Fish, Floodplains, and People: Reconstructing Ecological Change of New Mexico's Middle Rio Grande Basin

In the desert, water is life. For the American Southwest, rivers like the Rio Grande are lifelines, supplying water for urban and rural communities, agriculture, wildlife, and recreation. Rivers are also constantly changing, affecting the plants, animals, and people who depend on them, but long-term records of these dynamics are rare. This project will reconstruct 800 years of ecological change in the Rio Grande, the largest river in New Mexico. By comparing fish skeletons from archaeological sites with museum specimens and living fish captured by anglers, the team will build one of the first detailed, centuries-long records of a desert river. This record will help resource managers and the public understand what a healthy river looks like, and how human and natural forces shape it. This project will also advance biotechnology related to fisheries resources, generating data to support fish populations. This information is critical for guiding water use and wildlife management decisions in a river important to farmers, anglers, and the public. Because of this, outreach and community-based science are major components of this project. Through a partnership between University of New Mexico scientists and local K-12 educators from the Bosque School, the team will host FishFest, an annual summer program for high schoolers. Students will take part in fishing clinics and fieldwork with state and federal wildlife managers, covering fish identification, tackle, technique, and licensing. Students will also hear from stakeholders and contribute directly to the scientific research by sampling modern and historical fishes. This project reconstructs the trophic architecture of Middle Rio Grande fish communities over ~800 years, integrating zooarchaeological remains, museum specimens, and modern field collections. The team will quantify three dimensions of food web structure: (1) the diversity of basal energy channels supporting fishes, (2) the number of trophic levels present in the community, and (3) niche partitioning and overlap among native and introduced fishes. These metrics will be derived from bulk tissue and isotopic C and N values from amino acids paired with 3D-morphological models of fish body size. Using this dataset, the team will test three predictions: (1) that 20th century water management reduced the diversity of energy channels used by fishes, (2) that food chain length is positively correlated with energy channel diversity, and (3) that species introductions increased niche overlap among fishes. By linking archaeological, historical, and modern specimens through isotopic and morphometric techniques, the project addresses fundamental questions in freshwater ecology about the relative importance of autochthonous, allochthonous, and microbial energy sources, as well as the drivers of trophic structure in river systems. This project will also enhance the scientific value of vouchered specimens held in museum collections, as data products will be linked to museum specimens and support future genomic, morphological, and parasitological research. Along with FishFest, educational products will include a documentary narrated by student participants, children's activity books distributed to regional K–12 schools, and community-based outreach led by students, extending the project's public and educational reach. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.