By David Colgan, UC Los Angeles
Just three years after one of the most severe droughts ever recorded in California, the driest February in 150 years has spurred discussion of whether we’re in another drought — or if the last one even ended.
That’s bad news for the California newt, Taricha torosa, and other newts in the Taricha genus, particularly in the southern half of the state. A new study led by UC Los Angeles conservation biologist Gary Bucciarelli examined the body condition of newts from San Diego to Mendocino. Body condition, specifically an animal’s weight to length ratio, is a good overall measure of newt health. South of Big Sur, the of the newts decreased by an average of 20% from 2008–2016, Bucciarelli and colleagues report in the journal Scientific Reports.
The study found that newts in the north did not show a significant decline in body condition over the same time period. But if regions like the Bay Area mirror the decline in rainfall happening in Southern California, northern newts are likely to experience similar decreases to body condition.
With less body mass, newts are prone to diseases and less likely to survive and breed. “What we observed was extremely outside of what we predicted, based on body condition in the years leading up to the drought,” said Bucciarelli, a conservation biologist.
The large-scale research effort involved catching and measuring thousands of newts from streams and ponds during peak breeding season in the spring. Research sites included the NRS’s Stunt Ranch Santa Monica Mountains Reserve, where Bucciarelli is director of research. Students, researchers, faculty and government agency staff all participated in the fieldwork.
The decline in body condition was worse than models had predicted during an extended drought. In the Santa Monica Mountains, researchers have tracked one population for more than 25 years, marking and recapturing individual newts to see how they fare over time. More than two-thirds showed a decline in body condition.
Co-author Seth Riley, a wildlife expert at the National Park Service, said the study is part of a larger effort to try to understand how climate change will affect amphibians across the state, including California and Pacific tree frogs and western toads.
Climate change is already causing temperatures to rise and making extreme dry and wet weather more common.
“You see huge climate change impacts at the North Pole or Antarctica, or very high altitudes,” Riley said. “This study shows the impacts of temperature and precipitation here in Southern California where we think things may not be as extreme as in these other places.”
Riley said it’s important to not just pay attention to federally protected endangered species or charismatic animals such as mountain lions, but also to monitor wildlife that isn’t facing extinction. In California, he said, what happens in the southern part of the state may offer a glimpse of what happens to northern species in the future.
Amphibians are among the most threatened species in the Anthropocene extinction, an ongoing mass extinction event that results from human activity. They are estimated to be experiencing an extinction rate 45,000 times greater than they would without human influence.
“Amphibians get hit hard by this stuff,” said Brad Shaffer, study co-author and UCLA distinguished professor of ecology and evolutionary biology. “They’re so dependent on moisture. If it’s hot and dry, it really hammers them harder than it does more mobile animals.”
Human impacts also include land use and development, pollution, the introduction of invasive species such as crayfish, and increased wildfire frequency. Because amphibians are highly susceptible to environmental changes — and depend on land and aquatic habitats — they are seen in conservation as harbingers for what could happen with other species, Bucciarelli said.
So what can be done? The answer isn’t entirely clear. The areas newts depend on could be better monitored and protected. But conservation efforts may be only a stopgap solution while the world attempts to slow and mitigate the effects of climate change.
It can get personal when you look a newt in the eye, even for professionals who spend their careers studying wildlife.
“This is a biological equivalent of seeing Antarctic glaciers melting,” Shaffer said. “When you actually see that happen in your face, it’s really striking.”
“I think we’re getting past the point where we can say, ‘Mother nature can take care of herself,’” Shaffer added. “We’re going to have to be much more proactive. The most obvious action is assisted migration — moving animals that aren’t good at migrating to more favorable environments. But it’s hard to know what the appropriate interventions would even be. From a moral or ethical perspective, we’d like to be doing more than just watching them go down.”
Shaffer maintained that hope remains in such stopgap measures. Things may get worse, but they may get better. People’s behavior could change, and climate change might veer in a new direction. Assisting species in getting over the hump may prove a critical part of the healing process.
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