The Fugløy Reefs on the Norwegian-Barents Continental Margin: Cold-water Corals at 70°N, their acoustic signature, geologic, geomorphologic and oceanographic setting

• Main Authors: Björn Lindberg, Christian Berndt, Jürgen Mienert
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Barents Sea; Fugløy*; Lophelia pertusa
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.510.3180; http://www.noc.soton.ac.uk/gg/people/berndt/Lindberg_etal_Fugloy.pdf

This is the first in-depth study of a cluster of cold-water coral reefs, the Fugløy Reefs, found at 70°N on the Norwegian margin. Combining high resolution seismic reflection data, side-scan sonar, video-images, and oceanographic measurements reveals the geologic, geomorphologic and oceanographic setting in which the reefs occur. The reefs consist mainly of the scleractinian ahermatypic Lophelia pertusa, and exist below the thermocline at water depths between 140 m and 190 m. The reefs appear as cone-shaped, acoustically transparent features on seismic reflection data, consistently located in places characterized by the availability of hard substrate, high relief, and periodical exposure to high tidal cur-rents (>30 cm/s). These currents transport water of the Norwegian Atlantic Current to the reefs from an area with fluid expulsion-related pockmarks. The spatial relationship between reef and pockmark locations and current directions suggests that seepage of biogenic gas might be a catalyst to reef growth. With a height of more than 40 m some of the Fugløy reefs are among the highest reported from the Norwegian Margin. This indicates highly fa-vourable growth conditions, and conservative estimates indicate a net growth rate for the reefs of ~5 mm/yr. We expect that cold-water reefs will be found further north along the Barents Sea margin as general awareness on the geophysical signature and appearance of the reefs increases, because all known factors involved in reef establishment and growth are within the required intervals also further north.