Environmental Flow Optimization in the San Juan River, NM
The global human population is projected to reach 9.7 billion by the year 2050. As our population grows, so will our demand for fresh water. Combined with the predicted decrease in water availability due to climate change, our impact on freshwater ecosystems will likely be greater than ever before. In the American southwest, this conflict plays a large role, as the semi-arid climate places even more importance on water for both human society and freshwater ecosystems.
Researchers and managers are currently addressing this conflict by determining the quantity, quality, and patterns of water flows required to sustain freshwater ecosystems while also providing the services that human society relies on (also known as environmental flows). For regulated rivers, the predominant paradigm in environmental flows management is to emulate the natural flow regime that was present before human alteration (i.e. dams, diversions, irrigation channels, etc.). Studies have shown that native fishes are adapted to such a natural flow regime (e.g. Poff et al. 1997). However, this paradigm does not necessarily address the presence of nonnatives that expanded their range in response to the altered river and are now competing or preying upon native species. In fact, some studies have shown that emulating a natural flow regime may have only a limited effect, if any, on nonnatives.
Collaborating with Dr. Nathan R. Franssen and the New Mexico Department of Game and Fish, we are using tools from operations research and industrial engineering to improve the way we manage flows in the San Juan River, NM, which was dammed in 1962 to provide water for irrigation. We are developing a framework that prescribes options for water releases from the Navajo Reservoir that best balance three objectives: (1) maximizing benefits to native fish communities, (2) minimizing benefits to nonnative fish communities, and (3) minimizing the deficit between water provided to users on the San Juan versus the water they demand.
Transferring Flow-Ecology Knowledge across Space, Time, and Taxonomy
Environmental flow assessment is an emerging approach for balancing the water needs of freshwater ecosystems with the water needs of human society. By using knowledge of how freshwater species respond to patterns in streamflow (i.e. their flow-ecology relationships), scientists and managers have been able to use environmental flows to improve native fish spawning and recruitment, restore assemblages of native macroinvertebrates, and promote native riparian vegetation over invasive ones.
But what if we do not have the knowledge of species’ flow responses when we need to implement environmental flows? Because streamflow is so integral to the structure and function of riverine ecosystems, most environmental flow assessments are built on a foundation of understanding species’ flow-ecology relationships. Lacking this foundation may make environmental flows ineffective or even detrimental to the freshwater ecosystem we’re trying to sustain. On the other hand, the problems of increasing water scarcity and growing human water consumption will not wait for the development of the flow-ecology models necessary to prescribe effective environmental flows.
To address this challenge, we are investigating the transferability of species’ flow-ecology relationships across different locations and through time, using a suite of freshwater fishes across five river systems in the American southwest. We are also evaluating use of traits as a currency for transferring flow-ecology knowledge across different species, which can inform management of rarer species that are less likely to have established flow-ecology research.
Synchrony of Freshwater Fishes in the American Southwest
Just like how you’re advised to keep a diverse stock portfolio to avoid losing all your money in the event one stuck busts, having biological populations that are out of sync with each other can make a species more resilient to environmental disturbances. This “portfolio effect” has been well-studied for individual species such as salmon (e.g. Schindler et al. 2010), but less so for biological communities. We are interested in the synchrony of native and nonnative fish assemblages in southwestern American rivers. Has the flow homogenization of regulated rivers also homogenized population dynamics? Are native fish assemblages more synchronous than nonnatives, which would imply less resilience to future climate change impacts and greater nonnative dominance? Characterizing the synchrony of these communities will enable us to answer these questions.
Freshwater Invertebrate Occupancy Models
What traits influence a species’ ability to colonize or persist in an area? How can we track the presence of species if we are unable to detect them perfectly? Working with the Lytle Lab at Oregon State, the Muneepeerakul Lab at Arizona State, and the Department of Defense, we are using dynamic occupancy models to determine the biodiversity of aquatic invertebrates on dryland military bases in the Huachuca Canyon of Arizona, accounting for imperfect detection in stream sampling. Taking a Bayesian hierarchical approach, we are able to determine the rates at which these invertebrates are colonizing into and persisting within streams in the canyon. In addition, we can correlate these colonization and persistence rates with species traits such as dispersal ability and body size.
The Impact of Science Communication Training
Those engaged in science communication are already aware of the benefits of receiving training to interface with the general public about science. However, there has been little research effort into quantifying the impact of this training. This leaves STEM students hard-pressed to invest time into science communication training, especially when confronted with competing demands for time and perhaps disapproving advisors.
Working with other alumni of University of Washington’s Engage Speaking Seminar series, I am quantifying the impact of science communication training on students’ abilities to distill information, tell stories, consider their audience, and communicate the relevance of their research in oral presentations to public audiences. Using both self-evaluations and external reviews, we found that students were significantly better at speaking to the public in an accessible manner after being enrolled in Engage. Moreover, alumni of the program have stated the additional opportunities that were possible because of their acquired science communication skills.