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Daily compensation irradiation for net photosynthetic rates (ΣI comp) of Skeletonema costatum (Greville) Cleve, Chaetoceros ceratosporum Ostenfeld, Nitzschia sp., Thalassiosira nordenskiöldii Cleve, and Chroomonas salina (Wislouch) Butcher were measured during 1979 to obtain values for use in ecological models describing compensation and critical depths of marine phytoplankton. Batch cultures of these unicellular algae were exposed to temperatures and photoperiods varying from 6° to 15°C and 8.4 to 16.0 h, conditions typical of surface water in Saanich Inlet, a fjord in Vancouver Island, British Columbia, Canada. Results obtained with S. costatum and T. nordenskiöldii provided estimates of ΣI comp varying between 1.8 and 13 J cm-2 d-1, from which a mean value of 7.0 J cm-2 d-1 was calculated for use in ecological models with neritic phytoplankton. No seasonal variation in compensation irradiation was noted because photosynthetic efficiencies, which increased as division rates increased, were balanced by respiration rates, which increased as temperature increased. Results obtained with Chaetoceros ceratosporum, Nitzschia sp., and Chroomonas salina were difficult to interpret, because respiration rates were stimulated and depressed by light, respectively, for the first two species and the last one. This light effect was greatest when cells grew under conditions of low temperature and short photoperiod. Also, under winter and spring conditions, cells of Nitzschia sp. appeared to fix CO2 in the dark and with low irradiances by mechanisms other than photosynthesis. 相似文献
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The Politics of Carbon 总被引:1,自引:0,他引:1
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Ethan D. Schoolman Jeremy S. Guest Kathleen F. Bush Andrew R. Bell 《Sustainability Science》2012,7(1):67-80
Sustainability research is expected to incorporate concepts, methods, and data from a diverse array of academic disciplines.
We investigate the extent to which sustainability research lives up to this ideal of an interdisciplinary field. Using bibliometric
data, we orient our study around the “tripartite model” of sustainability, which suggests that sustainability research should
draw from the three “pillars” of the environmental, economic, and social sciences. We ask three questions: (i) is sustainability
research truly more interdisciplinary than research generally, (ii) to what extent does research grounded in one pillar draw
on research from the other two, and (iii) if certain disciplines or pillars are more interdisciplinary than others, then what
explains this variation? Our results indicate that sustainability science, while more interdisciplinary than other scientific
fields, falls short of the expectations inherent in the tripartite model. The pillar with the fewest articles published on
sustainability—economics—is also the most integrative, while the pillar with the most articles—environmental sciences—draws
the least from outside disciplines. But interdisciplinarity comes at a cost: sustainability research in economics and the
social sciences is centered around a relatively small number of interdisciplinary journals, which may be becoming less valued
over time. These findings suggest that, if sustainability research is to live up to its interdisciplinary ideals, researchers
must be provided with greater incentives to draw from fields other than their own. 相似文献
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Abalone are common herbivores throughout temperate and tropical waters, and yet the contribution of red and brown macroalgae
to the diet of wild abalone remains unclear. In the northern hemisphere, adult abalone are considered to consume predominantly
brown algae, but in the southern hemisphere abalone are thought to prefer red algae. Conventional methods such as gut content
analysis and feeding trials provide some insight into diet choice, but the associated biases of these techniques create uncertainty
surrounding the aforementioned variability in abalone diet. We use combined stable isotope and fatty acid analysis to determine
the relative contribution of red algae, brown algae and detritus/microalgae to the diet of wild abalone in Tasmanian waters.
Stable isotopes of carbon suggest that brown algae and/detritus are a more important source of carbon than red algae. Fatty
acid analysis confirmed the larger contribution of brown algae to the diet of abalone, and also identified the bacterial and
diatom component of detritus to be an important contributor to abalone diet. These results show combined use of chemical tracers
to be a promising technique for resolving abalone diet, and challenge current perceptions regarding spatial variability in
abalone diet choice. 相似文献