Meeting Abstract
Climate change and drought can lead to increased temperature and decreased dissolved oxygen in rivers. In the Central Valley, rivers are typically managed for salmonid survival based on temperature; however, oxygen saturation is another critical factor for managers to consider. Salmon embryos are particularly susceptible to high temperatures and low oxygen given that conditions within a redd, or nest, can differ from those of the river itself. To investigate how temperature and oxygen as single and combined stressors affect the survival and physiology of early life stage Chinook salmon, we reared embryos from fertilization to the fry stage under low temperature and high oxygen, low temperature and low oxygen, high temperature and high oxygen, and high temperature and low oxygen. Fish were sampled at four stages during development to test their upper thermal tolerance and low oxygen tolerance, measure growth, and analyze biochemical responses. Fish reared in low temperature or low oxygen developed more slowly than those in high temperature or full oxygen. Embryos reared in low oxygen had significantly reduced hatching success and the multiple stressor treatment with high temperature and low oxygen had greatly reduced hatching success. Acclimation to warm temperature or low oxygen increased thermal tolerance. Acclimation to low oxygen during development increased tolerance to low oxygen, while high temperature reduced low oxygen tolerance. These results demonstrate the importance of water management strategies that consider other abiotic stressors in addition to temperature to promote survival of early life stage Chinook salmon in the Central Valley and further explore the interaction between temperature and oxygen on fish physiology.
