Resource Documents: Germany (66 items)
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Author: Scholz, Carolin; and Voigt, Christian
[Abstract] Agricultural practice has led to landscape simplification and biodiversity decline, yet recently, energy-producing infrastructures, such as wind turbines, have been added to these simplified agroecosystems, turning them into multi-functional energy-agroecosystems. Here, we studied the trophic interactions of bats killed at wind turbines using a DNA metabarcoding approach to shed light on how turbine-related bat fatalities may possibly affect local habitats. Specifically, we identified insect DNA in the stomachs of common noctule bats (Nyctalus noctula) killed by wind turbines in Germany to infer in which habitats these bats hunted. Common noctule bats consumed a wide variety of insects from different habitats, ranging from aquatic to terrestrial ecosystems (e.g., wetlands, farmland, forests, and grasslands). Agricultural and silvicultural pest insects made up about 20% of insect species consumed by the studied bats. Our study suggests that the potential damage of wind energy production goes beyond the loss of bats and the decline of bat populations. Bat fatalities at wind turbines may lead to the loss of trophic interactions and ecosystem services provided by bats, which may add to the functional simplification and impaired crop production, respectively, in multi-functional ecosystems.
Carolin Scholz, Christian C. Voigt
Department Evolutionary Ecology, Leibniz Institute for Zoo and Wildlife Research, Berlin; and Plant Ecology and Nature Conservation, University of Potsdam, Germany
Conservation Science and Practice. 2022;4:e12744. doi:10.1111/csp2.12744
Author: Voigt, Christian
[Abstract] Evidence is accumulating that insects are frequently killed by operating wind turbines, yet it is poorly understood if these fatalities cause population declines and changes in assemblage structures on various spatial scales. Current observations suggest that mostly hill-topping, swarming, and migrating insects interact with wind turbines. Recently, the annual loss of insect biomass at wind turbines was estimated for Germany to amount to 1,200t for the plant growth period, which equates to about 1.2 trillion killed insects per year, assuming 1 mg insect body mass. Accordingly, a single turbine located in the temperate zone might kill about 40 million insects per year. Furthermore, Scheimpflug Lidar measurements at operating wind turbines confirm a high insect activity in the risk zone of turbines. These numbers and observations are alarming, yet they require further consolidation, particularly across all continents and climate zones where wind energy industry is expanding. We need to understand (a) how attraction of insects to wind turbines affect fatality rates and interactions of insect predators with wind turbines. (b) We have to connect insect fatalities at wind turbines with source populations and evaluate if these fatalities add to the decline of insect populations and potentially the extinction of species. (c) We need to assess how fatalities at wind turbines change insect-mediated ecosystem services. An ever-growing global wind energy industry with high densities of wind turbines may have long-lasting effects on insects and associated trophic links if negative impacts on insects are not considered during the erection and operation of wind turbines.
Christian C. Voigt, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
Conservation Science and Practice. 2021;3:e366. doi:10.1111/csp2.366
Download original document: “Insect fatalities at wind turbines as biodiversity sinks”
Offshore wind farms are projected to impact primary production and bottom water deoxygenation in the North Sea
Author: Daewel, Ute; et al.
Abstract – The wind wake effect of offshore wind farms affects the hydrodynamic conditions in the ocean, which has been hypothesized to impact marine primary production. So far only little is known about the ecosystem response to wind wakes under the premises of large offshore wind farm clusters. Here we show, via numerical modeling, that the associated wind wakes in the North Sea provoke large-scale changes in annual primary production with local changes of up to ±10% not only at the offshore wind farm clusters, but also distributed over a wider region. The model also projects an increase in sediment carbon in deeper areas of the southern North Sea due to reduced current velocities, and decreased dissolved oxygen inside an area with already low oxygen concentration. Our results provide evidence that the ongoing offshore wind farm developments can have a substantial impact on the structuring of coastal marine ecosystems on basin scales.
Ute Daewel, Naveed Akhtar, Nils Christiansen, Institute for Coastal Systems – Analysis and Modelling, Helmholtz-Zentrum Hereon, Geesthacht, Germany
Corinna Schrum, Institute of Oceanography, Centrum für Erdsystemforschung und Nachhaltigkeit, Universität Hamburg, Germany
Download original document: “Offshore wind farms are projected to impact primary production and bottom water deoxygenation in the North Sea”
Author: Christiansen, Nils; et al.
… Over time, the extraction of energy by offshore wind farms results in extensive areas of reduced wind speed and subsequently the decrease of the shear-driven forcing at the sea surface boundary. As this reduces the momentum transfer from the atmosphere into the ocean, horizontal velocities and turbulent mixing initially decrease several tens of kilometers around offshore wind farms. Thereby the induced perturbations imply significant changes for the residual currents in the respective areas. Furthermore, convergence and divergence of water masses lead to the formation of sea surface elevation dipoles, which over time merge into large coherent structures. As shown here, these large-scale anomalies in the sea surface elevation are one of the main drivers of wake-related processes in the ocean. In addition to the general reduction of turbulent mixing, the large- scale sea level alterations trigger lateral and vertical changes in the temperature and salinity distribution and affect the hydrodynamics in areas covered by offshore wind farms. However, the magnitude of these changes is rather small compared to the long-term variability of temperature and salinity and can hardly be distinguished from the interannual variability. A severe overall impact by the wake effects on the ocean’s thermodynamic properties is thus not expected but rather large-scale structural change in the stratification strength and unanticipated mesoscale spatial variability in the mean current field. Nevertheless, further investigations are necessary to assess possible feedback on the air-sea exchange and thus potential impact on the regional atmospheric conditions, since surface heating along with the reduction in turbulent mixing influences the upward heat and momentum fluxes from the ocean into the atmosphere.
In this study, the structural changes in stratification become noticeable in a couple of ways. Firstly, we observed large dipole-related changes in the potential energy anomaly, as the geostrophic and baroclinic changes alter the temperature and salinity distribution. Secondly, the reduction of mixing at offshore wind farms results in the enhancement of the stratification strength, in particular, during the decline of the summer stratification. While the structural changes in stratification are minor in shallow mixed waters, the pronounced alterations in stratified waters can translate to the mixed layer depth, which likely increases or decreases depending on the respective stratification changes. This, in turn, might be crucial for marine ecosystem processes (Sverdrup, 1953). During the stratified summer months, the mixed layer depth is acting as barrier for nutrients and phytoplankton and plays a major role for the ecosystem dynamics. Therefore, induced fluctuations of the mixed layer depth can entail the intrusion of nutrients from the pycnocline into the surface mixed layer or the spreading of the nutrient-poor surface layer, respectively. The alterations in the nutrient availability, in turn, might affect local primary production and the nutrient balance. Thus, further studies are required to elucidate the impact on marine ecosystems and organisms in the North Sea, with regard to current and future wind farm scenarios. …
Nils Christiansen, Ute Daewel, and Bughsin Djath, Institute of Coastal Systems, Helmholtz-Zentrum Hereon, Geesthacht, Germany
Corinna Schrum, Center for Earth System Research and Sustainability, Institute of Oceanography, Universität Hamburg, Germany
Download original document: “Emergence of Large-Scale Hydrodynamic Structures Due to Atmospheric Offshore Wind Farm Wakes”