Middle Loire River (France) hydrochemistry, biology, and metabolism data, 1980–2018

This is a dataset compiled to understand the links between river state changes and metabolism in the middle Loire River (France). At approximately 2005, the rivers shifted dramatically from being covered by phytoplankton to being mostly covered by macrophytes, but the reasons why were not clear, nor were the biogeochemical implications. To investigate this, we obtained monthly hydrochemistry from 1980–2018, hourly dissolved oxygen and temperature from 1993–2018, clam densities from 1990–2018, and macrophyte cover from 1990–2018. Using the dissolved oxygen and temperature data, we calculated whole river metabolism, which is presented here. The dissolved oxygen and temperature data are proprietary and cannot be provided without directly asking permission from the French Electric Company. The study river reach is located on the upper section of the middle Loire, France, between Saint-Satur (47.3degreeN 2.9degreeE) and Dampierre-en-Burly (47.4degreeN; 2.3degreeE). In this reach, the Loire is an 8th order river, with a catchment area of 35,500 km², a mean width of 250 m and a mean depth of 1 m during summer base flow. Dampierre-en-Burly is at an altitude of 123 m a.s.l., 110 km downstream from the confluence with the Allier River and 550 km from the source.