On Aug. 23, the nonprofit conservation organization completed its first-ever expedition to investigate and document the condition of two reefs in the Gulf of Mexico using cutting-edge technology. Project Alacranes focused on Scorpion Reef (Arrecife Alacranes in Spanish) and the Bajos del Norte National Park, which contain some of the greatest biodiversity in the Gulf.
Mariana Reyes, oceans and fisheries scientist at Oceana in Mexico, told EcoWatch, "These two sites are ecologically and economically relevant for the region." According to Oceana, Scorpion Reef is the largest reef in the southern Gulf of Mexico and is a designated marine protected area (MPA). Numerous endangered and commercial species reproduce within the MPA and migrate beyond that to fishing grounds when mature. The waters also support the important red snapper and grouper fisheries, and more than 15 percent of spiny lobster catches in the Yucatan are from Scorpion Reef and its surrounding area, Reyes added.
Diver and soft coral in Bajos del Norte. Rodrigo Friscionne
Expedition leader Mariana Reyna also shared Scorpion Reef's importance to a planet increasingly confronted by the climate crisis and warming oceans. The reef is included on a 2018 list by Conservation Letters of coral reefs that are "healthy and diverse enough to have a better chance of surviving the effects of climate change," said Reyes.
In the case of Bajos del Norte, the reef has been identified as a possible important connection between the Caribbean and the Gulf of Mexico, Reyes said.
Reyes pointed out that, in theory, these remote areas should be "relatively undisturbed" by the impacts of human activities — thanks to their distance from the coast. Nevertheless, Scorpion Reef shows signs of being affected by human impacts including tourism and Illegal, Unreported, and Unregulated (IUU) fishing. Luckily, Reyes said, Bajos del Norte shows very few signs of human impact. Scientists want to understand why this is and how to prevent further degradation of both reefs.
Branching coral in Alacranes. Rodrigo Friscionne
"Our objective is to collect scientific information that allows us to determine the current status of this marine protected area (MPA), and to use this information to promote the changes needed to protect and guarantee the future of this important ecosystem," said Renata Terrazas, leader of Oceana in Mexico.
"That is why it is so important to explore these places where few expeditions have been and with technology that has never been used in these areas to collect the evidence necessary to protect and preserve this habitat," Reyna said.
While Scorpion Reef is an MPA, "In the case of Bajos del Norte, the risk is greater because it has no legal protection, and very little research has been done on its status, nor on the species that live there," Terrazas added.
Over the 15-day expedition, scientists explored the two areas. They were happy to report that the reefs were "full of life with an abundance of fish, invertebrates, and other animals that are signs of a healthy reef," Reyes said. They also observed many corals with disease and mortality in two species. They will continue analyzing their findings.
Juvenile Bluehead Wrasse (Thalassoma bifasciatum) in Scorpion Reef (Arrecife Alacranes). Rodrigo Friscionne
The researchers also completed environmental DNA analysis and photomosaic modeling. The latter will be used to create 3D maps of the reefs and enable a census of species located thereon. This information can help managers evaluate current management tools for these reefs and determine how best to preserve them, Reyes said.
"The recovery and conservation of marine habitats in Mexico translate into greater economic and social benefits, especially for local fishermen. Adequate protection of these reefs ensures that future generations can enjoy their beauty and resources," said Miguel Rivas, director of habitat campaigns at Oceana.
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During this event, PADI dive centers, resorts and professional divers from around the world host local events to advance conservation awareness and engagement.
"Aware Week started in 2018 to bring together divers all over the world to be a voice for the ocean and act for change," said Kristin Valette Wirth, chief brand and membership officer for PADI Worldwide. "PADI and PADI AWARE Foundation believe in the power of people to help address threats facing our ocean today and that large-scale transformation starts with individuals acting locally for global impact."
This year's explicit conservation mandates include advancing PADI's Conservation Blueprint, an initiative encouraging conservation action in direct support of the United Nations Decade of Ocean Science for Sustainable Development, Valette Wirth told EcoWatch. According to PADI, the focus will be on how to take PADI's existing Vulnerable Species Protection and Marine Debris programs "to the next level" by also addressing critical marine issues such as climate change, marine protected areas and coral reefs. These represent the five key components of PADI's Blueprint for Ocean Action and directly align with and support UN efforts.
