Based on literature, it is recognised that differences in the (chemical - physical) habitat is reflected in differences in community composition (Fig. 3). Colonisation of areas will be an ongoing process, but follows the physical starting point. After a certain period, some organisms may be capable to influence their environment (eco-engineers) causing a reverse situation in which some physical parameters will follow the community development.

Figure 3: Conceptual meso-scale bedforms with bathymetry, macrozoobenthos and demersal fish characteristics, sediment characteristics and bed shear stress.

Important chemical-physical parameters are: salinity and dissolved oxygen content of seawater, sediment organic matter and silt content, sediment grainsize distribution, the existence of 'hard' substrate and seabed morphology. Most of these parameters are interrelated, being the result of transport mechanisms or existing energy at a certain location. A good indicating parameter for energy is bed shear stress. Relevant ecological parameters are species composition, species richness, diversity and biomass and could be determined for the infauna, the epifauna and demersal fish. Species composition has relevance to life history, age structure and feeding traits.

Bed shear stress is linked with in- and epifaunal and demersal fish species composition (De Jong et al. 2014, De Jong et al 2015a, De Jong et al. 2015b). Bed shear stress is directly related to the extraction depth of sand extraction and can therefore be used in the design of extraction sites.