In 2015, a video of hammerhead sharks and silky sharks swimming in an underwater volcano, with high water temperatures and acidity levels, went viral. Nicknamed “shark shark”, people wondered if there was any place where sharks couldn’t survive. (Spoiler alert: There are a few, like Mount Everest and your backyard pool.)
Silky sharks, Carcharhinus falciformis, were one of the species identified to swim in … [+]
Sharks (and a six-gill ray!) Were first found inside the volcano’s caldera by Brennan Phillips five years ago after the eruption of the underwater Kavachi volcano, which has been built above sea level by at least nine times since 1950. Located in the Solomon Islands (south of the Gatokae and Vangunu islands), it is known as one of the most active underwater volcanoes in the Pacific Ocean, although it has rarely been observed. Also known as Rejo te Kvachi, or “Kavachi Furnace”, it is said to be named after a local sea god. It seems fitting that sharks, who are also revered as sea gods in some parts of the world, lived here so many years ago. But what were they doing there? And how long could they survive here?
“The idea that there are large animals like sharks hanging out and living inside the caldera of the volcano conflicts with what we know about Kavachi, which is that it erupts,” Phillips, a doctor in biological oceanography. University of Rhode Island student said in a YouTube video. According to Dr. Michael Heithaus of Florida International University, the discovery shed light on the importance of underwater volcanoes in the marine ecosystem. “Seeing that got me thinking about how important volcanoes are to life in the ocean,” Heithaus told Newsweek. “And it’s not just about active volcanoes. It’s about the habitat they create in the middle of the ocean. “
More than 70 percent of all volcanic eruptions occur underwater, but researchers know little when it comes to understanding the behavior of the underwater volcano. While volcanic eruptions cause significant geological hazards, underwater volcanoes like Kavachi play an integral role in the way our planet works. “If there had been no volcanoes in certain areas, there would be no reefs and no land,” Heithaus continued. “That would mean that the shark species that need those habitats would not be able to live in those areas without the presence of a volcano.”
Sharks were first found inside the caldera of the volcano by Brennan Phillips five years ago after … [+]
The 2015 shark video has reappeared in a National Geographic documentary as part of “Sharkfest,” the three-week show dedicated to shark science and discoveries from around the world. The episode will focus on the extraordinary relationship between these predators and underwater volcanoes, with Heithaus traveling to various locations around the world to see how different species of sharks coexist with the unique conditions that underwater volcanoes provide. One of its stops is off the coast of Reunion Island, a French overseas territory in the Indian Ocean that is famous for its volcanoes, rain forests, coral reefs, and beaches. Here, she found bull sharks taking advantage of the turbulent water caused by the underwater volcano, using it as an invisibility cloak to better ambush the prey.
On the north of Guadalupe Island, a volcanic island located off the western coast of the Baja California peninsula, researchers found seals taking advantage of the island’s resources, and seal pups are an easy meal for sharks. According to Heithaus, volcanic islands like Guadalupe attract sharks because of the abundance of nutrients that flows into the surrounding water, helping to drive the environmental food chain from the bottom up. “And where you have a lot of food, you tend to have a lot of sharks, if there is not too much fishing to reduce their populations,” she said. According to the scientist, active underwater volcanoes like Kavachi also help supply nutrients to the surroundings, attracting large predators such as sharks. But what if it erupts? Well, Heithaus says that warm water can be used by pregnant women as a nursery area.
In the north of the island of Guadalupe, a volcanic island located off the western coast of Baja Mexico … [+]
It was previously unknown how vital this habitat was to some species of sharks. But, it makes sense according to the scientist. “Most of the open ocean is a place without a ton of food,” Heithaus explained. “In the open ocean, it is volcanoes that have created most of the land. So at the base level, many sharks depend on volcanoes in ways that most people would not think about.” Since this expedition, Heithaus has continued to study the behavior of sharks in relation to this habitat. “A big part of that work is understanding what determines where sharks occur naturally. The types of islands they associate with, including volcanoes, are part of that puzzle. Ultimately, what I really want to know is when Where and why sharks are important to the health and function of ecosystems so that we can begin to restore their populations and functions in the many places where their populations have crashed. “
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