On the marine debris front, PADI is inviting ocean enthusiasts and divers to collect trash from the shorelines and seafloor through its signature citizen-science diving program, Dives Against Debris. Everything collected is sorted, weighed and then added to a global database that can be used by marine researchers and policymakers for conservation action. The scuba organization hopes to use this data about what is entering our ocean to positively influence upstream policy changes to curb this flow.
"As divers, we have the skills and vantage point to gather data that no other community can," Valette Wirth explained to EcoWatch. "Around the world, more than 90,000 PADI Divers and Torchbearers for the ocean have removed and reported marine debris from underwater environments since 2011, representing the largest underwater citizen science database and movement for marine debris on the planet."
A diver removes a discarded face mask floating in the ocean during a dive. PADI
The impressive scale of data collected by the recreational dive community and its global nature allow for PADI AWARE to collaborate with scientists, researchers and independent research organizations to broaden and strengthen their data. In this way, marine debris trends and potential solutions can be addressed more quickly and effectively, Valette Wirth added.
Recently, data submitted from 118 different countries by PADI divers has been used in a global analysis of marine debris to identify marine debris hotspots and how they came to be. As different policy solutions are proposed, recreational scuba divers can help "in real time" through continued data collection that will speak to the effectiveness of any policies implemented, Valette Wirth said.
Essentially, PADI wants to galvanize the global diving community to clean our seas and put pressure on key decision makers to increase protections for the ocean, Valette Wirth said. Through the collective impact of their efforts, PADI believes global ocean impact can be achieved.
"Protecting the ocean requires the actions of everyone around the globe working together," said Valette Wirth. "Together with PADI AWARE Foundation, Seiko and our other partners in conservation, we recognize that anyone with passion for the ocean can become an ocean ambassador and contribute to worldwide efforts to save the ocean... AWARE Week 2021 will inspire people with a clear and effective path to action for the planet."
A novice Dive Against Debris participant removes and coils ghostline found on a coral reef during a Dive Against Debris. Tiffany Duong / Ocean Rebels
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The COVID-19 pandemic caused most of these sites to fall silent, including one of the world's busiest cruise-ship ports: the docks on Grand Cayman Island. In April 2020, the global pandemic shut down the island's port, which normally saw the arrival of dozens of cruise ships and thousands of tourists every month. The Cayman Islands was the only Caribbean nation to voluntarily halt its cruise economy, prioritizing the safety of its residents. Local businesses, hurt by the loss of tourism dollars, have already started going under; iconic local spots that make up much of the community's social fabric, for tourists and locals alike, are being lost.
A cruise ship visits Grand Cayman in 2019. David Reber / CC BY-SA 2.0
Soon, though, the ban on cruise ships will undoubtedly lift, and tourism will slowly return. And when that happens, the residents of Grand Cayman and nearby islands may find themselves worrying about another major threat posed by these cruise companies, one that runs the risk of being drowned out by the disruption caused by the pandemic.
In 2019 the Cayman Islands government announced a plan to move forward on a massive new port project in George Town Harbor, supported by two major cruise-ship operators. Without this project, cruise ships visiting the island must anchor offshore and shuttle passengers back and forth with smaller vessels — an important aspect of the local economy with historic roots in the coastal community.
The new project, estimated to cost $200 million, would allow cruise ships to come all the way to shore by building deep new docks capable of accommodating four cruise ships at a time, each of which could bring thousands of additional visitors to the island, according to the cruise companies and government supporters.
But getting to this point would require dredging 22 acres of George Town Harbor's seabed, destroying 10 to 15 acres of fragile coral reefs in the process.
If that happens, another vital part of the fabric of Grand Cayman life would be lost.
Coral vs. Corporate Influence
Given its role in the global financial industry, the Cayman Islands may seem like the last place in the world where rule of law and good governance would be a problem. Yet even here, the ever-growing power of multinational corporations to transform environmental policy is starting to be felt.
