NOAA's Response and Restoration Blog

An inside look at the science of cleaning up and fixing the mess of marine pollution


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Sea Grant Reports: Dolphins, Sea Turtles and the Impacts from Deepwater Horizon

photo of a bottlenose dolphin calf. Image credit: NOAA.

A bottlenose dolphin calf in the Gulf of Mexico. Image credit: NOAA

Two popular marine animals—dolphins and sea turtles—are the focus of new publications from the Sea Grant Oil Spill Science Outreach Team. In the aftermath of the largest oil spill in history, many expressed concern about its impact on these long-lived, slow-to-mature creatures. Now, almost seven years after the spill, scientists have a better understanding of how they fared. The team examined this research, synthesizing peer-reviewed findings into two easy-to-understand outreach bulletins.

Starting in 2010 a month before the Macondo blowout, scientists documented more than 1,000 stranded dolphins and whales along the northern Gulf of Mexico. From 2010 until 2014, they examined the health and stranding patterns of dolphins along the coasts of Louisiana, Mississippi, Alabama, and Florida, discovering that oiled areas had more sick and dead dolphins.

Scientists also found many sick and stranded pre-term and newborn dolphins. Overall, young dolphins in the study area were eight times more likely to have pneumonia or inflamed lungs and 18 times more likely to show signs of fetal distress than those from areas outside the Gulf. The Deepwater Horizon’s impact on bottlenose dolphins report examines all of the factors, including oil that scientists think contributed to dolphin populations’ drop in numbers during this time.

The Sea turtles and the Deepwater Horizon oil spill report details the impacts on threatened or endangered sea turtles species in the Gulf. In total, scientists estimate that the oil spill and related response activities killed between 95,000 and 200,000 sea turtles. Lasting impacts of these losses may take time to become clear. For example, scientists do not fully understand how oil exposure affects sea turtles’ ongoing reproductive abilities. They continue to monitor sea turtle populations by counting numbers of nests, hatchlings, and adult females on beaches.

Sea turtle in water. Image credit: Texas Sea Grant/Pam Plotkin

A healthy green sea turtle swims in the Gulf of Mexico. Image credit: Texas Sea Grant/Pam Plotkin

More articles about the impacts of Deepwater Horizon on marine mammals:

 

Tara Skelton is the Oil Spill Science Outreach Team Communicator for the Mississippi-Alabama Sea Grant Consortium. The Sea Grant Oil Spill Science Outreach Program is a joint project of the four Gulf of Mexico Sea Grant College Programs, with funding from partner Gulf of Mexico Research Initiative. The team’s mission is to collect and translate the latest peer-reviewed research for those who rely on a healthy Gulf for work or recreation. To learn more about the team’s products and presentations, visit gulfseagrant.org/oilspillscience.


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Hold on to Those Balloons: They Could End Up in the Ocean

Sea turtle being held.

Balloon debris can be harmful for wildlife, which may ingest or get entangled in it. Here, a sea turtle was found after ingesting balloon debris, likely mistaking it for food. (Photo Credit: Blair Witherington, Florida Fish and Wildlife Conservation Commission)

By NOAA Marine Debris Program

Balloons are a type of marine debris that many people don’t think about. Often used for celebrations or to commemorate special events, balloons are frequently intentionally or accidentally released into the environment. Unfortunately, once they go up, they must also come down; balloons released into the air don’t just go away, they either get snagged on something such as tree branches or electrical wires, deflate and make their way back down, or rise until they pop and fall back to Earth where they can create a lot of problems.

Balloon debris can be ingested by animals, many of which easily mistake it for real food, and can entangle wildlife, especially balloons with attached ribbons. Balloon debris can even have an economic impact on communities, contributing to dirty beaches which drive away tourists, or causing power outages from mylar balloons covered in metallic paint and their ribbons tangling in power lines.

