PHASE - Physical Forcing and Biogeochemical Fluxes in Shallow Coastal Ecosystems

The central objectives of the project were a) to determine how biogeochemical fluxes and trophic structure in coastal ecosystems are related to the nature and strength of physical forcing functions and b) to evaluate the importance of biological macrostructures in modifying the physical mixing processes in the benthic boundary layer.

More specifically the project would:

• Determine how turbulent dissipation rates and vertical mixing intensity respond to the physical forcing functions: tide, wind and heat flux;
• Determine the relationship between vertical mixing intensity and the role of macrobenthic suspension feeders in structuring and controlling planktonic populations;
• Determine the relationship between near-bed current velocity, particle flux and food uptake in macrobenthic suspension feeders. In this context, we are interested in to what extent the presence of macrobenthic organisms (e.g. mussels and macrophytes) modify near-bed turbulence and, hence, vertical food flux;
• Integrate the obtained knowledge into a mechanistic dynamic model for shallow coastal environments by linking a set of biogeochemical process models directly to a physical transport/turbulence model allowing a high spatial and temporal resolution.

The project used a combination of laboratory and field studies. A key element in the project was campaign periods carried out in 3 European coastal waters of contrasting energy input - the macrotidal eutrophic Oosterschelde estuary (Netherlands), the microtidal eutrophic Isefjord (Denmark) and the microtidal oligotrophic Jomqueet Bay (Spain).