It didn't used to be this way.
As I wrote in my recent scientific study on the Cayman Islands, their effective marine park system has stood out as a model for coral-reef management since it was put in place in the 1980s. This area is known for its vibrant coral reefs, well-protected through the ever-expanding network of marine parks. The Cayman Islands have strict constitutional provisions and laws for protecting coral reefs, as well as international environmental policy commitments. Caymanian history and culture are also closely tied to the reefs. The first dive tourism spots in the Caribbean blossomed from Bob Soto's little backwater dive shop on "Cheeseburger Reef" into today's multimillion-dollar dive tourism trade.
Despite the history and good governance, the cruise industry — notably Carnival and Royal Caribbean Cruise Lines — had, prior to the pandemic, announced plans to move ahead with their plans to build the new docking facility on George Town Harbor.
Fragile Reefs, Questionable Science, Vague Promises
Those docks would devastate the local ecology. A 2015 environmental impact assessment estimated that the project would not just destroy 15 acres of reef but also negatively affect another 15 to 20 acres of adjacent habitat and pose risks to the 26 coral species in the harbor — two of which are critically endangered.
Coral disease and bleaching from elevated surface temperatures have already put the Cayman Islands' coral reefs on the ropes; this could be the knockout punch.
R9 Studios / CC BY 2.0
The cruise companies pushing the infrastructure project have argued that there's a way to mitigate this damage, but their proposed solution doesn't hold much water.
They worked with the government on a plan that would pay an engineering company and a Florida-based NGO to relocate every coral lost or replant lab-grown corals in place of the ones they can't relocate. By my estimation, the partners would need to replant and grow more than 3 million corals to make up for this destruction — triple the stated replanting goal.
The government's replacement goal is based on the absurd notion that a reef is simply an independent collection of corals humans can easily re-create — a bold assumption, and one yet to be supported at the proposed scale.
The reality is that reefs are slow-growing, highly complex assemblies of living and non-living things that take centuries to develop. This promised "replanting" technology is scientifically unproven at best and greenwashing at worst — meant to soothe the conscience of those troubled by the grave choice to destroy a beloved coral reef with deep meaning to its community.
The government has promised vague jobs and economic benefits if the project is built. And the CEO of Royal Caribbean, Michael Bailey, promises no taxpayer money will be used to pay for the dock.
This is not true. The Caymanian government will hand over $2.32 in tourism taxes per passenger to the cruise lines that it would otherwise collect for the citizens of Cayman. Caymanians are, therefore, paying for this infrastructure, despite mounting environmental problems on the island including a trash pile so large that locals call it "Mount Trashmore."
Votes and Courts
There is some hope in this case, thanks to Caymanian community organizing.
Two years ago, Caymanian citizens successfully organized and secured a referendum through a robust people's movement. Community groups like Cruise Port Referendum Cayman (CPR Cayman) implemented an aggressive ground campaign with no outside financial backing, organized only by volunteers. They focused on educating the public on the risks and uncertainties underpinning this project. Their efforts triggered a public referendum, originally scheduled for Christmas 2019, the first in Caymanian history.
The status of the referendum is currently being worked out in the courts, and it's important that we pay attention. Currently, prominent members of CPR Cayman are acting as watchdogs to ensure the referendum, if it is ultimately held, will take place in a fair and impartial way. Before the court challenge, activists protested the original referendum, which was intentionally scheduled at the holidays, a time when many are simply not on the island — an incredibly cynical move, since under the Cayman constitution a missing vote counts as a de facto "yes" for the port.
Despite community opposition, cruise corporation leaders are actively speaking out in support of this project's resumption, with Michael Bayley, the CEO of Royal Caribbean, saying that they will make a decision to resurrect the pier project in the coming months.
That's why it's so important that we follow this ongoing case — CPR Cayman makes regular updates to their Facebook page — as local community activists continue to contest the project in court. Should our "New Normal" following the COVID-19 pandemic allow companies to break environmental laws for private gain?
