Patrick Meire

The macrozoobenthos of an important wintering area of the common scoter (Melanitta nigra)

In October 1994, 39 macrobenthic samples, divided between two areas, were taken on the western Belgian Coastal Banks. The two areas could not be clearly divided, concerning their macrobenthic communities. Multivariate techniques revealed five coherent communities, linked with typical sedimentological factors: (1) the Barnea candida community in a very compact muddy sediment (median 14u2006μm); (2) a second community characterized by the presence of spat of Mytilus edulis , with a medium sandy sediment (median 456u2006μm); (3) the Lanice conchilega community inhabiting a fine sandy sediment (median 211u2006μm); (4) the Nephtys cirrosa–Echinocardium cordatum community in a coarser fine sandy sediment (median 242 μm); and (5), closely related to the latter, the N. cirrosa community also occurring in a fine sandy sediment (median 224u2006μm). Only the L. conchilega community belongs to the diverse transition zone. The other four communities seem to be part of the heterogeneous, species-poor coastal zone associations. No open sea communities have been detected in the area. On the western Coastal Banks only the L. conchilega community, because of the high numbers of Abra alba, Tellina fabula , and Spisula subtruncata , can be interesting as feeding grounds for the common scoter ( Melanitta nigra (Aves: Mergini)). Comparison of the spatial distribution of the wintering common scoters and the L. conchilega community revealed no direct similarity. The factors possibly causing this dissimilarity have been discussed.

Determining discharges from the Table Mountain Group (TMG) aquifer to wetlands in the Southern Cape, South Africa

The focus of this study was to determine whether coastal wetlands in lowland settings could be dependent on groundwater from the deep circulating confined Table Mountain Group (TMG) aquifer. Groundwater interactions with wetlands are normally perceived to be limited to primary aquifers. A comparative study was done between two endorheic coastal wetlands in the southern Cape. Earlier reports stated that these groundwater dependent wetlands were fed by discharges from the fixed dunes surrounding them. On the basis of a three-dimensional electrical conductivity (EC) interpolation for Groenvlei, a hydrological link between the TMG aquifer and Groenvlei and Van Kervelsvlei was investigated by measuring water level and quality of groundwater and surface water. Water quality parameters used were EC, pH, Na+, Fe2+ and Cl−. The results from this, and an accompanying study, on the basis of water quality and plant nutrient cycling assessments, indicated direct groundwater discharges from the TMG to at least Van Kervelsvlei, with Groenvlei receiving secondary discharges from the TMG via Van Kervelslvlei. These findings significantly affect the current knowledge on which water balance models are based for the determination of groundwater availability for the area.

Integrated Water Management

The natural water system provides direct or indirectly numerous goods and services. For a long time these goods and services have been used to support society in various and important ways. We can distinguish visible and fast renewable resources as fish, crops, timber, and drinking water that distinctively can be linked to the water system. The water system also supports society through direct or indirect ecological services. The strong interdependence from the water system initially forced a certain harmony between the water system and its users. A combination of growing needs and a technological ability has resulted in an increased control and manipulation of the water system. These developments have also led to a serious degeneration of the system’s carrying capacity. The emergence of the first major environmental problems has led to the development of a fragmented water management approach. Initially focused on finding technological “end of pipe” solutions to maintain anthropogenic user functions. Over the last few decades, this fragmented and compartmental approach has shown little adequacy and led to a growing awareness that an integrated and holistic approach is necessary. The term “integrated” has been given many definitions and is still subject to various technical interpretations. Although the integrated water management concepts are intended to be holistic, it has been found that many practical attempts toward a truly integrated approach still focus heavily on controlling the water system to provide specific goods and services at the right time and place (Holling and Meffe 1996; Briggs 2003). Modeling efforts seldom consist of a truly holistic approach, and rather focus on aspects that are predictable, quantifiable and controllable (e.g., hydrology, water quality, etc) leaving out those aspects that are not. Many ecosystem services will never be eligible for command and control because they are involved with a complex web of processes that operate on various scales in time and space (Jakeman and Letcher 2003). An aversion of policy makers toward the unknown, uncertain and uncontrollable makes these services subordinate to those services that are controllable. This is reflected by the aversion of policy-makers to tools and models that try to deal with this complexity (Gustavson, Lonergan et al., 1999; Welp 2001; Quevauviller, Balabanis et al., 2005). Nevertheless, there is enough circumstantial evidence that the decline of vigor and resilience of our natural environment can be ascribed to the rigid management of rivers and its interwoven ecosystems. In this article, we look at concepts of J. STAES, H. BACKX AND P. MEIRE INTEGRATED WATER MANAGEMENT 265 catchment-level ecosystem functioning that should be considered in an integrated water management approach. Finally a conceptual framework for the development of river subbasin management plans is suggested.