Glacier melting and response of Daphnia oxidative stress

LASPOUMADERES, CECILIA; SOUZA, MARÍA SOL; MODENUTTI, BEATRIZ; BALSEIRO, ESTEBAN

JOURNAL OF PLANKTON RESEARCH

OXFORD UNIV PRESS

Año: 2017 p. 1 - 12

0142-7873

We analysed the antioxidant response of Daphnia commutata in an oligotrophic North-Patagonian lake (LakeMascardi) that receives inputs of glacial clay in one extreme, which creates a plume with a consequent gradient inunderwater light intensity (including ultraviolet radiation) and suspended solid material. This gradient in light intensityalso affects the light:nutrient ratio and hence the C:P ratio of the food for planktonic herbivores. In the field,along a 9 km transparency gradient, we measured the activities of glutathione S-transferase (GST) and catalase(CAT) enzymes involved in protection against UVR. Through laboratory experiments, we tested the possible role ofsuspended sediment particles as an additional stressor for a filter feeding zooplankter. Our results indicate that theinputs of glacial clay into the lake have antagonistic effects on Daphnia. Glacial clay was a stress mitigating factor toUVR (decrease in the antioxidant response of GST activity), but was also a source of stress that generated feedinginterference, increased respiration rates and consequently increased CAT activity. This light gradient also affectedthe C:P ratio of food and the maximum response in GST is also modulated by food quality (C:P ratio) that limits itsactivity in the transparent end of the gradient.