A pair of studies by researchers at UCSB’s National Center for Ecological Analysis and Synthesis have identified amphibians and tiny water fleas as good bellwethers for predicting the ecological consequences of environmental change.

The studies appeared in recent issues of the Proceedings of the National Academy of Sciences and the science journal Nature.

“Our study supports the role of amphibians as ‘canaries in the coal mine,’” said Lauren Buckley, a postdoctoral fellow at NCEAS and the first author of the study. “Amphibians are likely to be the first to respond to environmental changes and their responses can forecast how other species will respond.”

With their moist, permeable skin, amphibians are very sensitive to changes in their specific environments.

Buckley and Walter Jetz, an associate professor of biology at UC San Diego and the study’s other co-author, used maps of the environment and of amphibian and bird distributions to answer the question of how the environment — as well as the distribution of birds and amphibians — changes as one moves from place to place around the globe.

They found that if the environment changes rapidly from one location to another, the amphibian and bird communities also change rapidly. However, the species of amphibians would change more quickly than those of birds. This confirms that amphibians are particularly sensitive to changes in the environment, the researchers concluded, and that this sensitivity is particularly acute given their narrow distributions.

“Understanding how environmental changes over space influence biodiversity patterns provides important background for forecasting how biodiversity will respond to environmental changes over time, such as ongoing temperature increases,” said Buckley.

Meanwhile, a study of populations of tiny water fleas is helping ecologists understand population dynamics, which may lead to predictions about the ecological consequences of environmental change. The water flea, called Daphnia, plays a key role in the food web of many lakes.

Roger Nisbet, an ecologist at UCSB and co-author of the study, explained that a few animal populations, notably some insects, show huge “boom and bust” cycles. The populations alternate between periods of explosive growth when food is plentiful, and crashes when food is replaced too slowly to support the resulting large population.

This behavior is well understood by ecologists, and has been described by many simple mathematical models. However, most animal populations don’t behave in this extreme way. “A key question is why,” said Nisbet.

Edward McCauley, the study’s first author and an ecologist at the University of Calgary, studied the performance of individual water fleas within lab populations and found that some executed boom and bust cycles while others did not. This second group of populations exhibited what the investigators called “small amplitude” cycles.

Using a mathematical theory they developed several years ago, Nisbet and his collaborators had predicted that in the small amplitude cycles, individual animals would take much longer to develop to reproductive maturity. This was confirmed by McCauley’s experiments.

“More broadly, the work illustrates that ecologists at UCSB and elsewhere are getting a deeper understanding of how the physiological response of organisms to a changing environment is eventually expressed as population change,” said Nisbet.