X-irradiation effects on growth and metamorphosis of gastropod larvae (Crepidula fornicata): A model for environmental radiation teratogenesis

Little information is available on the effects of x-irradiation on the development of multicellular marine organisms. Larvae of the marine gastropod Crepidula fornicata were irradiated at 200 rad/min, 250 kVp x-rays, to doses between 500 and 20,000 rad in a single fraction. During the weeks following exposure, changes in shell length and biomass, incidence of metamorphosis to the juvenile stage of development, and mortality were measured. The results over a 20-day period demonstrated a dose-dependent decrease in growth rate of larval shells following doses above 2,000 rad (control at day 20=850±110 μm length, 820±11 μm for 500 rad, 750±30 μm for 2,000 rad, 710±30 μm for 5,000 rad, 620±30 μm for 10,000 rad, and 580±15 μm for 20,000 rad). Shell length-specific biomass was significantly decreased for doses above 10,000 rad. A significant increase in larval mortality was detected with doses above 2,000 rad. The cumulative percent of larval metamorphosis was decreased by exposures to 5,000 rad and was detectable as early as 18 days after irradiation; however, metamorphosis of larvae after 5,000 rad occurred faster by day 21 while other groups metamorphosis required 34-35 days for completion. Crepidula fornicata may provide a very sensitive and convenient system in which to study teratogenic effects of x-irradiation on multicellular organisms.