Sediment instability affects the rate and location of primary production and respiration in a sand-bed stream

• DOI: 10.1899/07-143.1
• Publication Date: 2008-06-24T19:05:05Z
• Authors: Bonnie L. Atkinson; Michael R. Grace; Barry T. Hart; Kellie E. N. Vand...
• Keywords: Hyporheic Zone; Periphyton; Stream bed

Creightons Creek, a rural stream in southeastern Australia, has been severely degraded by large-scale sedimentation of sand the streambed. Our paper highlights use whole-stream metabolism measurements, fluorescein diacetate hydrolysis studies, and situ enzyme mapping to examine effect sediment instability on benthic hyporheic across seasonal flow variations Creek. Median gross primary production (GPP) ecosystem respiration (ER24) rates, determined over 20-mo period with single-station diurnal O2 change method, ranged between 0 0.5 g m−2 d−1 0.6 3.7 d−1, respectively. These values gave photosynthesis/respiration (P/R) ratios 0.00 0.41, indicative heterotrophic system. Creek was expected support higher GPP because it an open canopy, clear water, warm temperatures, sufficient nutrients. However, this once-clay-bottomed now abrasive layer that moves continuously, even at low flows, inhibited growth producers (0–2 mg/m2 chlorophyll a). During high when scour abrasion from bed movement were maximum, highest relative activity located zone depth 7 12 cm, where more stable. occurred upper 4 cm profile. study shows is major factor determining rates locations metabolism.