Hypothermal and hyperthermal acclimation differentially modulate cadmium accumulation and toxicity in the zebrafish

Area of Science:

• Environmental toxicology
• Aquatic ecotoxicology
• Ecotoxicology

Background:

• Aquatic organisms are poikilothermic, making them susceptible to temperature-induced toxicity.
• Standard toxicity tests often overlook environmental temperature variations.
• Zebrafish are a key species for toxicity testing.

Purpose of the Study:

• To investigate the temperature dependence of cadmium accumulation and toxicity in zebrafish.
• To determine the effects of acclimation temperatures (18, 26, 30, 34°C) on 96-hour cadmium exposure.

Main Methods:

• Zebrafish were acclimated to four different temperatures.
• Acute 96-hour toxicity tests were conducted using various cadmium concentrations.
• Cadmium accumulation and LC50 values were measured at each temperature.

Main Results:

• Zebrafish exhibited high cadmium tolerance across tested temperatures (LC50 values 102.4–126.7 μM).
• Temperature-dependent toxicity showed a complex pattern, not a simple increase with temperature.
• At high cadmium concentrations, toxicity order was 26°C>18°C>30°C>34°C, suggesting acclimation effects.

Conclusions:

• Cadmium toxicity in zebrafish is influenced by both altered cadmium accumulation and sensitivity, which are temperature-dependent.
• Cold temperatures (18°C) increased cadmium sensitivity, possibly due to effects on sodium balance.
• Environmental quality standards may need to incorporate temperature effects to protect sensitive species at suboptimal temperatures.