Can increased glacial melting resulting from global change provide attached algae with transient protection against high irradiance?

NICOLÁS MARTINIUK ; BEATRIZ ESTELA MODENUTTI; ESTEBAN BALSEIRO,

FRESHWATER BIOLOGY (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2014 vol. 59 p. 2290 - 2302

0046-5070

1. Climate change is altering temperatures and precipitation patterns all over the world. Melting glaciersincrease surface run-off, thereby increasing the transport of suspended solids through streams.The increased load of suspended solids affects turbidity, which decreases the availability of photosyntheticallyactive radiation for primary producers.2. We analysed how glacial loading of clays influences the light : nutrient ratio and photosyntheticparameters (measured with a pulse amplitude modulated fluorometer) and the carbon : phosphorus(C : P) elemental ratio of periphytic primary producers. A field study was conducted in two canopyfreestreams that receive water from the glaciers of Mount Tronador (Patagonia, Argentina), one withhigh glacial load and the other with clear water. In addition, we conducted an in situ colonisationexperiment with three different light treatments.3. We observed that periphytic biomass (chlorophyll a and carbon content) in the streams and in theexperiment varied directly with turbidity. Moreover, photosynthetic parameters varied similarlybecause of an increase in the efficiency of electron transfer per open reactive centre in the moreturbid stream and a chronic photoinhibition of photosystem II in the clearer stream.4. Periphytic C : P also varied with turbidity as we observed a decrease in C : P with an increase inlight in both streams and in the experiment.5. Our main conclusion is that an increase in glacial melting with its associated increase in glacialclay load should protect primary producers against high irradiances (photosynthetic active radiation+ ultraviolet radiation) in canopy-free streams.