Rice Krispies? Rain hitting a tin roof? Bacon frying? How about
noisy creatures known as snapping shrimp.
Warm temperate and tropical coastal waters around the world are
teeming with these noisy little creatures. They snap their claws
so fast that they produce a bubble. When the bubble bursts, it
makes a loud popping sound.
"It's this sort of persistent background noise, these snapping
shrimp kind of crackling."
Aran Mooney, a marine biologist at Woods Hole Oceanographic Institution.
The shrimp produce the loud sound to stun prey. So how would this
persistent background noise be affected by oceans getting warmer
in coming years. To find out, Mooney and his colleague Ashlee Lillis
analyzed audio recordings of the critters in their natural environment.
They also performed lab experiments with snapping shrimp collected
from the wild, in water of varying temperatures. And they found
that when water heats up, the shrimp start snapping more-and the
water's soundscape gets louder. They shared their findings in February
at the Ocean Sciences Meeting 2020 in San Diego.
The researchers aren't sure what's causing this change in shrimp
behavior-but they have an idea. "We don't precisely know the mechanism
of why they're snapping more often. What we think is that these guys
are basically just ectothermic animals. So that means they're directly
responding to environmental conditions around them...so basically
as you increase the water temperature, it increases their metabolic
rate-they get more metabolically active, so they are able or trying
to snap more."
If these shrimp do make the ocean noisier as the climate warms, both
marine creatures and humans could face new problems. Many ocean animals
use sound to communicate. And both the Navy and fishermen rely on
marine acoustics to do their work.
"You know, we never really thought about how that ocean background
noise or its own fog is sort of naturally increasing, in what we think
is temperature driven or climate change driven...so as you raise those
levels, it gets harder to 'see' through that acoustic fog."