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Journal ArticleDOI

The Scheldt estuary: a description of a changing ecosystem

01 May 2005-Hydrobiologia (Springer Netherlands)-Vol. 540, Iss: 1, pp 1-11
TL;DR: In this paper, a description of the Scheldt estuary is presented, illustrating that human influence is intertwined with natural dynamics and possible future trends in both natural evolution and management are argued.
Abstract: Estuaries are naturally highly dynamic and rapidly changing systems, forming a complex mixture of many different habitat types. They are very productive biomes and support many important ecosystem functions: biogeochemical cycling and movement of nutrients, mitigation of floods, maintenance of biodiversity and biological production. Human pressure on estuaries is very high. On the other hand, it is recognized that estuaries have a unique functional and structural biodiversity. Therefore, these ecosystems are particularly important for integrating sound ecological management with sustainable economics. These opportunities are explored for the Scheldt estuary, a well-documented system with an exceptional tidal freshwater area. In this article a description of the Scheldt estuary is presented, illustrating that human influence is intertwined with natural dynamics. Hydrology, geomorphology, trophic status and diversity are discussed, and possible future trends in both natural evolution and management are argued.

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Book
01 Jan 2013
TL;DR: In this paper, the authors present insights on both critical water-related ecosystem services and also on the wider ecosystem services from wetlands, and show how recognizing, demonstrating, and capturing the values of ecosystem services related to water and wetlands can lead to better informed, more efficient, and fairer decision making.
Abstract: Executive Summary This report presents insights on both critical water-related ecosystem services and also on the wider ecosystem services from wetlands. The objective is encourage additional policy momentum, business commitment, and investment in the conservation, restoration, and wise use of wetlands. The report seeks to show how recognising, demonstrating, and capturing the values of ecosystem services related to water and wetlands can lead to better informed, more efficient, and fairer decision making. Appreciating the values of wetlands to both society and the economy can help inform and facilitate political commitment to policy solutions.

181 citations

Journal ArticleDOI
TL;DR: In this paper, the authors compared hydrodynamic forcing in terms of proxies relevant to bed sediment motion for four contrasting tidal flat and salt-marsh ecosystems, and found that the hyddynamic forcing on the bottom sediment (bed shear stress) was strongly influenced by wind-generated waves, more so than by tidal or wind-drive currents.
Abstract: To unravel the relation between hydrodynamic forcing and the dynamics of the tidal flat salt-marsh ecosystem, we compared hydrodynamic forcing in terms of proxies relevant to bed sediment motion for four tidal flat salt-marsh ecosystems that were contrasting in terms of wind exposure (sheltered vs exposed) and lateral development (shrinking vs expanding) Wave and current field measurements on these four contrasting tidal flat and salt-marsh ecosystems indicated that the hydrodynamic forcing on the bottom sediment (bed shear stress) was strongly influenced by wind-generated waves, more so than by tidal- or wind-drive currents The measurements further showed that the hydrodynamic forcing decreased considerably landward of the marsh cliff, highlighting a transition from vigorous (tidal flat and pioneer zone) to sluggish (mature marsh) fluid forcing Spatial wave modeling using measured wind, revealed that the time-integrated wave forcing on the intertidal mudflat in front of the marsh (ie, the potential bed sediment pickup) was a factor two higher for salt marshes that are laterally shrinking than for laterally expanding marshes, regardless of whether these marshes were exposed to or sheltered from the wind The same result could not be obtained from a straightforward wind speed and fetch length approach for estimating wave forcing This confirmed that wave force estimates required spatial modeling to be consistent with the sites trends of shrinking or expanding marshes and wind exposure is not enough to characterize the wave forcing at these sites Seasonal changes in wave forcing identified from wind measurements potentially provide an alternative mechanism for marsh cliff formation During the calm summer, fine sediments switches from the water column to the bed During the following winter, fine sediment is retained within the vegetated regions while being returned to the water column from the bare tidal flats The continuous slow upward growth of vegetated areas combined with the seasonal cyclic tidal flat elevations, could, during winter, cause a discontinuity at the bare/vegetated boundary If this discontinuity grows large enough for plant die-off to occur, then a small cliff will form Crown Copyright © 2010 Published by Elsevier Ltd All rights reserved

158 citations


Cites background from "The Scheldt estuary: a description ..."

  • ...2 m in 2005 at Antwerpen (Meire et al., 2005)....

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  • ...The tidal range and asymmetry has been slowly increasing since 1550 with no seasonality (van der Spek, 1997; Meire et al., 2005)....

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  • ...The Westerschelde estuary has freshwater inflow from the Schelde, which is a typical rain-fed lowland river, with an average discharge of 104 m3/s at Schelle (Meire et al., 2005), which strongly fluctuates over the seasons from 50 m3/s in summer and up to 400 m3/s in winter (Temmerman et al....

