Thorsten Blenckner - Profile on Academia.edu (original) (raw)

Papers by Thorsten Blenckner

Species composition and habitats are changing at unprecedented rates in the world's oceans, poten... more Species composition and habitats are changing at unprecedented rates in the world's oceans, potentially causing entire food webs to shift to structurally and functionally different regimes. Despite the severity of these regime shifts, elucidating the precise nature of their underlying processes has remained difficult. We address this challenge with a new analytic approach to detect and assess the relative strength of different driving processes in food webs. Our study draws on complexity theory, and integrates the network-centric exponential random graph modelling (ERGM) framework developed within the social sciences with community ecology. In contrast to previous research, this approach makes clear assumptions of direction of causality and accommodates a dynamic perspective on the emergence of food webs. We apply our approach to analysing food webs of the Baltic Sea before and after a previously reported regime shift. Our results show that the dominant food web processes have remained largely the same, although we detect changes in their magnitudes. The results indicate that the reported regime shift may not be a system-wide shift, but instead involve a limited number of species. Our study emphasizes the importance of community wide analysis on marine regime shifts and introduces a novel approach to examine food webs.

Regime shifts in marine communities: a complex systems perspective on food web dynamics

Proceedings of the Royal Society B: Biological Sciences, 2016

Species composition and habitats are changing at unprecedented rates in the world&amp... more Species composition and habitats are changing at unprecedented rates in the world's oceans, potentially causing entire food webs to shift to structurally and functionally different regimes. Despite the severity of these regime shifts, elucidating the precise nature of their underlying processes has remained difficult. We address this challenge with a new analytic approach to detect and assess the relative strength of different driving processes in food webs. Our study draws on complexity theory, and integrates the network-centric exponential random graph modelling (ERGM) framework developed within the social sciences with community ecology. In contrast to previous research, this approach makes clear assumptions of direction of causality and accommodates a dynamic perspective on the emergence of food webs. We apply our approach to analysing food webs of the Baltic Sea before and after a previously reported regime shift. Our results show that the dominant food web processes have remained largely the same, although we detect changes in their magnitudes. The results indicate that the reported regime shift may not be a system-wide shift, but instead involve a limited number of species. Our study emphasizes the importance of community-wide analysis on marine regime shifts and introduces a novel approach to examine food webs.

North Atlantic Oscillation signatures in ecosystems - a meta-analysis

Global Change Biology Pp 203 212, 2002

An empirical model of the Baltic Sea reveals the importance of social dynamics for ecological regime shifts

Proceedings of the National Academy of Sciences, 2015

Regime shifts triggered by human activities and environmental changes have led to significant eco... more Regime shifts triggered by human activities and environmental changes have led to significant ecological and socioeconomic consequences in marine and terrestrial ecosystems worldwide. Ecological processes and feedbacks associated with regime shifts have received considerable attention, but human individual and collective behavior is rarely treated as an integrated component of such shifts. Here, we used generalized modeling to develop a coupled social-ecological model that integrated rich social and ecological data to investigate the role of social dynamics in the 1980s Baltic Sea cod boom and collapse. We showed that psychological, economic, and regulatory aspects of fisher decision making, in addition to ecological interactions, contributed both to the temporary persistence of the cod boom and to its subsequent collapse. These features of the social-ecological system also would have limited the effectiveness of stronger fishery regulations. Our results provide quantitative, empirical evidence that incorporating social dynamics into models of natural resources is critical for understanding how resources can be managed sustainably. We also show that generalized modeling, which is well-suited to collaborative model development and does not require detailed specification of causal relationships between system variables, can help tackle the complexities involved in creating and analyzing social-ecological models.

