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441.
Erin R. Ricketts James P. Kennett Tessa M. Hill James P. Barry 《Marine Micropaleontology》2009,72(3-4):165-175
Deep-sea sequestration of CO2 is being considered as a possible mitigation tool to decrease atmospheric CO2 concentrations and its associated negative effects. This study investigated potential effects of liquid carbon dioxide (CO2) injection on deep-sea foraminiferal assemblages. Foraminifera are ideal for this ecological impact investigation because of differing test composition (calcareous and non-calcareous) and thickness, and diverse epifaunal and infaunal depth preferences. The experiment was conducted on August–September 2003, at 3600 m off the coast of Monterey Bay, California, aboard the R/V Western Flyer using the ROV Tiburon. The pH of the site was monitored throughout the experiment. Sediment push-cores were collected (both from the experimental and control sites) and stained to distinguish live (stained) from dead (unstained) individuals. Effects of CO2 injection on assemblages have been tracked both vertically (to 10 cm depth below sea floor) and horizontally (up to 10 m from CO2 injection sites), as well as between live and dead individuals. Within corrals (containing the injected CO2) and their underlying sediments, severe pH changes (near 4.0 units) were recorded. This compares with a record of small average reductions in ocean pH (− 0.05 units) combined with large episodic excursions (− 1.7 units) over the experimental area due to the injection of CO2. Exposure to this gradient of low pH caused increased mortality and dissolution of calcareous forms within corrals, as far as 5 m from the injection site, and to at least 10 cm depth in the sediments.This experiment revealed several major effects of CO2 injection on foraminiferal assemblages in surficial sediments: 1) total number of foraminifera in a sample decreases; 2) foraminiferal species richness decreases in both stained and unstained specimens; and 3) relative percentage of stained (live) forms in the remaining tests increases. Down-core trends (to 10 cm below sea floor) have revealed: 1) percent agglutinated forms decline and calcareous forms increase with depth; 2) agglutinated species richness decreases with depth; and 3) experimental core assemblages become increasingly similar with depth to those in control cores not subjected to CO2 injection. These results imply almost complete initial mortality and dissolution in the upper 10 cm throughout the corrals following liquid CO2 injection. Since calcareous foraminifera represent more than 50% of the total assemblages, this clearly indicates that emplacement of CO2 will result in negative effects to diversity and survivorship of the deep-sea benthic meiofauna. 相似文献
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Tessa Camenzind Anika Lehmann Janet Ahland Stephanie Rumpel Matthias C. Rillig 《Environmental microbiology》2020,22(8):3548-3560
The dependency of microbial activity on nutrient availability in soil is only partly understood, but highly relevant for nutrient cycling dynamics. In order to achieve more insight on microbial adaptations to nutrient limiting conditions, precise physiological knowledge is needed. Therefore, we developed an experimental system assessing traits of 16 saprobic fungal isolates in nitrogen (N) limited conditions. We tested the hypotheses that (1) fungal traits are negatively affected by N deficiency to a similar extent and (2) fungal isolates respond in a phylogenetically conserved fashion. Indeed, mycelial density, spore production and fungal activity (respiration and enzymatic activity) responded similarly to limiting conditions by an overall linear decrease. By contrast, mycelial extension and hyphal elongation peaked at lowest N supply (C:N 200), causing maximal biomass production at intermediate N contents. Optimal N supply rates differed among isolates, but only the extent of growth reduction was phylogenetically conserved. In conclusion, growth responses appeared as a switch from explorative growth in low nutrient conditions to exploitative growth in nutrient-rich patches, as also supported by responses to phosphorus and carbon limitations. This detailed trait-based pattern will not only improve fungal growth models, but also may facilitate interpretations of microbial responses observed in field studies. 相似文献
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Tessa Richards 《BMJ (Clinical research ed.)》1985,290(6461):52-53
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Tessa Roper 《Biodiversity and Conservation》1996,5(4):503-521
Fossil insects contained within a monolith of peat taken from Thorne Moors, to the northeast of Doncaster, UK, were studied. The changing entomofauna demonstrates clearly the development of raised mire from fen woodland. Many of the trees emerging from the peat have been severely burnt and the role of fire in the destruction of the woodland is considered. A number of species recovered from the lower peats are now extinct in Britain; others have extremely limited distributions in Europe today. 相似文献
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