Annual cycle of gross primary production and respiration in the Viroin River (Belgium)

Abstract

Gross primary production, community respiration and reaeration coefficient were determined during an annual cycle on the Viroin River (South Belgium), based on the daily variations of dissolved oxygen concentration.Reaeration coefficient remains remarkably constant (0.26 h-') during the year in spite of discharge variations. The autotrophic community is dominated by 'Ranunculusfluitans'. Primary production parallels the variations of total solar radiations. It ranges from 0 in winter to 8 g 02 m 2 d-in summer. In spring and summer, respiration variations parallel those of primary production (average value: 10 g 02 m 2 d-1 ); in the dry autumn, decomposition of dying macrophytes considerably enhances the community respiration (15 g 02 m 2 d-l).A P/R diagram is used to characterize the trophic state of the Viroin.

Periphyton metabolism along a nutrient gradient in a desert river (Truckee River, Nevada, USA)

“…This fi nding concurs with the general annual patterns of primary production and respiration rates typically observed in many streams (e.g., Cushing and Wolf, 1984;Servais et al, 1984;Uehlinger, 1993). Periphyton metabolism in the Truckee River lacked an apparent response to the enhanced nutrient availability downstream of the point source in November.…”

Variability of photosynthesis‐irradiance curves and ecosystem respiration in a small river

“…Temperature is an important regulator of photosynthesis and respiration (DeNicola, 1996). In rivers with moderate flow variability, linear temperature models may account for 55±75% of the seasonal variation in ecosystem respiration or gross primary production (Servais et al, 1984;Uehlinger, 1993).…”

Effects of aquatic plant management on stream metabolism and oxygen balance in streams

“…These changes decrease reaeration rates ( Thyssen et al , 1987 ), which, in turn, amplify diel oxygen variation that results from photosynthesis and respiration by macrophytes and associated epiphytic algae. The decomposition of macrophytes can also consume large amounts of oxygen ( Godshalk & Wetzel, 1978) and high ecosystem respiration rates coinciding with plant decay have been reported ( Dawson, Kern‐Hansen & Westlake, 1982; Servais, Debecker & Billen, 1984; Fisher & Grimm, 1988). The flow‐retarding effect of dense macrophyte stands enhances the deposition of fine sediments ( Butcher, 1933; Gregg & Rose, 1982; Marshall & Westlake, 1990; Sand‐Jensen, 1998) and the retention of organic detritus ( Westlake et al , 1972; Fisher & Carpenter, 1976 ).…”