AME 10:299-305 (1996)  -  doi:10.3354/ame010299

Natural UVB exposure changes the species composition of Antarctic phytoplankton in mixed culture

Davidson AT, Marchant HJ, de la Mare WK

Numerous investigators have demonstrated marked interspecific differences in tolerance of Antarctic marine phytoplankton to UVB exposure. Consequent changes in species composition have been proposed but as yet not demonstrated. We conducted competition experiments in which mixed cultures of Antarctic marine diatoms and colonial and flagellate stages in the life cycle of the haptophyte Phaeocystisantarctica were exposed to natural Antarctic solar irradiance. Results demonstrated UVB-induced changes in species composition favouring the colonial stage of P. antarctica following 2 d exposure or less. These data indicate the potential for altered trophodynamics and carbon flux in Antarctic waters as a result of ozone depletion. Our results also show the limited predictive value of results obtained using UVB exposures above those likely to be experienced in the natural environment.

UVB radiation . Antarctic phytoplankton . Species composition

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