different incubation temperatures were used to control the maturation of the juveniles before zinc exposures. These 96-h exposures used flow-through conditions and four chronological ages of fish with weights ranging from 0.148 to 1.432 g. Time-to-death (TTD) data were collected throughout the exposure along with the final mortality. The results indicate that chronological age does not play a predictable role in zinc tolerance for juvenile brown trout. However, a relationship between zinc tolerance and fish size was observed in all chronological age populations, which prompted us to conduct additional exploratory data analysis to quantify how much of an effect size had during this stage of development. The smallest fish (0.148-0.423 g) were shown to be less sensitive than the largest fish (0.639-1.432 g) with LC50 values of 868 and 354 µg Zn/L, respectively. The Kaplan-Meier product estimation method was used to determine survival functions from the TTD data and supports the LC50 results with a greater median TTD for smaller fish than larger juvenile fish. These results indicate that fish size or a related characteristic may be 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.

Acute Toxicity Bioassay of a Pyrethroid Pesticide Bifenthrin to the Asian stinging Catfish, Heteropneustes Fossilis (Bloch)

“…The present value of 96h LC 50 of bifenthrin to the exposed fish (3.407μg/l) is much higher in comparison to rainbow trout (1.47 μg/l), common carp (2.08 μg/l) and tilapia (0.80 μg/l) (Velisek et al, 2009, Liu et al, 2005. This variation may be because of difference in physicochemical parameters of the experimental water, age, size, health and species of fish (having accessory respiratory organ) used in the present study (Farah et al, 2004;Diedrich et al, 2015;Patra et al, 2015). Temperature of the test water may be a key factor in determining the degree of toxicity since lower temperature increases the toxic potential of bifenthrin to fish (Mauck et al, 1976).…”

Acute Toxicity of 6PPD‐Quinone to Early Life Stage Juvenile Chinook (Oncorhynchus tshawytscha) and Coho (Oncorhynchus kisutch) Salmon

“…However, size (i.e., weight)‐related differences in sensitivity to other contaminants has been reported in a number of salmonid studies, in particular. For example, the reported LC50 values for two sizes of juvenile brown trout ( S. trutta ) were 868 and 354 µg/L (a 2.5‐fold difference) between small fish that range from 0.148 to 0.423 g and larger juveniles ranging from 0.639 to 1.432 g (Diedrich et al, 2015). Similarly, small (2.0‐g) Chinook and coho, as well as rainbow trout have been shown to be less sensitive than larger (10.0‐g) juveniles to formalin, potassium permanganate, copper sulfate, acetic acid, and hydrogen peroxide (Taylor & Glenn, 2008).…”