Respiration of Amatitlania nigrofasciata at the action of toxicants used at different concentrations in model experiments

Abstract

The aim of model experiments were tracking temporal dynamics of breathing intensity tsyhlazoma aquarium fish-zebra (Amatitlania nigrofasciata) at the action of toxicants in different concentrations to determine the approximate levels of assess and the degree of toxicity of the aquatic environment. Fisheries regulations (maximum allowed concentration), caused using various concentrations of substances which are the most common contaminants of the aquatic environment. Fish respiration was assessed by difference in content of dissolved oxygen every 0.5 hrs during the exposure of individuals in the corresponding solution toxicants. The oxygen concentration was measured using instrumental method. As a test parameter coefficient of respiration fish was used. The rate was calculated as the ratio of test reactions version of the experiment and the control. The accuracy of the measu­rements was assessed by the closeness of approximation between the experimental data. The reliability levels of control deviation for each time interval of exposure was tested by Fisher criterion. Statistical rankings of experimental data was carried out within five groups, as recommended by the EU Water Framework Directive regarding the development of the rating scales of ecological state of the aquatic environment. The level of coefficient of fish respiration was ≤50.8 % as recorded in variants of experiment with concentrations of most chemicals at 10 MAC and certain substances at 5 MAC, which was seen as a manifestation of critical toxicity of the aquatic environment for fish. The coefficient of fish respiration within 51.1–101.6% were recorded in some embodiments experiment with concentrations of chemicals at 2 maximum allowed concentration, 3 maximum allowed concentration and 5 maximum allowed concentration, indicating high toxicity. The coefficient of fish respiration 101.7–52.4 % were recorded in variants with concentrations of certain substances at 2, 3 and 1 concentration, which may indicate a moderate or high toxicity. Indicators within 152.5–203.2 % – variations in the concentrations of certain substances at 0.5 concentration, 1 concentration and 2 concentration which was seen as evidence of a weak environment of toxicity to fish. The coefficient of fish respiration ≥203.2 % were recorded 0.5 maximum allowed concentration and 1 concentrations of substances, that was seen as a lack of toxicity. Thus, the methodology of toxicity bioassay of water environment in terms of the intensity of fish respiration, was improved namely: optimal exposure A. nigrofasciata aquarium fish in the experimental samples of water; specified formula of fish respiration intensity during the experiments; proposed indicative scale integrated assessment of the toxicity degree in the aquatic environment. This speeds to obtaining of the integra­ted response of the toxicity of water environment with the ability to reuse test objects.

Keywords

• respiration of fish
• toxicity
• exposure