Drivers of regime shift in the pampean lakes: a paleolimnological perspective.

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

San Diego

Congreso; ASLO 2020; 2021

ASSOCIATION FOR THE SCIENCES OF LIMNOLOGY AND OCEANOGRAPHY

The Pampean region (Argentina) contains many shallow lakes that provide essentialecosystem services, hence their needs for conservation and protection. Besidestheir importance, little is known about how Pampean lakes will respond to climatechange and anthropic impact. To understand this better, a paleolimnological andpaleoenvironmental reconstruction of four shallow lakes strategically located in anarid to semiarid transition zone, was produced. All lakes originated in the LateHolocene. At the beginning they were temporary lakes with clear waters; then ataround 500-700 yrs. BP they shifted to a different regime, and became permanentfeatures and sustained turbid waters; main agents of stress include water level,salinity and trophic state as indicated by the diatom record. The timing at which theregime shift occurred is correlated with the Little Ice Age (LIA). The LIA would haveproduce changes in precipitation seasonality favoring higher winter precipitation bythe strengthening of the zonal westerlies. Only two lakes have been affected byanthropic eutrophication. This suggest that these lakes are extremely sensible tochanges in precipitation that in turn control water volume and quality.