Seeing the light: high temporal frequency (5-10min resolution) measurements of dissolved oxygen, photosynthetically active radiation, temperature, and depth used to estimate metabolism in restored and unrestored Baltimore streams.

The continually increasing global population residing in urban
landscapes impacts numerous ecosystem functions and services provided
by urban streams. Urban stream restoration is often employed to offset
these impacts and conserve or enhance the various functions and
services these streams provide. Despite the assumption that ‘if you
build it, [the function] will come’, current understanding of the
effects of urban stream restoration on stream ecosystem functions are
based on short term studies which may not capture variation in
restoration effectiveness over time. We quantified the impact of
stream restoration on nutrient and energy dynamics of urban streams by
studying 10 urban stream reaches (five restored, five unrestored) in
the Baltimore, Maryland, USA, region over a two-year period. We
measured gross primary production (GPP) and ecosystem respiration (ER)
at the whole-stream scale continuously throughout the study and
nitrate (NO3-N) spiraling rates seasonally (spring, summer, autumn)
across all reaches. There was no significant restoration effect on
NO3-N spiraling across reaches. However, there was a significant
canopy cover effect on NO3-N spiraling, and directly comparing paired
sets of unrestored-restored reaches showed that restoration does
affect NO3-N spiraling after accounting for other environmental
variation. Furthermore, there was a change in GPP:ER seasonality, with
restored and open-canopied reaches exhibiting higher GPP:ER during
summer. The restoration effect, though, appears contingent upon
altered canopy cover, which is likely to be a temporary effect of
restoration and is a driver of multiple ecosystem services, e.g.,
habitat, riparian nutrient processing. Our results suggest that
decision-making about stream restoration, including evaluations of
nutrient benefits, clearly needs to consider spatial and temporal
dynamics of canopy cover and tradeoffs among multiple ecosystem
services. Here we provide the raw dissolved oxygen, temperature, light, depth,
and discharge data used to estimate whole-stream metabolism from 10
sites throughout the greater Baltimore area. These estimates are
included in the manuscript “Seeing the light: Urban stream restoration
affects stream metabolism and nitrate uptake via changes in canopy
cover” by A.J. Reisinger, T.R. Doody, P.M. Groffman, S.S. Kaushal, and
Emma J. Rosi, which is currently accepted for publication in
Ecological applications.