Climate change and recovery from eutrophication reduce benthic fauna and carbon processing in a coastal sea

2020 ◽  
Author(s):  
Eva Ehrnsten ◽  
Alf Norkko ◽  
Bärbel Müller-Karulis ◽  
Erik Gustafsson ◽  
Bo Gustafsson
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Coastal Ecosystems ◽  
Benthic Macrofauna ◽  
Combined Effects ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
The Future ◽  
The Baltic ◽  
Carbon Processing

<p>Nutrient loading and climate change affect coastal ecosystems worldwide. Unravelling the combined effects of these pressures on benthic macrofauna is essential for understanding the future functioning of coastal ecosystems, as it is an important component linking the benthic and pelagic realms. In this study, we extended an existing model of benthic macrofauna coupled with the physical-biogeochemical BALTSEM model of the Baltic Sea to study the combined effects of changing nutrient loads and climate on biomass and metabolism of benthic macrofauna historically and in scenarios for the future. Based on a statistical comparison with a large validation dataset of measured biomasses, the model showed good or reasonable performance across the different basins and depth strata in the model area. In scenarios with decreasing nutrient loads according to the Baltic Sea Action Plan, but also with continued recent loads (mean loads 2012-2014), overall macrofaunal biomass and carbon processing were projected to decrease significantly by the end of the century despite improved oxygen conditions at the seafloor. Climate change led to intensified pelagic recycling of primary production and reduced export of particulate organic carbon to the seafloor with negative effects on macrofaunal biomass. In the high nutrient load scenario, representing the highest recorded historical loads, climate change counteracted the effects of increased productivity leading to a hyperbolic response: biomass and carbon processing increased up to mid-21<sup>st</sup> century but then decreased, giving almost no net change by the end of the 21<sup>st</sup> century compared to present. The study shows that benthic responses to environmental change are nonlinear and partly decoupled from pelagic responses and indicates that benthic-pelagic coupling might be weaker in a warmer and less eutrophic sea.</p>

scholarly journals Future socioeconomic conditions may have a larger impact than climate change on nutrient loads to the Baltic Sea

AMBIO ◽  
2019 ◽  
Vol 48 (11) ◽  
pp. 1325-1336 ◽  
Author(s):  
Alena Bartosova ◽  
René Capell ◽  
Jørgen E. Olesen ◽  
Mohamed Jabloun ◽  
Jens Christian Refsgaard ◽  
...  
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Dynamic Modelling ◽  
Climate Change Scenarios ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
Nitrogen And Phosphorus ◽  
Socioeconomic Drivers ◽  
The Baltic ◽  
The Impact

Abstract The Baltic Sea is suffering from eutrophication caused by nutrient discharges from land to sea, and these loads might change in a changing climate. We show that the impact from climate change by mid-century is probably less than the direct impact of changing socioeconomic factors such as land use, agricultural practices, atmospheric deposition, and wastewater emissions. We compare results from dynamic modelling of nutrient loads to the Baltic Sea under projections of climate change and scenarios for shared socioeconomic pathways. Average nutrient loads are projected to increase by 8% and 14% for nitrogen and phosphorus, respectively, in response to climate change scenarios. In contrast, changes in the socioeconomic drivers can lead to a decrease of 13% and 6% or an increase of 11% and 9% in nitrogen and phosphorus loads, respectively, depending on the pathway. This indicates that policy decisions still play a major role in climate adaptation and in managing eutrophication in the Baltic Sea region.

A combination of species distribution and ocean-biogeochemical models suggests that climate change overrides eutrophication as the driver of future distributions of a key benthic crustacean in the estuarine ecosystem of the Baltic Sea

2020 ◽  
Vol 77 (6) ◽  
pp. 2089-2105
Author(s):  
Mayya Gogina ◽  
Michael L Zettler ◽  
Irene Wåhlström ◽  
Helén Andersson ◽  
Hagen Radtke ◽  
...  
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Action Plan ◽  
Future Climate Change ◽  
Suitable Habitat ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
Estuarine Ecosystem ◽  
Biogeochemical Models ◽  
The Baltic

Abstract Species in the brackish and estuarine ecosystems will experience multiple changes in hydrographic variables due to ongoing climate change and nutrient loads. Here, we investigate how a glacial relict species (Saduria entomon), having relatively cold, low salinity biogeographic origin, could be affected by the combined scenarios of climate change and eutrophication. It is an important prey for higher trophic-level species such as cod, and a predator of other benthic animals. We constructed habitat distribution models based occurrence and density of this species across the entire Baltic and estimated the relative importance of different driving variables. We then used two regional coupled ocean-biogeochemical models to investigate the combined impacts of two future climate change and nutrient loads scenarios on its spatial distribution in 2070–2100. According to the scenarios, the Baltic Sea will become warmer and fresher. Our results show that expected changes in salinity and temperature outrank those due to two nutrient-load scenarios (Baltic Sea Action Plan and business as usual) in their effect on S. entomon distribution. The results are relatively similar when using different models with the same scenarios, thereby increasing the confidence of projections. Overall, our models predict a net increase (and local declines) of suitable habitat area, total abundance and biomass for this species, which is probably facilitated by strong osmoregulation ability and tolerance to temperature changes. We emphasize the necessity of considering multiple hydrographic variables when estimating climate change impacts on species living in brackish and estuarine systems.