Ecosystem Health and Sustainability, 2015

As climatic changes and human uses intensify, resource managers and other decision makers are tak... more As climatic changes and human uses intensify, resource managers and other decision makers are taking actions to either avoid or respond to ecosystem tipping points, or dramatic shifts in structure and function that are often costly and hard to reverse. Evidence indicates that explicitly addressing tipping points leads to improved management outcomes. Drawing on theory and examples from marine systems, we distill a set of seven principles to guide effective management in ecosystems with tipping points, derived from the best available science. These principles are based on observations that tipping points (1) are possible everywhere, (2) are associated with intense and/or multifaceted human use, (3) may be preceded by changes in earlywarning indicators, (4) may redistribute benefits among stakeholders, (5) affect the relative costs of action and inaction, (6) suggest biologically informed management targets, and (7) often require an adaptive response to monitoring. We suggest that early action to preserve system resilience is likely more practical, affordable, and effective than late action to halt or reverse a tipping point. We articulate a conceptual approach to management focused on linking management targets to thresholds, tracking early-warning signals of ecosystem instability, and stepping up investment in monitoring and mitigation as the likelihood of dramatic ecosystem change increases. This approach can simplify and economize management by allowing decision makers to capitalize on the increasing value of precise information about threshold relationships when a system is closer to tipping or by ensuring that restoration effort is sufficient to tip a system into the desired regime.

AMBIO, 2015

Severe environmental problems documented in the Baltic Sea in the 1960s led to the 1974 creation ... more Severe environmental problems documented in the Baltic Sea in the 1960s led to the 1974 creation of the Helsinki Convention for the Protection of the Marine Environment of the Baltic Sea Area. We introduce this special issue by briefly summarizing successes and failures of Baltic environmental management in the following 40 years. The loads of many polluting substances have been greatly reduced, but legacy pollution slows recovery. Top predator populations have recovered, and human exposure to potential toxins has been reduced. The cod stock has partially recovered. Nutrient loads are decreasing, but deep-water anoxia and cyanobacterial blooms remain extensive, and climate change threatens the advances made. Ecosystembased management is the agreed principle, but in practice the various environmental problems are still handled separately, since we still lack both basic ecological knowledge and appropriate governance structures for managing them together, in a true ecosystem approach.

Ambio, 2015

Ecosystem-based management (EBM) has emerged as the generally agreed strategy for managing ecosys... more Ecosystem-based management (EBM) has emerged as the generally agreed strategy for managing ecosystems, with humans as integral parts of the managed system. Human activities have substantial effects on marine ecosystems, through overfishing, eutrophication, toxic pollution, habitat destruction, and climate change. It is important to advance the scientific knowledge of the cumulative, integrative, and interacting effects of these diverse activities, to support effective implementation of EBM. Based on contributions to this special issue of AMBIO, we synthesize the scientific findings into four components: pollution and legal frameworks, ecosystem processes, scale-dependent effects, and innovative tools and methods. We conclude with challenges for the future, and identify the next steps needed for successful implementation of EBM in general and specifically for the Baltic Sea.

Marine Ecology Progress Series, 2015

Coastal zones are facing climate-driven change coupled with escalating eutrophication. With incre... more Coastal zones are facing climate-driven change coupled with escalating eutrophication. With increasing shifts in hydrographic conditions during the past few decades, a focal task is to understand how environmental drivers affect zoobenthic communities, which play a crucial role in ecosystem functioning. By using long-term data, spanning 40 yr (1973 to 2013) in the northern Baltic Sea, we showed a disparity in zoobenthic responses with pronounced changes in community composition and a trend towards decreased biomass in sheltered areas, while biomasses increased in exposed areas of the coastal zone. We used generalized additive modeling to show that bottom oxygen saturation, sea surface temperature and organic load of the sediments were the main environmental drivers behind contrasting patterns in biomass progression. Oxygen saturation alone explained over one third of the deviation in the biomass developments in sheltered areas, while exposed areas were mainly limited by organic content of the sediments. We analyzed high-resolution climate-scenario simulations, following the Intergovernmental Panel on Climate Change scenarios for the Baltic Sea region in combination with different nutrient load scenarios, for the end of the 21st century. The scenario outcomes showed negative trends in bottom oxygen concentrations throughout the coastal and archipelago zone along with overall increasing temperatures and primary production, and decreasing salinity. Our results suggest that these projected future conditions will strengthen the observed pattern in decreasing zoobenthic production in the immediate coastal zones. Moreover, the potential intensification of unfavorable conditions expanding seaward may lead to an expansion of biomass loss to more exposed sites.

