April 13, 2024

How Tiger Sharks Using Cameras Revealed the World’s Largest Seagrass Ecosystem

Editor’s Note: Call to Earth is a CNN editorial series committed to reporting on the environmental challenges facing our planet, along with the solutions. Rolex’s Perpetual Planet initiative has partnered with CNN to promote awareness and education on key sustainability issues and to inspire positive action.


The largest predator in tropical seas, tiger sharks are notoriously fierce. They can grow to more than six meters (20 feet), have sharp serrated teeth, and are second only to great whites in the number of reported attacks on people. But in the Bahamas, tiger sharks have taken on a less ferocious role, as assistants to marine scientists.

Between 2016 and 2020, a team of researchers attached camera-equipped tags to tiger sharks so they could see the ocean floor from a new perspective. The data collected revealed what is the largest known seagrass ecosystem in the world, an area of ​​up to 92,000 square kilometers (35,000 square miles). in the Bahamas. According to their study, published in 2022, this expands the total known global seagrass coverage by more than 40%.

This is significant as seagrasses trap and store huge amounts of carbon in sediments and are therefore a vital tool in mitigating climate change.

Austin Gallagher, one of the report’s co-authors and founder and CEO of ocean research organization Beneath the Waves, believes tiger sharks and other marine life can help scientists map ocean ecosystems and lead to other significant discoveries. As guest editor of Call to Earth, he spoke to CNN about what it’s like to collaborate with tiger sharks and the importance of protecting the ocean’s carbon sinks.

The following interview has been edited for length and clarity.

CNN: When did the idea of ​​putting a camera on a tiger shark come about?

We’ve been putting cameras on animals for decades in the scientific community, and we’ve been doing it in the shark space for many years. So it wasn’t completely new, but we wanted to advance our work with tiger sharks to better understand what a day in the life of a tiger shark was like. To do this, we needed to be able to see what the animals saw, because we can infer all kinds of patterns based on their movement: where they go and how long they spend in certain areas and habitats. When we did that, it opened a whole Pandora’s box of new questions and ended up setting us on a path of radical discovery here in the Bahamas.

CNN: What did you discover from the tiger shark data?

We knew that tiger sharks spend a lot of time in the shallow water carbonate beds here in the Bahamas and we knew that there is an extensive seagrass ecosystem here, but that only happened when we got the data from those camera-equipped tiger sharks. that we really saw how important and expansive seagrasses can be. The light bulb came on for the first time: we need to map the amount of seagrass here.

We knew we needed to map it from space, because although tiger sharks gave us a dozen or more good tracks with these cameras, we had to use Earth-orbiting satellites and a remote sensing approach to map how much was there. . It would never be possible, as humans, or as tiger sharks, to occupy the entire exclusive economic zone of the Bahamas. So we did that and we were able to map it. We put divers in the water to validate all the predictions from space, took photos of the seafloor, and then used more tiger shark data, including 360-degree camera tags that gave us a complete, comprehensive look at what the animals were watching.

It ended up validating a prediction of up to 93,000 square kilometers (35,000 square miles) of the seagrass ecosystem here in the Bahamas, making it by far the largest on Earth. It was hidden in plain sight.

CNN: What else is there to discover?

We are just at the beginning of understanding how valuable and important this seagrass asset is and what role tiger sharks, sea turtles and other threatened biodiversity play in this relationship. And let’s also not forget humans and the role we play in the future in preserving these ecosystems.

Mapping and discovering them is just one part of it. Then it’s creating new protections around them and working with governments and environmental decision-makers to actually put all this data into the right packages and submit it to the right bodies that will ultimately issue things like carbon credits that can be used to leveraging protections, but also creating financial benefits and, ultimately, long-term financial returns for places like the Bahamas.

CNN: What is blue carbon and why is it so valuable?

Blue carbon is a term for all the carbon that ends up in the ocean. It happens naturally and is stored and sequestered in the ocean in its various sediments, mainly through plants – things like seagrasses, mangroves, salt marshes. These are what we call blue carbon ecosystems, and through natural processes like photosynthesis, these plants sequester and store enormous amounts of carbon – significantly more than their terrestrial counterparts.

If we want to try to create new protections for the ocean, if we want to try to build resilience, especially in low-lying countries and small island developing states, we have a real goal of building resilience in place of climate change. One of the ways we can do this is by working in partnership with nature: seagrasses, mangroves, are what we call a nature-based solution to climate change. If we want to try to improve coastal protection and create benefits for communities and biodiversity, going out and quantifying how much carbon and how large it is is extremely important for ocean research.

CNN: What is the ultimate goal of your research and scientific work?

The ultimate goal of the work I’m doing is to create empathy for the ocean and also preserve what we have for future generations. Living harmoniously with these ecosystems, finding ways to live harmoniously with sharks, protecting these ecosystems like seagrass. It’s about creating marine protected areas, it’s about improving existing conservation measures for threatened species like sharks, but it’s about ensuring that the legacy of these incredible ecosystems remains as intact as possible for as long as possible.

Leave a Reply

Your email address will not be published. Required fields are marked *