Balloon debris is a national issue and unfortunately, the Mid-Atlantic is not immune. Over a period of five years (2010-2014), 4,916 pieces of balloon litter were found in Virginia by volunteers participating in the International Coastal Cleanup, with over 3,000 of those pieces found on ocean beaches. In 2014, 236 volunteers found over 900 balloons in the Chincoteague National Wildlife Refuge in Virginia in a three-hour period. Recent surveys of remote islands on Virginia’s Eastern Shore documented up to 40 balloons per mile of beach. These statistics suggest that this Mid-Atlantic area is appropriate to research the balloon debris issue and to create an education and outreach program that could then be used in other states. So the Virginia Coastal Zone Management Program, with funding support from the NOAA Marine Debris Program, is doing just that. They’re exploring the issue of intentionally-released balloons and targeting that behavior through a social marketing campaign.

Blue and white balloon on beach.

Balloons that are intentionally or accidentally released have to come down somewhere! Unfortunately, they often find their way into our waterways or ocean. (Photo Credit: Russ Lewis)

So what can you do to help reduce balloon debris in the Mid-Atlantic and throughout the country? Consider using alternate decorations at your next celebration such as paper streamers or fabric flags. Rather than giving your child a helium balloon on a string, fill it with air and attach it to a stick—they still get the feeling of it floating above their heads without the risk of losing it into the environment. Most importantly, don’t intentionally release balloons into the air. With increased awareness about the issue, we can all work to reduce this very preventable form of marine debris in the Mid-Atlantic and beyond.


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Effects of the Deepwater Horizon Oil Spill on Sea Turtles and Marine Mammals

 

Dolphins on water surface.

Studies showed dolphins were impacted by the Deepwater Horizon oil spill. (NOAA)

The 2010 Deepwater Horizon oil spill resulted in significant environmental harm over a large area of the Gulf of Mexico and adjacent shorelines, and affected numerous species including endangered and threatened sea turtles and protected marine mammals. These populations will require significant restoration efforts to offset impacts from the spill.

A special issue of Endangered Species Research published Jan. 31, 2017, features 20 scientific articles summarizing the impacts of the oil spill on marine mammals and sea turtles.

The scientific studies, conducted by National Oceanic and Atmospheric Administration authors and partners, document the unprecedented mortality rate and long-term environmental impacts of the oil’s exposure and presents a synthesis of more than five years’ worth of data collection, analysis, and interpretation. Findings from these research studies, in addition to other studies on other parts of the ecosystem, formed the basis of the natural resources damage assessment settlement with BP for up to $8.8 billion.

All of the data associated with the settlement is available publicly in the Data Integration Visualization Exploration and Reporting database, but the Endangered Species Research special issue is the first time this information on sea turtles and marine mammals has been compiled together in peer-reviewed scientific publications. Find out more about Deepwater Horizon here.

 

 


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How Do Oil Spills Affect Sea Turtles?

Head and upper body of Kemp's Ridley sea turtle coated in thick brown oil.

A Kemp’s Ridley sea turtle covered in oil from the Deepwater Horizon oil spill in the Gulf of Mexico. (NOAA)

Sea turtles: These beloved marine reptiles have been swimming the seas for millions of years. Yet, in less than a hundred years, threats from humans, such as accidentally catching turtles in fishing gear (“bycatch”), killing nesting turtles and their eggs, and destroying habitat, have caused sea turtle populations to plummet. In fact, all six species of sea turtles found in U.S. waters are listed as threatened or endangered under the U.S. Endangered Species Act.

As we’ve seen in the Gulf of Mexico in recent years, oil spills represent yet another danger for these air-breathing reptiles that rely on clean water and clean beaches. But how exactly do oil spills affect sea turtles? And what do people do during and after an oil spill to look out for the well-being of sea turtles?

Living the Ocean Life

From the oil itself to the spill response and cleanup activities, a major oil spill has the potential to have serious negative effects on sea turtles. Part of the reason for this is because sea turtles migrate long distances and inhabit so many different parts of the ocean environment at different stages of their lives.

