How climate change and agriculture could reshape the midwestern stream fish communities

Dai, Qihong

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https://hdl.handle.net/2142/116200 Copy

Description

Title

How climate change and agriculture could reshape the midwestern stream fish communities

Author(s)

Dai, Qihong

Issue Date

2022-07-11

Director of Research (if dissertation) or Advisor (if thesis)

Suski, Cory D

Doctoral Committee Chair(s)

Suski, Cory D

Committee Member(s)

• Fuller, Rebecca C
• Larson, Eric R
• Cao, Yong
• Bunnell, David B

Department of Study

School of Integrative Biology

Discipline

Ecol, Evol, Conservation Biol

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• climate change
• global warming
• midwest
• heatwave
• heat wave
• extreme weathers
• agriculture
• conservation
• BMPs
• best management practices
• machine learning
• random forest
• models
• species distribution modeling
• spatial models
• biodiversity
• species richness
• functional diversity
• functional dispersion
• functional evenness
• watershed
• physiology
• metabolism
• swimming
• enzyme
• fish
• coolwater
• warmwater
• predator-prey
• streams
• rivers
• walleye
• largemouth bass
• fathead minnow
• temperature
• SWAT
• MO2
• respirometry
• metabolic rate
• CTmax
• environment
• environmental restoration
• fisheries
• freshwater
• lakes

Abstract

Global climate change is a major driver of freshwater fish community changes. Agriculture further intensifies the impacts of climate change in the Midwestern USA. To quantify such impacts on fish communities, physiological experiments can provide a mechanistic understanding, but have scaling issues, while ecological modeling can handle large-scale projections but lack resolution locally. It is with optimizing and integrating these approaches that we can offer better guidance in conservation planning. In this dissertation, I sought to demonstrate that physiological experiments can effectively quantify the impacts of short-term, small-scale extreme events, heatwaves, on individual species and species interactions. When it comes to longer-term and broader-scale understanding, ecological modeling coupled with physiological information can handle watershed-scale projections of different climate and agriculture scenarios. Thus, combining these two approaches together could help generate more effective and accurate conservation decisions. In this dissertation, Chapter 2 used physiological experiments to show that widespread, warmwater prey, fathead minnow (Pimephales promelas), had high thermal resilience under extreme heatwaves in agricultural landscapes, including rapid returns to metabolic homeostasis and transient increases in critical thermal maximum (CTmax). However, even for fathead minnow, experiencing heatwaves came with costs, including reduced anaerobic capacity and impaired antioxidant defense. Chapter 3 was built upon this finding and took these conclusions one step further to the fish community, by quantifying the influence of heatwaves and summer temperatures on both predator and prey fishes, as well as cool and warmwater fishes. Compared to the warmwater predator largemouth bass (Micropterus salmoides) and prey fathead minnow, the coolwater predator walleye (Sander vitreus) had many disadvantages in the local community under summer temperature with heatwaves, including higher standard metabolic rate, limited aerobic scope, low metabolic activity when encountering prey, and reduced swimming performance after experiencing a heatwave. Finally, Chapter 4 further broadened the scope to the watershed level by using ecological models coupled with physiological information for each species. In Chapter 4, I used contemporary fish and environmental records to build base models. These models showed that flow, temperature, nitrate, and watershed area were among the top predictors of functional dispersion, functional evenness, and species richness in local communities. Functional dispersion, the metric including physiological information, had > 50 % better performance than traditional species richness based on R2. Then, based on different climate and agricultural conservation scenarios, I projected possible fish community changes in the Kaskaskia River Watershed. Species richness and functional dispersion were predicted to decrease under climate change in most sites across the watershed, up to 20% and 4% by 2099, respectively. When potential agricultural conservation practices were simulated under climate change, the decreasing trends of species richness and functional dispersion remained, suggesting climate change outweighed potential agriculture conservation efforts. When considered together, the chapters included in this dissertation demonstrate the importance of 1) considering different scales (i.e., individual species, communities, and the whole watershed) and 2) considering both short-term extreme events and long-term overall trends when designing conservation plans. This dissertation also shows the value and the potential of combining experimental physiology and ecological modeling on freshwater conservation.

Graduation Semester

2022-08

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Qihong Dai

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