The Sound of One Shrimp Snapping


Spring in Sugarloaf Ridge State Park, in Northern California, is typically a natural symphony. Streams whoosh, swollen with winter rains, and birds — robins, sparrows, grosbeaks, woodpeckers and hawkstrill and chatter.

But in 2011, a yearslong drought set in. By spring 2015, a local creek had dried up and the valley had gone quiet. “The park went from an extremely vibrant habitat to one that was dead silent,” said Bernie Krause, a soundscape ecologist who has been recording in the park since 1993. “Nothing was singing, nothing was chirping, nothing was moving. It’s like it was dead.”

In the coming years, severe droughts are likely to become more common; as the water dries up, bird song could disappear along with it. It is just one example of how climate change may be altering the planet’s soundscapes, or “breaking Earth’s beat,” as Dr. Krause and his colleagues put it in a paper last year. Dr. Krause, who has amassed more than 5,000 hours of natural recordings for his company, Wild Sanctuary, wrote the paper with Jérôme Sueur, an ecoacoustician at the French National Museum of Natural History in Paris, and Almo Farina, an ecologist at the University of Urbino in Italy.

Climate change will silence some species and nudge others into new habits and habitats, changing when and where they sing, squeak, whistle, bellow or bleat. (In New York, several species of frogs now begin croaking nearly two weeks earlier in the spring than they did a century ago.) It will also alter the sounds that animals produce, as well as how such vocalizations travel.

These shifts could make it more difficult for wild creatures to attract mates, avoid predators and stay oriented, as well as force them to expend more energy to make themselves heard. They are also an audible symptom of ecosystems that are unwell Dr. Krause said: “When a habitat is under stress, or it’s been transformed by human endeavor in some manner and it’s not healthy, it shows in its voice.”

Here are five ways that the changing climate may modify animals’ acoustic behavior and remix the planet’s natural soundtracks

In the mid-1980s, Peter Narins, a neuroethologist at the University of California, Los Angeles, observed that the coqui frogs living in Puerto Rico’s Luquillo Mountains were different according to altitude. The farther up the mountain he traveled, the cooler the air became and the bigger the frogs grew. And the calls of the male frogs, which use a two-note chirp to defend territory and attract mates, varied accordingly.

“The calls of the little guys at the bottom of the mountain were high-pitched, rapid calls, kind of squeaky little calls,” Dr. Narins said. “And as you went up the mountain, they became lower and lower pitched, and they became longer and longer, and they produced them slower and slower.”

The lower pH doesn’t seem to damage the shrimp physically; rather, it simply alters their behavior, perhaps by acting directly on their nervous systems. “It’s not that ocean acidification completely takes away their ability to make loud snaps,” said Ivan Nagelkerken, a marine biologist who led the study. “They can still do that but essentially don’t want to do that any more.”

Ocean acidification is also likely to damage many of the shrimp’s habitats, including coral reefs and kelp forests, and could thus reduce their numbers, resulting in a further drop in sound. Many marine organisms, especially fish larvae, rely on the sound of snapping shrimp to navigate to suitable habitats; if the shrimp go silent, they could have trouble finding their way.



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