The Bassa Nera pond (Central Pyrenees), a potential sentinel of climatic changes over the last 15,000 years.

Over the last decades, significant increases in temperature and in the incidence of extreme climatic events have been registered in the Iberian Peninsula. Environmental changes  are easily recorded in high mountain lakes, due to their sensitivity and isolated location. Since paleolimnological information can be very useful for planning and modelling future climate change scenarios, it is necessary to find suitable lakes and test their sensitivity to current and past climatic shifts in order to adequately fulfill these tasks.

In order to test the suitability of the Bassa Nera pond as an indicator of global climatic change, this study aims to examine the variations of different  paleoindicators over the last 15,000 years. The variations of paleoenvironmental data can be then compared with the changes of different biological indicators (chironomids, diatoms, pollen), to find likely correlations that can be used to figure out future climatic scenarios and to provide information for environmental management.

For this study, a core of approximately 1,100 cm was extracted (PATAM 12-A-14) and dated with radiometric techniques. Sedimentological analysis was performed by applying conventional stratigraphic techniques and X-ray fluorescence methods. The variability of the sedimentary sequence allowed us to reconstruct the different climatic events. The pond recorded a long sedimentary sequence encompassing the last 15,000 years. The sedimentological analysis allowed us to establish 5 different stratigraphic units which we have separated in two principal sections. The first section is formed by organic rich facies while the remains of the core is composed mainly of clays and silts facies with some sand layers.

These data will be very useful to establish which and how past climatic events have affected this high mountain basin, when reconstructing the evolution of main paleolimnological indicators of environmental change. And in conjunction with subsequent studies, it will establish whether or not the suitability of the Bassa Nera as a sentinel of climatic global change. This in turn will allow the  establishment of a network of sentinel lakes in the Iberian Peninsula.