The effect of UVR on biological systems is wavelength dependent. Action spectrum for DNA damage is an essential component of understanding the effects of increased UVB on a range of Antarctic invertebrate larvae. The wavelength dependency is quantified using spectral weighting functions which provide information such as the target organelles/molecules of the UVR, the degree that organisms are ... influenced by wavelengths that are enhanced by the process of ozone depletion and the activity of sunscreening and anti-oxidant compounds. Biological weighting functions (BWFs) were made for 3 embryonic stages of Sterechinus (eggs, blastula, 4 armed larvae) and embryos of Acodantaster, Perknaster and Parbolarsis. The embryos and larvae were exposed to artificial lights for 3 days. Three filter treatments with 50% nominal cut-off at 280, 305, 320, 375 and 400nm wavelengths were used. DNA was analysed for cyclobutane pyrimidine dimers (CPDs). Using the species specific BWF and spectral irradiance data, biological effective irradiances were calculated for a given ambient light environment. Modelling of the species specific and stage specific effects of ozone depletion on larval stage were made using the BWFs and the change in ambient light field during ozone depletion.