Sediment-Associated Phototoxicity to Aquatic Organisms

ABSTRACT

Phototoxicity is a two to greater than 1000-fold increase in chemical toxicity caused by ultraviolet radiation (UV), which has been demonstrated in a broad range of marine and freshwater fish, invertebrates, and other aquatic organisms in water column exposures. Field collected sediments containing polycyclic aromatic hydrocarbons (PAHs) and other contaminants are phototoxic to sediment-dwelling organisms in laboratory tests, but in situ or field investigations of phototoxicity have not been reported. Sediment provides a pathway for the bioaccumulation of phototoxic chemicals through contact with and ingestion of bedded and suspended sediment, and maternal transfer, but risks are uncertain. Risks from sediment-associated phototoxicity will be greatest in areas of both high contaminant exposure (e.g., surficial and suspended sediments in harbors, outfall areas, and spill sites), and high UV exposure (e.g., high optical clarity or shallow depths). Organisms and life-stages most at risk will be those translucent to UV that inhabit the photic zone and near shore areas, but benthic organisms may have generally low UV exposure because of life history and morphological characteristics. Site-specific assessments are needed to characterize risks both spatially and temporally because of heterogeneous sediment contamination and large differences in species sensitivity and exposure pathways.

Keywords:

• sediment
• ultraviolet radiation
• phototoxicity
• aquatic organisms

ACKNOWLEDGMENTS

I thank Nile Kimble, Chris Ingersoll, and Michael Ahrens for sharing information, Lee Courtney for figure preparation, and Steve Diamond for reviewing a draft of this manuscript. This manuscript is contribution number 1238 of the Gulf Ecology Division of the U.S. Environmental Protection Agency Office of Research and Development's National Health and Environmental Effects Research Laboratory. It has been reviewed by the USEPA's National Health and Environmental Effects Research Laboratory, Gulf Breeze, Florida.

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