Seals help monitor Antarctica's ice melting
The deep waters of the Southern Ocean transport heat, oxygen and carbon dioxide from the surface to the deep ocean. This is the way through which anthropogenic CO2 is removed, in part, from the atmosphere.
However, due to climate change, the seasonal melting of floating ice platforms of Prydz Bay, East Antarctica, and the consequent entry of fresh water in the streams is hurting the formation of dense deep waters, which has vital importance for the Earth's climate system.
"In regions where dense deep waters dorm in the ocean is more difficult to increase the values of salinity in the water during ice formation if more fresh water is added," says Laura Herriaz-Borreguero, researcher at the Centre for Ice and Climate from the Niels Bohr Institute at the University of Copenhagen (Denmark).
The team of scientists, led by Guy Williams of the University of Tasmania, suggested in the journal Nature Communications that increased fusion of ocean water with fresh water could significantly reduce the formation of deep water in the Southern Ocean. To reach this conclusion, the researchers had the help of southern elephant seals (Mirounga leonina). "Mammals can reach places tha humans can't", the scientists explain.
The southern elephant seals provided data of the properties of the sea in Prydz Bay, unobtainable by ships. These animals can reach places that research vessels can not reach because of the thick ice in winter.
The dense water from the depths occur during the freezing of the seas surrounding Antarctica during winter, when ice rejects salt creating extremely dense waters at the surface. These end up sinking and help drive the movement of deep ocean currents.
According to scientists, most dense waters in the polynya - open-spaces of water surrounded by sea ice in winter and areas of intense formation of marine - ice systems that exist in only a few areas such as the Prydz Bay where three polynya systems exist. However, so far, available data suggest that the area produced less dense water than expected and questioned his contribution to the formation of deep water.
Whith the help of the southern elephant seals, scientists have demonstrated that even though the Bay's polynya systems produce dense surface water, the density is reduced significantly with the entry of fresh water.