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Sökning: WFRF:(Steenbeek Jeroen)

  • Resultat 1-6 av 6
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1.
  • Bauer, Barbara, et al. (författare)
  • Reducing eutrophication increases spatial extent of communities supporting commercial fisheries : a model case study
  • 2018
  • Ingår i: ICES Journal of Marine Science. - : Oxford University Press (OUP): Policy B - Oxford Open Option A / Elsevier. - 1054-3139 .- 1095-9289. ; 75:4, s. 1306-1317
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study we investigate if eutrophication management has the potential to substantially affect which areas are going to be most suitable for commercial fishing in the future. We use a spatial ecosystem model, forced by a coupled physical-biogeochemical model, to simulate the spatial distribution of functional groups within a marine ecosystem, which depends on their respective tolerances to abiotic factors, trophic interactions, and fishing. We simulate the future long-term spatial developments of the community composition and their potential implications for fisheries under three different nutrient management scenarios and changing climate. The three nutrient management scenarios result in contrasting developments of bottom oxygen concentrations and phytoplankton abundance, with substantial effects on fish production. Nutrient load reduction increases the spatial extent of the areas suitable for the commercially most valuable demersal fish predator and all types of fisheries. This suggests that strategic planning of fishery management strategies could benefit from considering future changes in species distributions due to changes in eutrophication. We show that combining approaches from climate research, physical oceanography, biogeochemistry, biogeography, and trophic ecology with economical information provides a strong foundation to produce scientific knowledge that can support a multisectoral management of ecosystems.
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2.
  • Lotze, Heike K., et al. (författare)
  • Global ensemble projections reveal trophic amplification of ocean biomass declines with climate change
  • 2019
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 116:26, s. 12907-12912
  • Tidskriftsartikel (refereegranskat)abstract
    • While the physical dimensions of climate change are now routinely assessed through multimodel intercomparisons, projected impacts on the global ocean ecosystem generally rely on individual models with a specific set of assumptions. To address these single-model limitations, we present standardized ensemble projections from six global marine ecosystem models forced with two Earth system models and four emission scenarios with and without fishing. We derive average biomass trends and associated uncertainties across the marine food web. Without fishing, mean global animal biomass decreased by 5% (+/- 4% SD) under low emissions and 17% (+/- 11% SD) under high emissions by 2100, with an average 5% decline for every 1 degrees C of warming. Projected biomass declines were primarily driven by increasing temperature and decreasing primary production, and were more pronounced at higher trophic levels, a process known as trophic amplification. Fishing did not substantially alter the effects of climate change. Considerable regional variation featured strong biomass increases at high latitudes and decreases at middle to low latitudes, with good model agreement on the direction of change but variable magnitude. Uncertainties due to variations in marine ecosystem and Earth system models were similar. Ensemble projections performed well compared with empirical data, emphasizing the benefits of multimodel inference to project future outcomes. Our results indicate that global ocean animal biomass consistently declines with climate change, and that these impacts are amplified at higher trophic levels. Next steps for model development include dynamic scenarios of fishing, cumulative human impacts, and the effects of management measures on future ocean biomass trends.
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3.
  • Metian, Marc, et al. (författare)
  • Mapping diversity of species in global aquaculture
  • 2020
  • Ingår i: Reviews in Aquaculture. - 1753-5123 .- 1753-5131. ; 12:2, s. 1090-1100
  • Tidskriftsartikel (refereegranskat)abstract
    • Aquaculture is the world's most diverse farming practice in terms of number of species, farming methods and environments used. While various organizations and institutions have promoted species diversification, overall species diversity within the aquaculture industry is likely not promoted nor sufficiently well quantified. Using the most extensive dataset available (FAO-statistics) and an approach based on the Shannon Diversity index, this paper provides a method for quantifying and mapping global aquaculture species diversity. Although preliminary analyses showed that a large part of the species forming production is still qualified as undetermined species (i.e. 'not elsewhere included'); results indicate that usually high species diversity for a country is associated with a higher production but there are considerable differences between countries. Nine of the top 10 countries ranked highest by Shannon Diversity index in 2017 are from Asia with China producing the most diverse collection of species. Since species diversity is not the only level of diversity in production, other types of diversity are also briefly discussed. Diversifying aquatic farmed species can be of importance for long-term performance and viability of the sector with respect to sustaining food production under (sometimes abrupt) changing conditions. This can be true both at the global and regional level. In contrast, selection and focus on only a limited number of species can lead to rapid improvements in terms of production (towards sustainability or not) and profitability. Therefore, benefits and shortcomings of diversity are discussed from both economical and social-ecological perspectives that concurrently are shaping the expanding aquaculture industry.
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4.
