| Marine organisms living in the euphotic zone are exposed to potentially damaging levels of solar ultraviolet radiation (UVR, 290--400nm) and may utilize multiple mechanisms to protect themselves against UV-damage. Here, I show that the adult green sea urchin, Strongylocentrotus droebachiensis , avoids UVR or covers itself with debris in response to it. The amount of covering correlates significantly with UVB (290--320 nm) and UVA (320--400 nm) independently, but not with photosynthetically active radiation (PAR, 400--700 nm).;Second, I demonstrate that adult sea urchins accumulate UV-absorbing, mycosporine-like amino acids (MAAs) and antioxidants in their ovaries and eggs. The concentrations of MAAs or ascorbic acid in ovaries and the gonadal index in S. droebachiensis collected from 0 to 10 in do not differ. Nevertheless, concentrations of MAAs and ascorbic acid vary by the site and season of collection. Ovaries of sea urchins accumulate significantly higher concentrations of one MAA, shinorine, when fed a diet rich in several MAAs than do those fed algae lacking MAAs. Neither the gonadal index nor the ovarian concentrations of MAAs or ascorbic acid are affected by exposure of adults to UVR. The percentages of ovarian cell types are not affected by diet or UVR and do not correlate with the concentrations of MAAs or ascorbic acid in ovaries.;Last, my results indicate that UVB affects development of S. droebachiensis, and that MAAs present in these early life stages reduce UV-induced damage. Eggs, embryos, and larvae contain principally two MAAs, shinorine and porphyra-334, which absorb across a wide range of UVA and UVB wavelengths. The concentrations of MAAs remain constant in embryos through the gastrula stage, but decrease significantly in pluteus larvae. Exposure to UVR does not affect the concentration of MAAs in embryos, although UVR induces delays and abnormalities during development. Removing UVB wavelengths eliminates this effect. The percentage of embryos that develop normally declines when embryos are exposed to UVR, but is positively related to the concentration of MAAs in eggs from which they develop, indicating that MAAs protect against UV-induced abnormalities during development. |
