Influence of changeable hydro‐meteorological conditions on dissolved organic carbon and bacterioplankton abundance in a hypertrophic reservoir and downstream river

Abstract

AbstractThe variability of dissolved organic carbon (DOC) and bacterioplankton abundance (BA) in a lowland humic reservoir and downstream river were studied in an attempt to find out whether meteorological and hydrological parameters influenced the studied factors during drier and wetter conditions. The study was carried out in two consecutive years (from June to October) that significantly differed in precipitation and hydrological parameters. Despite the observed consistently high values of DOC concentration in the studied waters (on average >20 mg l−1), DOC concentration range and dynamics differed significantly between the two compared periods; in the period of 20% lower accumulated precipitation, concentrations of DOC on all the analysed sites were 30% lower, on average. The observed hydrological changes caused by meteorological differences between the two studied periods significantly influenced DOC concentration, both in the dam and the downstream river. BA was much less variable and less dependent on meteorological factors; however, our study demonstrated that hydrological conditions exerted an important influence on DOC concentration, mostly in river. The other finding is the greater influence of hydrological conditions on BA in the reservoir than in the river, regardless of the period. No evident relations between DOC concentration and BA were observed. Water quality, together with hydrology, influences both DOC and BA changes. Copyright © 2015 John Wiley & Sons, Ltd.