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.
Eye-Catching Designs Made from Recycled Plastic Bottles
The company sells a range of eco-friendly items like leggings, rash guards, and board shorts that are made using recycled post-consumer plastic bottles. There are currently 16 causes represented by distinct marine-life patterns, from whale shark research and invasive lionfish removal to sockeye salmon monitoring and abalone restoration.
One such organization is Get Inspired, a nonprofit that specializes in ocean restoration and environmental education. Get Inspired founder, marine biologist Nancy Caruso, says supporting on-the-ground efforts is one thing that sets Waterlust apart, like their apparel line that supports Get Inspired abalone restoration programs.
"All of us [conservation partners] are doing something," Caruso said. "We're not putting up exhibits and talking about it — although that is important — we're in the field."
Waterlust not only helps its conservation partners financially so they can continue their important work. It also helps them get the word out about what they're doing, whether that's through social media spotlights, photo and video projects, or the informative note card that comes with each piece of apparel.
"They're doing their part for sure, pushing the information out across all of their channels, and I think that's what makes them so interesting," Caruso said.
And then there are the clothes, which speak for themselves.
Advocate Apparel to Start Conversations About Conservation
Waterlust's concept of "advocate apparel" encourages people to see getting dressed every day as an opportunity to not only express their individuality and style, but also to advance the conversation around marine science. By infusing science into clothing, people can visually represent species and ecosystems in need of advocacy — something that, more often than not, leads to a teaching moment.
"When people wear Waterlust gear, it's just a matter of time before somebody asks them about the bright, funky designs," said Waterlust's CEO, Patrick Rynne. "That moment is incredibly special, because it creates an intimate opportunity for the wearer to share what they've learned with another."
The idea for the company came to Rynne when he was a Ph.D. student in marine science.
"I was surrounded by incredible people that were discovering fascinating things but noticed that often their work wasn't reaching the general public in creative and engaging ways," he said. "That seemed like a missed opportunity with big implications."
Waterlust initially focused on conventional media, like film and photography, to promote ocean science, but the team quickly realized engagement on social media didn't translate to action or even knowledge sharing offscreen.
Rynne also saw the "in one ear, out the other" issue in the classroom — if students didn't repeatedly engage with the topics they learned, they'd quickly forget them.
"We decided that if we truly wanted to achieve our goal of bringing science into people's lives and have it stick, it would need to be through a process that is frequently repeated, fun, and functional," Rynne said. "That's when we thought about clothing."
Support Marine Research and Sustainability in Style
To date, Waterlust has sold tens of thousands of pieces of apparel in over 100 countries, and the interactions its products have sparked have had clear implications for furthering science communication.
For Caruso alone, it's led to opportunities to share her abalone restoration methods with communities far and wide.
"It moves my small little world of what I'm doing here in Orange County, California, across the entire globe," she said. "That's one of the beautiful things about our partnership."
Check out all of the different eco-conscious apparel options available from Waterlust to help promote ocean conservation.
Melissa Smith is an avid writer, scuba diver, backpacker, and all-around outdoor enthusiast. She graduated from the University of Florida with degrees in journalism and sustainable studies. Before joining EcoWatch, Melissa worked as the managing editor of Scuba Diving magazine and the communications manager of The Ocean Agency, a non-profit that's featured in the Emmy award-winning documentary Chasing Coral.
To date, we've lost more than 50 percent of the world's coral reefs. The main threats to corals are bleaching (caused by ocean warming) and ocean acidification. Most of the carbon dioxide we release into the atmosphere doesn't stay in the atmosphere, it gets absorbed by the oceans, making the oceans more acidic. And in a more acidic environment any animal that builds a shell or a skeleton can't form. This means by 2070 coral reefs will literally start dissolving. But they will likely die out much earlier than that, due to ocean warming. Scientists are now predicting that less than 10 percent of the world's coral reefs will survive past 2050, as bleaching events become more frequent. Mass bleaching has already claimed large chunks of the Great Barrier Reef.
Corals are a sort of canary in the coal mine, signaling trouble ahead for all life on Earth. There have been five mass extinction in the history of the planet and at least four of them have been attributed to ocean acidification. Now, we're causing the oceans to go acidic faster than at any other time in the history of the planet.
When coral reefs go down they signal the start of a mass extinction in the oceans, and that is something that will affect all of us.
