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Category: Oceans

Recovery, Resilience, and Coexistence: Nature-based Solutions on the Coast

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When it comes to balancing the needs of humans and the needs of nature, “Historically it was ‘develop or conserve’ or ‘develop or restore,’” says Carter Smith, Ph.D., a Lecturing Fellow in the Division of Marine Science & Conservation who researches coastal restoration.

However, according to Brian Silliman, Ph.D., Rachel Carson Distinguished Professor of Marine Conservation Biology, “We are having a new paradigm shift where it’s not just… ‘nature over here’ and ‘humans over here.’”

Instead, conservation initiatives are increasingly focusing on coexistence with nature and ecological resilience, according to this panel discussion of marine science experts during Duke Research and Innovation Week 2023.

Nature-based solutions — protecting and restoring natural shoreline habitats — have a proven role in protecting and restoring coastal ecosystems. According to the International Union for Conservation of Nature (IUCN), “Nature-based solutions… address societal challenges effectively and adaptively, simultaneously benefiting people and nature.”

The panel, moderated by Andrew J. Read, Ph.D., Stephen A. Toth Distinguished Professor of Marine Biology and Professor of Marine Conservation Biology, also included Brian Silliman, Carter Smith, and Stephanie Valdez, a Ph.D. Student in Marine Science & Conservation.

Living shorelines can help protect coastal ecosystems from storms while also offering benefits for climate and conservation. Photos by Carter Smith.

According to Smith, nature-based solutions can “leverage nature and the power of healthy ecosystems to protect people” while also preserving biodiversity and mitigating climate change. She spoke about living shorelines as an effective and ecologically responsible way to protect coastal ecosystems.

“The traditional paradigm in coastal protection is that you build some kind of hard, fixed structure” like a seawall, Smith said, but conventional seawalls can have negative effects on biodiversity, habitats, nutrient cycling, and the environment at large. “In this case, coastal protection and biodiversity really are at odds.”

After multiple hurricanes, living shorelines had significantly less visible damage or erosion than sites with conventional hardscape protection, like seawalls.

Nicholas Lecturing Fellow Carter Smith

That’s where living shorelines come in. Living shorelines incorporate plants and natural materials like sand and rock to stabilize coastal areas and protect them from storms while also creating more natural habitats and minimizing environmental destruction. But “if these structures are actually going to replace conventional infrastructure,” Smith says, it’s important to show that they’re effective.

Smith and colleagues have studied how living shorelines fared during multiple hurricanes and have found that living shorelines had significantly less “visible damage or erosion” compared to sites with conventional storm protection infrastructure.

After Hurricane Matthew in 2016, for instance, both natural marshes and conventional infrastructure (like seawalls) lost elevation due to the storm. Living shorelines, on the other hand, experienced almost no change in elevation.

Smith is also investigating how living shorelines may support “community and psychosocial resilience” along with their benefits to biodiversity and climate. She envisions future community fishing days or birdwatching trips to bring people together, encourage environmental education, and foster a sense of place.

PhD student Stephanie Valdez then spoke about the importance of coastal ecosystems.

Blue carbon ecosystems,” which include sea grasses, marshes, and mangroves, provide services like stabilizing sediments, reducing the destructive force of powerful waves, and storing carbon, she said. These ecosystems can bury carbon much faster than terrestrial ecosystems, which has important implications when it comes to climate change.

In the atmosphere, carbon dioxide and other greenhouse gasses contribute to global warming, but plants pull carbon dioxide out of the air during photosynthesis and convert it to carbohydrates, releasing oxygen as a byproduct. Therefore, ecosystems rich in fast-growing plants can serve as carbon sinks, reducing the amount of atmospheric carbon, Valdez explained.

Unfortunately, blue carbon ecosystems have suffered significant loss from human activities and development. We’ve replaced these wild areas with farms and buildings, polluted them with toxins and waste, and decimated habitats that so many other creatures rely on. But given the chance, these places can sometimes grow back. Valdez discussed a 2013 study which found that seagrass restoration led to a significantly higher carbon burial rate within just a few years.

Sea grasses, marshes, and mangroves provide services like stabilizing sediments, reducing the destructive force of powerful waves, and storing carbon.

PhD Student Stephanie Valde

Valdez also talked about the importance of recognizing and encouraging natural ecological partnerships within and between species. Humans have taken advantage of such partnerships before, she says. Consider the “Three Sisters:” beans, corn, and squash, which Native Americans planted close proximity so the three crops would benefit each other. Large squash leaves could provide shade to young seedlings, beans added nitrogen to the soil, and cornstalks served as a natural beanpole.

Recognizing that mutualistic relationships exist in natural ecosystems can help us preserve habitats like salt marshes. Valdez points to studies showing that the presence of oysters and clams can positively impact seagrasses and marshes. In restoration, it’s important “that we’re not focusing on one species alone but looking at the ecosystem as a whole”—from top predators to “foundation species.”

“There is hope for successful restoration of these vital ecosystems and their potential to aid in climate change mitigation,” Valdez said.

Finally, Prof. Brian Silliman discussed the role of predators in wider ecosystem restoration projects. Prioritizing the protection, restoration, and sometimes reintroduction of top predators isn’t always popular, but Silliman says predators play important roles in ecosystems around the world.

“One of the best examples we have of top predators facilitating ecosystems and climate change mitigation are tiger sharks in Australia,” he says. When the sharks are around, sea turtles eat fewer aquatic plants. “Not because [the sharks] eat a lot of sea turtles but because they scare them toward the shoreline,” reducing herbivory.

However, Silliman said it’s unclear sometimes whether the existence of a predator is actually responsible for a given benefit. Other times, though, experiments provide evidence that predators really are making a difference. Silliman referenced a study showing that sea otters can help protect plants, like seagrasses, in their habitats.