Graphic showing the life cycle of sea turtles in the ocean: egg laying; hatchling dispersal; oceanic feeding: small juveniles in sargassum; feeding on the continental shelf: large juveniles and adults, mating and breeding migration; and internesting near beach.

The life cycle of a sea turtle spans multiple habitats across the ocean, from sandy beaches to the open ocean. (NOAA)

For starters, sea turtles hatch (and females later return as adults to lay eggs) on sandy beaches. Then, they head to the vast open ocean where the tiny young turtles drift, hide from predators, and grow among floating islands of seaweed called sargassum. Finally, as larger juveniles and adults, they swim to the shallower waters of the continental shelf and near shore, where they spend the majority of the rest of their lives.

If a large offshore spill releases oil into the open ocean, currents and winds can carry oil across all of the habitats where sea turtles are found—and into the potential path of sea turtles of every age—as it makes its way to shore.

Another reason sea turtles can be particularly vulnerable to ocean oil spills is simply because they breathe air. Even though sea turtles can hold their breath on dives for extended periods of time, they usually come to the surface to breathe several times an hour. Because most oils float, sea turtles can surface into large oil slicks over and over again.

The situation can be even worse for very young sea turtles living among floating sargassum patches, as these small turtles almost never leave the top few feet of water, increasing their exposure to a floating oil slick. Furthermore, ocean currents and winds often bring oil to the same oceanic convergence zones that bring sargassum and young sea turtles together.

Turtle Meets Oil, Inside and Out

So, we know the many places sea turtles can run into an oil spill, but how exactly do they encounter the oil during a spill?

Graphic showing how spilled oil in the ocean can affect sea turtles at all stages of life and across ocean habitats: Oil on the shoreline can contaminate nesting females, nests, and hatchlings; larger turtles can inhale oil vapors, ingest oil in prey or sediment, and become coated in oil at the surface; winds and currents create ocean fronts, bringing together oil, dispersants, and sargassum communities, causing prolonged floating oil exposure; juvenile turtles ingest oil, inhale vapors, and become fatally mired and overheated; prey items may also be killed by becoming stuck in heavy oil or by dissolved oil components; and sargassum fouled by oil and dispersants can sink, leaving sargassum-dependent animals without food and cover and vulnerable to predators. Dead sea turtles may sink.

The potential impacts of an oil spill on sea turtles are many and varied. For example, some impacts can result from sea turtles inhaling and ingesting oil, becoming covered in oil to the point of being unable to swim, or losing important habitat or food that is killed or contaminated by oil. (NOAA)

It likely starts when they raise their heads above the water’s surface to breathe. When sea turtles surface in a slick, they can inhale oil and its vapors into their lungs; gulp oil into their mouths, down their throats, and into their digestive tracts while feeding; and become coated in oil, to the point of becoming entirely mired and unable to swim. Similarly, sea turtles may swim through oil drifting in the water column or disturb it in the sediments on the ocean bottom.

Female sea turtles that ingest oil can even pass oil compounds on to their developing young, and once laid, the eggs can absorb oil components in the sand through the eggshell, potentially damaging the baby turtle developing inside. Nesting turtles and their hatchlings are also likely to crawl into oil on contaminated beaches.

Not the Picture of Health

Graphic showing how oil spill cleanup and response activities can negatively affect sea turtles: Cleaning oil from surface and subsurface shores with large machines deters nesting; booms and other barriers prevent females from nesting; response vessels can strike and kill sea turtles and relocation trawlers can inadvertently drown them; application of dispersants may have effects on sea turtles; and skimming and burning heavy oil may kill some sea turtles, while also exposing others to smoke inhalation.

Oil spill cleanup and response activities can negatively affect sea turtles as well. For example, oil containment booms along beaches can prevent nesting females from reaching the shores to lay their eggs. (NOAA)

Once sea turtles encounter oil, what are the impacts of that exposure?

