An approach for coupling higher and lower levels in marine ecosystem models and its application to the North Sea

Abstract. End to end modelling is an attractive and rapidly developing approach to solve developing strategies in marine systems science and management. However problems remain in the area of data matching and sub-model compatibility. A mechanism and novel interfacing system (Couplerlib) is presented whereby a physical/biogeochemical model (GOTM-ERSEM) that predicts dynamics of the lower trophic level (LTL) organisms in marine ecosystems is coupled to a dynamic ecosystem model (Ecosim) that predicts food-web interactions among higher trophic level (HTL) organisms. Coupling is achieved by means of a bespoke interface which handles the system incompatibilities between the models and a more generic Couplerlib library which uses metadata descriptions in extensible mark-up language (XML) to marshal data between groups, paying attention to functional group mappings and compatibility of units between models. In addition, within Couplerlib, models can be coupled across networks by means of socket mechanisms. As a demonstration of this approach, a food web model (Ecopath with Ecosim, EwE) and a physical/biogeochemical model (GOTM-ERSEM) representing the North Sea ecosystem were joined with Couplerlib. The output from GOTM-ERSEM varies between years dependent on oceanographic and meteorological conditions. Although inter-annual variability was clearly present, there was always the tendency for an annual cycle consisting of a peak of diatoms in spring, followed by (less nutritious) flagellates and dinoflagellates through the summer resulting in an early summer peak in the mesozooplankton biomass. Pelagic productivity, predicted by the LTL model, was highly seasonal with little winter food for the higher trophic levels. The Ecosim model was originally based on the assumption of constant annual inputs and, consequently, when coupled, pelagic species suffered population loss over the winter months. By contrast, benthic populations were more stable (although the benthic linkage modelled was purely at the detritus level). The coupled model was used to examine long term effects of environmental change, and showed the system to be nutrient limited, relatively unaffected by forecast climate change, especially in the benthos. The stability of an Ecosim formulation for large higher tropic level food webs is discussed and it is concluded that this kind of coupled model formulation is better for examining the effects of long term environmental change than short term perturbations.

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<i>Couplerlib</i>: a metadata-driven library for the integration of multiple models of higher and lower trophic level marine systems with inexact functional group matching

Geoscientific Model Development ◽

10.5194/gmd-9-947-2016 ◽

2016 ◽

Vol 9 (3) ◽

pp. 947-964 ◽

Cited By ~ 2

Author(s):

Jonathan Beecham ◽

Jorn Bruggeman ◽

John Aldridge ◽

Steven Mackinson

Keyword(s):

Environmental Change ◽

Food Web ◽

Trophic Level ◽

Functional Group ◽

Coupled Model ◽

Ecosystem Model ◽

Biogeochemical Model ◽

Marine Systems ◽

The Stability

Abstract. End-to-end modelling is a rapidly developing strategy for modelling in marine systems science and management. However, problems remain in the area of data matching and sub-model compatibility. A mechanism and novel interfacing system (Couplerlib) is presented whereby a physical–biogeochemical model (General Ocean Turbulence Model–European Regional Seas Ecosystem Model, GOTM–ERSEM) that predicts dynamics of the lower trophic level (LTL) organisms in marine ecosystems is coupled to a dynamic ecosystem model (Ecosim), which predicts food-web interactions among higher trophic level (HTL) organisms. Coupling is achieved by means of a bespoke interface, which handles the system incompatibilities between the models and a more generic Couplerlib library, which uses metadata descriptions in extensible mark-up language (XML) to marshal data between groups, paying attention to functional group mappings and compatibility of units between models. In addition, within Couplerlib, models can be coupled across networks by means of socket mechanisms. As a demonstration of this approach, a food-web model (Ecopath with Ecosim, EwE) and a physical–biogeochemical model (GOTM–ERSEM) representing the North Sea ecosystem were joined with Couplerlib. The output from GOTM–ERSEM varies between years, depending on oceanographic and meteorological conditions. Although inter-annual variability was clearly present, there was always the tendency for an annual cycle consisting of a peak of diatoms in spring, followed by (less nutritious) flagellates and dinoflagellates through the summer, resulting in an early summer peak in the mesozooplankton biomass. Pelagic productivity, predicted by the LTL model, was highly seasonal with little winter food for the higher trophic levels. The Ecosim model was originally based on the assumption of constant annual inputs of energy and, consequently, when coupled, pelagic species suffered population losses over the winter months. By contrast, benthic populations were more stable (although the benthic linkage modelled was purely at the detritus level, so this stability reflects the stability of the Ecosim model). The coupled model was used to examine long-term effects of environmental change, and showed the system to be nutrient limited and relatively unaffected by forecast climate change, especially in the benthos. The stability of an Ecosim formulation for large higher tropic level food webs is discussed and it is concluded that this kind of coupled model formulation is better for examining the effects of long-term environmental change than short-term perturbations.