Restoring or reintroducing top predators in their natural habitats can help stabilize ecosystems impacted by climate change and other stressors.

And crucially, “Predators increase stress resistance.” When physical stressors reach a certain point in a given ecosystem, wildlife can rapidly decline. But wildlife that’s used to coexisting with a top predator may have a higher stress threshold. In our ever-changing world, the ability to adapt is as important as ever.

“I think there is great optimism and opportunity here,” Silliman says. The other speakers agree. “Right now,” Valdez says, “as far as restoration and protection goes, we are at the very beginnings. We’re just at the forefront of figuring out how to restore feasibly and at a level of success that makes it worth our time.”

Restoring or reintroducing top predators in their natural habitats can help stabilize ecosystems impacted by climate change and other stressors.

Brian Silliman

Smith emphasized the important role that nature-based solutions can play. Even in areas where we aren’t achieving the “full benefit of conserving or restoring a habitat,” we can still get “some benefit in areas where if we don’t use nature-based solutions,” conservation and restoration might not take place at all.

According to Valdez, “Previously we would see restoration or… conservation really at odds with academia itself as well as the community as a whole.” But we’re reaching a point where “People know what restoration is. People know what these habitats are. And I feel like twenty or thirty years ago that was not the case.” She sees “a lot of hope in what we are doing, a lot of hope in what is coming.”

“There’s so much that we can learn from nature… and these processes and functions that have evolved over millions and millions of years,” Smith adds. “The more we can learn to coexist and to integrate our society with thriving ecosystems, the better it will be for everyone.”

Post by Sophie Cox, Class of 2025

Applying the Ways of the Sea to Outer Space: A Conversation Hosted by Duke’s Space Diplomacy Lab

Whether it was Marco Polo traversing the Silk Road (which was more like Silk Routes), Columbus sailing the ocean blue, or even Moana restoring the heart to Te Fiti; oceans have been integral to our way of life as humans for thousands and thousands of years.

The Silk Road, mapped
The (fictional) story of Moana draws from (true) Polynesian history and seafaring lore

But humans have always been bad at sharing – most wars are fought over territory, land especially. And as time has passed, the things we share as humans has evolved – from oceans and land to the Internet and outer space. So how do you keep things diplomatic? Last Friday, Duke’s Space Diplomacy Lab, co-chaired by Dr. Benjamin Schmitt of Harvard University and Duke’s own Dr. Giovanni Zanalda, hosted a webinar on what space diplomacy can learn from ocean diplomacy. Featuring Dr. Clare Fieseler of the Smithsonian Institution and Dr. Alex Kahl of the National Marine Fisheries Service, the conversation covered everything from zoning to equity to even the lessons we can learn from Indigenous communities.

Sharing data and sharing fish

There are multiple challenges to sharing the world’s waterways. Fieseler did not start out her career studying ocean diplomacy. Initially stationed in the Persian Gulf, building a marine mammal monitoring network, she noticed that the fraught state of politic affairs in the region made it hard to share data on the animals that were washing up on the shore.

Dr. Fieseler presenting

Meanwhile, Kahl, who works in Hawaii as the National Resources Manager at the National Marine Fisheries Service, runs into problems not in sharing data but primarily in sharing fish. “How do you focus on the shared exploitation of a natural resource?” he asked.

Two key themes arose in linking the sharing of the ocean to the sharing of outer space.

First, Fieseler pointed out that engaging scientists can help in transcending politics, something that ocean diplomacy does well. She pointed to efforts to establish a Marine Peace Park between North Korea and South Korea, and that if two of the worlds most polarized countries could come to an agreement in the name of science and human betterment, then “surely other countries can too.”

Second, Kahl remarked, unlike in the ocean, the primary resource in space is, well, space. You need fish to eat to survive – do you need space to survive?   

Centering equity

On the topic of whether we really need space in space to survive, Kahl pointed to the significance that many celestial bodies have in cultures here on Earth, such as in Hawaii and the Pacific Islands. Does interfering with these celestial bodies cross a red line for cultures on Earth? It’s worth noting that as Kahl said, with space exploration, “very few people are profiting,” so balancing the interests of people on Earth as well as in space is important.

Dr. Kahl presenting

Fieseler spoke to the need to build equity in space through some sort of formal agreement, similar to the Law of the Sea. But, she says, that might be skipping a few steps. Right now, “many developing countries can’t even afford to go to space.” How can you build equity in a region where not everyone even has a seat at the table? Kahl pointed out that this marginalization impedes discussions on how to share space – something that should be consensus-driven.

Zoning

As Fiesler remarked, zoning of the ocean has been key to a relatively peaceful sharing of this resource for the variety of uses that people have for the sea. A good example of this is the Antarctic Treaty, which zoned different places in Antarctica for scientific use.

Kahl spoke to being a beneficiary of the Antarctic Treaty – “it reduces bureaucratic burdens, and the collective benefits are also increased.” However, he made the point that the slicing and dicing of space, as with anything, could lead to initial tensions.

Science should have a seat at the table

A central theme that ran throughout the conversation was that, as Kahl put it, scientists “rely on each other to level-set the truth” – even in spaces where they might be in the minority, such as in a room of politicians engaging in diplomatic talks.

Fieseler pointed to how in environmental justice work, her Indigenous colleagues were good at taking the initiative – and finding the urgency – to demand a seat at the table. “As scientists, we sit around, thinking that one day the phone will ring and someone will invite me to be a part of the conversation – but that’s not how it works.” Diplomacy will always be a necessity as we aim to navigate sharing the vast resources at our disposal, but many scientists hope that we won’t forget to center the pursuit of the truth as we make decisions.

Post by Meghna Datta, Class of 2023

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