Inhaling and swallowing oil generally result in negative health effects for animals, as shown in dolphins and other wildlife, hindering their overall health, growth, and survival. Lining the inside of sea turtles’ throats are pointy spines called esophageal papillae, which normally act to keep swallowed food inside while allowing water to be expelled. Unfortunately, these projections also seem to trap thick oil in sea turtles’ throats, and evidence of oil has been detected in the feces of oiled turtles taken into wildlife rehabilitation centers.

Oil can irritate sensitive mucus membranes around the eyes, mouth, lungs, and digestive tract of sea turtles, and toxic oil compounds known as polycyclic aromatic hydrocarbons (PAHs) can be absorbed into vital organ tissues such as the lungs and liver. Because sea turtles can hold their breath for long periods, inhaled oil has a greater chance of being absorbed into their bodies. Oil compounds that get passed from mother turtles to their young can interfere with development and threaten the survival of sea turtles still developing in the eggs.

Once inside their systems, oil can impede breathing and heart function in sea turtles, which can make diving, feeding, migrating, mating, and escaping predators more difficult. Being heavily covered in oil likewise impedes sea turtles’ abilities to undertake these activities, which puts them at risk of exhaustion and dehydration. In addition, dark oil under a hot summer sun can heat up turtles to dangerous temperatures, further jeopardizing their health and even killing them. In fact, sea turtles heavily coated in oil are not likely to survive without medical attention from humans.

Another, less direct way oil spills can affect the health of sea turtles is by killing or contaminating what they eat, which, depending on the species, can range from fish and crabs to jellyfish to seagrass and algae. In addition, if oil kills the sargassum where young sea turtles live, they lose their shelter and source of food and are forced to find suitable habitat elsewhere, which makes them more vulnerable to predators and uses more energy.

Spill response and cleanup operations also can harm sea turtles unintentionally. Turtles can be killed after being struck by response vessels or as a result of oil burning and skimming activities. Extra lighting and activity on beaches can disrupt nesting and hatchling turtles, as well as incubating eggs.

Help Is on the Way

A person holding a small clean Kemp's Ridley sea turtle over a blue bin.

A Kemp’s Ridley sea turtle ready to be returned to the wild after being cleaned and rehabilitated during an oil spill. (NOAA)

The harm that oil spills can cause to sea turtles is significant, and estimating the full suite of impacts to these species is a long and complicated process.  There are some actions that have been taken to protect these vulnerable marine reptiles during oil spills. These include activities such as:

  • Performing rescue operations by boat, which involve scooping turtles out of oil or water using dip-nets and assessing their health.
  • Taking rescued turtles to wildlife rehabilitation centers to be cleaned and cared for.
  • Monitoring beaches and coastlines for injured (and sometimes dead) turtles.
  • Monitoring nesting beaches to safeguard incubating nests.
  • Conducting aerial surveys to assess abundance of adults and large juvenile turtles potentially in the footprint of an oil spill.

Finally, the government agencies acting as stewards on behalf of sea turtles, as well as other wildlife and habitats, will undertake a scientific evaluation of an oil spill’s environmental impacts and identify restoration projects that make up for any impacts.

As an example, read about the impacts to sea turtles from the 2010 Deepwater Horizon oil spill, details about how they were harmed, and the proposed restoration path forward.


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What’s It Like Saving Endangered Baby Sea Turtles in Costa Rica?

This is a post by the Office of Response and Restoration’s Valerie Chu.

Three newly hatched Olive Ridley sea turtles crawl across sand.

Newly hatched Olive Ridley sea turtles make their way toward the ocean. (Used with permission of Julie Watanuki)

I was standing on a sandy Costa Rican beach in the dark of night when I received a hard lesson in the challenges of saving an endangered species. It was my first night volunteering during a seven-day stint on a sea turtle conservation project with the Asociación de Voluntarios para el Servicio en Áreas Protegidas (ASVO) in Montezuma, Costa Rica.

