Photosynthetic response of Halophila ovalis to heavy metal stress

This paper deals with the photosynthetic effects of a range of heavy metals on the seagrass Halophila ovalis. In this study, the photosynthetic response of laboratory-cultured H. ovalis to four heavy metals (Cu, Cd, Pb, Zn) was investigated. The results indicated clearly that chlorophyll a fluorescence was effective in monitoring the onset and development of stress, and occasional recovery, of H. ovalis when exposed to a wide range of heavy metals. Heavy metals in concentrations from 1 to 10 mg litre−1 produced several acute toxic responses. They had a variety of effects on the photosynthetic processes of this seagrass, with Cu and Zn having substantially greater effects than Pb and Cd. Quantum yield was the most sensitive measure of the photosynthetic processes affected by all heavy metals tested. With some exceptions, photosynthetic pigment content generally confirmed the chlorophyll a fluorescence responses