Glacial recession affecting light climate in Andean Patagonian lakes: Implications for planktonic phototrophs

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

Granada

Congreso; ASLO Meeting; 2015

Climate change is altering temperatures and precipitation patterns all over the world. In North Patagonia glaciers in mountain Tronador (41 °S) showed a continuous and maintained recession and these meltwaters are transported to the lake Mascardi via the Manso River that carries large amount of glacial clay. These suspended sediment particles cause a very sharp light longitudinal gradient along the western branch of Lake Mascardi (Brazo Tronador). Here we analyzed changes in the water transparency along the gradient, and how glacial loading of clays influences the light: nutrient ratio and photosynthetic parameters (measured with a pulse amplitude modulated fluorometer) of planktonic primary producers. Light penetration resulted directly related with the depth of the deep chlorophyll maxima since the increased load of suspended solids affects turbidity, which decreases the availability of photosynthetically active radiation for primary producers. However, the increase transparency towards the end of the gradient would imply a high exposure to UVR and PAR that can lead to photoinhibiton. Therefore, photosynthetic organisms are affected by a trade-off between light availability and photoinhibition.