An ongoing component of the Baltimore urban long-term ecological
research (LTER) project (Baltimore Ecosystem Study, BES) is the use of
the watershed approach and monitoring of stream water quality to
evaluate the integrated ecosystem functioning of Baltimore. The LTER
research has focused on the Gwynns Falls watershed, which spans a
gradient from highly urban, urban-residential, and suburban zones. In
addition, a forested watershed serves as a reference. The long-term
sampling network includes four longitudinal sampling sites along the
Gwynns Falls mainstem, as well as several small (40-100 ha) watershed
within or near the Gwynns Falls, providing data on water quality in
different land use zones of the watersheds. Each study site is
continuously monitored for discharge and is sampled weekly for water
chemistry. Those data are available elsewhere on the BES website.
We are interested in studying the bioreactivity of streams in our
watersheds in an attempt to quantify how streams themselves may affect
or be affected by water quality. To assess the bioreactivity of
streams, we measure whole stream metabolism, which is an integrative
metric which quantifies the production and consumption of energy by a
stream ecosystem. Stream metabolism represents how energy is created
(primary production) and used (respiration) within a stream; it can be
thought of as a stream breathing, with primary production being
similar to an inhale, and respiration as an exhale.
We are monitoring stream metabolism in each of our long-term water
quality monitoring stations by deploying sensors that record dissolve
oxygen and temperature of the stream every five minutes, and we also
have deployed light sensors to record irradiance every five minutes at
long-term BES water chemistry streams, which is needed for metabolism
modeling. In addition, each dissolved oxygen sensor is located near a
USGS gage which estimates discharge every 15 minutes. We used USGS
manual discharge estimations linked with channel geometry measurements
to develop a unique discharge-stream depth relationship (contact AJ
Reisinger for details). The combination of the USGS discharge data and
our discharge-depth relationship allows us to estimate average daily
discharge and depth. We have included these data as well as dissolved
oxygen, temperature, and PAR, allowing metabolism to be scaled on an
areal basis. Primary production and respiration of streams integrate
all biological activity in a stream, and therefore are good metrics to
assess the state of an ecosystem. These metrics can also be used to
predict other ecosystem functions.
This dataset includes all information needed for whole-stream
metabolism modeling using the streammetabolizer R package. Data will
updated as it becomes available from the core stream study sites (see
http://md.water.usgs.gov/BES for a detailed description of these
sites).