Effect of glacial lake outburst floods on the light climate in an Andean Patagonian lake: implications for planktonic phototrophs

BASTIDAS NAVARRO, M.; MARTYNIUK, N.; BALSEIRO, E.G; MODENUTTI, B.E.

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2018 vol. 816 p. 39 - 48

0018-8158

Climate change is altering temperatureand precipitation patterns all over the world. In NorthPatagonia, glaciers of the Tronador mountain (41S)show a continuous and maintained recession, andthese meltwaters are transported to Lake Mascardi viathe Upper Manso River that carries a large amount ofglacial clay. These suspended sediment particles causea very sharp light longitudinal gradient along thewestern branch of Lake Mascardi (Tronador arm).Here we analysed changes in the water transparencyalong the gradient, in particular before and after aglacial lake outburst flood (GLOF) event that occurredin the headwaters that feed Lake Mascardi. The GLOFcaused a significant decrease in turbidity over theyears following the event. The depth of the deepchlorophyll maxima (DCM) was directly related to thelight penetration, and the decrease in suspended solidsload deepened the DCM in the years after the GLOFevent. Among photosynthetic organisms, picocyanobacteriaand total nanoflagellates abundancesincreased after the GLOF event when transparencyincreased due to the decrease in the clay and sedimentinputs into the lake. Our data demonstrated that theDCM and phytoplankton are useful variables topredict changes in the lake light climate.