I was charged with protecting sea turtle nests in the ASVO hatchery from poachers and hungry wildlife. On the night of my very first shift, I discovered something terrible had happened. A net covering one of the sea turtle nests had been taken off, and when I looked inside, I found the remains of eight dead baby turtles with just their heads bitten off. When I looked in the back of the hatchery, I noticed that some eggs also had been dug up and eaten.

It was heartbreaking, but furthered my resolve to protect these vulnerable turtles.

Later that night, I discovered who the culprits were—two raccoons. Throughout my shift, the two raccoons would sneak back and I would scare them away each time. Fortunately, the raccoons did not come back in the following days. I was grateful I could play a small part in giving young sea turtles a head start in a long and dangerous journey.

Thinking (and Acting) Globally

Rows of nets cover sandy sea turtle nests, surrounded by fencing.

Volunteers with ASVO place sea turtle eggs collected from Costa Rican beaches into a hatchery with nets covering the nests to protect them from poachers, predators, and other threats. The eggs hatch less than two months later. (Used with permission of Valerie Chu)

Ever since I graduated from the University of Washington in 2012, I’ve wanted to make a positive impact on the dwindling populations of endangered species around the world. I started by volunteering to help orphaned and injured wildlife at the PAWS Wildlife Center near Seattle, Washington (where I recently volunteered during a vegetable oil spill).

As I’ve worked with these animals, my desire of making a global impact on wildlife conservation has increased more and more. In December 2015, I finally got my chance to do it when I traveled to Costa Rica to volunteer with ASVO.

ASVO’s primary goal is to promote active conservation in protected areas, beaches, and rural communities of Costa Rica. They have a volunteer program in around 20 different areas of the country, staffed by some 2,300 volunteers, comprising both local and international volunteers from around the world.

Turtle Time

I was working with Olive Ridley sea turtles, a vulnerable species likely to become endangered in the foreseeable future. Their main threats to survival are direct harvest of adults and eggs, incidental capture in commercial fisheries, loss of nesting habitat, and predators.

During nesting season in Costa Rica, people with ASVO patrol the beaches for female turtles laying their eggs and then gather the eggs and place them at a hatchery. This way, the eggs are protected from poachers, predators, and other threats, both human and environmental. The eggs incubate in the hatchery for between 52 and 58 days before hatching.

Because I had arrived at the end of sea turtle nesting season, I mostly handled the hatchlings and released them into the ocean. When the newly hatched turtles had completely emerged from their nests, I would—while wearing a glove—pick up each one from its nest and head to the ocean. I would then set the turtles down on the sand and watch them walk into the ocean. Some turtles would lose their way because they would walk in the wrong direction or get swept aside by a big wave, so it was my job to make sure they found their way to the ocean without mishap.

Most of my turtle volunteer shifts were at night, and because sea turtles are very sensitive to white light, we could only use a red light while handling them. During night shifts, we were always paired with a second person, allowing us to have one person handle the hatched turtles while the other could stand guard at the hatchery (a very important job, as I observed my first night).

After releasing the turtles, I had to record the number of turtles released, the time of the release, and other notes. Each of the nests held roughly 80-100 eggs, and about 50-70 eggs would hatch, which was an incredible sight.

Don’t Stop (Thinking About What You Can Do)

This trip was an absolutely amazing experience for me. By working with these turtles, I began to fulfill my dream of making a global impact on endangered species populations. On top of that, I was able to connect with other people who care about these issues and form a deep bond over this shared experience.

In the future, I hope to continue volunteering for the conservation of imperiled species like the tiny sea turtles I encountered in Costa Rica. In 2017, I plan to travel to Thailand to work with the endangered elephant population.

But there are lots of ways to protect endangered species at home too. How do you plan to help?

Three people help wash an oiled goose in big soapy wash tubs.

