Abstract
UV-B radiation damages DNA and is harmful to most organisms. The depletion of the ozone layer has resulted in increased exposure of UV-B to terrestrial and aquatic organisms. Members of the genus Daphnia are negatively impacted by UV-B exposure and employ several defensive measures to prevent over-exposure. Daphnia in marine systems and permanent ponds are well studied, but little information is available on vernal pool (temporary pond) species. Understanding Daphnia is one component to improving knowledge about these systems. In this study, I compared migration and melanin concentrations in vernal pool Daphnia to permanent pond counterparts in the Central Valley of California. A mesocosm experiment was also performed to mitigate for any melanin variation driven by the presence of planktivorous fish. Daphnia from permanent ponds and vernal pools preferred the lower water column, but did not show a preference for shaded locations. Vernal pool Daphnia had an average melanin concentration of (7.133 µg/mg), an amount similar to other melanin concentration analyses from similar studies, though significantly lower than permanent pond Daphnia in this experiment. Daphnia from either pond type did not show variation in melanin expression when exposed to a non-native predator. Daphnia localized to vernal pools do show behaviors and morphology that indicate they actively prevent over-exposure to UV-B.