RRS Discovery Cruise 248, 07 Jul-10 Aug 2000. A multidisciplinary study of the environment and ecology of deep-water coral ecosystems and associated seabed facies and features (The Darwin Mounds, Porcupine Bank and Porcupine Seabight)

Abstract

RRS Discovery Cruise 248 aimed to carry out a multidisciplinary study of the environment and ecology of deep-water coral ecosystems and associated seabed features in the northeast Atlantic. The study was primarily focused on the Darwin Mounds area, northern Rockall Trough (59° 49’N, 07° 22’W), but also examined a number of sites in the Porcupine Seabight area. The cruise was divided into two legs (Govan-Stornoway, 8 Jul-21 Jul 2000; Stornoway-Southampton, 22 Jul-10 Aug 2000). Leg 1 focused on the ecology of the Darwin Mounds area, with seabed photographic surveys (SOC SHRIMP system), coring (Box and Multiple cores) and trawling (Agassiz) forming the main activities. Leg 2 began with detailed geological investigations of the Darwin Mounds area, concentrating on piston coring and sidescan sonar surveys. Leg 2 concluded with combined ecological and geological studies of carbonate mound sites on the Porcupine Bank and in the Porcupine Seabight.Observations in the Darwin Mounds area confirmed the common occurrence of deep-water corals on these Mounds. The mounds themselves do not appear to be carbonate formations but may be better characterised as sand volcanoes. Numerous xenophyophores were observed in association with the mounds; however, no live specimens were recovered in any of the samples collected. Sidescan sonar images and seabed photography both suggested that the Darwin Mounds area had been subject to considerable commercial trawling with resultant apparent damage to the deep-water coral ecosystems.The various operations undertaken in the Porcupine Seabight area were also successful in imaging giant carbonate mounds and their associated coral communities with both sidescan sonar and seabed photography, and in recovering biological sample material from these areas. In common with the Darwin Mounds area, the observations made suggested that deep-water fishing impacts on coral ecosystems were also evident in this region