Spatio-temporal variation in microbial respiration in the shallow hyporheic zone of pre-Alpine rivers related to catchment land use
Debeljak, Barbara; Simčič, Tatjana; Ciglič, Rok; Pflieger, Maryline; Mori, Nataša
published: Nov 1, 2017
published online: Oct 24, 2017
manuscript accepted: Oct 5, 2017
manuscript received: Jun 23, 2016
ArtNo. ESP141019004000, Price: 29.00 €
Abstract The hyporheic zone is a key environment for biogeochemical processes in riverine ecosystems. These processes may vary due to different environmental pressures. Respiration is frequently used as an indicator of ecosystem functioning in river ecosystems, but is rarely studied in the hyporheic zone. We investigated the response of microbial respiration, measured as in situ oxygen consumption (R) and as respiratory electron transport system activity (ETSA), to different physicochemical parameters and land use patterns in five pre-Alpine rivers in Slovenia over two seasons (summer and winter) and at two depths (5 –15 and 20 – 40 cm). Inter-seasonal comparison revealed higher R and ETSA in the summer. The effect of land use was significant for R during summer and for ETSA in both seasons, indicating that land use, such as agriculture, near a stream, can affect biogeochemical processes in the hyporheic zone. The effect of land use on the amounts of suspendable fine sediments in the hyporheic zone was not observed. Multiple linear regression showed that water temperature (T), total nitrogen (Ntot), total phosphorus (Ptot), and dissolved organic carbon (DOC) were key factors affecting R in the shallow hyporheic zone. The main drivers of ETSA were conductivity and DOC at both depths, nitrates (NO3−) at depth 5 –15 cm and oxygen at depth 20 – 40 cm. The study confirmed that hyporheic processes are affected by the local environment, which can be influenced by land use changes. A combination of functional measures such as R and ETSA provided a deeper understanding of hyporheic zone functioning, which is important for sustainable management of streams and rivers.