Regional Climate Studies, 2015

Climate change effects on freshwater biogeochemistry and riverine loads of biogenic elements to t... more Climate change effects on freshwater biogeochemistry and riverine loads of biogenic elements to the Baltic Sea are not straight forward and are difficult to distinguish from other human drivers such as atmospheric deposition, forest and wetland management, eutrophication and hydrological alterations. Eutrophication is by far the most well-known factor affecting the biogeochemistry of the receiving waters in the various sub-basins of the Baltic Sea. However, the present literature review reveals that climate change is a compounding factor for all major drivers of freshwater biogeochemistry discussed here, although evidence is still often based on short-term and/or small-scale studies.

Environmental Impacts—Marine Ecosystems

Regional Climate Studies, 2015

Circulation Processes in Lakes

Encyclopedia of Earth Sciences Series, 2012

Auswirkungen des Kalkens versauerter Seen auf das Phytoplankton: Untersuchungen in einem norwegischen See

Synchronous regime shifts in Baltic Sea ecosystems: Similarities and dissimilarities in response to climate, nutrients and fisheries

Synchronous regime shifts in Baltic Sea ecosystems: Similarities and dissimilarities in response ... more Synchronous regime shifts in Baltic Sea ecosystems: Similarities and dissimilarities in response to climate, nutrients and fisheries Thorsten. Blenckner1, Rabea. Diekmann2, Christian. Möllmann2, Anna. Gårdmark3, Michele. Casini4, Lena Bergström3, Juha Flinkman5, ...

Långtidsutvärdering Av Det Gemensamma Miljökontrollprogrammet För Fiskodlingarna På Åland 1993-2003

regeringen.ax

Beräkning av omgivningsbeskrivande parametrar....................................................... more Beräkning av omgivningsbeskrivande parametrar........................................................ 5 Analys av jämförbara data............................................................................................ 5 Utvärdering av resultat ....................................... ... ... Bilaga 4. Kontroll-och referenspunkter med jämförbar ...

A physical lake model was employed to obtain a basis of discussing the impact of climate variabil... more A physical lake model was employed to obtain a basis of discussing the impact of climate variability and climate change on the ecology of Lake Erken, Sweden. The validity of this approach was tested by running the PROBE-lake model for a 30-year period (STD) with observed meteorological data. The lake is adequately modelled, as seen in the comparison with actual lake ob­ servations. The validated lake model was then forced with meteorological data obtained from a regional clim­ ate model (RCM) with a horizontal resolution of 44 km for present (CLTR) and 2 x CO, (SCEN) climate condi­ tions. The CLTR lake simulation compares reasonably with the STD. Applying the SCEN simulation leads to a climate change scenario for the lake. The physical changes include elevated temperatures, shorter periods of ice cover combined with two of ten years being totally ice-free, and changes in the mixing regime. The ecolog­ ical consequences of the physical simulation results are derived from the historic...

Climatically induced regime shifts in aquatic ecosystems can reorganize plankton communities and ... more Climatically induced regime shifts in aquatic ecosystems can reorganize plankton communities and thus alter structural and functional system properties. These changes may be synchronized over large spatial scales and across different types of aquatic ecosystems. We studied the timing and type of long-term changes for several indicators of abiotic and biotic system components. The synchrony of regime shifts was analyzed with regard to system type (marine, freshwater), season (spring, summer) and geographic location. We choose two marine systems (North Sea, Baltic Sea) and two lakes (Müggelsee, Lake Washington). We hypothesize coherent shifts of all physical system components in spring during the late 1980s in Europe – possibly synchronized by NAO dynamics-regardless of system type and location, but out of phase with the North American system. Further, biological responses were expected to be less coherent but still obvious shifts in ecosystems. In contrast, responses of all system co...

Modeling the Effects of Climate Change on the Seasonal Dynamics of Phytoplankton

The Impact of Climate Change on European Lakes, 2009

... between the control and future simulations are the predicted reductions in the early summer b... more ... between the control and future simulations are the predicted reductions in the early summer biomass of ... 15.3.4 Case Study 4: The Increased Incidence of Cyanobacterial Blooms in Galten ... the potential effects of changes in the climate on the growth of cyanobacteria in the most ...

