Primary production and light availability in Lake Onalaska: Results of a pilot study to evaluate continuous water quality monitors for use in Upper Mississippi River backwaters
Dates
Publication Date
1993-11
Summary
To evaluate the performance of a continuous monitoring device (Waterlogger) developed at Iowa State University, a pilot study was conducted on Lake Onalaska, Wisconsin (Navigational Pool 7 of the Upper Mississippi River), between June 28 and October 4, 1990. The devices recorded subsurface (20 cm) temperature and dissolved oxygen and surface and subsurface (50 cm) light (photon flux of photosynthetically active radiation) every 6 minutes at eight sites. The Waterlogger device stores its measurements electronically on battery-powered memory (RAM) within the unit and can transmitted the recorded data directly to a personal computer. Conversion of the Waterlogger readings to calibrated engineering units is achieved by additional processing [...]
Summary
To evaluate the performance of a continuous monitoring device
(Waterlogger) developed at Iowa State University, a pilot study
was conducted on Lake Onalaska, Wisconsin (Navigational Pool 7 of
the Upper Mississippi River), between June 28 and October 4, 1990.
The devices recorded subsurface (20 cm) temperature and dissolved
oxygen and surface and subsurface (50 cm) light (photon flux of
photosynthetically active radiation) every 6 minutes at eight
sites. The Waterlogger device stores its measurements
electronically on battery-powered memory (RAM) within the unit and
can transmitted the recorded data directly to a personal computer.
Conversion of the Waterlogger readings to calibrated engineering
units is achieved by additional processing of the data via
specific conversion equations developed by the user for each
device. The Waterloggers were durable and reliable generally, and
suffered no electronic malfunctions. Two of units exhibited minor
leakage and several oxygen probes exhibited a manufacturing defect
during this test. These problems were easily corrected. Two
Waterloggers kept in close proximity (5-m separation) during the
study generated highly dynamic, and closely parallel oxygen data
with regular diurnal patterns. Temperature data from the units
generally compared well with field reference values. The
performance of the units with regard to light was difficult to
evaluate due to the highly variable nature of this parameter, but
results seemed reasonable. The authors recommend that a network
of Waterloggers be established on the Upper Mississippi River and
that this network should initially include the six trend-analysis
pools currently being monitored by the Long Term Resource
Monitoring Program.