[Ocean sounds]
[Narrator]: Earth’s oceans are home to a symphony of aquatic life:
From gargantuan whales
to tiny shrimp and coral habitats.
Mixed in with the calls of creatures is the music of Earth itself:
from earthquakes
[sound of 2004 Sumatra earthquake]
to the patter of rain on the surface.
A new study assessed how these sonic sources have fared—
and often faltered—
in response to another, more recent phenomenon:
[foghorn sound]
the sounds of human civilization.
Compared to other human threats to marine ecosystems,
such as oil spills, trash, and overfishing,
sound pollution has taken a backseat in regulatory debates.
Many scientists—from oceanographers to marine biologists to ecologists—
have uncovered the dangers that human noise poses to the world’s oceans.
[sound of navy sonar]
But, to date,
their observations haven’t led to concrete policy efforts.
The new review in Science dredged up data
on ocean life and sound collected from isolated disciplines,
hoping to quantify the impacts of human activity on ocean soundscapes.
The authors divided ocean sounds into three sources:
biological, geological, and human—or biophony, geophony, and anthrophony.
Under biophony fell an array of sounds produced by sea animals:
The crackling of crustaceans foraging for food.
The trills of seals as they breed in the Arctic during spring.
The clicks and whistles of dolphins communicating with their pod.
Geophony consisted of mother nature’s ceaseless songs:
hurricanes, deep-sea faults, and polar ice cracking.
At the crux of the research was anthrophony:
the drumbeat of industrialized society.
Global shipping is a huge contributor:
it has increased its low-frequency ocean noise by 32 times.
[foghorn sound]
Offshore drilling has a large, chronic impact.
And fishing, by removing animals core to ecosystems,
has quieted habitats.
The authors found clear evidence
that the barrage of human-made sound affects ocean life.
438 papers
showed human sounds have a negative effect on marine animals.
The evidence was strongest for mammals, fish, and invertebrates.
The researchers also fear climate change has harmful effects on ocean soundscapes.
The Great Barrier Reef has declined significantly in recent decades, becoming far quieter.
Coral reefs are known to play key roles in species settling, reproducing, and hunting.
Animals that depend on reefs’ habitat noise
to breed and forage
could struggle to adapt to such drastic change.
The authors see reason for hope
that mitigation efforts could make a difference.
A recent study conducted near the Port of Vancouver—
where shipping traffic decreased by 21-percent during the COVID-19 pandemic—
showed an average 1.5 decibel decrease in nearby waterways.
And changes to ship machinery have proven effective
at increasing fuel efficiency while reducing noise.
[various ocean sounds]
The researchers are amassing a library of ocean sounds,
which they plan to analyze and diagnose
with the help of machine learning.
Coupling this with the review’s findings,
the researchers believe they can demand the attention of policymakers
and bring ocean soundscapes into the global spotlight.
[various ocean sounds]