Monday, June 4, 2007 - 3:30 PM
43

Whole-stream respiration and nighttime regression model for aeration

Alyssa J. Standorf and Walter K. Dodds. Division of Biology, Kansas State University, 116 Ackert Hall, Manhattan, KS 66506

Stream metabolism, as reflected by diurnal changes in O2, characterizes the allochthonous and autochthonous basis of stream food web production.  Whole-stream metabolism was measured in shrubby reaches of Kings Creek, whose watershed lies within Konza Prairie Biological Station.  These measurements require an aeration coefficient that corrects for the rate that gases escape from the water column to the atmosphere.  We measured aeration directly with inert gas, and constructed a model using the nighttime patterns of O2 to predict the aeration coefficient.  Modeling can be used to provide reasonable estimates of aeration as compared to gas tracer methods.  Our models provided better fit to the data in some cases when two rates of respiration were used.  Thus, whole-stream respiration is not always constant throughout a 24-hour period.  Possible explanations include: 1) algae use up stored organic carbon overnight, 2) photorespiration continues into the dark period or 3) photosynthetic algae leak available carbon that is used through the night by heterotrophs.  Differentiation between these possibilities is very difficult to determine.  The fact that respiration rates are not constant in some stream reaches needs to be considered when determining whole-stream metabolism.

See more of Biogeochemistry I
See more of Contributed Sessions

See more of The NABS 55th Annual Meeting