Despite the importance of water purification to society, it is one of the more difficult wetland ecosystem services to quantify. It remains an issue in ecosystem service assessments where rapid estimates are needed, and poor-quality... more
Despite the importance of water purification to society, it is one of the more difficult wetland ecosystem services to quantify. It remains an issue in ecosystem service assessments where rapid estimates are needed, and poor-quality indicators are overused. We attempted to quantify the water purification service of South African palmiet wetlands (valley-bottom peatlands highly threatened by agriculture). First, we used an instantaneous catchment-scale mass balance sampling approach, which compared the fate of various water quality parameters over degraded and pristine sections of palmiet wetlands. We found that pristine palmiet wetlands acted as a sink for water, major cations, anions, dissolved silicon and nutrients, though there was relatively high variation in these trends. There are important limitations to this catchment-scale approach, including the fact that at this large scale there are multiple mechanisms (internal wetland processes as well as external inputs) at work that ...
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Research Interests: Business, Chemistry, Ecosystem Services, Marine Protected Areas, Biology, and 15 moreBiodiversity, Medicine, Multidisciplinary, Earth and Environmental Sciences, Ecosystem Approach, Dynamics, Environmental Resource Management, Habitat, Framework, Connectivity, Ecosystem, Ecological Processes, Challenges, Marine ecosystem, and Coastal defense
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Land use change (deforestation) has several negative consequences for the soil system. It is known also to increase the erosion rate which affects the distribution of elements in soils. In this context, the crucial nutrient Si has... more
Land use change (deforestation) has several negative consequences for the soil system. It is known also to increase the erosion rate which affects the distribution of elements in soils. In this context, the crucial nutrient Si has received little attention, especially in a tropical context. Therefore we studied the effect of land conversion and erosion intensity on the biogenic silica pools in a subtropical soil in the south of Brazil. Biogenic silica (BSi) was determined using a novel alkaline continuous extraction where Si/Al ratios of the fractions extracted are used to distinguish biogenic silica and other soluble fractions: Si/Al > 5 for the biogenic AlkExSi (alkaline extractable Si) and Si/Al < 5 for the non-biogenic AlkExSi. Our study shows that deforestation will rapidly (< 50 years) deplete (10–53 %) the biogenic AlkExSi pool in soils . Depletion intensity depends on the slope of the study site. We demonstrate that hi...
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Ecological data provide crucial information to evaluate the present status of vegetation, fish andor wildlife communities. The assessment of the success (or failure) of river restoration (or rehabilitation) is only possible when... more
Ecological data provide crucial information to evaluate the present status of vegetation, fish andor wildlife communities. The assessment of the success (or failure) of river restoration (or rehabilitation) is only possible when ecological information was gathered before implementation. This means that monitoring is a crucial step in the planning of restoration projects and that it has to start in a very early stage of the planning process. During this project it was not our intention to start an extensive monitoring campaign. We decided to do a pre-restoration evaluation of the selected sites to see if restoration will most likely lead to a significant increase of the ecological value of the river system. In this paper we evaluate the fish assemblage and the macro-invertebrate communities, mainly on population level. These results were used to indicate the need for restoration. In one case (the Kemmelbeek) the pre-evaluation showed that restoration at the present state would probab...
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Tidal freshwater wetlands occur in the upstream reaches of many temperate estuaries.An estuary is “an inlet of the sea reaching into the river valley as far as the upstream limit of the tidal rise” (Fairbridge 1980).Within estuaries,... more
Tidal freshwater wetlands occur in the upstream reaches of many temperate estuaries.An estuary is “an inlet of the sea reaching into the river valley as far as the upstream limit of the tidal rise” (Fairbridge 1980).Within estuaries, tidal freshwater wetlands are restricted to the portion of the estuary where there is tidal action but little or no salinity. Depending on the magnitudes of tidal energy,river discharges and topography,freshwater tidal areas [practical salinity units (PSU) &lt;0.5 parts per thousand (ppt), or &lt;500 ppm] can be present between the highest point of tidal reach (i.e., the head of the estuary) and the oligohaline upper estuary,with PSU = 0.5-5.0 (McLusky 1993; Fig.6.1).In some settings, tidal freshwater areas can be found as far as 150 km from the mouth of the estuary (Van Damme et al. 1999). The location of the tidal freshwater zone within the estuary depends on the balance between water volume and velocity of the incoming tide and the discharge of the out-flowing river. Towards the upstream tidal limit, the horizontal movement of tide becomes less important as the tidal wave attenuates and the vertical tide movement becomes zero partly due to the prevention of river discharge by the higher tide in the estuary. Further downstream, both the horizontal and vertical movement of the tide is important. Tidal characteristics are strongly dependent on river discharge: during high discharge, the tidal limit may be much further downstream than during low discharge. Symmetrical tides (i.e., tides with similar duration of flood and ebb) occur in the saline zone of estuaries,but in tidal freshwater zone they are not symmetrical. In the latter, there typically is a short period of intense incoming tide and a longer period of ebbing tide.Moreover, in the tidal freshwater zone, hydrologic conditions interact with the funnel-shape of the river channel to produce a tidal range that can be as high as 6 m.
