RIVERMET©: An Excel-based tool to calculate river metabolism from diel oxygen–concentration curves

There is increasing awareness of the need to include ecosystem function into river assessment protocols. Metabolism, one of the most integrative ecosystem functions, is relevant across all sizes and types of rivers, and highly sensitive to many stressors. Continuous monitoring allows using Odum's classic method, but the mathematical analysis of long data series is arduous. Here we present RIVERMET©, a flexible, user-friendly software to assist in these calculations, that can be freely downloaded from the Internet. It consists in an Access database plus an Excel file to help import and store data, and in an Excel file with macros to make calculations. RIVERMET© can calculate the reaeration coefficient directly from night-time oxygen concentration, indirectly from empirical formulae, or can accept values obtained with any other method. It corrects the reaeration coefficient values so obtained for diel changes in temperature, and can automatically analyze the relationship between reaeration and discharge. All results can be graphed, outliers easily purged and results recalculated. Continuous monitoring of river discharge, temperature and oxygen concentration, combined with RIVERMET© allows to easily measure river metabolism, to monitor the function of river ecosystems, to assess the effect of natural or human disturbances, and to analyze post-disturbance recovery trajectories.