put this in some kind of human frame of reference: Imagine a crowded
bar and a bad rock band so loud you can’t make a pass at the girl on
the bar stool next to you. Doug Nowacek, a marine ecology and
bioacoustics expert at the Duke University Marine Laboratory in
Beaufort, is pretty sure that’s what whales and other sea creatures
that rely on sound to communicate or navigate are faced with when
high-decibel sound waves are used in the ocean to test for oil and
Nowacek and other experts said in a recently published paper, that the
sounds from seismic guns can “mask” the sounds that whales and other
creatures in the water rely upon to navigate, find food and avoid
predators. And research increasingly indicates that’s not just a
short-term problem; long-term exposure – and seismic testing can go on
for months, 24 hours a day, seven days a week – can cause severe stress
about living beside a jackhammer that doesn’t stop hammering. What
would you do? Move? And what if that jackhammer is in the area where
your main food supply is located, or in the hospital room where you’ve
gone to give birth?
of this, Nowacek and the other authors say in the paper points to the
need to monitor and control seismic testing like other kinds of
pollution. Joining Nowacek are scientists from Cornell University; Humu
Labs, a Massachusetts-based company that sells computer platforms for
researchers; the University of St. Andrews; the Wildlife Conservation
Society; the Natural Resources Defense Council; the University of
California at Santa Cruz; and Southall Environmental Associates.
in the September issue of "Frontiers in Ecology and the Environment,"
the paper says that the need for worldwide monitoring and controls
is becoming more obvious because we’re opening up new waters – the
Atlantic, for example, and the Arctic, where sea ice is rapidly melting
– not only to seismic testing, but also to noisy shipping.
In a nutshell, the paper states that:
- Marine seismic surveys produce intense sound impulses to explore the ocean floor for energy sources and for research purposes;
reviews of seismic surveys are seldom undertaken at scales necessary to
meaningfully assess, mitigate and monitor their impacts;
- Managing exposure of marine animals to these sounds requires additional attention and data;
exposure threshold criteria fail to account for the best available
science and the cumulative effects of simultaneous seismic surveys and
prolonged, repeated exposures;
marine seismic surveys, especially in ecologically sensitive areas,
require multi-institutional and international collaboration to
effectively manage risks; and
noise should be addressed by revising an existing treaty on ocean
pollution or negotiating a new one that more comprehensively evaluates
the associated risks, benefits and procedures.
key problem, Nowacek said in a recent interview, is the arbitrary
decibel level the federal government uses to assess the likelihood of a
sound or sounds harming marine mammals.
say 160 is harmful but 159 is not,” he said. “And each decibel is a
magnitude of 10. We know that the bowhead whale, a cousin of the
(endangered) right whale starts responding at 95 decibels.”
whales pass through the area where there is likely to be seismic
testing off the Carolinas, Nowacek said, and they do so after giving
birth in waters of Georgia and Florida. The mother and the young stay
close together in the calving grounds, but not much is known about how
close they stay together as they move north. But if they are far enough
apart, and their communications are made impossible by seismic or other
noise, Nowacek said, the calves’ chances of survival “are low,” like
the chances of any nursing mammal separated from its mother.
the chance of that happening? “Is it 50 percent? More?” Nowacek asked
rhetorically. “Maybe, maybe not. But we don’t know.”
point, he said, is that all the experts know for sure that decibel
levels at 160 or above can be and likely is harmful, but not so much is
known about the impacts of exposure of lower decibel levels, especially
over an extended time period. The 160-decibel threshold has been traced
back to 1999, Nowacek added, and while there’s no doubt it was an
attempt to find a reasonable number at the time, it’s 16-year-old
science, at best.
He cited effects on other mammals at decibel levels below 160:
- Harbor porpoise feeding buzzes decreased 15 percent with exposure to seismic air guns at 130–165 decibels.
- Blue whale call rates increase with exposure to seismic “sparkers” at 140 decibels.
whale call rates decrease and migratory disruption occurs when exposed
to seismic air gun surveys at 175 to 285 kilometers distance at noise
levels below shipping noise.
- Seismic survey activity disrupts the breeding display, or singing, of humpback whales.
- Blue whales ceased calling upon exposure to air gun signals of 143 decibels.
with at least five companies seeking seismic permits for waters off
North Carolina, it’s almost certain that testing would go on 24 hours a
day, seven days a week, for months. Further, Nowacek said, the area
thought to be the most popular spot for testing, and the most likely
spot for drilling off North Carolina – east of Cape Hatteras – is also
one of the largest gathering points in the world for marine mammals,
sea turtles and birds.
of us (authors of the paper) are Chicken Littles, running around saying
the sky is falling,” Nowacek said of himself and his co-authors.
Rather, they’re saying that lower decibel levels likely have impacts
that at least result in “harassment” of the mammals, and harassment at
the very least is potentially harmful.
practical terms, what this would mean, according to Nowacek, is that
the impact circles – the size of the zone around the seismic ships in
which impacts are likely, would be larger at a lower decibel level. And
that means more mammals would likely be within those circles at any
the very least, the paper states, “An integrated program for
monitoring, mitigating, and reporting would facilitate development of a
knowledge-based understanding of potential risks and solutions; the
establishment of such a program would necessitate coordination and
prudent planning. Efforts to monitor the undersea acoustic environment
and manage the impacts of noise generated by human activities have
reached a critical juncture.”
European Union, the paper notes, recognizes ocean noise as an indicator
of environmental quality and is in the process of developing targets
for achieving “good environmental activities.”
and other marine mammal experts, including fellow Duke researcher Andy
Read, included some of the concerns expressed in the paper in their
official comments to the National Marine Fisheries Service, which is
evaluating the seismic companies’ applications for permits. In
particular, they stressed the need for NMFS to consider cumulative
And in the paper, Nowacek and his co-authors recommended a framework that in the future would make such considerations the norm.
the transboundary scale and numerous sources of anthropogenic sound in
the world’s oceans – including noise from marine seismic surveys, which
are ubiquitous and increasing in abundance – we believe that a
responsible path forward should focus on the creation of legally
binding international commitments,” they wrote. Successful precedents
mostly involve international protocols and conventions for air
pollution and or pollution from ships, they wrote, but “various
international authorities, such as the convention on Biological
Diversity and Convention on Migratory Species, now classify ocean noise
as a pollutant.”
for now, he said, President Obama and the U.S. Secretary of the
Interior, Sally Jewell, have the authority to remove specific areas
from the list of waters whether seismic testing and oil and gas
production are allowed, and did so in Alaska, in 2014.
administration removed more than 52,000 square miles of Bristol Bay and
nearby waters – an area roughly the size of Florida – that the
president called one of the country’s great natural resources,
“something that’s too precious for us to be putting out to the highest
article is provided by Coastal Review Online, an online news service
covering North Carolina's coast. For more news, features, and
information about the coast, go to www.coastalreview.org.)