Study Shines Light on Noise and Whale Songs

For decades, humans have been enchanted with the songs of the humpback whale. First recorded in the 1960s, these songs have long captured our imagination and were even central to mobilizing support for the ‘Save the Whales’ Movement throughout the ‘60s and ‘70s.

Despite our fascination with humpback’s and their songs, however, there remain many unanswered questions as to why these whales are so musically inclined.

New research from scientists at Woods Hole Oceanographic Institute has provided some fresh insight into the world of whale songs. In a paper published this month in the journal Biology Letters, Aran Mooney and his team researched two components of whale songs: sound waves and particle velocity.

Unlike sound waves (the force that vibrates your ear drums), particle velocity (the physical vibration of a substance as sound moves through it) has yet to be studied thoroughly and is not fully understood. While researching off the coast of Maui, Mooney’s team discovered that particle velocity produced by whale songs—originally thought to travel a few meters at most—might travel much farther than originally thought.

Mooney found that they could measure vibrations from 200 meters away, but suspects that they could be felt as far as one kilometer away.

Humpback Whales Live in an Ocean of Increasing Noise

Previous research has shown that humpback whales could be potentially sensitive to particle vibrations in the water column. Unlike many marine mammals, humpbacks’ ear bones are fused to their skulls, which could allow for their jaws to act as giant, mammalian tuning forks, picking up particle velocity produced by other humpbacks, and potentially humans.

The humpback whale’s hearing evolved over millions of years in an ocean environment wholly different from the one we are now witnessing.

Today, a host of altogether new and alien sounds ring throughout the ocean. Offshore oil and gas explorations use literally earth-shaking blasts fired from airguns dragged along the surface. The blasts are powerful enough to penetrate the planet’s crust and bounce back to the surface, releasing the signatures of pockets of hydrocarbons from deep within the rock.

You need not be exploring for oil and gas to be adding to the sonic landscape of the oceans, however. According to Jesse Ausubel, the director of the Human Environment program at the Rockefeller University, “A cargo ship is basically a large rock concert passing by.”

And humpback whales don’t seem to show any affinity for this human-made noise. There is evidence to suggest that humpbacks respond negatively to anthropogenic sound, often ending their songs or even changing their songs’ frequencies in order to be heard over the unending and ever-increasing industrial drone.

With new shipping, mining, and construction ventures happening all the time, and ocean noise doubling every two decades, Mooney and his team’s findings could spell more problems for humpback whales. Most human-made noise in the ocean is low frequency, which contributes to low frequency particle motion. From Mooney’s research, it seems humpbacks could be especially sensitive to this noise. While we humans may not be able to hear well underwater, these sounds could come as relevant communication signals for humpbacks and other marine mammals.

A Call for Ocean Planning

Looking forward, a growing understanding of humpbacks, their songs, and their hearing capacity will continue to inform how we interact with these mammals, but also how we should protect them.

Though Mooney’s study took place off the coast of Maui, it has many implications for our dealings with humpback whales here in New England. Every year, humpbacks migrate mammoth distances, passing through our coastal waters in the spring and fall months, as they move between their tropical breeding grounds and their polar feeding grounds.

For us to be informed and prepared enough to accommodate these whales, it will be essential to look toward ocean planning and its potential for informing our relationship to the ocean. One component of the Northeast Ocean Plan is its data portal, which will include data and findings about marine mammals that’s accessible to everyone, and will be especially key for those in decision-making roles.

In New England, ocean planning continues to be of utmost importance and we hope decision makers will continue to rely on it in order to protect humpbacks and other marine animals traveling along our shores. The recent submission of the Northeast Ocean Plan marked a serious step forward in how we relate to our ocean resources and it will certainly prove invaluable as we look to protect our neighborhood humpbacks.

 

Threats to Marine Life from Ocean Acidification

As climate change moves to the forefront of our agenda, we are getting more concerned about what effect the increasing levels of carbon in the atmosphere are having on the planet’s biggest carbon sink; the ocean.

Atmospheric carbon dioxide is rising to levels unprecedented in modern geological history, and as a result our ocean is experiencing changes to its chemistry that may significantly alter habitats and affect marine organisms. Collectively, these changes are referred to as ocean acidification, or a lowering of global ocean water pH due to the absorption of excess carbon dioxide. Scientists have only begun to investigate this process, but it is likely to have a profound impact on New England waters and the species that coastal communities rely upon.

Ocean acidification is a relatively new term for most of us, as a large percentage of the research on this subject has been conducted within the past decade. Scientists have identified a number of changes that occur when CO₂ is dissolved in water. The primary outcomes include an increase in the concentration of hydrogen ions, lowering pH and ‘acidifying’ ocean waters, and the consumption of carbonate, an important component for shell-building organisms. These changes could place stress on marine-dwellers, particularly the critters that require carbonate, like oysters, mussels, clams, and corals, to build their shells or skeletons.