Democratic Reefs
Why do these reefs matter so much? They're what we would call "democratic reefs," easily accessed from the shore by the public using free parking lots and open stairs. Multiple generations of Caymanians have taken the quick swim out and snorkeled with their children. One man who spoke up at a 2019 community meeting told the story of how his father, he, and now his son all took the name "Eden" after the iconic Eden Rock Reef, which will be wrecked by this project.
For people like Eden and his family, this isn't just an environmental issue — this is about social justice. Coral reefs come with benefits for communities. They protect islands from hurricanes, provide food, attract tourism dollars and have deep cultural meaning. Lower-income people feel the loss of these services more intensely than those with more. Will the "replanted" reefs replace natural ones effectively? Or will low-income communities bear the consequences while foreign companies and scientists-for-hire sail home with increased profit? The losses for locals will stack up with eroding beaches erode, exposed homes, empty fishing grounds empty, and an end to their snorkeling trips with their children.
New Normal
The number of people standing up to this project continued to grow in 2020, even during the pandemic. This drew scorn of powerful government leaders such as McKeeva Bush, the speaker of the Legislative Assembly, who called community organizers "rascals" in public.
What happens next? Premier Alden McLaughlin hinted back in mid-April 2020 that he had grown weary of this dispute, suggesting that the vote will not happen during the current political term due to the pandemic.
That doesn't mean the port project is dead. It's just been pushed down the line for the next people who take office. "It will be another government that deals with that," McLaughlin said. Given the support expressed by leaders in the cruise industry, many believe this project will resume when cruise tourism resumes.
It may seem odd to talk about this while the world is just beginning to emerge from the pandemic, but the attention we pay to COVID-19 may distract us from closely watching corporations that stand to gain from the proposed destruction of coral reefs. This may be the window of opportunity the government needs to quietly move ahead while we're distracted with recovery.
We must unify as "rascals" to oppose corporations that continue to push their anti-environment agendas forward around the world. We must reject the false promises of scientists-for-hire.
If being a "rascal" means opposing the immoral destruction of coral reefs, consider me a rascal.
When and if the vote happens, I encourage the people of the Cayman Islands to vote no on the referendum. Likewise, I urge the people of the Cayman Islands to unite against companies violating their environmental laws. The returns are not worth the risks, namely the loss of their iconic reefs.
I encourage the U.S. public, and the wider world, to hold the cruise industry accountable for these types of immoral bypasses of domestic and international environmental policy. The industry's shocking record of customer safety amidst the pandemic remains in the news, but this is hardly its only sin. You only need to look to the industry's poor environmental record in the Bahamas to see what might happen in the Caymans moving forward.
If the reefs are destroyed and the restoration fails or even partially succeeds, the Caymanian people will be left to clean up, while the cruise industry continues to rake in record profits.
It is unethical to destroy coral reefs because they do not belong to us. They belong to everyone, and that includes future generations. If the project goes ahead, I hope that corporate leadership from the cruise industry will explain to young Eden, and other young Caymanians, why they cannot snorkel the reefs that their parents once did.
Kelly Heber Dunning is an assistant professor of conservation governance at Auburn University and a 2020 National Academies of Science, Engineering, and Medicine Early Career Fellow. She received her Ph.D. in Natural Resources from MIT and MSc in Environmental Policy from Oxford and is the author of Managing Coral Reefs (2018), a scientific book on coral reef management.
The opinions expressed above are those of the author and do not necessarily reflect those of The Revelator, the Center for Biological Diversity or its employees.
Reposted with permission from The Revelator.
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There's no question that the city is at increasing risk of flooding as sea level rises and storms intensify with climate change. A hurricane as powerful as 1992's Andrew or 2017's Irma making a direct hit on Miami would devastate the city.
But the sea wall the Army Corps is proposing – protecting only 6 miles of downtown and the financial district from a storm surge – can't save Miami and Dade County. Most of the city will be outside the wall, unprotected; the wall will still trap water inside; and the Corps hasn't closely studied what the construction of a high sea wall would do to water quality. At the same time, it would block the water views that the city's economy thrives on.