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Low-frequency variability in North Sea and Baltic Sea identified through simulations with the 3-D coupled physical–biogeochemical model ECOSMO

Earth System Dynamics ◽

10.5194/esd-8-801-2017 ◽

2017 ◽

Vol 8 (3) ◽

pp. 801-815 ◽

Cited By ~ 10

Author(s):

Ute Daewel ◽

Corinna Schrum

Keyword(s):

Baltic Sea ◽

North Sea ◽

Decadal Variability ◽

Model Simulation ◽

Ecosystem Model ◽

Biogeochemical Model ◽

Ecosystem Productivity ◽

The North ◽

The North Sea

Abstract. Here we present results from a long-term model simulation of the 3-D coupled ecosystem model ECOSMO II for a North Sea and Baltic Sea set-up. The model allows both multi-decadal hindcast simulation of the marine system and specific process studies under controlled environmental conditions. Model results have been analysed with respect to long-term multi-decadal variability in both physical and biological parameters with the help of empirical orthogonal function (EOF) analysis. The analysis of a 61-year (1948–2008) hindcast reveals a quasi-decadal variation in salinity, temperature and current fields in the North Sea in addition to singular events of major changes during restricted time frames. These changes in hydrodynamic variables were found to be associated with changes in ecosystem productivity that are temporally aligned with the timing of reported regime shifts in the areas. Our results clearly indicate that for analysing ecosystem productivity, spatially explicit methods are indispensable. Especially in the North Sea, a correlation analysis between atmospheric forcing and primary production (PP) reveals significant correlations between PP and the North Atlantic Oscillation (NAO) and wind forcing for the central part of the region, while the Atlantic Multi-decadal Oscillation (AMO) and air temperature are correlated to long-term changes in PP in the southern North Sea frontal areas. Since correlations cannot serve to identify causal relationship, we performed scenario model runs perturbing the temporal variability in forcing condition to emphasize specifically the role of solar radiation, wind and eutrophication. The results revealed that, although all parameters are relevant for the magnitude of PP in the North Sea and Baltic Sea, the dominant impact on long-term variability and major shifts in ecosystem productivity was introduced by modulations of the wind fields.

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Low frequency variability in North Sea and Baltic Sea identified through simulations with the 3-d coupled physical-biogeochemical model ECOSMO

10.5194/esd-2017-36 ◽

2017 ◽

Cited By ~ 1

Author(s):

Ute Daewel ◽

Corinna Schrum

Keyword(s):

Baltic Sea ◽

North Sea ◽

Decadal Variability ◽

Model Simulation ◽

Ecosystem Model ◽

Biogeochemical Model ◽

Ecosystem Productivity ◽

The North ◽

The North Sea

Abstract. Here we present results from a long-term model simulation of the 3d coupled ecosystem model ECOSMO II for a North and Baltic Sea setup. The model allows both multi-decadal hindcast simulation of the marine system and specific process studies under controlled environmental conditions. Model results have been analysed with respect to long-term multi decadal variability in both physical and biological parameters with the help of empirical orthogonal function (EOF) analysis. The analysis of a 61-year (1948–2008) long hind cast reveals a quasi-decadal variation on salinity, temperature and current fields in the North Sea in addition to singular events of major changes during restricted time frames. These changes in hydrodynamic variables where found to be associated to changes in ecosystem productivity that are temporally aligned with the timing of reported regime shifts in the areas. Our results clearly indicate that for analysing ecosystem productivity spatially explicit methods are indispensable. Especially in the North Sea a correlation analysis between atmospheric forcing and primary production (PP) reveals significant correlations for NAO and wind forcing for the central part of the region, while AMO and air temperature are correlated to long-term changes in the southern North Sea frontal areas. Since correlations cannot serve to identify causal relationship we performed scenario model runs with perturbing the temporal variability in forcing condition emphasizing specifically the role of solar radiation, wind and eutrophication. The results revealed that, although all parameters are relevant for the magnitude of PP in the North Sea and Baltic Sea, the dominant impact on long-term variability and major shifts in ecosystem productivity was introduced by modulations of the wind fields.

