Introduction

The FOODWEBIO project will investigate and unravel the relations between diversity of habitats and species, and the functioning food webs in European coastal waters.

The objectives of this project are:

• to assess (differences in the level of) benthic species diversity in different European coastal and estuarine systems and relate to environmental factors (tides, salinity, type of substratum, phanerogams)
• to identify and distinguish dominant (group of) species and their presumable trophic relations
• to delineate and quantify the transfers between trophic compartments in the system. This will include the feeding preferences of the main species and the estimation of trophic biodiversity, the effect of competition on resource partitioning and the impact of food preferences on the structuring of the system
• to build a model of the flows of carbon and nitrogen for the system as a whole and for selected subsystems where they can be reliably discriminated. The model will allow simulations of system function under defined organic matter regimes
• to compile a holistic description of the standing stocks and fluxes of the major communities and species in the system
• to obtain processing rates for the prominent species in the system. Size-specific process models will be derived for consumption (C), assimilation (A) and faeces (F). For the prominent species, rates-that are missing- will be measured experimentally, and for the remainder the rates will be estimated from the process models and literature
• to gather and store all results in a central database and make them available to researchers, students, managers and the public at large through reports, papers and a website

Background

Processes ongoing in the ecosystem and mediated by organisms are determined by interactions among organisms and between organisms and the ambient environment, thus by biodiversity (Heip et al., 1998). Diversity of habitats and species vary geographically across environmental and ecological gradients, structuring ecosystems and their functioning at local and global scales. Ecosystem metabolism is intimately linked to carbon and nitrogen fluxes from primary producers to consumers of higher trophic levels. This trophic transfer determines the productivity of ecosystems depending on the efficiency of the food webs. Systems with high diversity and complex trophic interrelations such as the Mediterranean Sea or the Atlantic are considered to be stable and productive (Loreau et al., 2001), while in systems such as the Baltic Sea average diversity is low and food web structure relatively simple. Despite such striking differences in their structures, the productivity of the food web in the Baltic is reported to be similar to that of the Atlantic. This would indicate that biodiversity might not be an essential prerequisite for ecosystem (food web) functioning. However, the number of interactions between species increases with their number and even so does the number of material cycles and pathways within a food web. Therefore the question arises, to what extent food web efficiency of an ecosystem (e.g. seagrass bed, mussel bed, subtidal sand, mudflats, etc.) is related to the entire diversity as well as to the species pool of the higher ranking systems.