The natural coastal hydrodynamics and morphology worldwide is altered by human interventions such as embankments, shipping and dredging, which may have consequences for ecosystem functionality. To ensure long-term ecological sustainability, requires capability to predict long-term large-scale ecological effects of altered hydromorphology. As empirical data sets at relevant scales are missing, there is need for integrating ecological modeling with physical modeling. This paper presents a case study showing the long-term, large-scale macrozoobenthic community response to two contrasting human alterations of the hydromorphological habitat: deepening of estuarine channels to enhance navigability (Westerschelde) vs. realization of a storm surge barrier to enhance coastal safety (Oosterschelde). A multidisciplinary integration of empirical data and modeling of estuarine morphology, hydrodynamics and benthic ecology was used to reconstruct the hydrological evolution and resulting long-term (50 years) large-scale ecological trends for both estuaries over the last. Our model indicated that hydrodynamic alterations following the deepening of the Westerschelde had negative implications for benthic life, while the realization of the Oosterschelde storm surge barriers had mixed and habitat-dependent responses, that also include unexpected improvement of environmental quality. Our analysis illustrates long-term trends in the natural community caused by opposing management strategies. The divergent human pressures on the Oosterschelde and Westerschelde are examples of what could happen in a near future for many global coastal ecosystems. The comparative analysis of the two basins is a valuable source of information to understand (and communicate) the future ecological consequences of human coastal development.

Human infrastructures can modify ecosystems, thereby affecting the occurrence and spatial distribution of organisms, as well as ecosystem functionality. Sustainable development requires the ability to predict responses of species to anthropogenic pressures. We investigated the large scale, long term effect of important human alterations of benthic habitats with an integrated approach combining engineering and ecological modelling. We focused our analysis on the Oosterschelde basin (The Netherlands), which was partially embanked by a storm surge barrier (Oosterscheldekering, 1986). We made use of 1) a prognostic (numerical) environmental (hydrodynamic) model and 2) a novel application of quantile regression to Species Distribution Modeling (SDM) to simulate both the realized and potential (habitat suitability) abundance of four macrozoobenthic species: Scoloplos armiger, Peringia ulvae, Cerastoderma edule and Lanice conchilega. The analysis shows that part of the fluctuations in macrozoobenthic biomass stocks during the last decades is related to the effect of the coastal defense infrastructures on the basin morphology and hydrodynamics. The methodological framework we propose is particularly suitable for the analysis of large abundance datasets combined with high-resolution environmental data. Our analysis provides useful information on future changes in ecosystem functionality induced by human activities.

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The morphology of the Eastern Scheldt inlet in the southwestern Netherlands has been changing for the past 25 years in response to the construction of the Eastern Scheldt storm-surge barrier in 1986. As a result of the barrier, there has been a decrease in tidal amplitudes, tidal volumes, and average flow velocities, and there is hardly any sediment exchange through the barrier. Bathymetrical measurements of the ebb-tidal delta show multiple effects: (1) An overall decrease in sediment volume, (2) a decrease in morphological activity, (3) erosion of the shoals and sedimentation in most channels, (4) northward reorientation of channels and shoals, and (5) an increase in wave-driven features. Results from a process-based model show that the erosion is related to the wave action, and the reorientation is related to the interaction between cross-shore and alongshore tide. The steady erosive trend, combined with the decline of morphological activity, points toward a system dominated by relatively small and mostly negative bed-level changes. This system is still far from any kind of equilibrium, and is still adapting itself to the new hydraulic forcing regime, even though sediment transport capacities have decreased. Coast. Eng. J. 2013.55. Downloaded from www.worldscientific.com by PURDUE UNIVERSITY on 04/12/15. For personal use only. 1350010-2 Coast. Eng. J. 2013.55. Downloaded from www.worldscientific.com by PURDUE UNIVERSITY on 04/12/15. For personal use only. 1350010-3 Coast. Eng. J. 2013.55. Downloaded from www.worldscientific.com by PURDUE UNIVERSITY on 04/12/15. For personal use only. 1350010-4 Coast. Eng. J. 2013.55. Downloaded from www.worldscientific.com by PURDUE UNIVERSITY on 04/12/15. For personal use only.

Information on the sedimentological composition of sediment beds in marine wetlands is important for the study of the complicated interactions between physical, biological and chemical processes. In situ soil sample collection and subsequent laboratory analyses using traditional methods is rather time consuming. The present paper presents the Medusa (Multi Detector system for Underwater Sediment Activity) RhoC system. ‘Rho’ refers to density and ‘C’ to the activity concentration of the decaying isotopes adhered to the sediments. The new instrument directly translates (the attenuation of) natural radioactivity to sedimentological data concerning the depth-averaged sediment composition and vertical density profiles of the upper 15 cm of the sediment bed. The accuracy and applicability of the instrument were assessed to illustrate its potential and limitations. Results from a field campaign on several intertidal flats and from similar measurements in the laboratory for controlled circumstances were compared with data obtained by traditional analyses. The instrument generates accurate results for the depth-averaged sediment composition. Vertical density profiles are also well represented by the RhoC after smoothing and correcting the data for partly saturated soils. Thus, Medusa RhoC is a useful and practical tool to provide accurate sedimentological data in a fast and cost-effective way. The combination of sedimentological relations with the data obtained by RhoC further increases the applicability of the new instrument.