Eos, Transactions American Geophysical Union, 2003

of the optical contrast of an oil film on a sea surf ace, Optics Express., 9,411-416,2001. Otremb... more of the optical contrast of an oil film on a sea surf ace, Optics Express., 9,411-416,2001. Otremba, Z., and J. Piskozub, Modeling the remotely sensed optical contrast caused by oil suspended in the sea water column, Optics Express., 77,2-6,2003. SWFDOG, Satellite images track "black water" event off Florida coast,Eos Truns.,AGU,83,28\,285,20O2.

Lake Ice Phenology

The Impact of Climate Change on European Lakes, 2009

In Chapter 5 of this book, it is shown that the formation of ice on the surface of a lake (‘ice-o... more In Chapter 5 of this book, it is shown that the formation of ice on the surface of a lake (‘ice-on’) and its thawing and ultimate disappearance (‘ice-off’) are complex phenomena governed by mechanisms that involve many interacting meteorological (and some non-meteorological) forcing factors. Linking ice phenology – the timing of ice-on and ice-off – to climatic forcing might therefore

Marine environments have undergone large-scale changes in recent decades as a result of multiple ... more Marine environments have undergone large-scale changes in recent decades as a result of multiple anthropogenic pressures, such as overfishing, eutrophication, habitat fragmentation, etc., causing often nonlinear ecosystem responses. At the same time, management institutions lack the appropriate measures to address these abrupt transformations. We focus on existing examples from social-ecological systems of European seas that can be used to inform and advise future management. Examples from the Black Sea and the Baltic Sea on long-term ecosystem changes caused by eutrophication and fisheries, as well as changes in management institutions, illustrate nonlinear dynamics in social-ecological systems. Furthermore, we present two major future challenges, i.e., climate change and energy intensification, that could further increase the potential for nonlinear changes in the near future. Practical tools to address these challenges are presented, such as ensuring learning, flexibility, and networking in decision-making processes across sectors and scales. A combination of risk analysis with a scenario-planning approach might help to identify the risks of ecosystem changes early on and may frame societal changes to inform decision-making structures to proactively prevent drastic surprises in European seas. . 2013. Attitudes of Scottish fishers towards marine renewable energy. Marine Policy 37: 239-244.

Species composition and habitats are changing at unprecedented rates in the world's oceans, poten... more Species composition and habitats are changing at unprecedented rates in the world's oceans, potentially causing entire food webs to shift to structurally and functionally different regimes. Despite the severity of these regime shifts, elucidating the precise nature of their underlying processes has remained difficult. We address this challenge with a new analytic approach to detect and assess the relative strength of different driving processes in food webs. Our study draws on complexity theory, and integrates the network-centric exponential random graph modelling (ERGM) framework developed within the social sciences with community ecology. In contrast to previous research, this approach makes clear assumptions of direction of causality and accommodates a dynamic perspective on the emergence of food webs. We apply our approach to analysing food webs of the Baltic Sea before and after a previously reported regime shift. Our results show that the dominant food web processes have remained largely the same, although we detect changes in their magnitudes. The results indicate that the reported regime shift may not be a system-wide shift, but instead involve a limited number of species. Our study emphasizes the importance of community wide analysis on marine regime shifts and introduces a novel approach to examine food webs.

Regime shifts in marine communities: a complex systems perspective on food web dynamics

Proceedings of the Royal Society B: Biological Sciences, 2016

Species composition and habitats are changing at unprecedented rates in the world&amp... more Species composition and habitats are changing at unprecedented rates in the world's oceans, potentially causing entire food webs to shift to structurally and functionally different regimes. Despite the severity of these regime shifts, elucidating the precise nature of their underlying processes has remained difficult. We address this challenge with a new analytic approach to detect and assess the relative strength of different driving processes in food webs. Our study draws on complexity theory, and integrates the network-centric exponential random graph modelling (ERGM) framework developed within the social sciences with community ecology. In contrast to previous research, this approach makes clear assumptions of direction of causality and accommodates a dynamic perspective on the emergence of food webs. We apply our approach to analysing food webs of the Baltic Sea before and after a previously reported regime shift. Our results show that the dominant food web processes have remained largely the same, although we detect changes in their magnitudes. The results indicate that the reported regime shift may not be a system-wide shift, but instead involve a limited number of species. Our study emphasizes the importance of community-wide analysis on marine regime shifts and introduces a novel approach to examine food webs.

