Toxicity tests using living organisms

Toxic chemicals pose a serious and continuous risk for specific parts of the food chain, leading to the extinction of different communities. The effects of toxins might be direct or indirect. The sub lethal effects lead to the change of the behavior of an organism. The acute or chronic tests might be performed for water or terrestrial organisms, according to the OECD standards, in different levels of the food chain and thus it is possible to predict the pollution effect in the ecosystem. This study has taken in consideration the acute and chronic tests using Daphnia sp. The goal of the research is the behavior evaluation of these organisms, common inhabitants of water systems, towards the change of the concentration of different chemicals. These organisms are taken from their natural habitat and then raised in laboratory conditions, in accordance with their natural habitat needs. Acute tests are performed using different concentrations of specific chemicals. Physical-chemical parameters of their natural water habitat are taken in consideration as well. The experimental laboratory data are then elaborated in order to determine the highest concentration of the tested chemical that shows adverse effects on Daphnia population, as well as the lowest concentration with no effect. The laboratory results are evaluated and compared with other similar studies