Tiny organisms in the ocean called phytoplankton are responsible for creating most of the oxygen in the air that we breathe. Two out of every three breaths we take come from plankton. Photosynthesizing on a massive scale, plankton are the reason the oceans are considered the blue lungs of the planet. Forty percent of the world's plankton populations are already gone. "We may be losing up to 1% a year because of ocean acidification ... It's like—why would do anything to disrupt the oxygen supply for the planet," asks Louie Psihoyos in Sea of Life.
What most people don't know about ocean acidification is that there's a lag time between the time it takes the carbon dioxide we release into the atmosphere to get absorbed into the ocean. So even if we stopped producing carbon dioxide today the oceans would have decades where they continue to become more acidic—20, or even 30 years. This means if we're going to solve ocean acidification we not only have to stop carbon emissions, we also have to pull carbon dioxide out of the atmosphere.
The filmmakers for Sea of Life visited a marine protected area in Mexico called Cabo Pulmo. The area had once been heavily overfished, to the point where there was almost nothing left. Clearly this couldn't continue, so the citizens decided to create a marine reserve, giving the ocean a break and allowing life to recover. Within the next 10 years they saw a 450 percent increase in biomass in the ocean. The fish came back, and now the waters off Cabo Pulmo are a thriving natural community.
Given the chance, nature will come back. Today, we know that 90 percent of the fish are gone and that 75 percent of the forests have been wiped out. If we let this life come back, we could sequester an enormous amount of carbon, creating a world where all species can thrive.
Sea of Life follows the environmental movement through large rallies in New York and at COP21 in Paris, where instead of celebrating the Paris agreement, long-time environmental activist Emily Hunter asserts that the agreement isn't enough. "We've done over 20 years of campaigning, more than 20 years of negotiations, and if this is the deal that we finally get then we've failed."
The entire environmental movement could be considered a failure. Despite years of campaigning, almost every environmental problem has gotten worse, not better. As Rob Stewart explains in Sea of Life, "Our greatest ambitions on climate change would buy us 1% more time on a hugely degraded planet where we're still fighting each other over what remains. We need to imagine a world that's beautiful enough for us to fight for."
Sea of Life asks audiences to imagine a world worth fighting for. What could this world look like if we got things right? What if we made this planet beautiful for us and all species?
The film features inspiring young activists who are making a difference, including Felix Finkbeiner, whose organization has planted 14 billion trees, and Madison Stewart who makes films to change people's perspective about sharks. The 21-year-old filmmaker behind Sea of Life began working on the movie when she was 16. She believes young people have an opportunity to become heroes for the planet, living lives that are full of meaning and adventure and having an amazing time doing it.
Julia Barnes is motivated by the scale of the problem. The worse things get, the greater the imperative to take action. And now, with all of life on Earth at stake, she believes action is no longer an option.
What is killing coral?
I wish we had an easy, straightforward answer for what's killing corals. We know there are many, many different factors influencing coral abundance, diversity, distribution and health these days, but I think the specific answer varies based on where you are.
Temperatures play a major role at global scales, and then you have all of these other, more local factors like disease, physical impacts of storms, or ship groundings.
We had the dredging of the Port of Miami channel a couple of years ago and that caused a lot of localized mortality due to sediment burial and sediment stress. You also have land-based sources of pollution that can damage by location and nutrient influence that causes algal overgrowth of corals.
Local factors are superimposed on regional factors directly related to global climate change. Changes in temperature, more temperature extremes, acidification of the water, changes in storm frequency and sea level rise— all are at different scales — but they all combine to cause coral mortality.
Factors vary both spatially and temporally, but the outcomes are all the same. Regardless of where you are, we've lost a tremendous amount of coral.
In the face of all those threats, can restoration work?
Historically, restoration was developed and used for acute disturbances. A ship runs aground, and so then there's a recovery, and funds are allocated to recovering the reef structure at a given location, and then corals are planted on top of that. But as global conditions decline for coral reefs, there's now a need to scale up. So, we're not just dealing with the localized impact—we're looking at species declining throughout their range.
We need other tools at larger scales, and that's where coral reef gardening has come into play, because it works at larger scales compared to just dumping cement and rebuilding reef structures, costly endeavors that recover just a very small footprint. We're growing and planting these organisms.
Do you worry about planted coral dominating the reefs?
Initially, these techniques were developed for fast-growing corals. The genus that we're focusing on, Acropora, is threatened, so these are very important reef-building species.
When abundant, they monopolize shallow environments. They form thickets, extensive areas of high-density colonies. That's the way they used to grow, until about three to four decades ago when they got wiped out by disease and other factors. The branching corals that we're working with grow between 10 and 15 cm per branch per year, so that's very fast growth.
