Individual study: Ecological evaluation of an experimental beneficial use scheme for dredged sediment disposal in shallow tidal waters
van der Wal D., Forster R.M., Rossi F., Hummel H., Ysebaert T., Roose F. & Herman P.M.J. (2011) Ecological evaluation of an experimental beneficial use scheme for dredged sediment disposal in shallow tidal waters. Marine Pollution Bulletin, 62, 99-108
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Landscape or artificially enhance the seabed (natural habitats)
A before-and-after, site comparison study in 2004–2009 of two sites in one sandy seabed area in the Westerschelde estuary, southwestern Netherlands (van der Wal et al. 2011) found that disposing of dredge material in a shallow subtidal zone to enhance natural habitat did not affect invertebrate community composition, nor promote species richness, abundance, or biomass after up to five years. Invertebrate community composition did not change over time and remained different to that of the natural site (before: 65%; after: 31% similarity). After five years, average species richness (1.8 species/sample), abundance (data not reported) and biomass (5.4 mg/m2) remained similar to pre-disposal values (species: 1.9; biomass: 7.2) and to values found at a nearby natural site (species: 1.7–1.8; biomass: 6.2–6.8). Dredged sand (500,000 m3) was disposed at one site in November–December 2004. A second site (2 km away) was left natural. Yearly in spring and autumn between 2004 and 2009, three sediment cores (30 cm depth, 8 cm diameter) were taken (then pooled) at each of twenty locations/site. Invertebrates (> 1mm) were identified, counted, and dry-weighed.
(Summarised by Anaëlle Lemasson)