Degraer, S.

Mavrfaki, N.

Vanaverbeke, J.

Open Marine Archive

 20 
Food web structure of fouling communities along the ecological 
zonation of artificial hard substrates in a North Sea offshore wind 
farm 
Mavraki Ninon
1
, Degraer Steven
2
 and Vanaverbeke Jan
2-3 
1
  Marine Ecology and Management, Operational Directorate Natural Environment, Royal Belgian 
Institute of Natural Sciences, 3de en 23ste Linieregimentsplein, 8400 Oostende, Belgium 
 E-mail: nmavraki@naturalsciences.be 
2
  Operational Directorate Natural Environment, Royal Belgian Institute of Natural Sciences, 
Gulledelle 100, 1200 Brussels, Belgium 
3
  Marine Biology Research Group, Ghent University, Krijgslaan 281 - S8, 9000 Ghent, Belgium 
 
Man-made structures provide habitat for sessile organisms altering the natural biodiversity. This 
alteration impacts both ecosystem structure and ecological functioning, e.g. food web interactions. 
An understanding of trophic linkages among organisms is a fundamental requirement to explain 
energy flow from primary carbon fixation to higher trophic levels and provide a mean to investigate 
how man-made structures impact ecosystem functioning. The aim of this study is to describe the 
structural and functional food web characteristics at different ecological depth zones along a wind 
turbine. Fouling organisms were collected at the intertidal, Mytilus edulis, Jassa herdmani and 
Metridium dianthus zones, and on the erosion protection layer (EPL) and the nearby soft substrate. 
Food sources (water particulate organic matter, plankton) and mobile predators were sampled from 
the surrounding water column. All organisms were identified at the lowest possible taxonomic level 
and were processed for stable isotope analysis (δ13C and δ15N). The results indicated that the food web 
structure is changing along different ecological zones; the largest standard ellipse area (SEA) was 
formed by the EPL community (16.81 ‰2) and the smallest one by the intertidal community (5.06 ‰2). 
Overlaps between the ellipses were estimated and it was found that the intertidal zone had the lowest 
overlap with all other communities. In contrast, the soft sediment community had the highest overlap 
SEA with all the other groups but no clear depth-related pattern was revealed. Based on SEAB, the 
probability that the SEA of Mytilus edulis zone is smaller than the SEA of EPL was found 100%. Variation 
in the highest trophic position in the different zones was large and ranged between 6.59 (Trisopterus 
luscus in the EPL) and 4.37 (Homarus gammarus in the soft substrate). The range in trophic positions 
within each zone was again highest in the EPL community (2.36 - 6.59), the narrowest range was 
observed for the intertidal community (1.89 - 3.33).  The species-specific study revealed the trophic 
plasticity of some species, such as Metridium dianthus and Ophiothrix fragilis, which shift food 
sources and trophic positions depending on the zone they inhabit. This study provides fundamental 
knowledge on the food web structure along a wind turbine and gives innovative information about 
the homogeneity of the trophic structure of fouling communities along the ecological zones formed 
at a 25 m depth. 
 
Keywords: stable isotope analysis; marine food chain; artificial hard substrates  


Food web structure of fouling communities along the ecological zonation of artificial hard substrates in a North Sea offshore wind farm

http://www.vliz.be/imisdocs/publications/311847.pdf

Food web structure of fouling communities along the ecological zonation of artificial hard substrates in a North Sea offshore wind farm

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