Final Report Summary - GWESCB (Global warming effects on the stream carbon balance)
The main objective of GWESCB was to assess the effects of the global warming driven alteration of the temperature regimes on the carbon metabolism of stream ecosystems. Specifically, we aimed to develop a mechanistic understanding of the temperature controls on the carbon metabolism, and to understand the effects of the alteration of the temporal components of the temperature regime (diel cycles and heatwaves) on carbon metabolism. To do so, we developed over year and a half the Experimental Streams Facility (ESF, more info at www.icra.cat) at the host institution (ICRA), tested its performance, and successfully performed one experiment on the effects of warmer night-time temperatures on the streams carbon metabolic balance, that is, the balance between primary production and respiration. Results from this first experiment indicate that a the temporal component of the warming matters for the balance between metabolic processes, as warmer night-time temperatures enhanced respiration, driving the carbon metabolism towards heterotrophy. Furthermore, this trend to heterotrophy was also enhanced by the differential sensitivity to temperature of primary production and respiration, as results indicated that respiration was more sensitive to temperature increases according to what predicted by the Metabolic Theory of Ecology. Overall, results from this first experiment stress the need to consider the changes in the diel temperature regime when predicting the effects of global warming on the carbon metabolism in stream ecosystems.
A second experiment on the effects of heatwaves is planned for this Spring 2014, as it was not possible to perform it during the reporting period owing to technical difficulties during the construction and testing of the ESF. Thus, regarding the project phases of the GWESCB, all were completed, but a delay in phase 2.1 involved delays in the posterior phases, which especially constrained the dissemination phase. Accordingly, no publications directly tied to this first experiment have been published. However, the GWESCB allowed the fellow to develop the ESF, which brought plenty of possibilities for research collaborations. In fact, the fellow has published during the reporting period 15 peer-reviewed publications, the last one of them in Science. Because of these achievements in terms of developed facilities, ongoing collaborations and projects, and publications, it can be summarized that the GWESCB has certainly contributed to consolidate the transition from postdoc (as Marie Curie Inter-European fellowship) to research scientist at the hosting institution.