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- Griffiths, Jennifer R., et al.
(author)
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The importance of benthic-pelagic coupling for marine ecosystem functioning in a changing world
- 2017
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In: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 23:6, s. 2179-2196
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Research review (peer-reviewed)abstract
- Benthic-pelagic coupling is manifested as the exchange of energy, mass, or nutrients between benthic and pelagic habitats. It plays a prominent role in aquatic ecosystems, and it is crucial to functions from nutrient cycling to energy transfer in food webs. Coastal and estuarine ecosystem structure and function are strongly affected by anthropogenic pressures; however, there are large gaps in our understanding of the responses of inorganic nutrient and organic matter fluxes between benthic habitats and the water column. We illustrate the varied nature of physical and biological benthic-pelagic coupling processes and their potential sensitivity to three anthropogenic pressures - climate change, nutrient loading, and fishing - using the Baltic Sea as a case study and summarize current knowledge on the exchange of inorganic nutrients and organic material between habitats. Traditionally measured benthic-pelagic coupling processes (e.g., nutrient exchange and sedimentation of organic material) are to some extent quantifiable, but the magnitude and variability of biological processes are rarely assessed, preventing quantitative comparisons. Changing oxygen conditions will continue to have widespread effects on the processes that govern inorganic and organic matter exchange among habitats while climate change and nutrient load reductions may have large effects on organic matter sedimentation. Many biological processes (predation, bioturbation) are expected to be sensitive to anthropogenic drivers, but the outcomes for ecosystem function are largely unknown. We emphasize how improved empirical and experimental understanding of benthic-pelagic coupling processes and their variability are necessary to inform models that can quantify the feedbacks among processes and ecosystem responses to a changing world.
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| 2. |
- Gårdmark, Marie
(author)
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Characterization of the antinociceptive effects of morphine and its glucuronides : Pharmacokinetic-pharmacodynamic modeling
- 1998
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Doctoral thesis (other academic/artistic)abstract
- Pharmacodynamic modeling was used to quantify the time aspects of theantinociceptive effect in rats following administration of morphine, morphine-3-glucuronide (M3G) and morphine-glucuronide (M6G). M6G acts as a potentagonist of morphine actions, whereas the pharmacodynamic role of M3G has beenunclear. The nociceptive effect was measured as the response to electrical stimulation to the tail and the respiratory effect was obtained by measuring the blood gas status. The electrical stimulation vocalization method was shown to be a suitable method for measuring morphine antinociception. Pharmacodynamic models were applied to the data and parameters describing the concentration-effect relationship were estimated.The data analysis was performed in NONMEM and PCNONLIN.The antinociceptive effect of M6G developed slowly with an equilibrationhalf-life of 1.4 h. This is considerably longer than the half-life of 0.5 h estimated for morphine. Acute tolerance was observed following morphine administration and developed with a half-life of 0.8 h. Following M6G administration acute tolerance was observed, but could not be described by the pharmacodynamic model applied. M3G was demonstrated to have a minor antagonistic influence on morphine antinociception. Based on behavioral observations and literature data, the interaction was hypothesized to be caused by the behavioral effects of M3G.The interchangeability and predictive performance of empirical tolerancemodels, some of which are used in this thesis, were evaluated. There was a large degree of interchangeability among the models. The predictive capability of a model was linked to the original study design, whereas the correlation between type of model and predictive performance was weak or absent. For the model selecting process it is suggested that several models
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