Poster Presentation Freshwater Sciences 2023

Assessing longitudinal patterns in stream metabolism across a heterogeneous landscape (#692)

Katherine X. PĂ©rez Rivera 1 , Stephen Plont 1 , Erin R. Hotchkiss 1
  1. Biological Sciences , Virginia Polytechnic Institute and State University , Blacksburg , Virginia, United States of America

Ecological processes in streams are influenced by changes in hydrology, land use, and water chemistry. We thus expect ecological processes will also change within a stream as it flows through a heterogeneous landscape, but we rarely characterize the longitudinal dynamics of ecosystem functions in a single stream as it moves through engineered structures and across land cover changes. To address this knowledge gap, we are characterizing how ecosystem metabolism (gross primary production and ecosystem respiration; GPP and ER) changes along a stream as it (1) flows out of buried pipes in a developed area before entering a series of retention ponds, (2) through low-intensity development and open-canopy agricultural fields, and (3) eventually through more forested parts of the watershed. We deployed high-frequency sensors to measure dissolved oxygen (DO), temperature, and water level at 10-minute intervals along 3 sections of Stroubles Creek in Blacksburg, VA, USA for one year. Preliminary results from sensor data show distinct diel signals in DO among our three study reaches, supporting our prediction that our three study sites within a single stream had different GPP and ER rates, patterns, and responses to flow changes throughout the year. The comparison of DO among sites show differences in mean annual DO for the 3 monitored sections of the stream, reflecting the differences in land cover, stream morphology, and canopy cover. Diel DO concentrations ranges were highest at the open-canopy agricultural reach, followed by the forested downstream site and the upper stream segment downstream of a buried reach. Future work will use sensor data to model GPP and ER to address how in-stream metabolic processes differ along streams draining heterogeneous landscapes informing overall freshwater ecosystem function and susceptibility to environmental changes.