The consistent occurrence of the ozone hole over Antarctica has initiated many studies that have demonstrated the effects of UV radiation on primary production of phytoplankton communities. The effects, if any, of UV radiation on the planktonic phases of marine invertebrates in any ecosystem has received considerably less attention. Concern about ozone depletion has resulted in a growing awareness of the separate and interacting effects of UV radiation on marine organisms. These studies have also shown that stratospheric ozone depletion is not restricted to the Antarctic. In fact, precipitous declines in northern latitudes of the Northern Hemisphere have already been detected. This project will address, using both laboratory and field studies, the role of solar ultraviolet radiation-induced photooxidative stress for gametes, embryos, and larvae of- two dominant echinoderms from the shallow subtidal zone of the Gulf of Maine. Like other marine organisms, temperate invertebrates contain mycosporine-like amino acids (MAAs), which absorb environmentally relevant wavelengths of UV radiation (310-360 nm). MAAs are not synthesized in animals, so their origin in heterotrophic marine invertebrates is uncertain, but presumed to be from their diet. It is known that microalgae and various seaweeds are rich in MAAs, and these dietary sources of MAA's can be translocated to the invertebrate tissues, especially the ovaries. This results in a fixed amount of MAA within the newly spawned eggs and developing embryos or larvae (although planktotrophic larvae could obtain additional MAAs from feeding on phytoplankton), whose planktonic phase is naturally exposed to higher doses of UV radiation than the adult benthic: population. The sea urchin, Strongy1ocentrotus droebachiensis and the sea star, Asterias vulgaris are dominant members of the benthic community in the Gulf of Maine that obtain a suite of MAAs from their diet. This project addresses whether the accumulation of MAAs provides effective protection from the direct and indirect effects of UV radiation using field and laboratory experiments on embryos and larvae from these two important benthic species. Exposure to ultaviolet radiation results in the photodynamic production of reactive oxygem species that can damage various cellular components. Measurements of DNA photoproducts production and simultaneous differential display-PCR to examine differentially expressed genes (e.g. cell cycle and antioxidant) known to be affected by exposure to UV radiation and oxidative stress will be conducted. The results from this work will have implications for the role of trophically accumulated UV absorbing compounds, DNA damage, the molecular response of cell cycle genes to environmental stress, and photooxidative defenses of embryos and larvae of temperate echinoderms exposed to the photodynamic effects of UV radiation. The effects of UV radiation on different life-history phases of benthic: invertebrates must be examined to understand the potential ecological consequences on the benthos, and in marine food chains, a genuine concern for the community ecology of the benthos as current predictions suggest that annual decreases in stratospheric ozone over temperate latitudes will to continue for the next 25 years.
