Human activity is causing mammals to avoid daylight and seek the protection of darkness, reports a new study led by College of Natural Resources scientists. The study, published in June in Science and supported in part by the National Science Foundation, represents the first effort to quantify the global effects of humans on the daily patterns of wildlife. It sheds light on the process by which animals are altering their behaviors in reaction to human disturbance.

“Catastrophic losses in wildlife populations and habitats as a result of human activity are well documented,” said environmental science, policy, and management (ESPM) PhD candidate and study lead author Kaitlyn Gaynor, “but the subtler ways in which we affect animal behavior are more difficult to detect and quantify.”

Gaynor and her co-authors—including ESPM professor Justin Brashares and alumna Cheryl Hojnowski, PhD ’17 ESPM—used data for 62 species across six continents to look for global shifts in the timing of mammals’ daily activity in response to humans.

Data collection involved such approaches as remotely triggered cameras, GPS and radio collars, and direct observation. For each species in a study site, the authors quantified the difference in nocturnality under conditions of low and high human disturbance.

“While we expected to find a trend toward increased wildlife nocturnality around people, we were surprised by the consistency of the results around the world,” Gaynor said. “Animals responded strongly to all types of human disturbance, regardless of whether people actually posed a direct threat, suggesting that our presence alone is enough to disrupt their natural patterns of behavior.”

— Mackenzie Smith

A study published in Global Change Biology in April demonstrates that hydropower—a critical energy source for humans worldwide—introduces artificial flow patterns into rivers, negatively affecting invertebrate biodiversity downstream. The study’s lead author, Albert Ruhi, joined the Department of Environmental Science, Policy, and Management as an assistant professor in January.

Aquatic invertebrates are very diverse in running waters and perform key roles: Many convert algae or detritus into living animal biomass, funneling energy into and out of river habitats. Each species has a different suite of roles, and maintaining that diversity is key to a river ecosystem’s healthy functioning.

Using time-series methods like wavelets, Ruhi and his collaborators found that flow-regime alterations caused by hydropower dams often corresponded to the industrial workweek, resulting in hydropeaking (sudden releases of water to support peak power demand) Monday through Friday. This artificial schedule had varying effects on invertebrates. While 3 groups did well under this regime of periodic pulses, 16 were negatively affected—causing a net decrease in functional diversity.

Ruhi and his colleagues analyzed 11 years’ worth of data on invertebrates and combined it with river-discharge data that the U.S. Geological Survey has been recording since 1942. They focused their study on the Chattahoochee River, below Lake Lanier in northern Georgia, then showed that the “workweek effect” is widespread across the American Southeast.

The researchers were further able to project that the risk of observing functional-diversity losses within the next four years would decrease by an average of 17 percent if hydropeaking were lessened.

“We must work to better mitigate the ecological impacts of flow management for hydropower,” Ruhi said. “Understanding how freshwater biodiversity responds to different facets of streamflow alteration may be a first step toward operating dams in a greener way.”

— Kirsten Mickelwait

In a July article published in Nature Sustainability, two Energy and Resources Group (ERG) researchers identified the global risks of the planet’s increasing reliance on bottled water. The rapid growth of the market for bottled water and its normalization as daily drinking water cannot guarantee universal access, argued Isha Ray, an ERG associate professor, and Alasdair  Cohen, PhD ’16 Environmental Science, Policy, and Management (ESPM), a postdoctoral researcher. Instead, the most viable means of achieving universal safe water access continues to be sustained investment in centralized and community utilities.

While economically developed countries have reached near-universal access to drinking water through publicly owned or regulated water utilities, in most low- and middle-income countries (LMICs), the adoption of safe piped water has been slow. Bottled water is now the fastest-growing form of access to purportedly safe drinking water in LMICs.

Of the top 10 bottled-water-consuming nations over the past decade, 6 have been LMICs (Brazil, China, India, Indonesia, Mexico, and Thailand). The latter countries’ consumption of bottled water increased by 174 percent during that period, compared with a 26 percent increase for the high-income countries in the group.

Primarily using bottled water has negative implications across social, economic, health, and environmental lines. “In the short to medium term,” the authors note, “LMIC governments should evaluate non-tap options that could expand safe water access.”

Community-scale kiosk models, in which disinfected municipal water is delivered at low or no cost in reusable 19-liter bottles, are more sustainable and affordable than commercially sold bottled water.

“If governments and development agencies allow the bottled water sector to continue meeting the rising demand for safe water, then access will continue to grow, but it will likely not be reliably safe or universally affordable,” Ray said.

— Kirsten Mickelwait