Increasing sediment load affects bottom-dwelling sea creatures
A series of research dives around the Antarctic Peninsula suggest that melting glaciers are diminishing the region’s biodiversity. Scientists think the main cause may be increased levels of sediment in the water.
Over the past five decades, temperatures have risen nearly five times as rapidly on the western Antarctic Peninsula than the global average. Yet the impacts of the resulting retreat of glaciers on bottom-dwelling organisms remain unclear.
The new study, published in the journal Science Advances, helps show those impacts.
In 1998, 2004 and 2010 divers photographed the species communities at three different stations and at different water depths: the first, near the glacier’s edge; the second, an area less directly influenced by the glacier; and the third, in the cove’s minimally affected outer edge.
They also recorded the sedimentation rates, water temperatures and other oceanographic parameters at the respective stations, so that they could correlate the biological data with these values.
They found that some species are extremely sensitive to higher 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 Dr Doris Abele, a biologist with the Alfred Wegener Institute and co-author of the study. “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,” Abele said.
The study may have missed some of the earliest global warming impacts because the research just started recently, said marine ecologist Ricardo Sahade from the University of Cordoba and Argentina’s National Scientific and Technical Research Council CONICET.
“Combining this series of observations, accompanying ecological research on important Antarctic species, and mathematical modelling allows us to forecast the changes to the ecosystem in future scenarios,” said co-author Fernando Momo from Argentina’s National University of General Sarmiento.