Influence of sunlight on DNA damage in mussels exposed to polycyclic aromatic hydrocarbons

Abstract

DNA single-strand break levels were compared in mussels deployed in San Diego Bay. Mussels were deployed at two locations, a reference site and at a location known to have high concentrations of PAHs. Two vertically oriented lines of mussels were deployed at each location for a period of 32 days. Mussels were attached to the lines at depths of 0.3, 1 and 3 m. One line was fully exposed to ambient sunlight, the other was shaded from sunlight to examine the role of PAH light activation on the expression of DNA damage in hemocytes and whole organism growth. Damage and growth measurements were made on days 0, 5, 14, and 32. Temperatures at the stations varied only by ≈0.5 °C. Hydrocarbon levels at the high PAH station were on average six times higher than the reference station. Slower growth and higher DNA damage was observed in cells from light exposed mussels at the PAH contaminated site. These effects decreased with depth. High levels of DNA damage could be induced with low intensity ultraviolet light exposure of cells from depurated or shaded mussels exposed to PAHs. DNA damage in mussels from the high impact site could be reduced to baseline levels after 24 h depuration in the dark. These results confirm previous findings showing increased DNA damage in PAH and sunlight exposed mussels, and demonstrate the significant impact of photoactivation on the health of these organisms.