Biologists record increasing amounts of plastic litter in the Arctic deep sea

Science Daily: The sea bed in the Arctic deep sea is increasingly strewn with litter and plastic waste, according to researchers. The study is published in the advance online publication of the scientific journal Marine Pollution Bulletin by Dr. Melanie Bergmann, biologist and deep-sea expert at the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association. The quantities of waste observed at the AWI deep-sea observatory HAUSGARTEN are even higher than those found in a deep-sea canyon near the Portuguese capital Lisbon.

For this study Dr. Melanie Bergmann examined some 2100 seafloor photographs taken near HAUSGARTEN, the deep-sea observatory of the Alfred Wegener Institute in the eastern Fram Strait. This is the sea route between Greenland and the Norwegian island Spitsbergen. "The study was prompted by a gut feeling. When looking through our images I got the impression that plastic bags and other litter on the seafloor were seen more frequently in photos from 2011 than in those dating back to earlier years. For this reason I decided to go systematically through all photos from 2002, 2004, 2007, 2008 and 2011," Melanie Bergmann explains.

The deep-sea scientists from the HGF-MPG Group for Deep-Sea Ecology and Technology of the Alfred Wegener Institute regularly deploy their towed camera system OFOS (Ocean Floor Observation System) during Polarstern expeditions to the HAUSGARTEN. At the central HAUSGARTEN station it is towed at a water depth of 2500 metres, 1.5 metres above the sea bed, and takes a photograph every 30 seconds. Deep-sea biologists principally use these photographs to document changes in biodiversity with respect to larger inhabitants such as sea cucumbers, sea lilies, sponges, fish and shrimps. However, for Melanie Bergmann they also provided evidence of increasing deep-sea pollution: "Waste can be seen in around one percent of the images from 2002, primarily plastic. In the images from 2011 we made the same discovery on around two percent of the footage. The quantity of waste on the sea bed has therefore doubled," the scientist says. If we consider the time span between 2007 and 2011 the amount has even risen by an order of magnitude.

At first sight, the "two percent" result may not cause much concern. However a comparison demonstrates the true extent of the pollution in the Arctic deep sea: "The Arctic Ocean and especially its deep-sea areas have long been considered to be the most remote and secluded regions of our planet. Unfortunately, our results refute this notion at least for our observatory. The quantities observed were higher than those recorded from a deep-sea canyon not far from the industrialised Portuguese capital Lisbon," Melanie Bergmann explains. It is also important to bear in mind that, according to recent research, more plastic waste will accumulate in deep-sea canyons than in open slope environments such as HAUSGARTEN....

The OFOS-system of the HGF-MPG Joint Research Group on Deep-Sea Ecology and Technology. Graphic: Normen Lochthofen, Alfred Wegener Institute