MYCOSPORINE-LIKE AMINO-ACIDS - POSSIBLE UV PROTECTION IN EGGS OF THE SEA HARE APLYSIA-DACTYLOMELA

We investigated mycosporine amino acid (MAA) involvement as protective sunscreens in spawn of the sea hare Aplysia dactylomela to determine if adult diet and ultraviolet (UV) exposure affected the UV sensitivit y of developing embryos. Adults were fed a red alga rich in MAAs (Acan thophora spicifera) or a green alga poor in MAAs (Ulva lactuca). Adult s on each diet were exposed for 2 wk to ambient solar irradiance with two types of acrylic filters; one allowed exposure to wavelengths >275 nm (designated UV) and one to wavelengths only >410 nm (designated NO UV). Spawn from each adult group was likewise treated with UV or NOUV and monitored during development for differences in mortality and meta bolic rate (measured as oxygen consumption: (V) over dot(O2)). Also re corded were number of eggs or embryos per capsule, times to hatching, hatching success, size at hatching, and (V) over dot(O2), of adults. S pawn from adults eating red algae was almost twice as rich in MAAs as spawn from adults eating green algae, suggesting that MAA content is d iet-related. Although overall quantities of MAAs in the spawn reflecte d MAA contents of the adult diet, specific MAAs were differentially se questered in the spawn. Thus, porphyra-334, found in high concentratio n in Aplysia dactylomela's preferred red algal food, was present in on ly low concentration in the spawn. Conversely, mycosporine-glycine, in low concentration in red algal food, was the most abundant MAA in the spawn. UV treatment of adults had no effect on quantities of MAAs in the spawn. Adults exposed to UV had significantly higher (V) over dot( O2)'s and spawned twice as often. The UV-treated adults produced spawn with significantly higher (V) over dot(O2)s and their embryos develop ed to hatching sooner. The only significant effect of UV exposure of t he spawn was to reduce the percentage of veligers hatching from 71 to 50%. There was no significant effect on hatching time or size of the v eligers at hatching, nor on number of eggs per capsule.