The transfer of photosynthetically active (PAR) and ultraviolet radiation (UVR) into the Southern Ocean and its effects on the marine ecosystem are dependant on multiple dynamic atmospheric, oceanographic and biological factors. Comparison of the spectral absorption properties of particulate material in the several areas of the pack ice of Southern Ocean in winter, spring and summer illustrates a dynamic progression where particulates’ PAR absorption properties are dominated by detritus (and some algae) to a situation where PAR absorption is overwhelmingly dominated by pigmented ice biota (a general progression that is due to the growth and succession of ice microalgal communities). The progression of UV absorption by bulk particulates also follows a similar pattern. However, a more detailed analysis of the UV absorption features of the microalgae shows a general lack of UV-absorbing features/compounds in the winter and early spring, whereas these features become highly pronounced in the spring and summer. Extremely high UV-absorption peaks at ~320 nm often reach four- to tenfold higher than the absorption peaks attributable to photosynthetic pigments and correspond to absorption peaks expected from micosporine amino-like acids (MAAs). High UVR absorption features occur in microalgae in high light environments in the spring and summer and these features are reduced or absent in ice environments where the UVR and PAR are highly attenuated. Thus, the general progression of enhanced UVR in the spring and summer appears to initiate a sea-ice ecosystem-based response whereby broad expanses of sea ice harbor biota that synthesize MAAs and reduce UVR penetration into the Southern Ocean. The question remains as to whether the enhanced UVR imparted by the ozone hole has substantially influenced the structuring of the Antarctic sea-ice ecosystems and whether this measurable response in the sea ice has effects or implications for UVR interactions in the water column.