Valerie Chu is an Environmental Scientist who has been providing support for the Office of Response and Restoration’s Emergency Response Division software projects since 2012, when she obtained her undergraduate degree in Environmental Science and Resource Management and then started working with NOAA and Genwest. During her spare time, she volunteers with animal welfare-related causes such as PAWS and Zazu’s House Parrot Sanctuary.


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Explore Oil Spill Data for Gulf of Mexico Marine Life With NOAA GIS Tools

In the wake of the Deepwater Horizon oil spill, the sheer amount of data scientists were gathering from the Gulf of Mexico was nearly overwhelming. Everything from water quality samples to the locations of oiled sea turtles to photos of dolphins swimming through oil—the list goes on for more than 13 million scientific records.

So, how would anyone even start to dig through all this scientific information? Fortunately, you don’t have to be a NOAA scientist to access, download, or even map it. We have been building tools to allow anyone to access this wealth of information on the Gulf of Mexico environment following the Deepwater Horizon oil spill.

We’re taking a look at two of our geographic information systems tools and how they help scientists, emergency responders, and the public navigate the oceans of environmental data collected since the 2010 Deepwater Horizon oil spill.

When it comes to mapping and understanding huge amounts of these data, we turn to our GIS-based tool, the Environmental Response Management Application, known as ERMA®. This online mapping tool is like a Swiss army knife for organizing data and information for planning and environmental emergencies, such as oil spills and hurricanes.

ERMA not only allows pollution responders to see real-time information, including weather information and ship locations, but also enables users to display years of data, revealing to us broader trends.

View of Environmental Response Management Application showing map of Gulf of Mexico with varying probabilities of oil presence and sea turtle oiling during the Deepwater Horizon oil spill with data source information.

In the “Layer” tab on the right side of the screen, you can choose which groups of data, or “layers,” to display in ERMA. Right click on a data layer, such as “Turtle Captures Probability of Oiling (NOAA) (PDARP),” and select “View metadata” to view more information about the data being shown. (NOAA)

For instance, say you want to know the likelihood of sea turtles being exposed to heavy oil during the Deepwater Horizon oil spill. ERMA enables you to see where sea turtles were spotted during aerial surveys or captured by researchers across the Gulf of Mexico between May and September 2010. At the same time, you can view data showing the probability that certain areas of the ocean surface were oiled (and for how long), all displayed on a single, interactive map.

View of Environmental Management Application map of Gulf of Mexico showing varying probabilities of oil presence and sea turtle exposure to oil during the Deepwater Horizon oil spill with map legend.

Clicking on the “Legend” tab on the right side of the screen shows you basic information about the data displayed in ERMA. Here, the red area represents portions of the Gulf of Mexico which had the highest likelihood of exposing marine life to oil. Triangles show sea turtle sightings and squares show sea turtle captures between May and September 2010. The color of the symbol indicates the likelihood of that sea turtle receiving heavy exposure to oil. (NOAA)

Perhaps you want to focus on where Atlantic bluefin tuna were traveling around the Gulf and where that overlaps with the oil spill’s footprint. Or compare coastal habitat restoration projects with the degree of oil different sections of shoreline experienced. ERMA gives you that access.

You can use ERMA Deepwater Gulf Response to find these data in a number of ways (including search) and choose which GIS “layers” of data to turn on and off in the map. To see the most recently added data, click on the “Recent Data” tab in the upper left of the map interface, or find data by browsing through the “Layers” tab on the right. Or look for data in special “bookmark views” on the lower right of the “Layers” tab to find data for a specific topic of interest.

Now, what if you not only want to see a map of the data, what if you also want to explore any trends in the data at a deeper level? Or download photos, videos, or scientific analyses of the data?

That’s where our data management tool DIVER comes in. This tool serves as a central repository for environmental impact data from the oil spill and was designed to help researchers share and find scientific information ranging from photos and field notes to sample data and analyses.

