Response of shallow lakes in the arid-semiarid Pampas of Argentina to Late Holocene hydroclimatic change

SEITZ, C.; VELEZ CAICEDO, M.I.; PERILLO, G.M.E.

QUATERNARY INTERNATIONAL

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2022 vol. 607 p. 35 - 47

1040-6182

This study presents a paleolimnological and paleoclimatological reconstruction based on diatoms and phytolithsof four Pampean shallow lakes (from south to north, La Salada, Sauce Grande, Los Chilenos, and Puan) strategicallylocated along a climatic gradient from arid (south) to semiarid conditions (north). This research aims toidentify the main drivers and mechanisms of long-term ecological change, and the main climatic mechanismsbehind the regional hydroclimatic variability. It was found that these lakes were initially temporary, with clearwaters, and eventually, became permanent with turbid waters. We propose that this change is due to an increasein precipitation in the last ca 1000 years, which resulted in higher lake levels and an increase in surface area,leading to an increased fetch and subsequent resuspension of sediment. This climatic amelioration occurred after~910 cal yr BP, first in what is today the arid Pampean region, then in the semiarid region, and finally in themodern humid region at ~ -9 cal yr BP (1959 CE). Variations in lake?s water level were the main driver ofecological change, followed by salinity (in Puan and La Salada) and nutrient load (in Los Chilenos and SauceGrande). In general, those lakes on the southwest, located closer to the limit of moisture influence originating inthe Pacific and Atlantic oceans (Arid Diagonal) were more sensitive to hydroclimatic changes than those locatedin the central Pampean region.