ELSAM and ELTRA have established an offshore wind farm with an output of 160 MW in the waters of Horns Rev 14–20 km off Blåvands Huk, which is the most westerly point of Denmark. The first phase of construction of the wind farm started in spring 2002.
The monitoring programme of the benthic fauna was carried out in September 2003 after the wind farm had become operational. Baseline surveys for the present monitoring programme were conducted in the wind farm area on three occasions prior to the construction of the offshore wind farm: spring 1999, spring 2001 and September 2001. In designated reference areas, surveys were conducted in spring 1999 and September 2001. The reference areas in 1999 and September 2001 were placed at two different geographical locations because the survey in September 2001 was planned to be a part of a fish-monitoring programme. Assessment of possible impacts of the establishment of the wind farm was mainly done by comparing results from September 2003 with the results from the baseline study conducted in September 2001.
The survey in September 2003 included collection of bottom fauna at 6 turbine sites, a total of 18 stations in the wind farm, and at 6 stations in a designated reference area outside the wind farm area. The stations in the wind farm were situated respectively 5, 25 and 100 metres in a leeward direction from the scour protection of the wind turbine towers at each turbine site.
The bottom samples were collected by SCUBA divers. Additional samples were collected for sediment analysis.
In the laboratory samples for identification of species composition, abundance and biomass were carefully sieved through a 1.0 mm test sieve. A total of 42 species were identified from the surveys in the Horn Rev area in September 2003, whereas 47 species were recorded in the survey from September 2001.