Selective accumulation of mycosporine-like amino acids in ovaries of the green sea urchin Strongylocentrotus droebachiensis is not affected by ultraviolet radiation

Field sampling and laboratory experiments examined whether ultraviolet radi ation (UVR) affects the reproduction or the accumulation of mycosporine-lik e amino acids (MAAs) and ascorbic acid in ovaries of the green sea urchin S trongylocentrotus droebachiensis (Muller). Ovaries of sea urchins sampled a cross a depth gradient (0.5-10 m) in March 1998 did not differ in their gon adal index, or in concentrations of MAAs, or ascorbic acid. Concentrations of MAAs and ascorbic acid in ovaries were higher in sea urchins collected f rom a kelp bed compared with those collected from a community of crustose c oralline algae. The concentrations of MAAs in ovaries varied seasonally, pe aking in March, when sea urchins had high gonadal indices just before spawn ing. Ovaries of sea urchins maintained on controlled diets from October 199 7 to April 1998 accumulated significantly higher concentrations of MAAs whe n fed a diet rich in MAAs than did ovaries of sea urchins fed an alga lacki ng MAAs, but the gonadal indices did not differ between diets. Sea urchins accumulated principally one MAA, shinorine, but not others that were availa ble in high concentrations in their diet. Neither the gonadal index nor the ovarian concentrations of MAAs were affected by daily exposure of adult ur chins to UVR for 6 months. Concentrations of ascorbic acid in ovaries did n ot differ among diets or UV-treatments. The percentages of nutritive phagoc ytes and gametic cells were not affected by diet or UVR, and did not co-var y with concentrations of MAAs or ascorbic acid in ovaries. These data suppo rt previous demonstrations that female sea urchins accumulate MAAs from the ir diet of macroalgae, but further show that the accumulation is selective for specific MAAs, particularly shinorine, and that adult S. droebachiensis do not accumulate MAAs in their ovaries or eggs in response to UV-exposure . These are also the first experimental studies to address whether MAAs are affected by or regulate gametogenesis, and indicate that they do not.