Bioclimatic influence on water chemistry and dissolved organic matter in shallow temperate lakes of Andean Patagonia: a gradient approach

MANSILLA FERRO, CAROLINA; GARCÍA, PATRICIA; REISSIG, MARIANA; DIÉGUEZ MARÍA DEL CARMEN

FRESHWATER BIOLOGY (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2024 p. 1 - 15

0046-5070

1. We addressed the influence of bioclimatic drivers (precipitation, temperature and vegetation) on physico-chemical properties, carbon (C) and nutrients dynamics in shallow temperate lakes in the Northern Patagonian Andes.2. Four shallow lakes (mean depth < 15 m) located along the Andean Patagonian bioclimatic gradient, and characterized by a west-to-east decrease in precipitation, increase in temperature, and changes in vegetation type, were studied during wet and dry periods. Physico-chemical variables, total nitrogen and phosphorus (TN and TP) and particulate and dissolved organic matter (POM and DOM) were analyzed. Multivariate analyses were performed to evaluate the influence of environmental variables on lake water chemistry and to identify the main factors driving spatial and temporal differences in lake DOM pools.3. The spatial and seasonal decreases in precipitation and warming were reflected in the reduction of the hydrologic connectivity of the lakes. The reduced connectivity resulted in increased conductivity, pH, alkalinity, dissolved organic carbon (DOC) and TN concentrations. Such conditions favored the loss of lake DOM aromaticity, humic content, and molecular weight/size, and increased the degradation signals and the biologically produced DOM fraction.4. Lakes responded uniformly to changes in climate variables along the Andean Patagonian gradient. Lakes differences in water chemistry and DOM composition, driven at the gradient scale by variations in precipitation, temperature and vegetation of the surrounding catchment, may provide insights into C and water chemistry trajectories under forecasted climate trends.5. Our results suggest that drought and warming trends could result in a lower hydrologic connectivity, shrinking terrestrial DOM fluxes to lakes while concomitantly increasing internal degradation processes.