Interactions between nutritional status and long-term responses to ultraviolet-B radiation stress in a marine diatom |
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Authors: | M J Behrenfeld H Lee II L F Small |
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Institution: | (1) AScI, U.S. EPA Environmental Research Laboratory, 97365-5260 Newport, Oregon, USA;(2) U.S. EPA Environmental Research Laboratory, 97365-5260 Newport, Oregon, USA;(3) College of Oceanic and Atmospheric Sciences, Oregon State University, 97331-5503 Corvallis, Oregon, USA |
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Abstract: | Influences of nutritional status on the photoinhibitory effects of ultraviolet-B radiation (UVBR: 290 to 320 nm) on the specific growth rates (obs) and biomass of Phaeodactylum tricornutum were determined using nutrient-replete batch cultures and nutrient-limited continuous cultures. P. tricornutum cultures were exposed to UVBR doses representative of current mid-latitude and ozone-depletion intensities. Specific growth rates and biomass were inhibited from 2 to 16% by UVBR during nutrient-replete growth. However, no effect of UVBR on obs or biomass was detectable when nutrient limitation exceeded the potential for limitation by UVBR. Thus, a competitive interaction appears to occur between macronutrient stress and UVBR stress, such that obs and biomass will be determined by the most limiting factor. Our results suggest that measurable decreases in phytoplankton obs and biomass from UVBR are most likely in nutrient-rich areas of the ocean, while these parameters may not be appropriate for measuring UVBR stress in regions of nutrient limitation. |
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