Much of Miami is built right up to the water's edge. On average, it's 6 feet above sea level. Ryan Parker / Unsplash
To protect more of the region without losing Miami's vibrant character, there are ways to pair the strength of less obtrusive hardened infrastructure with nature-based "green" solutions. With our colleagues at the University of Miami's Rosenstiel School of Marine and Atmospheric Science and the College of Engineering, we have been designing and testing innovative hybrid solutions.
Natural Storm Management
Living with water today doesn't look the same as it did 50 years ago, or even 20 years ago. Parts of Miami now regularly see "sunny day" flooding during high tides. Salt water infiltrates basements and high-rise parking garages, and tidal flooding is forecast to occur more frequently as sea level rises. When storms come through, the storm surge adds to that already high water.
Hurricanes are less common than tidal flooding, but their destructive potential is greater, and that is what the Army Corps is focused on with its sea wall plan.
If Miami Beach were an undeveloped barrier island, and if thick mangrove forests were still common along the South Florida shoreline, the Miami area would have more natural protection against storm surge and wave action. But most of those living buffers are long gone.
There are still ways nature can help preserve the beauty of Miami's marine playground, though.
For example, healthy coral reefs break waves, dissipating their energy before the waves reach shore. Dense mangrove forests also dissipate wave energy with their complex root systems that rise above the water line, dramatically reducing the waves' impact. In areas where coastal flooding is an increasing problem, low-lying communities can be relocated to higher ground and the vacant land turned into wetlands, canals or parks that are designed to manage storm surge flooding.
Coral reefs like these in Biscayne National Park have struggled with warming waters. National Park Service
Each area of coastline is unique and requires different protective measures based on the dynamics of how the water flows in and out. Given Miami's limited space, living shorelines alone won't be enough against a major hurricane, but there are powerful ways to pair them with solid "gray" infrastructure that are more successful than either alone.
Hybrid Solutions Mix Green and Gray
Nobody wants to look at a cement breakwater offshore. But if you're looking at a breakwater covered with corals and hospitable to marine life, and you can go out and swim on it, that's different.
Corals help the structure dissipate wave energy better, and at the same time they improve water quality, habitat, recreation, tourism and quality of life. For a lot of people, those are some of Miami's main selling points.
By pairing corals and mangroves with a more sustainable and eco-friendly hard infrastructure, hybrid solutions can be far less obtrusive than a tall sea wall.
For example, a cement-based breakwater structure submerged offshore with coral transplants could provide habitat for entire ecosystems while providing protection. We're working with the city of Miami Beach through the University of Miami Laboratory for Integrative Knowledge to implement three hybrid coral reefs just offshore that we will monitor for their engineering and ecological performance.
Closer to shore, we're experimenting with a novel modular marine and estuarine system we call "SEAHIVE." Below the water line, water flows through hollow hexagonal channels of concrete, losing energy. The top can be filled with soil to grow coastal vegetation such as mangroves, providing even more protection as well as an ecosystem that benefits the bay.
We're currently working on testing SEAHIVE as a green engineering alternative for North Bay Village, an inhabited island in the bay, and as the infrastructure of a newly developed marine park where these "green-gray" reef and mangrove designs will be showcased.
What About the Rest of Miami?
The Army Corps of Engineers' draft plan – a final version is expected in the fall – would give nature-based solutions little role beyond a fairly small mangrove and sea grass restoration project to the south. The Corps determined that natural solutions alone would require too much space and wouldn't be as effective as hard infrastructure in a worst-case scenario.
Instead, the Army Corps' plan focuses on the 6-mile sea wall, flood gates and elevating or strengthening buildings. It basically protects the downtown infrastructure but leaves everyone else on their own.
Sea walls and flood gates can also affect water flow and harm water quality. The Corps' own documents warn that the sea walls and gates will affect wildlife and ecosystems, including permanent loss of protective corals, mangroves and sea grass beds.
Mangrove roots rising above the water help break up the energy of waves at the shoreline. Florida Guidebook / Unsplash
We would like to see a plan for all of Miami-Dade County that considers the value that green and hybrid solutions bring for marine life, tourism, fishing and general quality of life, in addition to their protective services for the shoreline.
