The Tautra Cold-Water Coral Reef - Mapping and describing the biodiversity of a cold-water coral reef ecosystem in the Trondheimsfjord by use of multi-beam echo sounding and video mounted on a remotely operated vehicle

摘要

The Tautra sill is one of three sill dividing Norway s third largest fjord, the Trondheimsfjord. Knowledge of cold-water corals in the fjord has been known for centuries and has been a popular object of interest in regards to research. As anthropogenic impact on the oceans world-wide is increasing, an urgent need to gain knowledge about the many habitats is a necessity. The three-dimensional reef structures formed by the cold-water coral Lophelia pertusa are considered a biodiversity hotspot and important for many commercial fish stocks. By combining non-invasive technology in the form of video and multibeam echo sounder, mounted on a remotely operated vehicle, to map the seabed and the cold-water corals in the Trondheimsfjord, new biological information was gathered. Two surveys were performed, at the Tautra sill and at Hoøyskjæret in the Beitstadfjord. The surveys aimed to gain knowledge about the Lophelia pertusa reef as a habitat and to map cold-water coral occurrence in relation to topography and biodiversity. To illustrate how biodiversity may change along a 1 km long transect, a spatial resolution of 2 m was analysed for megafauna taxa diversity. High correlations between sponge occurrences and Lopehlia pertusa were found, as well as higher biodiversity located around the reefs. The combination of the two non-invasive mapping techniques was used to further suggest areas of interest for future inspection and management.