In the heart of Arizona’s Burro Creek, a silent battle is unfolding beneath the water’s surface, one that’s reshaping the very lifeblood of native fish populations. A groundbreaking study, published in the journal “Ecosphere” (which translates to “Biosphere” in English), is shedding light on how invasive species are altering the lifetime dietary habits of native fish, with potential repercussions that ripple through entire ecosystems—and even the energy sector.
At the helm of this research is Jessica O. Diallo, a scientist from the School of Aquatic and Fishery Sciences at the University of Washington in Seattle. Her work is the first to reconstruct the lifetime trophic trajectories of individual fish, offering a unique lens into the chronic impacts of invasive species.
Traditionally, scientists have relied on muscle tissue to study the diets of fish, but this only provides a snapshot in time. Diallo’s innovative approach combines stable isotope analysis of fish eye lens tissue with aging techniques, allowing her to trace the dietary history of individual fish throughout their lives.
“What we’ve found is quite striking,” Diallo explains. “Native fish species like the roundtail chub, Sonora sucker, and desert sucker are being forced to shift their diets to lower trophic levels and rely more on aquatic resources when invasive species are present.”
This dietary shift is driven by asymmetric competition, where invasive species like green sunfish and bullhead catfish outcompete native species for resources. The result is a significant decrease in the carbon isotope ratio (δ13C) in native fish as they grow, indicating a shift in their diet.
The implications of this research are far-reaching. For instance, the reduced growth and fitness of native fish could have cascading effects on the ecosystem, potentially impacting water quality and aquatic biodiversity. In the context of the energy sector, these changes could influence water management strategies, particularly for power plants that rely on consistent water quality for cooling and other processes.
Moreover, this study opens up new avenues for research. As Diallo notes, “Stable isotope analysis of fish eye lens tissue offers a powerful tool to study the lifetime chronology of individual feeding habits. This method can be applied to explore the impacts of invasive species and environmental change throughout ontogeny.”
The findings also underscore the importance of considering the lifetime impacts of invasive species on native populations. As Diallo concludes, “Our results demonstrate the prolonged trophic impact of nonnative fishes on native fishes beyond a single life stage. This has significant implications for management and conservation efforts.”
In the face of mounting invasive species threats, this research provides a compelling case for a more holistic approach to ecosystem management. By understanding the lifetime impacts of invasive species, we can better protect native populations and preserve the delicate balance of our aquatic ecosystems. And in doing so, we may also safeguard the vital resources that underpin our energy infrastructure.