Both types – green and gray – would take time to build out, particularly if the sea wall plan were challenged in court. And both run a risk of failure. Corals can die in a heat wave, and a storm can damage mangroves; but storms can also undermine engineered solutions, like the New Orleans levee system during Hurricane Katrina. To help build resilience, our colleagues at the University of Miami have been breeding corals to be more resistant to climate change, investigating novel cementitious materials and noncorrosive reinforcements and developing new designs for coastal structures.
Miami in the Future
Miami will be different in the coming decades, and the changes are already starting.
High ground is at a premium, and that's showing up in real estate decisions that are pushing lower-income residents out and into less safe areas. Anybody looking back at Miami will probably think the region should have done a better job of managing growth and maybe even managing some form of retreat from threatened areas.
We don't want to see Miami become Venice or a city walled off from the water. We think Miami can thrive by making use of the local ecosystem with novel green engineering solutions and an architecture that adapts.
Landolf Rhode-Barbarigos is an Assistant Professor of Civil, Architectural and Environmental Engineering at the University of Miami.
Brian Haus is a Professor of Ocean Sciences at the University of Miami.
Disclosure statement: Landolf Rhode-Barbarigos receives funding from the National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) for the research and development of the SEAHIVE - Sustainable Estuarine and Marine Revetment.
Brian Haus receives funding from the National Cooperative Highway Research Program (NCHRP) Innovations Deserving Exploratory Analysis (IDEA) for the research and development of the SEAHIVE - Sustainable Estuarine and Marine Revetment.
Reposted with permission from The Conversation.
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On Tuesday of last week, its state Senate approved Senate Bill 132, which would ban all sunscreens containing the chemicals avobenzone or octocrylene. The bill then moved to the House, where it passed its first reading on Thursday, March 11. If approved, it would build on a 2018 law that banned sunscreens containing the chemicals oxybenzone and octinoxate, which went into effect this January.
Coastal Oahu, Hawaii and the Kualoa Ranch. Hawaii is considering banning more reef-harming sunscreens to protect its unique coral reefs. Art Wager / E+ / Getty Images
"This is great news for our imperiled coral reefs and marine life," Maxx Phillips, Hawai'i director and staff attorney at the Center for Biological Diversity (CBD), said in response to the Senate vote. "People can protect their skin without harmful petrochemicals while Hawai'i protects public and environmental health."
The bill comes amidst growing scientific awareness of the impact of common sunscreen chemicals on marine life. These chemicals can make corals more susceptible to viral infections and bleaching, as well as disrupting the reproductive systems of fish and other animals, the Honolulu Star Advertiser reported.
In particular, octocrylene can disrupt human hormones and harm marine animals, according to the CBD. A soon-to-be-published study has found it can break down into the carcinogenic benzophenone, which also kills plants and disrupts reproduction. Avobenzone, meanwhile, is also an endocrine disruptor and can make coral less resilient to the high temperatures caused by the climate crisis.
"Studies show fish exposed to octocrylene exhibited endocrine disruption, brain deformities in larvae and reproductive toxicity," ecotoxicologist Craig Downs told the CBD. "Because octocrylene bioaccumulates, what does that mean for people eating these fish, especially pregnant women and keiki? Avobenzone may cause a dysfunction with the powerhouse of the cell, which may kill cells and induce a bleaching effect in corals."
The CBD has petitioned the Food and Drug Administration (FDA) to ban these chemicals on the national level, but for now it falls to Hawaii to protect its unique ecosystems: Around one fourth of all of the plants, fish and invertebrates found on Hawaii's reefs are native to the archipelago.
If it passes, the bill would go into effect Jan. 1, 2023. It will ban the sale or distribution of any sunscreen containing the targeted chemicals unless the buyer has a valid prescription. For those looking to protect themselves from the sun without harming ocean life, scientists and the National Oceanic and Atmospheric Administration (NOAA) recommend products containing non-nanoized titanium dioxide and non-nanoized zinc oxide, the Honolulu Star Advertiser reported.
