By Courtney Swyden
Marc Russell, a former University of Texas marine sciences graduate student, and advising professor, Dr. Paul Montagna, developed a hydrological/biological model to determine the effects that freshwater inflow has on an estuarine function.
An estuary is freshwater inflow mixing with salt water. The function, productivity and impairment of an estuarine ecosystem are linked to a watershed through freshwater inflow, but their relationships to the watershed are unclear, Russell said.
The model compiled hydrologic and climatic characteristics, and landscape characteristics like soil types, land use and land cover, and meteorological data. Data gathered helped to find the range of freshwater inflow.
Changes in freshwater inflows affect the water quality of a watershed because of the change in the amounts of inorganic and organic compounds. The function of an ecosystem is characterized by heterotrophic, having a high respiration rate; autotrophic, primary productivity is greater than the respiration rate; or balanced.
“I have been involved in numerous nutrient and dissolved oxygen assessments in Texas Bays and through these experiences began to question how landscape characteristics and climate affect the bays,” said Russell, a recipient of a $5,000 2004-05 U.S. Geological Survey research grant.
Russell and Montagna used net ecosystem metabolism, measured from dissolved oxygen rates, as an indicator of ecosystem function.
His research assessed the changes in metabolic rates due to climate change and watershed development in the Aransas River watershed in South Texas. They compared the changes to current levels of impairment and concluded that “human development in watersheds and their effects on climate change are directly linked to the vast ecological resources provided by estuarine ecosystems.”
They also estimated the metabolic response of estuarine ecosystems to predicted urban development within a watershed and predicted climate change over the next one hundred years.
“Scientists and managers of ecological and water resources can use the methods and results of my research to help create tools for linking landscape modifications to estuarine responses,” he said. “Proper stewardship of landscapes can help sustain the estuarine processes that serve as the foundation for valued economic and ecological sectors.”
Russell is currently working as an ecologist for the Smithsonian Institute Environmental Research Center in Maryland. He is working on developing landscape indicators of watershed impairment. He hopes to one day advance into an academic position as a research professor, or a research position with the EPA or other government agency.
His research was funded by TWRI through the U.S. Geological Survey as part of the National Institutes for Water Research annual research program. TWRI is the designated institute for water resources research for Texas.
For more information on Russell’s research, visit “USGS Research Grants”.