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Long-term changes in the North Sea ecosystem

Environmental Reviews ◽

10.1139/a01-005 ◽

2001 ◽

Vol 9 (3) ◽

pp. 131-187 ◽

Cited By ~ 37

Author(s):

R A Clark ◽

C LJ Frid

Keyword(s):

North Sea ◽

Primary Productivity ◽

Trophic Levels ◽

Benthic Fish ◽

Nutrient Inputs ◽

Climatic Fluctuations ◽

The North ◽

Long Term Changes ◽

The North Sea

Long-term data on the North Sea ecosystem are available for phytoplanktonic, zooplanktonic, benthic, fish, and seabird communities. Temporal changes in these have been examined by numerous researchers over the course of the 20th century, their main objective being to determine how the interannual dynamics of these communities are controlled. Ultimately, long-term changes in the North Sea ecosystem appear to be driven by two wide-ranging, but separate processes. In the northern, western and central areas of the North Sea, long-term changes are predominantly influenced by climatic fluctuations. Here, primary productivity during a particular year is related to the effect of weather on the timing of stratification and the resulting spring bloom. In the southern and eastern areas of the North Sea, the lack of stratification and the large inputs of nutrients mean that primary productivity is more strongly influenced by variations in anthropogenic nutrient inputs, and is only weakly related to climatic variation. Long-term changes at higher trophic levels (zooplankton, benthic, fish, and seabirds) are generally affected by fluctuations in their food source (i.e., the lower trophic levels), although because of the high complexity of the North Sea ecosystem there are many exceptions to these general patterns. However, the weight of evidence shows that long-term changes in the ecosystem may ultimately be related to long-term changes in either climate or nutrients, although the long-term dynamics of certain taxa and communities do show evidence of being influenced by both anthropogenic factors and (or) internal factors such as competition and predation. Key words: long-term changes, North Sea, time series, climate change, ecosystem functioning, anthropogenic impacts.

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Stable isotope evidence of long-term changes in the North Sea food web structure

Marine Ecology Progress Series ◽

10.3354/meps07635 ◽

2008 ◽

Vol 368 ◽

pp. 1-8 ◽

Cited By ~ 34

Author(s):

JT Christensen ◽

K Richardson

Keyword(s):

Stable Isotope ◽

Food Web ◽

North Sea ◽

Food Web Structure ◽

The North ◽

Web Structure ◽

Long Term Changes ◽

The North Sea ◽

Isotope Evidence

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A Modular Approach for Modelling of the North Sea Ecosystem

Water Science & Technology ◽

10.2166/wst.1991.0270 ◽

1991 ◽

Vol 24 (10) ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

A. Malmgren-Hansen ◽

J. W. Baretta ◽

P. Ruardij

Keyword(s):

Food Web ◽

North Sea ◽

Algal Growth ◽

Ecosystem Model ◽

Trophic Levels ◽

Basic Knowledge ◽

Modular Approach ◽

The North ◽

The North Sea

A modular approach for generating an ecosystem model for the North Sea is presented. The model structure consists of modules describing physical, chemical and biological processes. The modular approach is selected to facilitate stepwise improvements in the total ecosystem model by replacing existing modules with improved modules being developed. The modules constituting the pelagic ecosystem describe the biological and chemical dynamics of particle production and dissolution simulating the flux of carbon and nutrients (N, P, Si) through the food web. This might be done as a suite of submodules based on functional groups of organisms or as modules describing the different trophic levels based on size distributions. Algal growth is dependent on cellular content of the limiting nutrient, or on net photosynthesis, whichever is the most restricting, allowing for “luxury uptake” of nutrients which may be stored for subsequent periods of shortage. The role of bacteria and other microorganisms is emphasized in recognition of the importance of the “microbial loop”. The Zooplankton module describes prey ingestion in terms of feeding behaviour and the partitioning of ingested carbon, nitrogen and phosphorus into growth and reproduction and the losses through respiration, excretion and defecation. The benthic modules concentrate on describing the small food web, since benthic biological activity in terms of carbon flow, as well as mineralization, are often dominated by micro- and meiofauna in the generally soft sediments of the North Sea. Macrobenthos are described as being a major link between the benthic small food web and higher trophic levels in the ecosystem. Higher trophic levels are described in separate modules taking into account in principle the role of fish, mammals and seabirds. Nutrient cycling is described, focusing on the identification and conceptual modelling of the chemical processes and mechanisms in order to describe the relationships between the biology of the North Sea and the nutrient chemistry. This represents a first step towards forecasting the response of the system to long-term changes due to e.g. eutrophication. The modelling of the nutrient sediment-water interaction emphasizes the role of sedimentation of particulates and the regeneration of inorganic components to the water column. This totally modular concept of the North Sea ecosystem model reflects the authors' view on the present state of the North Sea, the basic knowledge about ecosystem behaviour and a way of creating models as a tool for better understanding of the ecosystem and how man affects the North Sea environment.

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