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As many estuaries, the Schelde estuary was heavily degraded due to habitat loss, pollution and disturbance. Already in the sixties initiatives were taken to protect some of the remaining estuarine habitats and ecologically valuable... more
As many estuaries, the Schelde estuary was heavily degraded due to habitat loss, pollution and disturbance. Already in the sixties initiatives were taken to protect some of the remaining estuarine habitats and ecologically valuable habitats in the former floodplain. These initiatives could however not stop further degradation. More stringent environmental legislation resulted in a better water quality, especially in the fresh and brackish part of the estuary, as from the nineties. This, and the emerging concept of nature development triggered the elaboration of a nature restoration plan, mainly oriented towards habitat restoration as a key for restoring the biodiversity of the system.
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Ecosystem services (ES) are defined as the benefits that humans derive from nature. These services represent different benefits for human well-being. The ES framework helps to analyse the impacts humans have on ecosystems and the... more
Ecosystem services (ES) are defined as the benefits that humans derive from nature. These services represent different benefits for human well-being. The ES framework helps to analyse the impacts humans have on ecosystems and the feed-back effects these changes have for the ecosystem benefits to humans. Today many industries, including those in the maritime sector, are in the process of applying ES to evaluating their processes of manufacturing and delivering products. To that end, the Ecosystem Management Research Group (ECOBE), Department of Biology, University of Antwerp, Belgium and the International Association of Dredging Companies (IADC) have joined forces to explore the subject as regards dredging. This article is the first result of that research. The aim of this joint effort is to show that with the use of ES a more integrated evaluation of the consequences of maritime infrastructure projects can be achieved. The presented method of ES evaluation is applied to a dredging-r...
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The Schelde estuary was subjected to major human impacts leading to major environmental problems such as pollution, habitat loss, but also increasing water levels leading to higher risks of inundations. In this paper we describe how an... more
The Schelde estuary was subjected to major human impacts leading to major environmental problems such as pollution, habitat loss, but also increasing water levels leading to higher risks of inundations. In this paper we describe how an approach using the ecosystems service concept was applied as a basis for restoration of the estuary.
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This study will try to improve the insight in the current bathymetry of the Western Scheldt. Morphological management can give possibilities to optimize and harmonize three important estuarine functions: accessibility, safety and ecology.... more
This study will try to improve the insight in the current bathymetry of the Western Scheldt. Morphological management can give possibilities to optimize and harmonize three important estuarine functions: accessibility, safety and ecology. With morphological management we mean the modification of bed morphology by strategic dredging and disposal of sediment, and construction, adaptation or removal of hard structures such as groynes, dike-protection measures and dikes. The aim is to identify those morphological modifications that can have a combined positive effect on flood defence, port accessibility and ecology.
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Both models deliver the following parameters: maximum flow velocity (a good relationship between maximum flow velocity at a location and the D50 sediment value was found, so sediment composition is included in the model by the maximum... more
Both models deliver the following parameters: maximum flow velocity (a good relationship between maximum flow velocity at a location and the D50 sediment value was found, so sediment composition is included in the model by the maximum flow velocity), salinity range, average salinity, depth and dry time, i.e. the time a location is not covered by water. These parameters are used by a benthos distribution model (developed by Cozzoli F.) to predict for every location (= calculation node) in the model the community indices and distribution of single species.
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The vulnerability of the world’s tidal marshes to sea-level rise threatens their substantial contribution to fisheries, coastal protection, biodiversity conservation and carbon sequestration. Feedbacks between relative sea-level rise... more
The vulnerability of the world’s tidal marshes to sea-level rise threatens their substantial contribution to fisheries, coastal protection, biodiversity conservation and carbon sequestration. Feedbacks between relative sea-level rise (RSLR) and the rate of mineral and organic sediment accumulation in tidal wetlands, and hence elevation gain, have been proposed to ameliorate this risk. Here we report on changes in tidal marsh elevation and shoreline position in relation to our network of 387 fixed benchmarks in tidal marshes on four continents measured for an average of 10 years. During this period RSLR at these marshes reached on average 6.6 mm yr-1, compared to 0.34 mm yr-1 over the past millenia. While the rate of sediment accretion corresponded to RSLR, the loss of elevation to shallow subsidence increased in proportion to the accretion rate. This caused a deficit between elevation gain and RSLR which increased consistently with the rate of RSLR regardless of position within the ...