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In a recently published study, an Australian research team used drone surveys, satellite imagery, and observations of individual sea cucumbers to estimate how much poop the sea cucumbers of Heron Island Reef produced per year. Heron Island Reef is part of the southern Great Barrier Reef system off the coast of Queensland, Australia.
Historically, one of the major problems scientists have faced when trying to assess the importance of sea cucumbers (and their excrement) in the reef ecosystem is the difficulty in assessing just how many sea cucumbers there are in a given area, said Jane Williamson, the study's lead author and head of the Marine Ecology Group at Macquarie University.
Previous research used footage from boats or information collected by divers to estimate sea cucumber numbers, said Williamson. But boats stir up the water, making it difficult to see the animals, and divers can collect information over only relatively small areas, resulting in a high degree of uncertainty when their observations were used to extrapolate the population of the entire reef.
So Williamson and her team, which included coral reef geomorphologist Stephanie Duce, remote sensing expert Karen Joyce, and marine ecologist Vincent Raoult, wanted to try a different method. Using images captured by drones, the team surveyed sea cucumbers over tens of thousands of square meters in two different geomorphic zones (the inner and the outer reef flats). Researchers then used satellite imagery to determine the area of each of these geomorphic zones to extrapolate the number of sea cucumbers present on the entire reef. These methods indicated that there were more than 3 million sea cucumbers on the reef flats surrounding Heron Island Reef.
The team also collected dozens of individual sea cucumbers to observe their bioturbation rates—that is, how much each sea cucumber pooped in a given day. On average, each sea cucumber produced about 38 grams of poop in 24 hours. Using this information, along with their estimates of the reef's sea cucumber population, researchers determined that on a single reef, sea cucumbers produced more than 64,000 metric tons of poop per year—more than the weight of five Eiffel Towers.
By measuring how much individual sea cucumbers pooped per day and estimating the number of sea cucumbers on the reef using drones and satellite images, researchers determined how much poop sea cucumbers contributed to the Heron Island Reef. Credit: Associate Professor Jane Williamson et al., 2021, Macquarie University; Dr. Stephanie Duce, James Cook University; Dr. Karen Joyce, James Cook University; and Dr. Vincent Raoult, University of Newcastle. https://doi.org/10.1007/s00338-021-02057-2
The Importance of Excrement
Scientists think that all of that poop plays an important role in ecosystem health as well as in the biogeochemical cycles of the reef.
"Sea cucumbers can be considered like a long sausage, almost," said Williamson. "Sediment goes in and sediment comes out.… By eating the sediment and then pooping it out again, they're actually aerating the sediment, which makes the sediment a healthier place for other animals to live, like small crabs or polychaetes, which are worms, or small mollusks that live inside the sediment in the surface layer."
Sea cucumbers are also involved in the nitrogen cycles of the reef ecosystem. As sea cucumbers eat and excrete sediment, "they're releasing nitrogen that's trapped in between the sediments," said Williamson. "So this is really important because nitrogen in particular is a limiting nutrient on coral reefs.… The corals need nitrogen, and the algae need nitrogen, everything sort of locks it up really quickly when it's available, so the sea cucumbers are doing them a big favor in terms of the growth rate of these organisms."
Sea cucumbers could even help protect coral reefs against one of the harmful side effects of climate change: ocean acidification. "The oceans are becoming more acidic, which means that the calcium carbonate which makes the skeletons of the corals and things is less available and in some cases is actually dissolving off the corals." In addition to releasing nitrogen, sea cucumbers also increase the availability of calcium carbonate as they eat their way through the sediment, said Williamson. "So for the sea cucumbers to release more calcium carbonate that's been trapped in the sediments into the environment that the corals and other animals can use is super important."
"These little sausages are playing a really key role that people just don't think about," said Williamson.
Steven Purcell, a marine scientist at Southern Cross University in Lismore, Australia, who was not associated with the study, said that more than 70 countries harvest sea cucumbers. Because these animals are of great ecological value, it's important to keep tabs on their numbers to make sure they're not being overharvested. He noted that drone surveillance techniques like the one used in this paper could also be used to assess populations of other exploited shallow-water reef species, like giant clams.
This story originally appeared in Eos and is republished here as part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.