Melting coastal glaciers cause loss in biodiversity

21.11.2015 15:15
Kategorie: News

Seabed ecosystem affected by sedimentation

Divers of the Dallmann Expedition at Potter Cove © Alfred-Wegener-Institut, Anders Torstensson
Divers of the Dallmann Expedition at Potter Cove
© Alfred-Wegener-Institut, Anders Torstensson

Melting glaciers will lead to a reduction of species biodiversity among the benthos (bottom-dwelling organisms) community in the coastal waters off the Antarctic Peninsula, and this in turn will impact an entire ecosystem on the seabed. The theory has been verified through repeated immersion studies, according to a study by scientists from Argentina, Germany and the UK, and the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), published in the journal Science Advances.

They attribute the dwindling biodiversity to increased turbidity of the water. This occurs when coastal glaciers start to melt due to global warming, resulting in large quantities of sediment being carried into the seawater.

In the last fifty years, temperatures at the western Antarctic Peninsula have increased almost five times faster than the global average. Currently, the effects of how the retreat of glaciers would affect life on the seabed are still poorly understood. Therefore, scientists at Dallmann Laboratory are currently mapping and analyzing the benthos in Potter Cove, a bay on King George Island off the western Antarctic Peninsula. Here, the AWI and the Argentine Antarctic Institute (IAA) operate Dallmann Laboratory as part of the Argentine Carlini Station. The laboratory has been monitoring the benthic flora and fauna for more than two decades.

In 1998, 2004 and 2010, divers photographed the plant communities at three different sites and at different depths. The three locations were: near the glacier’s edge, an area that experienced less effects from the glacier and in the cove’s outer edge which experienced minimal influence.

Sea Squirts (Benthos Community), Potter Cove © Alfred-Wegener-Institut, Cristian Lagger (CONICET)
Sea Squirts, Potter Cove
© Alfred-Wegener-Institut, Cristian Lagger (CONICET)

They also recorded the sedimentation rates, water temperatures and other oceanographic parameters at the three locations, so that such data could be linked with the biological data collected. In the end, the researchers concluded that certain species were very sensitive to high sedimentation rates. "Particularly tall-growing ascidians like some previously dominant sea squirt species can’t adapt to the changed conditions and die out, while their shorter relatives can readily accommodate the cloudy water and sediment cover," said AWI biologist and co-author of the study Dr Doris Abele.

"The loss of important species is changing the coastal ecosystems and their highly productive food webs, and we still can’t predict the long-term consequences," she added.

The Dallmann Laboratory at Carlini (former Jubany Station) was launched in 1994 as a joint facility by the AWI and IAA. Since then, it has proven itself to be a reliable platform for international and interdisciplinary research programmes supported by the European Union and the Argentine funding organisations in the past decade. "Sustainable long-term research and coordinated interdisciplinary Antarctic research programmes are essential in order to explain the local changes in coastal ecosystems in connection with global warming," said Abele.

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