Benthic production and energy export from man-made structures to natural soft bottoms: repercussions for food provisioning services?
Over the last decade, the installation and operation of extensive offshore wind farms led to a substantial increase in artificial substrates in the North Sea. Man-made structures (MMS) such as wind turbines represent additional hard-substrate habitats in the areas of the North Sea that are predominantly characterized by soft sediments. Man-made structures, colonised by fouling populations, may have potential effects by additional biomass discharge from MMS on the benthic soft bottom systems. At the same time, many ecosystem goods and services of the North Sea such as long-term carbon storage and natural resources (e.g. for fish, birds, mammals and finally humans) are intimately linked to the benthic system. Benthic invertebrates form the major food source for many commercially exploited fish species and thus the production (i.e. species energy that is turned into biomass) of benthic communities is of direct relevance for the food provisioning ecosystem service. In this study, production was calculated based on species populations as a quantification of energy flow and trophic interactions. The obtained results may thus provide clear signals for status and possible responses of populations and entire ecosystems to the introduction of MMS. The analysis included different datasets from various monitoring programs of offshore wind farms (i.e. the production and biomass of fouling communities and of natural soft-bottom community) from the Southern North Sea over several years. We analysed production changes due to environmental parameters and the presence of the structures in a meta-analysis. The analysis revealed clear modifications in the upper parts of MMSs, where the highest production values and potential biomass export to soft bottoms were detected. The outcome may thus represent a first step to disentangle the potential effects of additional biomass discharge from MMS on the ecological functioning of benthic systems. Future monitoring should therefore focus on specific targeted monitoring, i.e. investigate the cause-effect relationships to understand changes in energy flow and how this might affect (positive-neutral-negative) the food provisioning in marine ecosystems.
AWI Organizations > Institutes > HIFMB: Helmholtz Institute for Functional Marine Biodiversity