SOLAR UVB-INDUCED DNA-DAMAGE AND PHOTOENZYMATIC DNA-REPAIR IN ANTARCTIC ZOOPLANKTON

The detrimental effects of elevated intensities of mid-UV radiation (U VB), a result of stratospheric ozone depletion during the austral spri ng, on the primary producers of the Antarctic marine ecosystem have be en well documented. Here we report that natural populations of Antarct ic zooplankton also sustain significant DNA damage [measured as cyclob utane pyrimidine dimers (CPDs)] during periods of increased UVB flux. This is the first direct evidence that increased solar UVB may result in damage to marine organisms other than primary producers in Antarcti ca. The extent of DNA damage in pelagic icefish eggs correlated with d aily incident UVB irradiance, reflecting the difference between acquis ition and repair of CPDs. Patterns of DNA damage in fish larvae did no t correlate with daily UVB flux, possibly due to different depth distr ibutions and/or different capacities for DNA repair. Clearance of CPDs by Antarctic fish and krill was mediated primarily by the photoenzyma tic repair system. Although repair rates were large for all species ev aluated, they were apparently inadequate to prevent the transient accu mulation of substantial CPD burdens. The capacity for DNA repair in An tarctic organisms was highest in those species whose early life histor y stages occupy the water column during periods of ozone depletion (au stral spring) and lowest in fish species whose eggs and larvae are abu ndant during winter. Although the potential reduction in fitness of An tarctic zooplankton resulting from DNA damage is unknown, we suggest t hat increased solar UV may reduce recruitment and adversely affect tro phic transfer of productivity by affecting heterotrophic species as we ll as primary producers.