North Atlantic Oscillation signatures in ecosystems - a meta-analysis

Global Change Biology Pp 203 212, 2002

An empirical model of the Baltic Sea reveals the importance of social dynamics for ecological regime shifts

Proceedings of the National Academy of Sciences, 2015

Regime shifts triggered by human activities and environmental changes have led to significant eco... more Regime shifts triggered by human activities and environmental changes have led to significant ecological and socioeconomic consequences in marine and terrestrial ecosystems worldwide. Ecological processes and feedbacks associated with regime shifts have received considerable attention, but human individual and collective behavior is rarely treated as an integrated component of such shifts. Here, we used generalized modeling to develop a coupled social-ecological model that integrated rich social and ecological data to investigate the role of social dynamics in the 1980s Baltic Sea cod boom and collapse. We showed that psychological, economic, and regulatory aspects of fisher decision making, in addition to ecological interactions, contributed both to the temporary persistence of the cod boom and to its subsequent collapse. These features of the social-ecological system also would have limited the effectiveness of stronger fishery regulations. Our results provide quantitative, empirical evidence that incorporating social dynamics into models of natural resources is critical for understanding how resources can be managed sustainably. We also show that generalized modeling, which is well-suited to collaborative model development and does not require detailed specification of causal relationships between system variables, can help tackle the complexities involved in creating and analyzing social-ecological models.

Ecosystem Health and Sustainability, 2015

As climatic changes and human uses intensify, resource managers and other decision makers are tak... more As climatic changes and human uses intensify, resource managers and other decision makers are taking actions to either avoid or respond to ecosystem tipping points, or dramatic shifts in structure and function that are often costly and hard to reverse. Evidence indicates that explicitly addressing tipping points leads to improved management outcomes. Drawing on theory and examples from marine systems, we distill a set of seven principles to guide effective management in ecosystems with tipping points, derived from the best available science. These principles are based on observations that tipping points (1) are possible everywhere, (2) are associated with intense and/or multifaceted human use, (3) may be preceded by changes in earlywarning indicators, (4) may redistribute benefits among stakeholders, (5) affect the relative costs of action and inaction, (6) suggest biologically informed management targets, and (7) often require an adaptive response to monitoring. We suggest that early action to preserve system resilience is likely more practical, affordable, and effective than late action to halt or reverse a tipping point. We articulate a conceptual approach to management focused on linking management targets to thresholds, tracking early-warning signals of ecosystem instability, and stepping up investment in monitoring and mitigation as the likelihood of dramatic ecosystem change increases. This approach can simplify and economize management by allowing decision makers to capitalize on the increasing value of precise information about threshold relationships when a system is closer to tipping or by ensuring that restoration effort is sufficient to tip a system into the desired regime.

AMBIO, 2015

Severe environmental problems documented in the Baltic Sea in the 1960s led to the 1974 creation ... more Severe environmental problems documented in the Baltic Sea in the 1960s led to the 1974 creation of the Helsinki Convention for the Protection of the Marine Environment of the Baltic Sea Area. We introduce this special issue by briefly summarizing successes and failures of Baltic environmental management in the following 40 years. The loads of many polluting substances have been greatly reduced, but legacy pollution slows recovery. Top predator populations have recovered, and human exposure to potential toxins has been reduced. The cod stock has partially recovered. Nutrient loads are decreasing, but deep-water anoxia and cyanobacterial blooms remain extensive, and climate change threatens the advances made. Ecosystembased management is the agreed principle, but in practice the various environmental problems are still handled separately, since we still lack both basic ecological knowledge and appropriate governance structures for managing them together, in a true ecosystem approach.

Ambio, 2015

Ecosystem-based management (EBM) has emerged as the generally agreed strategy for managing ecosys... more Ecosystem-based management (EBM) has emerged as the generally agreed strategy for managing ecosystems, with humans as integral parts of the managed system. Human activities have substantial effects on marine ecosystems, through overfishing, eutrophication, toxic pollution, habitat destruction, and climate change. It is important to advance the scientific knowledge of the cumulative, integrative, and interacting effects of these diverse activities, to support effective implementation of EBM. Based on contributions to this special issue of AMBIO, we synthesize the scientific findings into four components: pollution and legal frameworks, ecosystem processes, scale-dependent effects, and innovative tools and methods. We conclude with challenges for the future, and identify the next steps needed for successful implementation of EBM in general and specifically for the Baltic Sea.

