Interactions between fisheries, biodiversity and food webs (BioWeb).

Background and Objective

The overall objective of BioWeb is to analyze changes in biodiversity within the food web of the southern North Sea, in order to investigate the extent to which they are caused by environmental processes and human influences. The focus lies on the impact of the factors fishing and nutrient input. Both have declined in intensity over recent decades, and they have opposing effects on the food web: reduced fishing increases the feeding pressure exerted by predators on smaller fish, indirectly affecting their prey. Meanwhile, lower nutrient concentrations at the base of the food web limit the primary production of phytoplankton.

Together, BioWeb project partners investigate taxonomic groups across all levels of the food web to identify ecosystem-relevant changes, using functional traits. A food web model will be applied to generate predictions for alternative development scenarios, and to derive an impact assessment of future biodiversity changes. Possible consequences for commercially exploited species and for regional fisheries will be highlighted in an exchange with various stakeholders within the North Sea coastal area.

Target Group

Science, politics, public

Approach

In BioWeb, time series of biological data from various research surveys form the basis for analyses of development trends in marine biodiversity. Shifts in functional relationships within the communities will be explored across taxa, ranging from plankton, benthic invertebrates and fish to marine mammals. At the Thünen Institute, data from fisheries surveys will be combined over different spatial and temporal scales. Various statistical analysis methods will be used to obtain a comprehensive picture of change processes and their possible causes.

The knowledge gained will be incorporated into a food web model for the southern North Sea, in order to simulate the feeding relationships of all groups of organisms involved. In particular, the so far insufficiently quantified relationships between fish and lower trophic levels will be better resolved. In addition, special groups that have so far been underrepresented, such as squid, will be included.

Functional properties of organisms (traits) that influence ecosystem processes will also be integrated into the food web model. The effects of biodiversity changes will be estimated for different time horizons. Based on the derived future scenarios, options for action will be developed at regional level together with stakeholders from industry and administration.

Our Research Questions

• How does the combination of reduced fishing pressure, diminished nutrient loads, and climate change affect biodiversity in the southern North Sea?
• How have shifts in dominance among species and their functional traits been affecting the food web?
• Which future scenarios result for biodiversity and ecosystem processes in the southern North Sea, and which development opportunities and options for action for regional actors do they entail?

Links and Downloads

Do the large predators return? https://www.senckenberg.de/de/pressemeldungen/kehren-die-grossen-raeuber-in-die-nordsee-zurueck/