Phototoxicity in tropical reef animals

Phototoxicity refers to the toxic effects of chemicals caused or enhanced by light. Long known in man and terrestrial animals, it was first reported in freshwater animals in 1983. Our purpose was to test the process in marine species. Laboratory and outdoor trials in animals, representing Porifera, Cnidaria, Annelida, Arthropoda, Mollusca and Chordata, showed μg/liter levels of the polycyclic aromatic hydrocarbons (PAHs), anthracene and pyrene, to be phototoxic to most of them, although non-toxic in the dark and light-colored animals were more sensitive than were dark ones. Uptake of the PAHs followed by absorption of ultraviolet (UV) radiation appeared necessary for phototoxicity, which also depended on PAH concentration, wavelength and UV intensity. Dissolved oil and tar components may be particularly hazardous to shallow-water biota exposed to sunlight.