As Ocean Conservancy’s Elizabeth Fetherston put it:

Until recently, there was no real way to combine all of these disparate pixels of information into a coherent picture of, for instance, a day in the life of a sea turtle. DIVER, NOAA’s new website for Deepwater Horizon assessment data, gives us the tools to do just that.

Data information and integration systems like DIVER put all of that information in one place at one time, allowing you to look for causes and effects that you might not have ever known were there and then use that information to better manage species recovery. These data give us a new kind of power for protecting marine species.

One of the most important features of DIVER, called DIVER Explorer, is the powerful search function that allows you to narrow down the millions of data pieces to the precise set you’re seeking. You do it one step, or “filter,” at a time.

DIVER software dialog box showing how to build a query by workplan topic area for marine mammals studied during the Deepwater Horizon oil spill.

A view of the step-by-step process of building a “query,” or specialized search, in our DIVER tool for Deepwater Horizon oil spill environmental impact data. (NOAA)

For example, when you go to DIVER Explorer, click on “Guided Query” at the top and then “Start to Explore Data,” choose “By Workplan Topic Area,” hit “Next,” and finally select “Marine Mammals” before clicking “Run Query” to access information about scientific samples taken from marine mammals and turtles. You can view it on a map, in a table, or download the data to analyze yourself.

An even easier way to explore these data in DIVER, however, is by visiting https://www.doi.gov/deepwaterhorizon/adminrecord and scrolling down to and clicking on #5 Preassessment/Assessment (§§ 990.40 – 990.45; 990.51). This will reveal a list of various types of environmental impacts—to birds, sea floor habitat, marine mammals, etc.—which the federal government studied as part of the Deepwater Horizon oil spill’s Natural Resource Damage Assessment.

Say you’re interested in marine mammals, so you click on 5.6 Marine Mammal Injury and then 5.6.3 Data sets. You can then download and open the document “NOAA Marine Mammal data related to the Deepwater Horizon incident, available through systems such as DIVER and ERMA, or as direct downloads. (September 23, 2015).”

Under the section “Data Links,” you can choose from a variety of stored searches (or “queries”) in DIVER that will show you where and when, for example, bottlenose dolphins with satellite tags traveled after the spill (tip: zoom in to view this data on the map)—along with photographs to go with it (tip: click on the “Photos” tab under the map to browse).

Map view of DIVER software map showing where tagged dolphins swam in the Gulf of Mexico after the Deepwater Horizon oil spill.

A map view of DIVER shows where tagged dolphins traveled along the Gulf Coast, showing two populations that stayed in their home bases of Barataria Bay and Mississippi Sound. (NOAA)

This can tell us key information, such as the fact that certain populations of dolphins stay in the same areas along the coast, meaning they don’t travel far from home. We can also look at data about whether those dolphin homes were exposed to a lot of oil, which would suggest that the dolphins that lived there likely were exposed to oil again and again.

Both of these tools allow us to work with incredible amounts of data and see their stories brought to life through the power of geographic information systems. So, go ahead and start exploring!


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What Happens When Oil Spills Meet Massive Islands of Seaweed?

Floating bits of brown seaweed at ocean surface

Floating rafts of sargassum, a large brown seaweed, can stretch for miles across the ocean. (Credit: Sean Nash/Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic license)

The young loggerhead sea turtle, its ridged shell only a few inches across, is perched calmly among the floating islands of large brown seaweed, known as sargassum. Casually, it nibbles on the leaf-like blades of the seaweed, startling a nearby crab. Open ocean stretches for miles around these large free-floating seaweed mats where myriad creatures make their home.

Suddenly, a shadow passes overhead. A hungry seabird?

Taking no chances, the small sea turtle dips beneath the ocean surface. It dives through the yellow-brown sargassum with its tangle of branches and bladders filled with air, keeping everything afloat.