Marine Ecology Progress Series, 2015

Coastal zones are facing climate-driven change coupled with escalating eutrophication. With incre... more Coastal zones are facing climate-driven change coupled with escalating eutrophication. With increasing shifts in hydrographic conditions during the past few decades, a focal task is to understand how environmental drivers affect zoobenthic communities, which play a crucial role in ecosystem functioning. By using long-term data, spanning 40 yr (1973 to 2013) in the northern Baltic Sea, we showed a disparity in zoobenthic responses with pronounced changes in community composition and a trend towards decreased biomass in sheltered areas, while biomasses increased in exposed areas of the coastal zone. We used generalized additive modeling to show that bottom oxygen saturation, sea surface temperature and organic load of the sediments were the main environmental drivers behind contrasting patterns in biomass progression. Oxygen saturation alone explained over one third of the deviation in the biomass developments in sheltered areas, while exposed areas were mainly limited by organic content of the sediments. We analyzed high-resolution climate-scenario simulations, following the Intergovernmental Panel on Climate Change scenarios for the Baltic Sea region in combination with different nutrient load scenarios, for the end of the 21st century. The scenario outcomes showed negative trends in bottom oxygen concentrations throughout the coastal and archipelago zone along with overall increasing temperatures and primary production, and decreasing salinity. Our results suggest that these projected future conditions will strengthen the observed pattern in decreasing zoobenthic production in the immediate coastal zones. Moreover, the potential intensification of unfavorable conditions expanding seaward may lead to an expansion of biomass loss to more exposed sites.

Regional Climate Studies, 2015

Climate change effects on freshwater biogeochemistry and riverine loads of biogenic elements to t... more Climate change effects on freshwater biogeochemistry and riverine loads of biogenic elements to the Baltic Sea are not straight forward and are difficult to distinguish from other human drivers such as atmospheric deposition, forest and wetland management, eutrophication and hydrological alterations. Eutrophication is by far the most well-known factor affecting the biogeochemistry of the receiving waters in the various sub-basins of the Baltic Sea. However, the present literature review reveals that climate change is a compounding factor for all major drivers of freshwater biogeochemistry discussed here, although evidence is still often based on short-term and/or small-scale studies.

Environmental Impacts—Marine Ecosystems

Regional Climate Studies, 2015

Circulation Processes in Lakes

Encyclopedia of Earth Sciences Series, 2012

Auswirkungen des Kalkens versauerter Seen auf das Phytoplankton: Untersuchungen in einem norwegischen See

Synchronous regime shifts in Baltic Sea ecosystems: Similarities and dissimilarities in response to climate, nutrients and fisheries

Synchronous regime shifts in Baltic Sea ecosystems: Similarities and dissimilarities in response ... more Synchronous regime shifts in Baltic Sea ecosystems: Similarities and dissimilarities in response to climate, nutrients and fisheries Thorsten. Blenckner1, Rabea. Diekmann2, Christian. Möllmann2, Anna. Gårdmark3, Michele. Casini4, Lena Bergström3, Juha Flinkman5, ...

Långtidsutvärdering Av Det Gemensamma Miljökontrollprogrammet För Fiskodlingarna På Åland 1993-2003

regeringen.ax

Beräkning av omgivningsbeskrivande parametrar....................................................... more Beräkning av omgivningsbeskrivande parametrar........................................................ 5 Analys av jämförbara data............................................................................................ 5 Utvärdering av resultat ....................................... ... ... Bilaga 4. Kontroll-och referenspunkter med jämförbar ...

