Water Resources Research Act Program

Details for Project ID 2019MT160B

Variation in oxygen, temperature and flow in streams and how they influence the behavior of the giant salmonfly, Pteronarcys californica

Institute: Montana
Year Established: 2019 Start Date: 2019-03-01 End Date: 2020-02-28
Total Federal Funds: $1,750 Total Non-Federal Funds: $770

Principal Investigators: Jackson H. Birrell

Project Summary: Stream ecosystems are important to the ecology, culture and economic development of Montana. However, anthropogenic disturbances including damming, pollution and climate change have decreased water quality, causing declines in aquatic biodiversity and distribution throughout the state1. Such declines are largely due to changes in stream temperature, dissolved oxygen (DO) and flow rates2. Understanding how each of these factors affect aquatic organisms is critical to managing stream ecosystems. Oxygen uptake in aquatic organisms is particularly challenging as water contains 33 times less oxygen than air and oxygen diffuses about 300,000 times slower in water3. Fish and aquatic insects have adapted morphologically, physiologically and behaviorally to enable them to live in these challenging conditions4. However, aquatic organisms can become oxygen limited when flows are low or when water temperatures are high5,6. This is because oxygen uptake is a complex function of the organism’s metabolic rate (which depends on body size and water temperature), the pool of available oxygen in the environment (levels of DO) and the thickness of the boundary layers on respiratory surfaces (determined by flow rates)7. In terrestrial environments, conditions such as temperature can vary greatly over small spatial scales8 and these small variations impact the distribution of plants and animals9. Current low spatial resolution methods of measuring climate are often not representative of the conditions that organisms experience8. This may also be true for aquatic environments. However, little is known about microclimates in streams and how small-scale variation in temperature, flow and DO affect animal distributions. Current methods of measuring DO may overlook a high degree of small-scale variation in streams. Furthermore, little is known about how conditions vary across aquatic microhabitats. Our study will begin to fill this knowledge gap and inform management as to whether current measurement practices accurately represent stream conditions that small aquatic organisms, such as fish and macroinvertebrates, are experiencing. Our study will also help determine how small-scale variation in stream conditions affect the behavior of P. californica. Understanding how stoneflies interact with microclimatic variation is a basic component of understanding whether or not they are at risk in particular streams. Added knowledge from this study will therefore inform management and conservation practices to help protect the aquatic resources of Montana. It will also benefit agriculture, fishermen and the economies they support, which rely on healthy streams.