Detecting ecosystem service trade-offs and synergies: A practice-oriented application in four industrialized estuaries
Introduction
Ecosystem services (ES) are the aspects of ecosystems, utilized actively or passively, to produce human well-being (Fisher et al., 2009). The science of ecosystem services aims to classify, describe and assess these natural assets, their demand and supply functions, quantification, valuation and management. ecosystem services are currently categorized in provisioning, regulating, and cultural services. All of those are eventually generated, supported and ensured by ecosystems in all their diversity (MA, 2005, TEEB, 2010).
Estuaries and coastal marine ecosystems – as the transitional zone between land-based ecosystems and the world ocean – are among the most productive biomes of the world, serving important life-support systems for human beings (Day et al., 1989). A distinctive feature contrasting estuaries from other biomes is the nature and variability of the physicochemical forces that influence these ecosystems. Within small geographic regions, many estuaries experience widely varying conditions of temperature, salinity, concentrations of a wide variety of chemicals, and plant and animal densities, many of whose are mediated by water movement over relatively short timescales (Jacobs, 2009, Elliot and McLusky, 2002). Estuarine biotas are therefore geomorphologically very dynamic and ephemeral systems, influenced by both sea and land changes, resulting in a complex mixture of many different habitat types. Natural processes and structures provide intermediate services (also called functions) which lead to final services, directly linked to benefits. Supporting functions include biogeochemical cycling and movement of nutrients, purification of water, mitigation of floods, maintenance of biodiversity, and biological production (Jacobs et al. 2009; Daily et al., 1997, see Fig. 1). Moreover, many estuaries are economically and socially important, and they are among most heavily used and threatened natural systems globally (Lotze, 2006, Worm et al., 2006, Halpern et al., 2008). Human activities provoke an intense and increasing deterioration, and this has a direct impact on the services delivered by estuaries.
Assessing ecosystem services is critically important for improving estuarine management and designing better integrated policies (Barbier et al., 2011). Particularly in estuaries, where ecological as well as social system functioning is inherently complex, many uncertainties persist, while decisions affect a multitude of societal groups (Granek et al., 2010). Many benefits have not been estimated reliably, and even for those services that have been valued, only few dependable studies have been conducted (Barbier et al., 2011). Interactions between different services generate trade-offs and synergies between services, and between current and future delivery.
In this paper, we address the following research questions:
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What are key ecosystem services for industrialized estuaries?
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How does ES-demand and supply vary between estuaries and along the salinity gradient, and supply between habitats?
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What are potential trade-offs or synergies in supply of ecosystem services?
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How were findings applied in estuarine management during and after the project?
In this paper presents the results of a participative ecosystem service screening for four North-West EU estuaries, with the objective to inform estuarine management in practice. The research was performed within the TIDE project1 and focused on estuaries with important port and industrial activities on the one hand, but a full tidal influence over their salinity gradient on the other hand. The screening was performed to generate a complete spatial inventory of demand, supply and interdependences of ecosystem services. The objective was to raise awareness on ecological and socio-economic complexity of estuarine systems among estuarine decision makers, and to provide concrete input for estuarine management decisions.
Section snippets
Methods
The research questions were addressed through a broad participative screening exercise on ecosystem services in four intensively used NW-European estuaries. All four studied estuaries – the Scheldt (Belgium), the Elbe (Germany), the Weser (Germany) and the Humber (UK) – are situated in densely populated areas, and consist of major transport and industry hubs of well developed countries within the same political region and climatologic context, while all joining the North Sea. All four estuaries
Ecosystem service demand
The demand survey has an acceptable reliability (alpha: 0.798), inter-estuarine consistence (ICC-c: 0.798) and agreement (ICC-A: 0.792). The four estuaries have also a high similarity concerning ES-demand (Omega-H: 0.77). Based on consensus demand scores given by stakeholder groups of four estuaries twenty ecosystem services (average score>‘less important’) were selected for further screening (‘focal ecosystem services’ sensu Granek et al., 2010). Three were provisioning, twelve regulating, one
Conclusions
In this last section, we briefly resume the three first research objectives of this paper and discuss the practical application of findings in estuarine management.
Key ecosystem services for four industrialized estuaries were determined based on a broad demand survey among regional working group experts of four estuaries. ES-demand in the four estuaries is remarkably similar. A notable difference is the lower demand for sedimentation–erosion regulation by biological mediation, extreme water
Acknowledgements
This paper builds on research performed within the TIDE project. TIDE (Tidal River Development, EU—INTERREG IVB North Sea Region Program, www.tide-project.eu, www.tide-toolbox.eu/). The ecosystem service screening was the first step of this project. The authors thank all survey respondents from both surveys for their time, patience and sharing of knowledge. We also thank all partners of TIDE for the inspiring meetings, conversations and good cooperation, an anonymous reviewer and Kati Vierikko
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