FLATHEAD LAKE – Rivers and streams are similar to arteries and blood vessels in the human body. Therefore, monitoring metabolic respiration and production rates of Earth’s fresh water can help us understand the overall health of our planet.
Current and former researchers at the University of Montana’s Flathead Lake Biological Station were part of a science team that used modern environmental sensor technology to track stream vitals in near real time.
The new system they developed acts almost like a Fitbit to monitor the country’s freshwater ecosystems. It allows researchers to better predict how freshwater vital signs might change with land development, climate change and other disturbances.
UM researchers Maite Arroita, Joanna Blaszczak, Alice Carter and Lauren Koenig, along with FLBS stream ecology professor Bob Hall, were part of an effort led by University professor Emily Bernhardt Duke. Their pioneering work was recently published in the prestigious Proceedings of the National Academy of Sciences.
Waterway scientists monitor the fluctuations of oxygen and carbon that occur in waterways as gases are absorbed and released by organisms such as microbes, algae, insects and fish as part of their basic vital functions.
In the past, to study stream metabolism, scientists relied on instantaneous data consisting of measurements taken from a small number of streams over a few hours or days. Now, using years of data combined with new computational and statistical methods, a research team has created an approach to converting water quality and environmental data into estimates of photosynthesis and respiration for rivers and specific types of rivers.
From more than 10 academic and government institutions, the scientists analyzed at least one year of data from more than 220 rivers and streams across the United States. Environmental sensors recorded dissolved oxygen and temperature every 15 minutes day and night. The study areas ranged from the deserts of Arizona and the rainforests of Puerto Rico to the farmlands of the Midwest.
The researchers compiled and uploaded the data to a web portal for public use.
“When we monitor a river continuously instead of just taking snapshots, a picture begins to emerge of what river life is really like,” said Carter, the study’s author. “Disruption and change are the norm. Measuring the “pulse” of a river allows us to see how it influences the life of organisms and how humans alter these patterns. »
While analyzing the data, the researchers made an interesting discovery. Although changes in mean annual temperature and precipitation often explain changes in terrestrial ecosystem productivity, for streams the most important controls are annual light availability and flow stability.
Stream flow changes seasonally, day-to-day, and even minute-to-minute with sudden storms, so stream organisms have to deal with flows ranging from a trickle to a torrent. Highly variable flows tend to dislodge algae and organic matter, reducing metabolic rates. Strong light stimulates photosynthesis.
The researchers argue that paying more attention to sun exposure and changes in water levels due to droughts or floods will greatly improve scientists’ ability to predict the dynamics of river ecosystems in ways that may change. basically how rivers are studied in the future.
The study also found that rivers breathed in more carbon than they produced, showing that organic matter transported from land to water subsidizes river metabolism.
“Our study provides a lens from which we can examine how changes in land use and climate may affect energy inputs to river food webs across many rivers over time,” Hall said. , an FLBS conservationist. “Our approach will allow managers to monitor ecosystem processes in addition to water quality measures such as dissolved oxygen.”
As far as the future of our river ecosystems is concerned, their state will probably depend on human activity. The study authors point out that changes in light and flow in streams have a huge impact on their communities and conditions. Changes in shade-producing streambank vegetation, changes in rainfall caused by climate change, and flow regulation by dams can all affect the amount of energy available to stream food webs.
If human-induced changes influence river and stream flows, food webs, fish populations, outdoor recreation and other related industries that depend on our rivers may also be affected.
To put it another way, researchers say that whether it’s a river in the rainforests of Puerto Rico or the icy, sun-dappled flows of the Flathead River here in Montana, the future ecological health of our rivers depends on us.
This study was made possible by the National Science Foundation. For the full study, visit https://www.pnas.org/doi/full/10.1073/pnas.2121976119. Data from the study is publicly available at https://data.streampulse.org/.