Comparing Metabolism and Hypoxia Tolerance of Native and Non-Native Florida Freshwater Fishes in Climate Change Scenarios

Author

Benjamin A. Share, Nova Southeastern UniversityFollow

Defense Date

12-2-2024

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Biological Sciences

First Advisor

David W. Kerstetter, Ph.D.

Second Advisor

J. Matthew Hoch, Ph.D.

Third Advisor

Paul Arena, Ph.D.

Keywords

Centrarchidae, Cichlidae, invasive species, Everglades, Lake Okeechobee, water hyacinth, metabolism, hypoxia, climate change, respirometry

Abstract

As climate change brings rising water temperatures and lower dissolved oxygen (DO) concentrations to freshwater bodies, it has become increasingly important to understand how this will affect ecosystems with established non-native or invasive species. Fishes of the family Cichlidae are the most pervasive non-native fishes in the Everglades and may increase their range further north under a changing climate. To better understand potential invasibility and competition with native fishes, the metabolism and hypoxia tolerance of non-native Blue Tilapia Oreochromis aureus was compared to native Bluegill Lepomis macrochirus when acclimated across a range of seasonal and projected temperatures. Intermittent-flow respirometry was used to determine the maximum metabolic rate (MMR), standard metabolic rate (SMR), aerobic scope (AS), and critical oxygen saturation (S_crit) of each species at 22, 30, 32, and 34°C. None of these values significantly differed between the two fishes, indicating strong physiological similarity and competitive exclusion unlikely to occur based on these traits. MMR and AS significantly increased with temperature, but SMR and S_crit were unaffected – reflecting an increase in energy availability and no change in hypoxia tolerance with rising temperatures. To directly apply these findings in an ecological context, DO measurements were taken from beneath invasive water hyacinth Pontederia crassipes mats in Lake Okeechobee. All levels of the water column in July were beneath the S_crit of both species, indicating that they may avoid invaded areas or experience reduced energetic efficiency. Overall, both species are expected to withstand near-future conditions with little-to-no metabolic disadvantage.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

NSUWorks Citation

Benjamin A. Share. 2024. Comparing Metabolism and Hypoxia Tolerance of Native and Non-Native Florida Freshwater Fishes in Climate Change Scenarios. Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, . (196)
https://nsuworks.nova.edu/hcas_etd_all/196.