Do urban heat islands facilitate tropical species invasions?

A test integrating course-based undergraduate research and a multi-institution researcher network

Timeline: 2026-2030
Collaborators: Chu-lin Cheng (UT-Rio Grande Valley), David Hoeinghaus (University of North Texas)
Funded by: National Science Foundation CAREER Program
Overview: Tropical freshwater fishes are popular aquarium pets throughout the United States and often become invasive when aquarists release unwanted pets into lakes, streams, and wetlands where they consequently impact native species and the freshwater resources upon which humanity depends. Most of these tropical fishes are intolerant of cold winters and subsequently establish invasive populations only within subtropical regions like Florida and southern portions of California, Arizona, and Texas. However, environmental change and the growth of cities that absorb solar heat are causing freshwater environments to warm, and this warming may facilitate the northward expansion of invasive tropical fishes. This research will use laboratory experiments to measure the cold tolerance and growth potential of three tropical freshwater fishes in order to understand their ability to expand their invasive range northward. A subset of these experiments will be performed by students enrolled in course-based undergraduate research at the University of Texas at San Antonio. At the same time, research teams composed of undergraduate students and faculty from three universities in south, central, and north Texas will monitor winter water temperatures in streams to understand baseline temperatures in their respective regions as well as the urban heat island effects that increase temperatures beyond the baseline and therefore potentially facilitate the expansion of the three tropical invasive fishes. Lastly, the laboratory physiology and field temperature data will be combined with climate models to build forecast maps of future invasion risks for the three focal species.