Response of Chlorophyll and Metabolism of an Andean Stream to a Temperature Increase in an ex situ Experiment

The variation in temperature associated with climate change in the tropics may affect biodiversity of river ecosystems, favoring the arrival of warmer water species. The variation in temperature can also affect the trophic relationships and metabolism of the river ecosystem. In the present study, we sought to determine the effect of 2-4 Celsius degrade increase of water temperature in the river Tota (Andean high mountain) on the diatoms assemblage and river metabolism. For this purpose, artificial recirculation channels were used, and physicochemical variables (pH, conductivity, temperature, dissolved oxygen and water velocity) were daily measured, diatoms were collected and identified, chlorophyll-a was measured, and metabolism was estimated by means of recirculating chambers. We find significant differences in the physicochemical variables. Qualitative changes in chlorophyll and metabolism were observed, but significant differences in response variables attributable to the increase in temperature could not be detected. The experimental work represents an input to studies about temperature increase impact over high mountain lotic systems. The results illustrate the possible changes that can be recorded in the Andean high mountain systems as a result of climate change.