The monitoring of 'ecological' beach nourishment impacts on macrobenthos, within a Special Area of Conservation (SAC) along the Belgian coast
Vanden Eede, S.; Bonte, D.; Vincx, M. (2013). The monitoring of 'ecological' beach nourishment impacts on macrobenthos, within a Special Area of Conservation (SAC) along the Belgian coast, in: Vanden Eede, S. Impact of beach nourishment on coastal ecosystems, with recommendations for coastal policy in Belgium = Impact van zandsuppleties op kustecosystemen met aanbevelingen voor het Belgische kustbeleid. pp. 59-81
In: Vanden Eede, S. (2013). Impact of beach nourishment on coastal ecosystems, with recommendations for coastal policy in Belgium = Impact van zandsuppleties op kustecosystemen met aanbevelingen voor het Belgische kustbeleid. PhD Thesis. Ghent University: Gent. ISBN 978-90-90278-4-38. xxx, 301 pp., meer
The expected increase in intensity and frequency of storm events combined with the undeniable rise in sea water level, both connected to climate change, poses a threat to coastal low lands. As it safeguards the natural dynamics of the coast, beach nourishment has rapidly become the preferred protective and restoring measure in coastal zones worldwide. We tested whether optimizing the main technical aspects of a nourishment according to ecological recommendations, e.g. a gentle sloped beach with nourished sand resembling the original sediment very closely (average median grain size of 224 µm), leads to an ‘ecological’ nourishment with minor to no impact effects on the macrobenthos.Monitoring of nourishment impact effects on the macrobenthic community structure can be regarded as a ‘natural experiment’ and is based on a BACI (Before/After, Control/Impact) design. A putatively impacted area and a matching control site are monitored in a time series (2000 – 2012) straddling the impact event (2009). Impact effects should then show up as interactions between the temporal and spatial factors. A wider, higher and flatter intertidal beach with coarser sediment (from 215.89 ± 3.63 µm in 2008 to 280.23 ± 8.94 µm in spring 2010) was created and no return to the pre-nourishment conditions in sedimentology was visible three years after nourishment. The sediment grain size distribution had changed as well, showing slow recovery in the three post-nourishment years. The analysis of the macrobenthos community structure showed that the nourishment under ecological optimal conditions on the beach of Lombardsijde yielded no significant effects on both the intertidal and shallow subtidal beach ecosystem 6 months after the nourishment. Within this time frame, the macrobenthos community had seemingly recovered from the impact of the ecological nourishment. Ecological nourishment thus proves to be the least ecologically damaging way of combating erosion, compared to all other coastal engineering activities.
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