Home Sweet Sargassum

This little turtle isn’t alone in seeking safety and food in these buoyant mazes of seaweed. Perhaps nowhere is this more obvious than a dynamic stretch of the Atlantic Ocean off the East Coast of North America named for this seaweed: the Sargasso Sea. Sargassum is also an important part of the Gulf of Mexico, which contains the second most productive sargassum ecosystem in the world.

Some shrimp, crabs, and fish are specially suited to life in sargassum. Certain species of eel, fish, and shark spawn there. Each year, humpback whales, tuna, and seabirds migrate across these fruitful waters, taking advantage of the gathering of life that occurs where ocean currents converge.

Cutaway graphic of ocean with healthy sargassum seaweed habitat supporting marine life.

Illustration of sargassum and associated marine life, including fish, sea turtles, birds, and marine mammals. Sargassum is a brown algae that forms a unique and highly productive floating ecosystem on the surface of the open ocean. (NOAA) Click to enlarge.

The Wide and Oily Sargasso Sea

However, an abundance of marine life isn’t the only other thing that can accumulate with these large patches of sargassum. Spilled oil, carried by currents, can also end up swirling among the seaweed.

If an oil spill made its way somewhere like the Sargasso Sea, a young sea turtle would encounter a much different scene. As the ocean currents brought the spill into contact with sargassum, oil would coat those same snarled branches and bladders of the seaweed. The turtles and other marine life living within and near the oiled sargassum would come into contact with the oil too, as they dove, swam, and rested among the floating mats.

That oil can be inhaled as vapors, be swallowed or consumed with food, and foul feathers, skin, scales, shell, and fur, which in turn smothers, suffocates, or strips the animal of its ability to stay insulated. The effects can be toxic and deadly.

Cutaway graphic of ocean with potential impacts of oil on sargassum seaweed habitat and marine life.

Illustration of the potential impacts of an oil spill on sargassum and associated marine life in the water column. (NOAA) Click to enlarge.

While sea turtles, for example, as cold-blooded reptiles, may enjoy the relatively warmer waters of sargassum islands, a hot sun beating down on an oiled ocean surface can raise water temperatures to extreme levels. What starts as soothing can soon become stressful.

Depending on how much oil arrived, the sargassum would grow less, or not at all, or even die. These floating seaweed oases begin shrinking. Where will young sea turtles take cover as they cross the unforgiving open ocean?

As life in the sargassum starts to perish, it may drop to the ocean bottom, potentially bringing oil and the toxic effects with it. Microbes in the water may munch on the oil and decompose the dead marine life, but this can lead to ocean oxygen dropping to critical levels and causing further harm in the area.

From Pollution to Protection

Young sea turtles swims through floating seaweed mats.

The floating habitat that sargassum creates provides food, refuge, and breeding grounds for an array of marine species, including sea turtles. (NOAA)

NOAA and the U.S. Fish and Wildlife Service have designated sargassum as a critical habitat for threatened loggerhead sea turtles.

Sargassum has also been designated as Essential Fish Habitat by Gulf of Mexico Fishery Management Council and National Marine Fisheries Service since it also provides nursery habitat for many important fishery species (e.g., dolphinfish, triggerfishes, tripletail, billfishes, tunas, and amberjacks) and for ecologically important forage fish species (e.g., butterfishes and flyingfishes).

Sargassum and its inhabitants are particularly vulnerable to threats such as oil spills and marine debris due to the fact that ocean currents naturally tend to concentrate all of these things together in the same places. In turn, this concentrating effect can lead to marine life being exposed to oil and other pollutants for more extended periods of time and perhaps greater impacts.

However, protecting sargassum habitat isn’t impossible and it isn’t out of reach for most people. Some of the same things you might do to lower your impact on the planet—using less plastic, reducing your demand for oil, properly disposing of trash, discussing these issues with elected officials—can lead to fewer oil spills and less trash turning these magnificent islands of sargassum into floating islands of pollution.

And maybe protect a baby sea turtle or two along the way.