  • Piroddi, Chiara, et al. (författare)
  • Effects of Nutrient Management Scenarios on Marine Food Webs : A Pan-European Assessment in Support of the Marine Strategy Framework Directive
  • 2021
  • Ingår i: Frontiers in Marine Science. - 2296-7745. ; 8
  • Tidskriftsartikel (refereegranskat)abstract
    • Eutrophication is one of the most important anthropogenic pressures impacting coastal seas. In Europe, several legislations and management measures have been implemented to halt nutrient overloading in marine ecosystems. This study evaluates the impact of freshwater nutrient control measures on higher trophic levels (HTL) in European marine ecosystems following descriptors and criteria as defined by the Marine Strategy Framework Directive (MSFD). We used a novel pan-European marine modeling ensemble of fourteen HTL models, covering almost all the EU seas, under two nutrient management scenarios. Results from our projections suggest that the proposed nutrient reduction measures may not have a significant impact on the structure and function of European marine ecosystems. Among the assessed criteria, the spawning stock biomass of commercially important fish stocks and the biomass of small pelagic fishes would be the most impacted, albeit with values lower than 2.5%. For the other criteria/indicators, such as species diversity and trophic level indicators, the impact was lower. The Black Sea and the North-East Atlantic were the most negatively impacted regions, while the Baltic Sea was the only region showing signs of improvement. Coastal and shelf areas were more sensitive to environmental changes than large regional and sub-regional ecosystems that also include open seas. This is the first pan-European multi-model comparison study used to assess the impacts of land-based measures on marine and coastal European ecosystems through a set of selected ecological indicators. Since anthropogenic pressures are expanding apace in the marine environment and policy makers need to use rapid and effective policy measures for fast-changing environments, this modeling framework is an essential asset in supporting and guiding EU policy needs and decisions.
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5.
  • Schewe, Jacob, et al. (författare)
  • State-of-the-art global models underestimate impacts from climate extremes
  • 2019
  • Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • Global impact models represent process-level understanding of how natural and human systems may be affected by climate change. Their projections are used in integrated assessments of climate change. Here we test, for the first time, systematically across many important systems, how well such impact models capture the impacts of extreme climate conditions. Using the 2003 European heat wave and drought as a historical analogue for comparable events in the future, we find that a majority of models underestimate the extremeness of impacts in important sectors such as agriculture, terrestrial ecosystems, and heat-related human mortality, while impacts on water resources and hydropower are overestimated in some river basins; and the spread across models is often large. This has important implications for economic assessments of climate change impacts that rely on these models. It also means that societal risks from future extreme events may be greater than previously thought.
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6.
  • Tittensor, Derek P., et al. (författare)
  • A protocol for the intercomparison of marine fishery and ecosystem models : Fish-MIP v1.0
  • 2018
  • Ingår i: Geoscientific Model Development. - 1991-959X .- 1991-9603. ; 11:4, s. 1421-1442
  • Tidskriftsartikel (refereegranskat)abstract
    • Model intercomparison studies in the climate and Earth sciences communities have been crucial to building credibility and coherence for future projections. They have quantified variability among models, spurred model development, contrasted within- and among-model uncertainty, assessed model fits to historical data, and provided ensemble projections of future change under specified scenarios. Given the speed and magnitude of anthropogenic change in the marine environment and the consequent effects on food security, biodiversity, marine industries, and society, the time is ripe for similar comparisons among models of fisheries and marine ecosystems. Here, we describe the Fisheries and Marine Ecosystem Model Intercomparison Project protocol version 1.0 (Fish-MIP v1.0), part of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP), which is a cross-sectoral network of climate impact modellers. Given the complexity of the marine ecosystem, this class of models has substantial heterogeneity of purpose, scope, theoretical underpinning, processes considered, parameterizations, resolution (grain size), and spatial extent. This heterogeneity reflects the lack of a unified understanding of the marine ecosystem and implies that the assemblage of all models is more likely to include a greater number of relevant processes than any single model. The current Fish-MIP protocol is designed to allow these heterogeneous models to be forced with common Earth System Model (ESM) Coupled Model Intercomparison Project Phase 5 (CMIP5) outputs under prescribed scenarios for historic (from the 1950s) and future (to 2100) time periods; it will be adapted to CMIP phase 6 (CMIP6) in future iterations. It also describes a standardized set of outputs for each participating Fish-MIP model to produce. This enables the broad characterization of differences between and uncertainties within models and projections when assessing climate and fisheries impacts on marine ecosystems and the services they provide. The systematic generation, collation, and comparison of results from Fish-MIP will inform an understanding of the range of plausible changes in marine ecosystems and improve our capacity to define and convey the strengths and weaknesses of model-based advice on future states of marine ecosystems and fisheries. Ultimately, Fish-MIP represents a step towards bringing together the marine ecosystem modelling community to produce consistent ensemble medium- and long-term projections of marine ecosystems.
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