Organismal responses of freshwater fish to elevated carbon dioxide

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Climate change, aquaculture, and aquatic invasive species management all expose freshwater fishes to elevated CO2 and it is therefore imperative to understand the consequences of high CO2 on fish. For example, recent data from the Laurentian Great Lakes and European reservoirs show that increasing CO2 in freshwater environments is pervasive; evidence from many aquaculture facilities suggest that high CO2 limits fish production; and, barriers made by injecting CO2 are being used to limit the distribution of aquatic invasive species. Largely unknown, however, is how freshwater fish respond to prolonged changes to environmental CO2. My long-term objective is to understand responses of freshwater fishes to elevated CO2 across biological and evolutionary scales. Over the next five years, I will address three short-term objectives: 1) determine organismal and molecular responses to elevated CO2 in freshwater fishes; 2) assess fish responses to elevated CO2 when faced with other abiotic and biotic challenges, such as parasitic load, nutritional status, and thermal stress; and 3) explore multigenerational responses in freshwater fishes to elevated CO2 (e.g., reproductive output, parental effects, and transgenerational acclimation). Completing studies under Objective 1 will allow me to determine the degree to which individuals experience negative consequences to high CO2 and will be applicable to understanding how high CO2 limits aquaculture production and the rate at which acute changes in CO2 might influence wild fishes. Objective 2 will build on the above objective by understanding the role that other challenges, specifically thermal stress, parasitic load, and nutritional status, have on fish responses to elevated CO2. Addressing Objective 3 will allow me to project into the future the phenotypic responses to high CO2 that will relate to population-level changes. My aim is to improve our understanding of environmental CO2 effects on freshwater fishes by monitoring responses across biological (e.g., metabolism to whole-animal) and evolutionary (e.g., reproductive output to multigenerational) scales. My research will support policy decisions and conservation practices related to climate change, aquaculture technology, and invasive species management. Therefore, my research program is relevant and can improve Canadian fish production at aquaculture facilities and inform conservation management of Canada's natural fish populations and aquatic environments. Ultimately, I will help predict how global freshwater fish populations may be altered by rising CO2 levels.