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There is increasing interest in the use of nature-based approaches for mitigation of storm surges along coasts, deltas, and estuaries. However, very few studies have quantified the effectiveness of storm surge height reduction by a... more
There is increasing interest in the use of nature-based approaches for mitigation of storm surges along coasts, deltas, and estuaries. However, very few studies have quantified the effectiveness of storm surge height reduction by a real-existing, estuarine-scale, nature-based, and engineered flood defense system, under specific storm surge conditions. Here, we present data and modelling results from a specific storm surge in the Scheldt estuary (Belgium), where a hybrid flood defense system is implemented, consisting of flood control areas, of which some are restored into tidal marsh ecosystems, by use of culvert constructions that allow daily reduced tidal in- and outflow. We present a hindcast simulation of the storm surge of 6 December 2013, using a TELEMAC-3D model of the Scheldt estuary, and model scenarios showing that the hybrid flood defense system resulted in a storm surge height reduction of up to half a meter in the estuary. An important aspect of the work was the impleme...
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Fast-growing, aerobic, heterotrophic bacteria from the root surface of young sugar beet plants were inventoried. Isolation of the most abundant bacteria from the root surface of each of 1,100 plants between the second and tenth leaf stage... more
Fast-growing, aerobic, heterotrophic bacteria from the root surface of young sugar beet plants were inventoried. Isolation of the most abundant bacteria from the root surface of each of 1,100 plants between the second and tenth leaf stage yielded 5,600 isolates. These plants originated from different fields in Belgium and Spain. All isolates were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of total cellular proteins. Comparison of protein fingerprints allowed us to inventory the bacteria of individual plants of different fields or leaf stages and to analyze the composition and variability of the rhizobacterial population of young sugar beet plants. Each field harbored a specific population of bacteria which showed a highly hierarchic structure. A small number of bacteria occurring frequently at high densities dominated in each field. The major bacteria were identified as Pseudomonas fluorescens, Xanthomonas maltophilia, Pseudomonas paucimobilis , and P...
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River systems are highly complex, hierarchical and patchy systems which are greatly influenced by both catchment surroundings and in-stream processes. Natural and anthropogenic land uses and processes affect water quality (WQ) through... more
River systems are highly complex, hierarchical and patchy systems which are greatly influenced by both catchment surroundings and in-stream processes. Natural and anthropogenic land uses and processes affect water quality (WQ) through different pathways and scales. Understanding under which conditions these different river and catchment properties become dominant towards water chemistry remains a challenge. In this study we analyzed the impact of land use and spatial scales on a range of WQ variables within the Kleine Nete catchment in Belgium. Multivariate statistics and spatial descriptors (Moran's and Asymmetric Eigenvector Maps) were used to assess changes in water chemistry throughout the catchment. Both land use and complex mixes of spatial descriptors of different scales were found to be significantly associated to WQ parameters. However, unidirectional, upstream-downstream changes in water chemistry, often described in river systems, were not found within the Kleine Nete...
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Accelerated mass loss from the Greenland ice sheet leads to glacier retreat and an increasing input of glacial meltwater to the fjords and coastal waters around Greenland. These high latitude ecosystems are highly productive and sustain... more
Accelerated mass loss from the Greenland ice sheet leads to glacier retreat and an increasing input of glacial meltwater to the fjords and coastal waters around Greenland. These high latitude ecosystems are highly productive and sustain important fisheries, yet it remains uncertain how they will respond to future changes in the Arctic cryosphere. Here we show that marine-terminating glaciers play a crucial role in sustaining high productivity of the fjord ecosystems. Hydrographic and biogeochemical data from two fjord systems adjacent to the Greenland ice sheet, suggest that marine ecosystem productivity is very differently regulated in fjords influenced by either land-terminating or marine-terminating glaciers. Rising subsurface meltwater plumes originating from marine-terminating glaciers entrain large volumes of ambient deep water to the surface. The resulting upwelling of nutrient-rich deep water sustains a high phytoplankton productivity throughout summer in the fjord with mari...
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Research Interests: Environmental Science, Chemistry, Remote Sensing, Photography, Biomass, and 15 moreBiology, Environmental Monitoring, Rivers, Medicine, Spatio Temporal Analysis, Multidisciplinary, GE, Aerial Photography, Plants, Environmental monitoring and assessment, Ecosystem, Altitude, Gb, Turbidity, and image resolution
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ABSTRACT