Agency of Nature and Forest

Leuven, Belgium

Agency of Nature and Forest

Leuven, Belgium
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Van Liefferinge C.,University of Antwerp | Van Liefferinge C.,Agency of Nature and Forest | Dillen A.,Agency of Nature and Forest | Dillen A.,Ghent University | And 6 more authors.
Journal of Applied Ichthyology | Year: 2012

Summary: Implementation of the Controlled Reduced Tide (CRT) technique could increase the total surface of tidal freshwater marshes in Europe and ease implementation of restoration projects in coastal defense and riverine ecosystems. The goal was to determine whether a regularly flooded area connected to a freshwater tidal river could act as an important foraging area for European eel, and if so, to what extent the diet of eels in this flooding area differed from that of eels foraging in the river itself. The stomach contents of eels from the River Schelde were compared with eels from the Lippenbroek, an adjacent CRT area. Prey diversity (H′) of individual eels was about four times higher in the Lippenbroek than in the River Schelde. Moreover, 12 prey categories in eel stomachs from the Lippenbroek were found whereas only three categories were retrieved from eels in the River Schelde. In the Lippenbroek, eels fed on terrestrial organisms (lumbricids, caterpillars and other insects), but also on fish and fish eggs and to a lesser extent on other aquatic prey (Lumbricullidae, chironomids and Hirudinea). In contrast, eels from the main river fed mainly on tubificids, fish, and some gammarids. Consequently, eels in the Schelde estuary are opportunistic feeders, but with a preference for large benthic prey. The number and weight of aquatic organisms ingested by eels in the Lippenbroek is not significantly different from the River Schelde. However, eels foraging in the Lippenbroek area had consumed significantly more terrestrial prey. Furthermore the total caloric value estimated for the ingested prey of eels from the Lippenbroek (derived from the literature) was about twice as high as that for eels from the River Schelde. While the condition index remained inconclusive, an Ancova revealed that eels captured in the Lippenbroek were significantly heavier for a given length than eels captured in the Schelde. The study showed that with a controlled reduced tide to restore lateral connectivity of large tidal rivers with their adjacent floodplains, high quality habitats for the European eel are created. These measures could significantly contribute to the production of eels in better condition, which have better chances to reproduce successfully. Hence, wetland restoration could enhance the recovery of the European eel stocks. © 2012 Blackwell Verlag, Berlin.

Ide C.,Ghent University | De Schepper N.,Ghent University | Christiaens J.,Ghent University | Van Liefferinge C.,University of Antwerp | And 7 more authors.
Journal of Zoology | Year: 2011

The existence of two morphotypes, broadheaded and narrowheaded, in European eels Anguilla anguilla is common knowledge among fishermen and eel biologists in Europe. To test whether European eels really are dimorphic in head shape, a total of 277 specimens from two locations in Belgium (Scheldt-Lippenbroek and Lake Weerde), in combination with a larger data set of 725 eels from river systems across Flanders (the northern part of Belgium) were examined. Our biometric data support the hypothesis that a head shape variation in 'Belgian' European eel is best described as having a bimodal distribution. Literature data suggest that this may be the result of phenotypic plasticity related to trophic segregation between morphs. © 2011 The Authors. Journal of Zoology © 2011 The Zoological Society of London.

Wolfram G.,DWS Hydro Okologie GmbH | Hoss S.,Ecossa | Orendt C.,Orendt Hydrobiologie | Schmitt C.,University of Antwerp | And 13 more authors.
Science of the Total Environment | Year: 2012

The aim of this study was to combine different lines of evidence on the impact of chemical pollution on benthic invertebrate communities in three European river basins (Elbe, Scheldt, and Llobregat). The study integrates chemical analyses, a battery of different sediment toxicity tests, and field data from soft-sediment meio- and macrobenthic fauna within a sediment-quality triad in which chironomids, oligochaetes, and nematodes are identified on the species level. The use of TU (toxic units) and msPAF (multi-substance potentially affected fraction) in an approach assessing the chemical impact as well as the integration of sediment toxicity tests with bacteria (Vibrio fischeri), benthic invertebrates (Caenorhabditis elegans, Potamopyrgus antipodarum, Lumbriculus variegatus, Chironomus riparius), and fish embryos (Danio rerio), together with univariate and non-parametric multivariate statistical analyses of the biological data revealed significant differences between unpolluted and polluted sites in all three river basins. To combine the different results obtained in the sediment-quality triad, a scoring system was successfully developed based on a simple algorithm. This system provides an easily understandable scheme for non-experts among decision makers and water managers. © 2012 Elsevier B.V..

van Liefferinge C.,University of Antwerp | van Liefferinge C.,Agency of Nature and Forest | Simoens I.,Research Institute for Nature and Forest | Vogt C.,Goethe University Frankfurt | And 7 more authors.
Hydrobiologia | Year: 2010

The spatial variation in the fish communities of four small Belgian rivers with variable habitat diversity was investigated by electric fishing to define the minimum sampling distance required for optimal fish stock assessment and determination of the Index of Biotic Integrity. This study shows that the standardised sampling distance of 100 m was not always sufficient to collect most species present. The required minimum sampling distance seems to be correlated with habitat diversity. In homogeneous streams, a mean sample distance of 282, 452 and 572 m is necessary to capture 80, 90 and 95% of all species present, respectively. In heterogeneous streams, these sample distances decrease to 217, 380 and 503 m. Hence, at least 300 m should be sampled to catch most species present with a single-pass sampling method. However, our results show that a 100 m sampling distance as presently used in the Flemish monitoring programs is sufficient to accurately describe the ecological quality since differences in IBI evaluation between adjacent stretches could at least for some rivers be explained by differences in habitat heterogeneity. © Springer Science+Business Media B.V. 2010.

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