Through recent advances in coral aquaculture, we're now also able to grow massive species, the ones that grow very slowly. Mote Marine Lab has developed microfragmentation techniques where they can cut coral colonies very, very small and make them grow very, very fast. Although we focused on branching corals initially, now most of the programs, especially here in Florida, are expanding onto other threatened species.
Can these efforts solve the problem, or are they a placeholder until climate stabilizes?
You hit the nail on the head. One of the early criticisms of reef restoration was the scale issue and spending a lot of resources working on a very small footprint.
We've dealt with that now, over the past 10 years we've expanded to the point where we're growing thousands and thousands of corals—we're planting thousands and thousands of corals—so that issue of scale is no longer a valid criticism.
The other major criticism is that, even though we're planting a lot of corals, we're planting them onto environments where the same stressors that caused their initial mortality are in place. Now there is ocean acidification and increased temperatures, so things have gotten, in some cases, progressively worse.
That is a valid concern if we were just planting corals, but we're not just doing that. We're still concentrating on all of the other aspects of reef restoration, setting up marine protected areas to protect fish stocks and coral impacts, working to curb land-based sources of pollution, and setting up sedimentation and nutrient controls. And then, on a much larger scale, we're all trying to curb carbon emissions, trying to limit the greenhouse impacts and acidification impacts. All these tools just help us buy time.
We're also doing a lot of genomics work to see how corals can increase their resilience. A colleague of mine here at the Rosenstiel School at University of Miami, Andrew Baker, is stress-hardening corals. He works on coral symbiosis, and he found that by applying a little bit of non-lethal stress, he can make corals shuffle their Zooxanthellae, which are the endosymbiotic microalgae that provide energy to the corals. In that process, they're able to uptake Zooxanthellae that are more thermally tolerant. So, through the forced shuffling of symbionts, you may be able to buy these corals one or two degrees of tolerance, so that they become more tolerant to bleaching in future years. That is cutting-edge science.
We're trying to actually find out what makes corals survive, and trying to beef up their defenses and their resilience over time. And that's because we have access to all these coral genotypes through the active propagation from coral gardening.
Reposted with permission from our media associate Nexus Media.
"They promote biodiversity and coastal protection," said Chiara Lombardi, a scientist with the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). "Also, they play an active role in the carbon cycle."
The bad news, however, is that, like coral, they are vulnerable to the ravages of climate change and ocean acidification.
"They become more fragile, and they bleach, and they aren't able to create a healthy habitat for biodiversity," Lombardi said. "Thus, their survival and, as a cascading effect, the survival of the associated species, is at risk."
Lombardi and her colleagues, including Federica Ragazzola, a marine biologist at the University of Portsmouth in the UK, initiated an unusual experiment recently to try to protect these algae—scientific name Ellisolandia elongata—from increasing harm.
Last month, they installed the first of several artificial coralline algae reefs—made of highly elastic rubber material—near real coralline algae reefs in the Gulf of La Spezia, in northwest Italy. The goal is that these plastic mimics—as the artificial reefs are known—which look and move like the real thing, will shelter and host the tiny creatures who typically live on the algae, and also will become scaffolds for real coralline algae to grow.
The 60 synthetic mini reefs, each with 20 fronds, are just 10 centimeters (approx. 3.9 inches) in diameter, making them easy to place in a natural reef. Snorkelers attached the artificial reefs using epoxy resin. Hampered by bad weather, they had to make three separate runs to finish the job. "The resin needs 24 hours to become hard, so if waves occur during this period, the risk of detachment is very high," Lombardi said.
The material's properties are similar to that of the algae and non-toxic to the marine ecology. The mimics won't ultimately become plastic ocean litter. "After one year of exposure, they will be removed and brought to the laboratory" for further experiments, Lombardi said.
The research will "clarify the function of the coralline algae reef as a buffer for diversity, abundance, reproductive, ecological and structural characteristics of the associated fauna," Lombardi said. The results "will be important for the planning of future protection and management strategies."
This is not the first time artificial "substrates" have been used experimentally, but they have never before been made to mimic the properties of natural algae. "The majority of the studies simulating reef are mainly focused on corals," Lombardi said. She stressed the importance of preserving algae.
"They provide services that will benefit human lives," Lombardi said. "They are a resource, not only for marine life. We tend to consider protection of nature very far from human beings—but we are all connected, and it is important to understand this connection. Protecting the natural ecosystem will benefit the lives of all future generations."
Reposted with permission from our media associate Nexus Media.