No abstract

To assess the potential impacts of ozone depletion on photosynthesis in the Southern Ocean, we need to know more about effects of ultraviolet radiation (UV) on phytoplankton in Antarctic waters, where, in addition to variable stratospheric ozone, temporal and regional differences in vertical mixing might influence photosynthesis and photoacclimation of phytoplankton assemblages. Toward this end, we quantified the responses to UV of Antarctic phytoplankton in the Weddell-Scotia Confluence during the austral spring of 1993. Experimental results on spectral sensitivity of photosynthesis were fit statistically to a model that incorporated uninhibited photosynthesis as a function of photosynthetically available radiation (PAR), wavelength-dependence of inhibition, and the kinetics of photosynthesis during exposure to UV. In contrast to previous results on UV-induced photoinhibition in a diatom culture at 20°C natural phytoplankton from open waters of the Antarctic showed no ability to counter UV-induced inhibition of photosynthesis during exposures of 0.5-4 h: the rate of photosynthesis declined exponentially as a function of cumulative exposure, and inhibition was not reversed during incubations for up to 3.5 h under benign conditions. The results suggest that nonlinear exposure-response relationships are necessary for modeling UVdependent photosynthesis in the surface mixed layer of the springtime Weddell-Scotia Confluence. Consequently, we modified our laboratory-based model of photosynthesis and photoinhibition to describe photoinhibition as a nonlinear function of biologically weighted cumulative exposure to damaging irradiance. The model described -90% of the spectrally dependent experimental variation in photosynthetic rate, and yielded six biological weighting functions (BWFs) for phytoplankton in the Weddell-Scotia Confluence. Assemblages from different stations showed substantial variability in sensitivity to UV. Tolerance of UV was generally highest in assemblages from shallower mixed layers, which presumably had experienced higher irradiance, including UV, prior to sampling. The BWFs of assemblages that seemed acclimated to low irradiance showed the highest sensitivity to UV yet seen for Southern Ocean phytoplankton. The pattern of UV sensitivity was consistent with acclimation, but also with selection against less tolerant species.Stratospheric ozone depletion has focused efforts on determining the effects of solar ultraviolet radiation (UV, 290-400 nm) on phytoplankton photosynthesis, especially in the Southern Ocean. During the austral spring (October-November), chlorine chemistry within the Antarctic polar vortex results in complete destruction of ozone within much of the middle stratosphere and a >50% decrease in total column ' Present

No abstract

The incidence of academic dishonesty has been increasing throughout the past few decades. Past research has indicated that business students cheat more than their peers in other disciplines across the university. And, of particular concern to marketing educators, the current research finds that marketing majors cheat significantly more than their peers in other business disciplines. The research results also indicate that students are much more likely to cheat in situations in which friends (versus mere acquaintances) are involved. The study identifies a robust false consensus effect in which the respondents significantly overestimate the degree to which others cheat. Finally, the research investigates behaviors, beliefs, and propensities related to cheating on electronic exams. The article suggests tactical and strategic measures that business schools and their faculty can use to reduce the incidence of academic dishonesty.

No abstract