Glacier melting, UVR impact and stoichiometric implications for zooplankton species distribution.

BALSEIRO, E.G; MODENUTTI, B.E.; SOUZA, M.S.; LASPOUMADERES, C.; BASTIDAS NAVARRO, M.

Córdoba

Congreso; 16th International Photobiology Congress; 2014

International Union of Photobiology

Glaciers around the globe are melting rapidly, threatening the receiving environments of the world?s fresh water reservoirs with significant changes. The meltwater, carried by rivers, contains large amounts of suspended sediment particles, producing longitudinal gradients in the receiving lakes. These gradients may result in changes in water transparency affecting UVR penetration but also food quality for zooplankton by changes the light-nutrient ratio in the water column. Lake Mascardi, located in the North-Patagonian Adean lake district, is a deep ultra-oligotrophic lake that receives the Upper Manso River, which begins at the largest glacier of Tronador Mountain (3554 m a.s.l.). Glacier fluctuations on Mountain Tronador have been observed since 1976 and show a continuous recession. We took advantage of the light gradient in Lake Mascardi, analyzing interannual variations in water transparency, UVR penetration and food quality as interacting factors affecting zooplankton populations. We analyze the oxidative stress due to UVR in Daphnia commutata and how this factor can modulate the coexistence with other potential competitors such as the copepod Boeckella gracilipes. In addition, we found significant differences in light:nutrient ratio and stoichiometric food quality of the seston, together with a switch from dominance of P-rich Daphnia in low carbon:nutrient stations to dominance of low-P copepods in high carbon:nutrient stations. In summary, here we showed how climate change would affect zooplankton via changes in water transparency and UVR effect.