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Journal ArticleDOI
TL;DR: In this paper, the results of 7 years of integrated monitoring along the Scheldt estuary were presented, and the combination of two datasets resulted in a full description of the estuaries water quality parameters from the mouth to the upper boundary, including an extended fresh water tidal part.
Abstract: This paper presents the results of 7 years of integrated monitoring along the Scheldt estuary. The combination of two datasets resulted in a full description of the estuaries water quality parameters from the mouth to the upper boundary, including an extended fresh water tidal part. A synthesis of the monitoring results and all relevant ecological knowledge on the Scheldt allowed to identify opportunities to optimize its management. The results show that the effect of discharge on salinity has a distinct maximum in the polyhaline to mesohaline transition area. Oxygen conditions, nitrogen removal and phytoplankton regulation can be enhanced and improved through management measures within the estuary. To lower carbon and phosphorous loads however measures should be taken within the catchment. To restore most of its ecological functions the estuary needs more space. Optimal locations to address specific functions can be derived from the monitoring results.

141 citations


Cites background from "The Scheldt estuary: a description ..."

  • ...It is characterized by a notorious history of pollution and eutrophication (Wollast, 1988; Boderie et al., 1993), and the estuarine intertidal habitats have suffered from important area reduction and quality degradation (Meire et al., 2005)....

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  • ...important area reduction and quality degradation (Meire et al., 2005)....

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Journal ArticleDOI
TL;DR: In this paper, the authors analyzed historical records of intertidal elevation surveys and aerial pictures from the macrotidal current-dominated Western Scheldt estuary (SW Netherlands) and found that the abrupt nonlinear shift between low-lying bare flats and high-elevation vegetated marshes can be considered as alternative stable landscape states with the occurrence of rapid catastrophic shifts between them.
Abstract: [1] Low-elevation bare intertidal flats and high-lying vegetated marshes are the main components of intertidal areas of estuaries, deltas and coastal embayments. Large-scale transitions between them have been reported worldwide. Because vegetated marshes provide significant services to coastal societies, predicting transitions between vegetated and unvegetated states is of widespread importance. Previous theoretical and modeling work highlighted the potential bistable nature of intertidal elevations, with low-elevation bare flats and high-elevation vegetated marshes being two alternative stable states. However, empirical evidence of this bistable condition is limited. In this study, we tested empirically the hypothesis that bare flats and vegetated marshes can be considered as alternative stable landscape states with the occurrence of rapid catastrophic shifts between them. We analyzed historical records of intertidal elevation surveys and aerial pictures from the macrotidal current-dominated Western Scheldt estuary (SW Netherlands). We found (1) a bimodal distribution of intertidal elevations corresponding to either a completely bare state or a densely vegetated state. (2) The shift from bare to vegetated state is accompanied with a relatively rapid shift in elevation, i.e., the mean accretion rate during the shift is 2 to 8 times larger than during the equilibrium state. (3) A threshold elevation could be identified above which the shift from bare to vegetated state has a high chance to occur. Hence, our results demonstrate the abrupt nonlinear shift between low-lying bare flats and high-elevation vegetated marshes, suggesting that the occurrence of catastrophic shifts between alternative stable states is indeed a potential mechanism in intertidal systems.

103 citations

Journal ArticleDOI
TL;DR: In this article, a two-dimensional, nested grid, hydrodynamic, and reactive-transport model of the macrotidal Scheldt estuary and its tributaries has been developed to identify the driving forces controlling the temporal and spatial dynamics of primary production during a summer diatom bloom.
Abstract: [1] A two-dimensional, nested grid, hydrodynamic, and reactive-transport model of the macrotidal Scheldt estuary (B/NL) and its tributaries has been developed to identify the driving forces controlling the temporal and spatial dynamics of primary production during a summer diatom bloom. The hydrodynamic model indicates that energy dissipation reaches its maximum 90 km upstream from the mouth, closely followed by a minimum farther upstream. Suspended particulate matter (SPM) dynamics is simulated to provide the transient light conditions in the water column. Results show that the spatial distribution of SPM mirrors closely the profile of energy dissipation. The temporal SPM dynamics is highly sensitive to fluctuations in river discharge, whose influence decreases downstream. Peaks in SPM are triggered by high discharges and can be recorded as far as 50 km seaward of the upstream model boundary. Results from the phytoplankton model demonstrate the fast response of diatom growth to changes in the physical environment, especially those due to daily variations in river discharge which continuously modify the SPM concentrations and residence times. Episodes of persistent low flow conditions lead to a progressive depletion of dissolved silica. Simulated diatom growth becomes increasingly controlled by silica availability, until primary production collapses. The spatiotemporal evolution of primary production is explored over the entire domain of forcing conditions. The distribution of the daily maximum of net primary production and its location reveal that four different system states can be identified in the forcing planes. The transition from one state to the other characterizes the diatom growth response in the estuary.

98 citations


Cites background from "The Scheldt estuary: a description ..."

  • ...Small horizontal temperature gradients (D Temp 2C) can be observed between the saline and the brakish/freshwater estuary [Meire et al., 2005]....

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  • ...[7] Monthly monitoring programmes reveal the development of a spring and a summer phytoplankton bloom in the freshwater tidal reaches of the Scheldt [Meire et al., 2005; Muylaert et al., 2005]....

