Identifying the Effects on Fish of Changes in Water Pressure during Turbine Passage
Migratory and resident fish in the Columbia River are exposed to stresses associated with hydroelectric power production, including pressure changes during turbine passage and dissolved gas supersaturation. We investigated the responses of fall Chinook salmon (Oncorhynchus tshawytscha), rainbow trout (Oncorhynchus mykiss), and bluegill sunfish (Lepomis macrochirus) to these two stresses, singly and in combination, in the laboratory. Fish were exposed to total dissolved gas levels of 100%, 120%, or 135% of saturation while being held at either surface or 30 ft of pressure. Some of these fish were then subjected to decreases in pressure simulating passage through a Kaplan turbine under “worst case” (to 0.1 atmospheres) or more “fish friendly” (to 0.5 atmospheres) scenarios. Surface- and depth-acclimated Chinook salmon and bluegill, with no exposure to dissolved gas above ambient levels, were subjected to decreases in pressure simulating passage through a bulb turbine under “worst case” (to 0.68 atmospheres) or more “fish friendly” (to 1.0 atmospheres) scenarios. Bluegill, the most pressure-sensitive among the three species, incurred injuries that ranged from mild (internal hemorrhaging) (bulb turbine) to death (Kaplan turbine). For each type of turbine passage, bluegill acclimated to 30 ft depth and subjected to the more severe pressure nadir were more susceptible to injury/death. However, even control bluegill (i.e., not subjected to simulated turbine passage) experienced mild to moderate injury from rapidly ascending from 30 ft of pressure to surface pressure. The dissolved gas level had only a small additive effect on the injury/death rate of bluegill subjected to simulated Kaplan turbine passage. Thus, while physoclistous fish, such as bluegill, appear to be susceptible to injury from any rapid pressure decrease, those that are most severe (e.g., Kaplan turbine passage) are likely to be most injurious. Chinook salmon and rainbow trout were much less susceptible than bluegill to death/injury from simulated Kaplan turbine passage, and Chinook salmon incurred no visible injuries from simulated bulb turbine passage under any scenario. Acclimation to 30 ft depth had little additional effect on the injury/death rate of Chinook salmon and rainbow trout subjected to Kaplan turbine passage. However, these species were much more susceptible to acute gas bubble trauma than bluegill, particularly those acclimated at surface pressure at 120% or 135% of saturation. Consequently, it would be advantageous to develop advanced turbines that operate efficiently under more “fish friendly” pressure regimes and to reduce the amount of gas supersaturation.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 15004606
- Report Number(s):
- PNNL-SA-37872; HYREE8; 820101000; TRN: US201015%%758
- Journal Information:
- Hydro Review, 22(5):32-42, Vol. 22, Issue 5; ISSN 0884-0385
- Country of Publication:
- United States
- Language:
- English
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