The coastal waters of the Southern Bight of the North Sea receive large quantities of nutrients of anthropogenic origin via rivers and the atmosphere. Eutrophication is apparent in the coastal zone in the form of undesirable qualitative changes in the structure and functioning of the planktonic ecosystem, and can be observed in the form of occasional accumulation of foul-smelling foam on beaches. Guaranteeing sustainable North Sea resources for future generations and protecting the quality of coastal waters is now both a national and an international concern. National and international regulations on sewage treatment facilities and farming practices aiming at the reduction of nutrient supply to the coastal sea have already been implemented in the various countries which border the North Sea. However, the scientific knowledge needed for a rational estimate of the reduction required and of the nutrient(s) which have highest priority for reduction (ammonium, nitrates and/or phosphates) is currently lacking.
This research project contributes to the implementation of an integrated land-coastal zone research methodology to assess and predict the eutrophication level of the coastal North Sea and the associated undesirable effects. The ultimate aim is to reduce the current context of uncertainty in which decisions to counteract the eutrophication of the North Sea and protect its natural resources are made.
The environmental questions involved
What is the natural capacity of the coastal North Sea planktonic system to absorb surplus nutrients resulting from human activities in the surrounding river basins ?
What is the level of nutrient reduction required to protect biological resources from the harmful effect of nutrient enrichment?
What are the relative contributions made by natural processes and human activities to the phenome-non of eutrophication and is there a synergy?
to establish an observational data base of key biogeochemical parameters from which changes in the quality of North Sea coastal waters can be monitored, signs of future deterioration can be rapidly detected and the positive and negative results of new purification regulations can be evaluated.
Sampling site selected: station 330, 20 miles offshore of Ostend and subject to the influence of water from the Scheldt. The reference station has been sampled by ULB-GMMA since 1988 under the joint framework of the National Programmes for joint Oceanographic Research Activities and the Impulse in Marine Science and the European Commission's Environment and MAST Programmes (Phaeocystis projects and COMWEB). Results so far indicate that station 330 is sensitive to disturbances induced both by natural changes (meteorological conditions) and/or by anthropogenic factors. The current set of nutrient and phytoplankton monitoring parameters has been extended to secondary trophic levels.
to improve understanding of the mechanisms which structure coastal trophic networks in response to changes in the input of nutrients.
Two principal questions will be dealt with and studied by conducting process-level studies in natural and laboratory-controlled conditions :
. How does the structure of the phytoplankton community change when the input of nutrients alters?
. And what are the related changes in the higher trophic levels, particularly zooplankton?
The knowledge gained will be integrated in a mathematical model resulting from the ‘on-line’ coupling of a 1km-resolution 2D-hydrodynamic model simulating the dispersal of the waters of the Scheldt in the coastal zone with an upgraded version of the existing mechanistic biogeochemical model MIRO, revised on the basis of knowledge gained in the process-level studies.
MIRO is an ecological model developed by ULB-GMMA which describes the dynamics of Phaeocystis colonies blooms in the North Sea coastal zone in response to riverine nutrients loads. Although already operational, the model suffers from weak points as regards the low resolution of hydrodynamic and related resuspension processes and the lack of knowledge of some physiological parameters for which adequate measurement methods are presently lacking. Resolving these uncertainties is UGMM's main task in co-operation with ULB-GMMA and VUB-ECOL.
Main deliverables expected
A list of key physico-chemical and biological indicators allowing the rapid diagnosis and prediction of significant trophic changes and their harmful effects. A "Green Book" will be published listing the parameters, how they are measured and the sampling strategy.
A validated mathematical model to be used as a scientific tool for predicting eutrophication phenomena in the Belgian coastal zone and their effects on adjacent zones and to guide decision-making regarding the reduction of the input of nutrients into the sea.
A data bank gathering physico-chemical and biological data recorded at station 330 of the Belgian monitoring network since 1988. This will be used for (i) the long term assessment of trophic changes in the ecosystem, (ii) the validation of the mathematical model and (iii) the evaluation of the effects of present and future water treatment policies.
The co-ordinator, the Microbiology of Aquatic Environments Group (Groupe de Microbiologie des Milieux Aquatiques, ULB-GMMA) of the Free University of Brussels (Dr. C. Lancelot), an internatio-nally recognised expert in coastal eutrophication, the initiator of the monitoring programme at station 330 and originator of the MIRO ecological model.
The laboratory for Ecology and Taxonomy (VUB-ECOL) of the free University of Brussels (Dr. M. Tackx), specialist in zooplankton dynamics and the evaluation of its trophic influence with 20 years experience.
The Management Unit of the Mathematical Models of the North Sea (MUMM) (Dr. Ir. G. Pichot), specialised in mathematical modelling of marine systems and active in exploiting scientific research to provide support for decision-making.