A physical lake model was employed to obtain a basis of discussing the impact of climate variabil... more A physical lake model was employed to obtain a basis of discussing the impact of climate variability and climate change on the ecology of Lake Erken, Sweden. The validity of this approach was tested by running the PROBE-lake model for a 30-year period (STD) with observed meteorological data. The lake is adequately modelled, as seen in the comparison with actual lake ob­ servations. The validated lake model was then forced with meteorological data obtained from a regional clim­ ate model (RCM) with a horizontal resolution of 44 km for present (CLTR) and 2 x CO, (SCEN) climate condi­ tions. The CLTR lake simulation compares reasonably with the STD. Applying the SCEN simulation leads to a climate change scenario for the lake. The physical changes include elevated temperatures, shorter periods of ice cover combined with two of ten years being totally ice-free, and changes in the mixing regime. The ecolog­ ical consequences of the physical simulation results are derived from the historic...

Climatically induced regime shifts in aquatic ecosystems can reorganize plankton communities and ... more Climatically induced regime shifts in aquatic ecosystems can reorganize plankton communities and thus alter structural and functional system properties. These changes may be synchronized over large spatial scales and across different types of aquatic ecosystems. We studied the timing and type of long-term changes for several indicators of abiotic and biotic system components. The synchrony of regime shifts was analyzed with regard to system type (marine, freshwater), season (spring, summer) and geographic location. We choose two marine systems (North Sea, Baltic Sea) and two lakes (Müggelsee, Lake Washington). We hypothesize coherent shifts of all physical system components in spring during the late 1980s in Europe – possibly synchronized by NAO dynamics-regardless of system type and location, but out of phase with the North American system. Further, biological responses were expected to be less coherent but still obvious shifts in ecosystems. In contrast, responses of all system co...

Modeling the Effects of Climate Change on the Seasonal Dynamics of Phytoplankton

The Impact of Climate Change on European Lakes, 2009

... between the control and future simulations are the predicted reductions in the early summer b... more ... between the control and future simulations are the predicted reductions in the early summer biomass of ... 15.3.4 Case Study 4: The Increased Incidence of Cyanobacterial Blooms in Galten ... the potential effects of changes in the climate on the growth of cyanobacteria in the most ...

Eos, Transactions American Geophysical Union, 2003

of the optical contrast of an oil film on a sea surf ace, Optics Express., 9,411-416,2001. Otremb... more of the optical contrast of an oil film on a sea surf ace, Optics Express., 9,411-416,2001. Otremba, Z., and J. Piskozub, Modeling the remotely sensed optical contrast caused by oil suspended in the sea water column, Optics Express., 77,2-6,2003. SWFDOG, Satellite images track "black water" event off Florida coast,Eos Truns.,AGU,83,28\,285,20O2.

Lake Ice Phenology

The Impact of Climate Change on European Lakes, 2009

In Chapter 5 of this book, it is shown that the formation of ice on the surface of a lake (‘ice-o... more In Chapter 5 of this book, it is shown that the formation of ice on the surface of a lake (‘ice-on’) and its thawing and ultimate disappearance (‘ice-off’) are complex phenomena governed by mechanisms that involve many interacting meteorological (and some non-meteorological) forcing factors. Linking ice phenology – the timing of ice-on and ice-off – to climatic forcing might therefore

Marine environments have undergone large-scale changes in recent decades as a result of multiple ... more Marine environments have undergone large-scale changes in recent decades as a result of multiple anthropogenic pressures, such as overfishing, eutrophication, habitat fragmentation, etc., causing often nonlinear ecosystem responses. At the same time, management institutions lack the appropriate measures to address these abrupt transformations. We focus on existing examples from social-ecological systems of European seas that can be used to inform and advise future management. Examples from the Black Sea and the Baltic Sea on long-term ecosystem changes caused by eutrophication and fisheries, as well as changes in management institutions, illustrate nonlinear dynamics in social-ecological systems. Furthermore, we present two major future challenges, i.e., climate change and energy intensification, that could further increase the potential for nonlinear changes in the near future. Practical tools to address these challenges are presented, such as ensuring learning, flexibility, and networking in decision-making processes across sectors and scales. A combination of risk analysis with a scenario-planning approach might help to identify the risks of ecosystem changes early on and may frame societal changes to inform decision-making structures to proactively prevent drastic surprises in European seas. . 2013. Attitudes of Scottish fishers towards marine renewable energy. Marine Policy 37: 239-244.