Past, current, and future freshwater inflows to the Baltic Sea under changing climate and socioeconomics

2020 ◽  
Author(s):  
Alena Bartosova ◽  
René Capell ◽  
Jørgen E. Olesen ◽  
Berit Arheimer
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Large Scale ◽  
Mitigation Measures ◽  
Nutrient Loads ◽  
Socioeconomic Conditions ◽  
The Baltic Sea ◽  
Nitrogen Loads ◽  
The Baltic ◽  
Freshwater Inflows

<p>The Baltic Sea is suffering from eutrophication caused by nutrient discharges from land to sea. These freshwater inflows vary in magnitude from year to year as well as within each year due to e.g. natural variability, weather patterns, and seasonal human activities. Nutrient transport models are important tools for assessments of macro-nutrient fluxes (nitrogen, phosphorus) and for evaluating the connection between pollution sources and the assessed water body. While understanding of current status is important, impacts from changing climate and socio-economics on freshwater inflows to the Baltic Sea also need to be taken into account when planning management practices and mitigation measures.</p><p>Continental to global scale catchment-based hydrological models have emerged in recent years as tools e.g. for flood forecasting, large-scale climate impact analyses, and estimation of time-dynamic water fluxes into sea basins. Here, we present results from the pan-European rainfall-runoff and nutrient transfer model E-HYPE, developed as a multi-purpose tool for large-scale hydrological analyses. We compared current freshwater inflows from land with those from dynamic modelling with E-HYPE under various climate and socioeconomic conditions. The socioeconomic conditions (land use, agricultural practices, population changes, dietary changes, atmospheric deposition, and wastewater technologies) were evaluated for 3 additional time horizons: 2050s using the Shared Socioeconomic Pathways, 1900s using historical data, and a reference period using a synthetic “no human impact” scenario. An ensemble of 4 climate models that preserves the range of projected changes in precipitation and temperature from a larger ensemble was selected for analysis of climate impacts in 2050s.  </p><p>We show that while climate change affects nutrient loads to the Baltic Sea, these impacts can be overshadowed by the impacts of changing socioeconomic factors. Historical nitrogen loads were estimated as 43% and 33% of the current loads for the 1900s and the “no human impact” scenarios, respectively. Average nitrogen loads are projected to increase by 4-10% (8% on average) as a response to climate change by 2050s. Purely mitigation measures that did not address the magnitude of the nutrient sources reduced the total nitrogen load by <5%, with local efficiencies being reduced through retention processes. However, changes in the socioeconomic drivers led to significant changes in the future loads with the range of impacts spanning 30% of the current load depending on the socioeconomic pathway to be followed. This means that policy decisions have by far the largest impact when managing eutrophication in the Baltic Sea region.</p><p>Bartosova, A., Capell, R., Olesen, J.E. et al. (2019). Future socioeconomic conditions may have a larger impact than climate change on nutrient loads to the Baltic Sea. Ambio 48, 1325–1336 doi:10.1007/s13280-019-01243-5</p>

Projections for Temperature, Precipitation, Wind, and Snow in the Baltic Sea Region until 2100

2018 ◽  
Author(s):  
Ole Bøssing Christensen ◽  
Erik Kjellström
Keyword(s):  
Climate Change ◽  
Wind Speed ◽  
Baltic Sea ◽  
Climate Models ◽  
Global Climate Models ◽  
Anthropogenic Climate Change ◽  
The Baltic Sea ◽  
Baltic Sea Region ◽  
The Future ◽  
The Baltic

The ecosystems and the societies of the Baltic Sea region are quite sensitive to fluctuations in climate, and therefore it is expected that anthropogenic climate change will affect the region considerably. With numerical climate models, a large amount of projections of meteorological variables affected by anthropogenic climate change have been performed in the Baltic Sea region for periods reaching the end of this century.Existing global and regional climate model studies suggest that:• The future Baltic climate will get warmer, mostly so in winter. Changes increase with time or increasing emissions of greenhouse gases. There is a large spread between different models, but they all project warming. In the northern part of the region, temperature change will be higher than the global average warming.• Daily minimum temperatures will increase more than average temperature, particularly in winter.• Future average precipitation amounts will be larger than today. The relative increase is largest in winter. In summer, increases in the far north and decreases in the south are seen in most simulations. In the intermediate region, the sign of change is uncertain.• Precipitation extremes are expected to increase, though with a higher degree of uncertainty in magnitude compared to projected changes in temperature extremes.• Future changes in wind speed are highly dependent on changes in the large-scale circulation simulated by global climate models (GCMs). The results do not all agree, and it is not possible to assess whether there will be a general increase or decrease in wind speed in the future.• Only very small high-altitude mountain areas in a few simulations are projected to experience a reduction in winter snow amount of less than 50%. The southern half of the Baltic Sea region is projected to experience significant reductions in snow amount, with median reductions of around 75%.

