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 vol. 39 p. 675 - 686

0142-7873

We analysed the antioxidant response of Daphnia commutata in the oligotrophicNorth-patagonian lake (Lake Mascardi) that receives inputs of glacial clay inone extreme, which creates a plume with a consequent gradient in underwaterlight intensity (including ultraviolet radiation) and suspended solid material.This gradient in light intensity also affects the light:nutrient ratio andhence the C:P ratio of the food for planktonic herbivores. In the field, alonga 9 km transparency gradient, we measured the activities of glutathioneS-transferase (GST) and catalase (CAT) enzymes involved in protection againstUVR. Through laboratory experiments, we tested the possible role of suspendedsediment particles as an additional stressor for a filter feeding zooplankter.Our results indicate that the inputs of glacial clay into the lake haveantagonistic effects on Daphnia.Glacial clay was a stress mitigating factor to UVR (decrease in the antioxidantresponse of GST activity), but was also a source of stress that generatedfeeding interference, increased respiration rates and consequently increasedCAT activity. This light gradient also affected the C:P ratio of food and themaximum response in GST is also modulated by food quality (C:P ratio) thatlimits its activity in the transparent end of the gradient.