To develop efficient analytical, numerical and experimental methods for assessing and predicting the effects of nutrient (N, P, Si) supply on the stability and persistence of pelagic food web structure and function in coastal areas.
Marine pelagic systems are highly dynamical and flexible with respect to nutrient enrichment, and the structure of the pelagic ecosystem may strongly affect the fate of the nutrients and hence the eutrophication process of coastal waters. Comweb is an integrated holistic approach to mechanisms behind coastal eutrophication and impact assessment of human and natural nutrient supply.
Comweb will examine the effects of variable nutrient supply to coastal pelagic waters by analysis of the flows and components of the major biogenic elements C, N, P, and Si in the lower pelagic food web. The integrated information of flows and components of a given element in the food web are denoted flow networks. The project will establish optimized flow networks for the major types of European coastal waters by use of mathematical inverse methods. Flow networks represent unified information which allow comparison of coastal waters over wide biogeographical and trophic state gradients, and the project will contribute to further develop and improve these methods.
Five cases of European coastal waters will be studied in the project: 1) The Baltic Sea, 2) The Mediterranean Sea, 3) NE-Atlantic waters; unaffected by humans, 4) NE-Atlantic waters; artificially eutrophicated, and 5) NE-Atlantic waters; eutrophicated. These cases involve both a geographic gradient (1-3) and a trophic state gradient for NE Atlantic waters (3-5). Regional representative flow networks of C, N, P and Si will be established for all these cases of coastal waters.
The data needed to establish the representative regional flow networks and the respective flow networks following nutrient perturbation will be obtained in combined laboratory, mesocosm, and field experiments. The laboratory experiments will involve studies of processes, mechanisms and functional characteristics of key components needed to establish flow networks of the regional food webs and to improve the understanding of the fundamental mechanisms behind coastal eutrophication. The persistence and stability of the regional pelagic food webs, following perturbation of nutrient supply, will be examined based on the flow networks derived in mesocosms and a lagoon system. The effects of nutrient supply rate, the elemental composition of the nutrients, and the temporary mode of nutrient supply will all be considered in the experiments. The flow networks established based on time series data at Station 330 in the North Sea will be used as reference for eutrophic coastal waters.
The knowledge gained on components, flows, and mechanisms behind coastal eutrophication will be used to further improve an established biogeochemical mechanistic model for assessment of coastal eutrophication in global change. The regional flow networks will also form the basis of the search and the evaluation of diagnostic assessment tools for state and quality analysis of coastal waters.
Important contributions will be 1) publications, describing the elemental flow, mechanisms, and characteristics of key components of regional coastal waters, 2) computational methods for comparative analysis of pelagic food webs, 3) conceptual framework for diagnostic assessment tools for analysing state and quality of coastal marine waters, and 4) improved and validated biogeochemical mechanistic model for assessment of coastal eutrophication.
Funding SchemeCSC - Cost-sharing contracts