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The role of bioenergetic budgets in defining elevation limits and modeling geographic ranges of species

Timeline: 2022-2025
Collaborators: Xingli Giam (University of Tennessee), Conservation Fisheries, Inc.
Funded by: National Science Foundation, Organismal Response to Climate Change (ORCC)
Overview: This project will develop the next generation of species distribution models (SDMs) by integrating organism-level bioenergetic budgets with community-level predator-prey interactions. The goal is to improve understanding of how physiological and behavioral traits as well as multiple, simultaneous environmental factors associated with climate and land use change drive geographic range limits. This next-gen SDM framework will be validated using a species comparative approach, focusing on low- and high-elevation pairs of pelagic (water column) minnows and benthic (stream bottom) darters. SDMs will be projected under future scenarios of temperature, stream flow, and prey abundance to forecast shifts in species elevational and latitudinal limits. 


The Emory River draining the Cumberland Plateau within the Tennessee River basin. Photo credit: Matt Troia


The Little River draining the Blue Ridge Mountains within the Tennessee River basin. Photo credit: Matt Troia

Developing and validating bioenergetics models for Guadalupe Bass (Micropterus treculii)

Timeline: 2023-2025
Collaborators: Preston Bean (TPWD)
Funded by: Texas Park and Wildlife Department
Overview: The first objective of this project is to measure in the lab the four essential physiological parameters for Guadalupe bass, which include the temperature- and mass-dependence of consumption and respiration. Next, field-based and lab-based measurements of Guadalupe bass growth will be used to validate a bioenergetics model. Lastly, the validated bioenergetics model will be used to project and compare prey demand and growth potential across 8,119 perennial inter-confluence stream reaches (hereafter ‘reaches’) spanning the entire geographic range of Guadalupe bass. These projections will explore alternative scenarios of temperature (e.g., under climate change and/or spring-flow declines) and prey availability (e.g., altered by competition with other micropterids).


A Guadalupe bass from the Mission Reach of the San Antonio River Photo credit: Matt Troia


Measuring routine respiration of a fish (a Mexican tetra) using an intermittent flow respirometer in the Fish Ecophysiology Lab. Photo credit: Matt Troia

Thermal sensitivity and exposure of spring-associated fishes in South Texas

Timeline: 2022-2025
Collaborators: Nick Loveland/Garrett Tucker (UTSA), Warren Schlechte (TPWD), Sarah Robertson (TPWD), Marty Kelly (TPWD), David Young (TPWD)
Funded by: Texas Park and Wildlife Department
Overview: This research will use (1) lab-based physiology experiments to characterize thermal sensitivity of spring-associated fishes and field-based monitoring of stream temperature regimes to characterize thermal exposure. Focal species include: the Guadalupe bass (Micropterus treculii), Guadalupe roundnose minnow (Dionda nigrotaeniata), Devils River minnow (D. diaboli), Rio Grande darter (Etheostoma grahami), and plateau shiner (Cyprinella lepida). Monitoring will take place in San Felipe and Pinto Creeks in south Texas and numerous streams draining the Edwards Plateau. By integrating sensitivity and exposure data, we will produce a comprehensive view of spatially-explicit and species-specific vulnerability to warming. This information will inform conservation actions to mitigate climate change, land use change, and groundwater management.


The Guadalupe River. One of many Hill Country streams we are studying. Photo credit: Matt Troia


San Felipe Creek in Del Rio, Texas is a designated Critical Habitat for the Federally Threatened Devils River Minnow (Dionda diaboli). We have deployed temperature loggers to monitor temperature regimes in this spring-fed stream. Photo credit: Matt Troia

Monitoring and mapping non-native crayfish in the lower Colorado River System (Arizona and New Mexico)

Timeline: 2021-2023
Collaborators: Tony Javiya (UTSA), Jen Smith (UTSA), Jeff Sorensen (AZGFD)
Funded by: United States Fish and Wildlife Service
Overview: Objectives of this research are to (1) perform presence-absence surveys of non-native virile crayfish (Faxonius virilis) and (2) use in situ data loggers to monitor temperature/flow intermittency at 108 sites in the lower Colorado River basin. We are using these field-based data to develop occupancy models and species distribution models with the goal of understanding niche dimensions of crayfish and mapping habitat suitability across ~ 60,000 confluence-to-confluence stream reaches. This research will develop tools (e.g., GIS layers) to inform management decisions (e.g., prioritizing eradication efforts). Ultimately, this work will help to conserve the unique and imperiled fauna of invertebrates, fishes, and herps in the Desert Southwest.



Sabino Creek, Arizona, one of 108 survey locations in the lower Colorado River basin. Photo credit: Matt Troia

A virile crayfish (Faxonius virilis). Photo credit: Jen Smith

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