Science Buddies: "Ask an Expert"

For my project I'm going to be testing the effects of pollutants on a species. I need to find a way to measure the pollutant and water that will dilute it in a way that will have an effect on the species (daphnia magna) but not kill them. What amount should I use and how should I measure it? Any help would be great!

17CKieley,

Thank you for your questions. Water toxicity can be measured in its acidity level, known as pH. Your culture can be made more acidic or basic based on your pollutants which can be directly measured easily. As for affecting your organisms, I'm not sure you'll get away without harming any, but I would have several cultures ranging from no pollution (your control) up to significant increase or decrease in pH such that you see a difference in population growth, possibly indicating an effect on reproductive rates. I found several scholarly articles on Google scholar by typing daphnia magna in the search line.