Understanding how species will respond to projected future climate change has become important. However, the impacts of climate change on the ecosystem are very complex and uncertain, we need a reliable tool for approaching it. Mechanistic modeling can be one of the solution for handling the various factors and responses of test organisms in regard to climate change. We introduce the case study on the copper toxicity on D. magna and show the applicability of these mechanistic model approaches. The overall objective of this case study was to simulate the chronic toxicity of copper on Daphnia magna using dynamic energy budget theory with the improved toxicity module component. The toxicity module includes toxic effects on allocation of reserve, structure, and maturity energy in the D. magna. Model calibration and verification were performed using data sets obtained from a laboratory experiment that include growth, maturity and survival measurement data of D. magna during copper exposure. The simulation results show that the response of D. magna under copper exposure was well estimated by toxicity module. Overall, the results show the dynamics model based on DEB theory can be used for estimating long-term metal toxicity on D. magna. Thus, mechanistic modeling can be utilized as a approach tool for evaluating the impacts of climate change on the ecosystem with more mechanistic description.

Environmental risk assessment aims to estimate the impacts of various stressors on populations and communities in the environment. However, most of the exposure tests conducted under the laboratory level. This gap between the controlled condition of the experiments and the complexity of the field situation can lead to irrelevant estimation of stress effects. For this reason, dynamic model approach in ecology that including integrated mechanistic understanding has become important. The dynamic models at the individual level can be used to interpret the individual’s response to stress, extrapolate which response to untested conditions, and predict the impacts on the higher ecological level. The overall objective of this case study was to simulate the chronic toxicity of copper on Daphnia magna using dynamic energy budget theory with the improved toxicity module component. The model system was constructed and evaluated, using the PowersimⓇ software. The toxicity model system was integrated with toxic effects on allocation of reserve, structure, and maturity energy of D. magna into improved toxicity module. The model was calibrated and verified by actual data sets where obtained from a laboratory experiment including growth, maturity and survival measurement of D. magna during copper exposure. The simulation results showed that the response of D. magna under copper exposure was well estimated by model system.

We evaluated the effect of water pH (6, 7, 8 and 9) and hardness (40mg/L and 160mg/L as CaCO3) on the growth of H. incongruens. Both water pH and hardness affected the growth parameter of H. incongruens such as head capsule width and maturity time. The head capsule width of the adults in the highest ph condition was 9.7% increased compared to the lowest ph condition. The maximum difference of the maturity time was 192 hours among the test conditions. Overall, as water ph level increase makes head capsule size of the test animal large, the inter-molt period and maturity time become shorter significantly. The effect of water hardness increasing showed a similar tendency with ph level. Especially, the difference of the growth parameter among the test conditions was increased by growing test animal. There are strong correlation between available amount of intake calcium and growth parameters of test animal. These results indicate that because of calcium demand for growth, water pH level and hardness are the important effect factor in life-cycle of the H. incongruens..