20 research outputs found
Ocean acidification and warming in the Norwegian and Barents Seas: impacts on marine ecosystems and human uses
This report synthesizes the results about the impacts of climate change and ocean acidification on marine ecosystems and ecosystem services in Norway, from interviews and a workshop with stakeholders in 2013
Detecting inhomogeneous chiral condensation from the bosonic two-point function in the -dimensional Gross-Neveu model in the mean-field approximation
The phase diagram of the -dimensional Gross-Neveu model is
reanalyzed for (non-)zero chemical potential and (non-)zero temperature within
the mean-field approximation. By investigating the momentum dependence of the
bosonic two-point function, the well-known second-order phase transition from
the symmetric phase to the so-called inhomogeneous phase is
detected. In the latter phase the chiral condensate is periodically varying in
space and translational invariance is broken. This work is a proof of concept
study that confirms that it is possible to correctly localize second-order
phase transition lines between phases without condensation and phases of
spatially inhomogeneous condensation via a stability analysis of the
homogeneous phase. To complement other works relying on this technique, the
stability analysis is explained in detail and its limitations and successes are
discussed in context of the Gross-Neveu model. Additionally, we present
explicit results for the bosonic wave-function renormalization in the
mean-field approximation, which is extracted analytically from the bosonic
two-point function. We find regions -- a so-called moat regime -- where the
wave function renormalization is negative accompanying the inhomogeneous phase
as expected.Comment: 27 pages (main text 20, appendix 7), 2 tables, 13 figures (plot data
included in arXiv source file); Updated, published versio
Editorial: Managing for the future: challenges and approaches for disentangling the relative roles of environmental change and fishing in marine ecosystems
En prens
Management Strategy Evaluation: Allowing the Light on the Hill to Illuminate More Than One Species
Management strategy evaluation (MSE) is a simulation approach that serves as a âlight on the hillâ (Smith, 1994) to test options for marine management, monitoring, and assessment against simulated ecosystem and fishery dynamics, including uncertainty in ecological and fishery processes and observations. MSE has become a key method to evaluate trade-offs between management objectives and to communicate with decision makers. Here we describe how and why MSE is continuing to grow from a single species approach to one relevant to multi-species and ecosystem-based management. In particular, different ecosystem modeling approaches can fit within the MSE process to meet particular natural resource management needs. We present four case studies that illustrate how MSE is expanding to include ecosystem considerations and ecosystem models as âoperating modelsâ (i.e., virtual test worlds), to simulate monitoring, assessment, and harvest control rules, and to evaluate tradeoffs via performance metrics. We highlight United States case studies related to fisheries regulations and climate, which support NOAAâs policy goals related to the Ecosystem Based Fishery Roadmap and Climate Science Strategy but vary in the complexity of population, ecosystem, and assessment representation. We emphasize methods, tool development, and lessons learned that are relevant beyond the United States, and the additional benefits relative to single-species MSE approaches
Ecological comparison of cellular stress responses among populations â normalizing RT-qPCR values to investigate differential environmental adaptations
Background: Rising temperatures and other environmental factors influenced by global climate change can cause increased physiological stress for many species and lead to range shifts or regional population extinctions. To advance the understanding of speciesâ response to change and establish links between individual and ecosystem adaptations, physiological reactions have to be compared between populations living in different environments. Although changes in expression of stress genes are relatively easy to quantify, methods for reliable comparison of the data remain a contentious issue. Using normalization algorithms and further methodological considerations, we compare cellular stress response gene expression levels measured by RT-qPCR after air exposure experiments among different subpopulations of three species of the intertidal limpet Nacella.
Results: Reference gene assessment algorithms reveal that stable reference genes can differ among investigated populations and / or treatment groups. Normalized expression values point to differential defense strategies to air exposure in the investigated populations, which either employ a pronounced cellular stress response in the inducible Hsp70 forms, or exhibit a comparatively high constitutive expression of Hsps (heat shock proteins) while showing only little response in terms of Hsp induction.
Conclusions: This study serves as a case study to explore the methodological prerequisites of physiological stress response comparisons among ecologically and phylogenetically different organisms. To improve the reliability of gene expression data and compare the stress responses of subpopulations under potential genetic divergence, reference gene stability algorithms are valuable and necessary tools. As the Hsp70 isoforms have been shown to play different roles in the acute stress responses and increased constitutive defenses of populations in their different habitats, these comparative studies can yield insight into physiological strategies of adaptation to environmental stress and provide hints for the prudent use of the cellular stress response as a biomarker to study environmental stress and stress adaptation of populations under changing environmental conditions