But the ocean is huge! How do we know that these changes are occurring on a scale large enough to affect global ocean chemistry? Scientists have information about past atmospheric and oceanic conditions from clues in the geological record. They can compare these records to projections about how much carbon is likely to be in our atmosphere- and subsequently our oceans- in 20, 50 or even 100 years. The ocean’s pH has dropped from 8.2 to 8.1 since the Industrial era- that’s a 30% increase in acidity– and is projected to fall another 0.3-0.5 units by 2100. Researchers claim that this drop in pH is unlike anything the ocean has undergone in the last 300 million years!

One recent study has shown that the waters of the Gulf of Maine are particularly susceptible to acidification due to already low pH and carbonate levels relative to other regions along the Atlantic coast. This means that we New Englanders could end up with a front row seat to the impacts of ocean acidification!

What does this mean for ocean-dwelling animals? It’s impossible to know how every species will react to changes in ocean chemistry. Some studies have shown that rapid changes in water chemistry can place heightened stress on shellfish, affecting growth, development rates, and even survival. Another study has shown that acidified waters impair organ development in our already-depleted Atlantic cod. “Adapt or die!” –says Darwin, but these human-made changes may be happening too fast for nature to keep up.

The ocean is so important to us, and it’s difficult to imagine how these changes might affect our daily lives. Many fish and shellfish species are critical to our economy, and are relied upon as integral parts of people’s livelihoods. Seafood lovers can’t deny the importance of the ocean as a food source. Beyond our stomachs, the ocean also appeals to our emotions. CLF’s Keren Bitan recently discussed how learning about sea critters can foster a strong personal connection to the ocean and its ecosystems. And anyone who’s explored the tiny world of a tidal pool, or taken a morning walk on a sandy beach, can appreciate the beauty and complexity of the ocean and its habitats. These connections are often what compel us to realize just how important it is that we continue to protect ocean habitat and do what we can to prevent climate change from taking its toll on the world’s oceans.

We have explored less than 5% of our ocean, and yet we may be changing it in ways we are only beginning to understand. We will continue to work to protect the ocean’s resources, animals and habitats, even as the uncertain effects of climate change become apparent.

Ellie Milano is a current Masters student at Tufts University studying Conservation Medicine, an innovative program that seeks solutions to global environmental and health issues. Her thesis work focuses on public opinion of global climate change, and understanding how extreme weather events affect attitudes toward climate change. She is a recent graduate of Hobart and William Smith Colleges in Geneva, NY, where she double majored in Biology and Environmental Studies. During college, she spent two summers at Cornell University studying aquatic ecology. She grew up in the Berkshires of Massachusetts, and her interests include horseback riding, recreational hiking and rock climbing. 

Now is the Time to be Part of Ocean Planning in New England!

Amazing wildlife like this feeding humpback whale, gorgeous scenery, a natural playground to enjoy with our children – there are so many reasons to appreciate New England’s ocean. But there is also an unprecedented amount of change in the ocean right now: renewable energy has hit the water, our fisheries are in tremendous flux and some of our most iconic and economically important stocks are in true peril, our waters are rapidly warming and getting more acidic, and we are seeing accelerating coastal erosion in some of our most heavily developed shorelines.

 

The consequences of coastal erosion in New England are likely to be sever in the coming decades, as seen on the coast of Plymouth, MA. Photo by David L. Ryan of the Boston Globe.
The consequences of coastal erosion in New England are likely to be sever in the coming decades, as seen on the coast of Plymouth, MA. Photo by David L. Ryan of the Boston Globe.

 

NOW is the time for you to be part of the planning process that is taking place to better coordinate our coastal and ocean uses in the face of all these changes. Everyone who cares about the ocean and how we use it should have a voice in the planning – a “seat at the table.”

 

 

Ralf Meyer, Green Fire Productions Creative Director, on location in Boston Harbor. Photo by Green Fire Productions.
Ralf Meyer, Green Fire Productions Creative Director, on location filming Ocean Frontiers in Boston Harbor. Photo by Green Fire Productions.

 

How can you get involved?

Learn about ocean planning! There is a fantastic new film called Ocean Frontiers that tells stories about ocean planning from people and places that might surprise you: farmers in Iowa, shipping companies in New England, and fishermen in Oregon – all committed to planning and doing things better for ocean health. Find an Ocean Frontiers screening near you, or host your own!