scholarly journals Global climate change and the Baltic Sea ecosystem: direct and indirect effects on species, communities and ecosystem functioning

2021 ◽  
Author(s):  
Markku Viitasalo ◽  
Erik Bonsdorff
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Food Web ◽  
Experimental Work ◽  
Ecosystem Functioning ◽  
The Baltic Sea ◽  
Food Web Dynamics ◽  
The Future ◽  
Modelling Studies ◽  
The Baltic

Abstract. Climate change has multiple direct and indirect potentially synergistic effects on Baltic Sea species, organism communities, and on ecosystem functioning, through physical and biogeochemical environmental characteristics of the sea. Associated indirect and secondary effects on species interactions, trophic dynamics and ecosystem function are expected to be significant. Evidence on effects of climate are compiled from and reviewed for field studies, experimental work, as well as modelling studies primarily from published literature after 2010. The responses vary within and between species groups, even between sibling species. Such subtle differences, as well as secondary feedbacks and altered trophic pathways, make projections difficult. Some common patterns arise from the wealth of recent studies, however. It is likely that the combined effects of increased external nutrient loads, stratification and internal loading will improve the conditions for cyanobacterial blooms in large parts of the Baltic. In the northernmost areas the increasing allochtonous DOM may further complicate the picture by increasing heterotrophy and by decreasing food web efficiency. This effect may, however, be counteracted by the intensification of the bacteria-flagellate-microzooplankton-mesozooplankton link, which may change the system from a bottom-up controlled one to a top-down controlled one. In deep benthic communities, continued eutrophication may promote higher sedimentation of organic matter and increase zoobenthic biomasses, but eventually increasing stratification and hypoxia/anoxia will disrupt benthic-pelagic coupling, leading to reduced benthic biomass. In the photic benthic systems warmer winters with less ice and nutrient increase enhances eutrophication. The projected salinity decline suppresses marine species, and temperature increase overgrowth of perennial macroalgae by annual filamentous alga throughout the growing-season, and major changes in the marine entire ecosystem are expected. The changes in environmental conditions probably also lead to increased establishment of non-indigenous species, potentially affecting food web dynamics in large areas of the Baltic Sea. However, several modelling studies have concluded that nutrient reductions according to the Baltic Sea Action Plan of Helsinki Commission may be a stronger driver for ecosystem functions in the Baltic Sea than climate change. Such studies highlight the importance of studying the Baltic Sea as an interlinked socio-ecological system. Knowledge gaps include uncertainties in projecting the future salinity level as well as stratification under different climate forcings. This weakens our ability to project how overall biodiversity, pelagic productivity, fish populations, and macroalgal communities may change in the future. Experimental work must be better integrated into studies of food web dynamics, to get a more comprehensive view of the responses of the pelagic and benthic systems to climate change, from bacteria to fish. Few studies have holistically investigated the shallow water ecosystems holistically. There are complex climate-induced interactions and multiple feedbacks between algae, grazers and their predators, that are poorly known, as are the effects of non-native invasive species. Finally, both 2D species distribution models and 3D ecosystem models could benefit from better integration of approaches including physical, chemical and biological parameters.

Climate change and the Baltic Sea action plan: Model simulations on the future of the western Baltic Sea

2012 ◽  
Vol 105-108 ◽  
pp. 175-186 ◽  
Author(s):  
René Friedland ◽  
Thomas Neumann ◽  
Gerald Schernewski
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Action Plan ◽  
The Baltic Sea ◽  
Model Simulations ◽  
The Future ◽  
The Baltic

scholarly journals Remediating Agricultural Legacy Nutrient Loads in the Baltic Sea Region

2021 ◽  
Vol 13 (7) ◽  
pp. 3872
Author(s):  
Julia Tanzer ◽  
Ralf Hermann ◽  
Ludwig Hermann
Keyword(s):  
Baltic Sea ◽  
Agricultural Soils ◽  
Economic Benefits ◽  
Current Data ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
Nutrient Emissions ◽  
Long Run ◽  
The Baltic ◽  
Agricultural Legacy

The Baltic Sea is considered the marine water body most severely affected by eutrophication within Europe. Due to its limited water exchange nutrients have a particularly long residence time in the sea. While several studies have analysed the costs of reducing current nutrient emissions, the costs for remediating legacy nutrient loads of past emissions remain unknown. Although the Baltic Sea is a comparatively well-monitored region, current data and knowledge is insufficient to provide a sound quantification of legacy nutrient loads and much less their abatement costs. A first rough estimation of agricultural legacy nutrient loads yields an accumulation of 0.5–4.0 Mt N and 0.3–1.2 Mt P in the Baltic Sea and 0.4–0.5 Mt P in agricultural soils within the catchment. The costs for removing or immobilising this amount of nutrients via deep water oxygenation, mussel farming and soil gypsum amendment are in the range of few tens to over 100 billion €. These preliminary results are meant as a basis for future studies and show that while requiring serious commitment to funding and implementation, remediating agricultural legacy loads is not infeasible and may even provide economic benefits to local communities in the long run.

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