Search results for "LEVEL"
showing 10 items of 3465 documents
Local environment and space drive multiple facets of stream macroinvertebrate beta diversity
2018
AIM: Understanding variation in biodiversity typically requires consideration of factors operating at different spatial scales. Recently, ecologists and biogeographers have recognized the need of analysing ecological communities in the light of multiple facets including not only species‐level information but also functional and phylogenetic approaches to improve our understanding of the relative contribution of processes shaping biodiversity. Here, our aim was to disentangle the relative importance of environmental variables measured at multiple levels (i.e., local, catchment, climate, and spatial variables) influencing variation in macroinvertebrate beta diversity facets (i.e., species, tr…
Inferring species interactions from ecological survey data: A mechanistic approach to predict quantitative food webs of seed feeding by carabid beetl…
2021
Abstract Ecological networks are valuable for ecosystem analysis but their use is often limited by a lack of data because many types of ecological interaction, for example, predation, are short‐lived and difficult to observe or detect. While there are different methods for inferring the presence of interactions, they have rarely been used to predict the interaction strengths that are required to construct weighted, or quantitative, ecological networks.Here, we develop a trait‐based approach suitable for inferring weighted networks, that is, with varying interaction strengths. We developed the method for seed‐feeding carabid ground beetles (Coleoptera: Carabidae) although the principles can …
Small pelagic fish in the new millennium: A bottom-up view of global research effort
2021
The present review is an outcome of discussions at the ICES-PICES Symposium on Drivers of Dynamics of Small Pelagic Fish convened in Victoria, B.C., Canada in spring 2017.-- This review is a first contribution of a new international Working Group on Small Pelagic Fish started jointly by ICES (WGSPF) and PICES (WG43) to continue world-wide collaboration to advance knowledge on the drivers of populations of SPF.
Food-web structure and mercury dynamics in a large subarctic lake following multiple species introductions
2016
Summary The rate of non-native fish introductions into freshwater ecosystems has more than doubled during the past three decades, posing a serious threat to native biodiversity. Despite potential benefits for fisheries, little is known about how introduced species interact with native communities at the food-web level, or impact energy transfer dynamics and accumulation of contaminants in lake ecosystems. Here, we explored the trophic structure of a large, oligotrophic subarctic lake and assessed the trophic niche use and potential ecosystem-wide consequences of two introduced salmonid species: piscivorous lake trout (Salvelinus namaycush) and zooplanktivorous vendace (Coregonus albula). We…
Species interactions, environmental gradients and body size shape population niche width
2021
1. Competition for shared resources is commonly assumed to restrict population-level niche width of coexisting species. However, the identity and abundance of coexisting species, the prevailing environmental conditions, and the individual body size may shape the effects of interspecific interactions on species’ niche width. 2. Here we study the effects of interspecific and intraspecific interactions, lake area and altitude, and fish body size on the trophic niche width and resource use of a generalist predator, the littoral-dwelling large, sparsely rakered morph of European whitefish (Coregonus lavaretus; hereafter LSR whitefish). We use stable isotope, diet and survey fishing data from 14 …
Whole-Lake Sugar Addition Demonstrates Trophic Transfer of Dissolved Organic Carbon to Top Consumers
2017
Terrestrial dissolved organic carbon (DOC) provides an external carbon source to lake ecosystems. However, there is ongoing debate about whether external DOC that enters a lake can pass up the food web to support top consumers. We show, from experimental manipulation of a whole lake, that externally loaded DOC can contribute appreciably to fish biomass. Monthly additions of cane sugar with a distinct carbon stable isotope value during 2 years rapidly enriched the 13C content of zooplankton and macroinvertebrates, with a more gradual 13C enrichment of fish. After sugar addition stopped, the 13C content of consumers reverted towards original values. A simple isotope mixing model indicated tha…
Effect of Metal Complexation on the Conductance of Single-Molecular Wires Measured at Room Temperature
2014
The present work aims to give insight into the effect that metal coordination has on the room-temperature conductance of molecular wires. For that purpose, we have designed a family of rigid, highly conductive ligands functionalized with different terminations (acetylthiols, pyridines, and ethynyl groups), in which the conformational changes induced by metal coordination are negligible. The single-molecule conductance features of this series of molecular wires and their corresponding Cu(I) complexes have been measured in break-junction setups at room temperature. Experimental and theoretical data show that no matter the anchoring group, in all cases metal coordination leads to a shift towar…
Broker and Federation Based Cloud Networking Architecture for IaaS and NaaS QoS Guarantee
2016
International audience; Today, the Cloud networking aspect is a critical factor for adopting the Cloud computing approach. The main drawback of Cloud networking consists in the lack of Quality of Service (QoS) guarantee and management in conformance with a corresponding Service Level Agreement (SLA). This paper presents a framework for resource allocation according to an end-to-end SLA established between a Cloud Service User (CSU) and several Cloud Service Providers (CSPs) in a Cloud networking environment. We focus on QoS parameters for Network as a Service (NaaS) and Infrastructure as a Service (IaaS) services. In addition, we propose algorithms for the best CSPs selection to allocate Vi…
The adoption of green energy technologies: The role of policies in Austria, Germany, and Switzerland
2017
We contribute to the existing research about policy-induced technology adoption in several ways. First, we suggest a new survey design to measure the energy-related policy environment. Second, we simultaneously estimate the policy effects for the adoption propensity and the adoption intensity simultaneously and, third, we compare the policy effects in the three countries, Austria, Germany, and Switzerland. Based on a representative sample of firms for all three countries we find that policies essentially promote the adoption of technologies and they are practically ineffective for the intensity, which poses a great challenge to future policy designs. Voluntary agreements or demand-related f…
The tougher the environment, the harder the adaptation? A psychological point of view in extreme situations
2021
IF: 2.8 (Q1); International audience; Grounded within a multidimensional and multilevel approach, the aim of this study was to investigate the time course of Psychological Adaptation Process (PAP) dimensions (social, emotional, occupational, and physical) during one-year polar winter-overs in Subantarctic and Antarctic stations. The effects of perceived control (PC) at the start of polar winter on the dynamics of the PAP dimensions were also examined. The present findings clarify some changes in PAP in extreme environments: (a) The dimensions of psychological adaptation evolved differently as a function of environmental conditions; and (b) PC influenced the trajectories of PAP dimensions. T…