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  • ...Small horizontal temperature gradients (D Temp 2oC) can be observed between the saline and the brakish/freshwater estuary [Meire et al., 2005]....

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References
More filters
Journal ArticleDOI
15 May 1997-Nature
TL;DR: In this paper, the authors have estimated the current economic value of 17 ecosystem services for 16 biomes, based on published studies and a few original calculations, for the entire biosphere, the value (most of which is outside the market) is estimated to be in the range of US$16-54 trillion (10^(12)) per year, with an average of US $33 trillion per year.
Abstract: The services of ecological systems and the natural capital stocks that produce them are critical to the functioning of the Earth's life-support system. They contribute to human welfare, both directly and indirectly, and therefore represent part of the total economic value of the planet. We have estimated the current economic value of 17 ecosystem services for 16 biomes, based on published studies and a few original calculations. For the entire biosphere, the value (most of which is outside the market) is estimated to be in the range of US$16-54 trillion (10^(12)) per year, with an average of US$33 trillion per year. Because of the nature of the uncertainties, this must be considered a minimum estimate. Global gross national product total is around US$18 trillion per year.

18,139 citations

Book
17 Jun 2004
TL;DR: In this article, the authors study the effect of human-induced changes in the ecology of the environment and management of estuarine production and its use in the management of forests.
Abstract: 1. The Estuarine Environment 2. Life in Estuaries 3. Primary Producers: plant production and its availability 4. Primary Consumers: herbivores and detritivores 5. The Secondary Consumers: carnivores 6. Estuarine Uses and Users 7. Methods for Studying Human-Induced Changes in Estuaries 8. The Management of Estuaries

821 citations


"The Scheldt estuary: a description ..." refers background in this paper

  • ...…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 time scales (Day et al., 1989; McLusky & Elliott, 2004)....

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01 Jan 2007
TL;DR: In this paper, the authors identify and monitor ecosystem services both locally and globally, and for the incorporation of their value into decision-making processes, which is a critical need for identification and monitoring of ecosystem services.
Abstract: Human societies derive many essential goods from natural ecosystems, including seafood, game animals, fodder, fuelwood, timber, and pharmaceutical products. These goods represent important and familiar parts of the economy. What has been less appreciated until recently is that natural ecosystems also perform fundamental life-support services without which human civilizations would cease to thrive. These include the purification of air and water, detoxification and decomposition of wastes, regulation of climate, regeneration of soil fertility, and production and maintenance of biodiversity, from which key ingredients of our agricultural, pharmaceutical, and industrial enterprises are derived. This array of services is generated by a complex interplay of natural cycles powered by solar energy and operating across a wide range of space and time scales. The process of waste disposal, for example, involves the life cycles of bacteria as well as the planet-wide cycles of major chemical elements such as carbon and nitrogen. Such processes are worth many trillions of dollars annually. Yet because most of these benefits are not traded in economic markets, they carry no price tags that could alert society to changes in their supply or deterioration of underlying ecological systems that generate them. Because threats to these systems are increasing, there is a critical need for identification and monitoring of ecosystem services both locally and globally, and for the incorporation of their value into decision-making processes.

717 citations


"The Scheldt estuary: a description ..." refers background in this paper

  • ...…ecosystem functions: biogeochemical cycling and movement of nutrients, purification of water, mitigation of floods, maintenance of biodiversity, biological production (nursery grounds for several commercial fish and crustacean species) etc. (Daily et al., 1997; De Groot, 1997; Meire et al., 1998)....

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Book
01 Jan 1981
TL;DR: In this article, the authors present an overview of plant and microbial production in estuaries, and the main consumers of estuarine organisms are primary producers, primary consumers, secondary consumers, and secondary consumers.
Abstract: 1 The Estuarine Environment.- 1.1 Introduction.- 1.2 Estuarine circulation.- 1.3 Estuarine sediments.- 1.4 Other physico-chemical factors.- 1.5 Distribution of estuarine organisms.- 1.6 The problems of life in estuaries.- 1.7 The estuarine food web.- 2 Primary Producers Plant production and its availability.- 2.1 Introduction.- 2.2 Salt marshes.- 2.3 Intertidal plants.- 2.4 Phytoplankton.- 2.5 Detritus.- 2.6 Summation of plant and microbial production in estuaries.- 3 Primary Consumers Herbivores and detritivores.- 3.1 Introduction.- 3.2 The mud dwellers.- 3.3 The surface dwellers.- 3.4 Meiofauna.- 3.5 Zooplankton.- 3.6 The primary consumer community.- 4 The Secondary Consumers Carnivores.- 4.1 Introduction.- 4.2 Fish.- 4.3 Invertebrates.- 4.4 Birds.- 4.5 The impact of the secondary consumers.- 5 Estuarine Pollution.- 5.1 Introduction.- 5.2 Mankind's use of estuaries.- 5.3 Methodologies of studying pollution.- 5.4 Organic enrichment.- 5.5 Industrial contamination.- 5.6 Reclamation and engineering works.- 6 The Management of Estuaries.- 6.1 Introduction.- 6.2 Policies.- 6.3 Planning.- 6.4 Practice.- Reading List.

490 citations