Wildfire smoke significantly impacts lake ecosystems

As much as 70% of California, including most lakes, was blanketed by wildfire smoke during parts of 2020 and 2021, according to a new study led by the University of California, Davis.

The research used lake-based sensors and satellite imagery to reveal that maximum smoke cover has increased by about 116,000 square miles since 2006.

History of wildfire smoke

The study examined lake responses to wildfire smoke during California’s largest fire seasons in 2018, 2020, and 2021.

On average, lakes experienced 33 days of high-density smoke from July to October, with the peak smoky days in August and September.

This research highlights the significant and prolonged exposure of lake ecosystems to wildfire smoke during these critical periods, emphasizing the need to understand and address the impacts on aquatic health and function.

Since the 1970s, the extent of wildfires in California has increased fivefold, yet the impact of smoke on lake ecosystems remains poorly understood.

“We’re looking at a scenario where for the next 100 years or longer, smoke will be a feature on the landscape,” said senior author Steven Sadro, a UC Davis limnologist and associate professor in the Department of Environmental Science and Policy.

“What does that mean for fundamental ecology? What are the implications of those changes? Those are the big questions we’re focused on in aquatic systems.”

Wildfires and lakes

Addressing these questions required a bit of serendipity. Scientific instrumentation needs to be present in lakes when and where wildfire smoke occurs to measure effects. As smoke settled over California during the three main study years, sensors in 10 lakes recorded changes.

The lakes varied widely, ranging from cold mountain lakes to warmer, murkier waters. They included Castle Lake in the Klamath Mountains, Lake Tahoe, Emerald Lake in the southern Sierra Nevada, Clear Lake in the Coast Range, and a site in the Sacramento-San Joaquin River Delta.

“We were measuring things like temperature, light, and oxygen in the water,” said lead author Adrianne Smits, a research scientist in the UC Davis Environmental Science and Policy Department.

“These are all components of lake productivity and health. We were interested in how those things change under smoky conditions.”

Impact of wildfire smoke on lake ecosystems

The researchers hypothesized that smoke and ash would “dim the lights,” affecting photosynthesis and respiration rates of the lake’s plant and aquatic life, which are fundamental to healthy lake ecosystems.

The study confirmed that wildfire smoke alters light, water temperature, and oxygen in lakes — key drivers of lake function and health — but these changes are as variable as the lakes themselves.

Smits emphasized that there is no single answer to how wildfire smoke impacts lakes. The responses depend on factors such as lake size, depth, smoke cover, and nutrient levels. However, changes are evident.

“We’re seeing changes — often decreases — in photosynthesis and respiration rates that drive almost everything else,” Smits said. “Food webs, algal growth, the ability to emit or sequester carbon — those are dependent on these rates. They’re all related, and they’re all being changed by smoke.”

Study significance and future directions

These findings underscore the need for more research to understand how the scale, scope, and intensity of recent and future wildfires affect lake ecosystems.

“We need to reframe how we’re thinking about wildfire smoke — as a seasonal weather phenomenon and not just an ‘event’ that happens and goes away,” Smits explained. “We think about it for our health, but we should be thinking about it for ecosystem health, as well.”

Recognizing wildfire smoke as a recurring environmental factor allows us to better prepare and mitigate its impacts on both human and ecological health.

This awareness leads to improved strategies for protecting air quality, public health, and natural ecosystems. By understanding smoke’s effects on lakes and other environments, we can develop more effective conservation and management plans.

This proactive approach ensures that communities and ecosystems are resilient to the challenges posed by increasing wildfire activity, fostering a healthier and more sustainable future for all.

The study is recently published in the journal Nature Communications.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–