Civil Engineering ETDs

Publication Date

Fall 10-16-2019


Streams and rivers process and transport carbon to downstream systems and are important components of global and regional carbon budgets. Ecosystem functions, including gross primary production (GPP) and ecosystem respiration (ER), can be used to improve understanding of carbon cycling and ecosystem health in lotic systems. Whole-stream metabolism (GPP and ER) has been studied extensively in headwater streams. However, we know less about the variability in GPP and ER in aridland rivers and tributary streams despite being globally abundant and vulnerable systems to changing climate. This dissertation explores temporal and spatial variation of GPP and ER in a montane stream and along the Middle Rio Grande (MRG) using long-term, high-resolution water quality data. Analysis of temporal signals reveal strong inter-annual variability in ER and GPP and shifts from autotrophic to heterotrophic status within and across years for these open canopy sites. We found snowmelt discharge to be an important driver of metabolism, however, the response varied across sites either increasing or decreasing with increasing snowmelt. During the summer, short and frequent pulses in turbidity levels from monsoon rainstorms decreased GPP at sites along the MRG. Our findings suggest that complex combinations of temporally variable factors such as snow accumulation and melt, and their role in connecting terrestrial and aquatic ecosystems, can lead to substantial within-stream variation in autotrophic or heterotrophic status. At sites along the MRG, a combination of discharge, turbidity, geomorphology and substrate type are key determinants of daily GPP and trophic conditions.


Stream Metabolism, aridland river, snowmelt discharge, El Nino-Southern Oscillation, trophic status

Document Type




Degree Name

Civil Engineering

Level of Degree


Department Name

Civil Engineering

First Committee Member (Chair)

Mark Stone

Second Committee Member

David Van Horn

Third Committee Member

Laura Crossey

Fourth Committee Member

Rebecca Bixby

Fifth Committee Member

Jose Cerrato


Please process this information asap due to external time constraints to received a degree completion certification form so that NSF can finalize my application for my post-doctoral research fellowship. Thank you so much!