Be part of the process! We are in the throes of a first-in-the-nation regional ocean planning process, and we need you to get involved! The Northeast Regional Planning Body is holding a series of public meetings throughout New England to tell people what’s going on in ocean planning and to find out what your questions and comments are. This process is so much more effective and meaningful when people who care about the management of our ocean and coasts get involved.

Stay Informed! We will keep bringing you stories about ocean planning here and at CLF.org. Check out the New England Ocean Action Network  to stay up on the latest planning news. NEOAN is a network of diverse groups – fishermen, surfers, aquariums, conservationists, renewable energy developers, and others – who all support the ocean planning process in New England.

Does New England’s ocean inspire you, comfort you, or leave you awestruck? If you care about the ocean, then make your connection with the sea part of our new ocean planning story.

The Sounds of Stellwagen Bank

As we celebrate the 20th anniversary of Stellwagen Bank National Marine Sanctuary, some of the scientists and experts there are introducing us to the fascinating research and activities they are involved with. Here Leila Hatch, the Sanctuary’s Marine Ecologist, talks about her research on underwater sound in Stellwagen Bank. – Ed.

More than 2,000 years ago Aristotle told us that he was listening underwater. Leonardo Da Vinci followed up during the 1400s with the knowledge that ships could be heard underwater from far away. In the 1900s, some of the earliest applications of that knowledge were dedicated to navigation purposes in Boston Harbor. We have been able to record underwater sounds for decades. And yet, even today, we cannot identify all of the sounds recorded in Massachusetts Bay, despite knowing that some of them are biological in origin.

As a marine ecologist at Stellwagen Bank National Marine Sanctuary I specialize in the underwater acoustic habitat of this federally designated protected area at the mouth of Massachusetts Bay. I work with a team of collaborators from NOAA, universities and companies. We monitor the sound field of the sanctuary in order to better understand contributions made to it by a variety of marine animals, natural processes, and by humans.

Sound, and particularly low frequency or “low keys on the piano” sound, is transmitted extremely efficiently underwater. For this reason, animals rely on their hearing underwater as a primary means for interacting with their environment and with each other. Light degrades quickly underwater, but not sound. Some sounds can travel without losing significant energy for tens of thousands of kilometers, and, under some conditions, from pole to pole. During the course of two World Wars and beyond, humans invested large amounts of time and money to develop systems that attempted to match the abilities of marine mammals. Some products closely resemble the animals’ natural capabilities, such as long distance ship to ship communication and detection of objects of interest over large distances.

Like many other species, we want to be able to navigate the ocean or locate areas of high prey abundance. In addition to these purposeful uses of sounds, many of the sounds we make in the ocean are incidental by-products. The construction of offshore platforms and the laying of pipelines produce loud sounds. We also move more than 98% of all retail products by ship. And we are moving more and more of those products every day. Ship propellers create bubbles that produce sounds when they cavitate or burst. The low frequency sounds from large container ships and tankers travel far and wide and add to an increasing hum in the world’s oceans. This growing background noise is highest in the same frequencies used for communication by many marine species, including some of our most endangered baleen whales.

There are some places in the world that are particularly important to both baleen whales and human commerce. Stellwagen Bank National Marine Sanctuary is one of those places. Several baleen whale populations, all of which are vocally active, use these waters to feed and nurse their young every year. But the sanctuary is also bisected by the Boston Traffic Separation Scheme—the in and outbound lanes of commercial shipping to the Port of Boston. In addition, this ocean-going traffic is supplemented by active tug-tow and barge transits, fishing and whale-watching trips, recreational boating excursions, research cruises and more. It’s a busy place.

Since 2006, sanctuary researchers have been working with our partners at NOAA’s Northeast Fisheries Science Center, Cornell University’s Bioacoustics Research Program, and Marine Acoustics, Inc. to develop methods to characterize the contributions of vessels to the sanctuary’s sound field and further determine how these noises are influencing the “acoustic habitats” of baleen whales. From this work we can begin to understand how shipping noise impacts whales’ ability to communicate with each other. In particular, we can estimate the loss of communication opportunities for calling whales as shipping traffic and noise increases over time.

Many questions still remain, including how these lost opportunities to communicate affect the longevity of these species. Baleen whales evolved to exploit a very particular niche. These largest of animals eat some of the smallest of prey, so their ability to survive is based on finding and gorging on huge amounts of that small stuff. As patches of high quality food become less predictable or move due to climate change, whales’ communication systems become all the more imperative. If those systems are compromised, we can assume consequences. But much more science is needed from places like Stellwagen Bank sanctuary to fill in these answers.

Photo above: Whales and ships share space in Stellwagen Bank
National Marine Sanctuary.  SBNMS file photo by WCNE.  Photo
taken under NOAA permit #981-1707.