Abstract
In laboratory culture, D. magna is very sensitive to environmental conditions such as temperature, water chemical composition, pH value, illumination, food quality and quantity, and population density. Unfavourable conditions affect reproductive performance and survival. In this work, the reproductive success of D. magna was compared in different types of water recommended in toxicity test guidelines and in the literature on cultivation. Four types of water were compared, two natural types of water (dechlorinated tap water and unpolluted surface water) and two synthetic types of water (ISO dilution water and MS media) with ten D. magna individuals per water type. The best reproductive results in terms of cumulative number of neonates and brood size were obtained for MS media (P < 0.005) containing vitamins, macronutrients and trace elements. ISO dilution water and tap water showed similar reproductive results (no significant differences). All three types of water met the validity criteria of the OECD guidelines of a mean ≥ 60 surviving offspring per parent and ≤ 20% mortality in 21 days. The worst results were obtained for surface water, probably due to the unfavourable chemical composition and high conductivity of the water. This study confirmed that the chemical composition of the culture water has a pronounced effect on the reproductive potential of D. magna.