For more than 20 years, a team led by Michael Türkay of the Senckenberg Research Institute in Frankfurt has been collecting samples from about 40 locations at the bottom of the central North Sea at the same time each year. Their results indicate that as water temperatures have warmed, southern species are increasingly expanding northward.
‘Our results clearly indicate that a regime change began in the North Sea in 2000, and that the fauna’s composition has been undergoing massive changes from then on,’ said Türkay. ‘Warm-water species increasingly spread north and east, thus blurring the formerly stable boundaries between different faunal regions.’
Long-term studies in the Helgoland Trench, which is found to the south of the eponymous North Sea island in the German Bight confirm this trend. Since 2000, the ratio of warm-water species there has steadily increased and is becoming more stable, with species once found only sporadically now becoming dominant elements of the marine community. ‘The crabs that we studied are like living measuring instruments – their occurrence and expansion are reactions to a changing environment,’ Türkay said.
This story was published in the August 2014 edition of Geographical Magazine