UBC Theses and Dissertations
Towards a comprehensive understanding of gas bubble trauma in fish Pleizier, Naomi Kathryn
Features such as river dams can generate total dissolved gas (TDG) supersaturation in water downstream, which can lead to harmful bubble growth in the tissues of aquatic animals, known as gas bubble trauma (GBT). Despite numerous previous studies, there remain many unknowns about the factors that affect GBT and the indirect effects of GBT on aquatic animals. I conducted a series of studies to determine key factors that affect the induction of GBT and to describe the outcomes in fish. My systematic review and meta-analysis of the relationship between TDG and GBT in fish generated models that identified depth, dissolved oxygen to nitrogen ratios, temperature, body size, and species as important factors affecting the progression of GBT. Depth has a protective effect against GBT by causing bubbles to dissolve in animal tissues, but the empirical relationship was untested. I conducted an experiment to test the relationship between depth, TDG, and GBT in rainbow trout (Oncorhynchus mykiss). My results indicate that 47 cm of depth compensated for 4.1% (±1.3% SE) TDG supersaturation, as predicted. Based on this result, I proposed an equation for the threshold for GBT at depth. Conversely, locomotion is predicted to promote GBT in fish tissues. I tested the relationship between locomotion and GBT in rainbow trout. My results suggest that there is no significant effect of locomotion on the progression of GBT. I also conducted an experiment to determine whether fish can detect and avoid harmful levels of TDG supersaturation. I found no statistically significant difference in the duration spent by fish in a channel with a lethal level of TDG supersaturation compared with a channel containing air-equilibrated water. I summarized the primary factors affecting the progression of GBT on freshwater fish and the direct and indirect effects of GBT that are supported by my data and the literature. I propose directions for future research and recommendations for TDG monitoring and management.
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