The study, whose first results were published in the scientific journal Scientific Reports, of the Nature group, states the fact that scientists demonstrate “with experimental data that the increase in temperature and salinity, due to global warming, represents a risk for the ecological integrity of groundwater ecosystems", said Ana Reboleira to the Lusa agency, adding that this "will have direct consequences on the quality of these important strategic water reserves for humanity".
The extent of the impacts of human activity on underground ecosystems is being studied under the international project "HiddenRisk", led by the Portuguese scientist at the University of Copenhagen (Denmark) and funded by the Danish foundation Villum Fonden.
"We are now beginning to see the first results of almost three years of studies in different parts of the world published, ranging from Australia to the arctic regions of northern Norway," said Ana Sofia Reboleira, saying that "under our feet are 97 percent of freshwater resources available for immediate human consumption", as well as "the largest water resources for food production and for industry".
Groundwater is “the habitat of a surprising and unknown diversity of life forms adapted to the darkness, with very rare species, without eyes, without colour, and that have a fundamental role in maintaining the quality of these waters”, explained the biologist, stressing the risks already mentioned for the ecological integrity of these ecosystems.
"Although we have found that rising temperatures alone pose a risk to animals living in groundwater reserves (especially microscopic crustaceans), global warming also aggravates the problem of salinisation of groundwater reserves," concluded the study, which shows also that the survival of animals that live in these ecosystems "is threatened by the increase in salt in these freshwater reserves".
According to the scientists involved in the study, the ability of organisms to tolerate salinity is related to how they deal with osmotic stress, that is, how they control the loss of water from inside their bodies to the salt solution.
For this reason, groundwater salinisation is “a global environmental problem”, as human activities “can induce groundwater salinisation in several ways, such as the intrusion of seawater into coastal aquifers, caused by the increase in the level of medium of sea water or by excessive pumping of groundwater, and even by the direct application of salt, for example, to prevent the formation of ice on the roads”, underlined the researcher.
The salinisation processes associated with human activities “are dramatically intensified in arid and semi-arid regions, which are much more vulnerable to the effects of climate change, particularly the increase in temperature due to global warming”, said Ana Sofia Reboleira, exemplifying with the fieldwork carried out in arid and semiarid areas of south-eastern Australia, as well as the various experiments carried out in the laboratory, at a time when the Portuguese scientist was a visiting associate professor at Macquarie University in Sydney, Australia.
"Most of our fieldwork is done in large underground spaces, such as caves, which act as a window for observing these ecosystems. In this case, we have been working on sandstone aquifers, a type of rock that only allows the access to phreatic levels through holes that were made for scientific research and through which the studied organisms were extracted”, she said.
The study is co-authored by doctoral student Andrea Castaño-Sánchez, from the University of Copenhagen, and Professor Grant Hose, from Macquarie University, in Sydney.
By the end of the year, further conclusions from investigations carried out in temperate, subarctic, subtropical and tropical zones will also be released, as well as Portuguese groundwater ecosystems.