Ecological evaluation of an experimental beneficial use scheme for dredged sediment disposal in shallow tidal waters.
An experiment was performed to test an alternative dredging strategy for the Westerschelde estuary. Clean sand dredged from the navigation channel was disposed seawards of an eroding intertidal flat in order to modify morphology and hydrodynamics, improving the multi-channel system with ecologically productive shallow water habitat. Five years of intensive monitoring revealed that part of the disposed sediment moved slowly towards the flat, increasing the very shallow subtidal and intertidal area, as planned. The sand in the impact zone became gradually finer after disposal, possibly due to reduced current velocities. Nevertheless, no changes in macrobenthic biomass, density, species richness and composition were detected in the subtidal zone, also demonstrating rapid macrobenthic recovery. In the intertidal zone, no ecological effects could be revealed superimposed on trends associated with long-term sediment fining. Thus, despite morphological success and absence of detected negative ecological impacts of the experiment, new beneficial habitat was not created.
van der Wal
Daphne
D
Netherlands Institute of Ecology (NIOO-KNAW), Centre for Estuarine and Marine Ecology, P.O. Box 140, 4400 AC Yerseke, The Netherlands. d.vanderwal@nioo.knaw.nl
Forster
Rodney M
RM
Rossi
Francesca
F
Hummel
Herman
H
Ysebaert
Tom
T
Roose
Frederik
F
Herman
Peter M J
PM
D059001:Aquatic Organisms; D044822:Biodiversity; D018533:Biomass; D003247:Conservation of Natural Resources / Q000379:methods*; D017753:Ecosystem; D004784:Environmental Monitoring; D052918:Environmental Restoration and Remediation / Q000379:methods*; D019015:Geologic Sediments / Q000737:chemistry*; D015999:Multivariate Analysis; D009426:Netherlands; D012623:Seawater / Q000737:chemistry*