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Large Artificial Reef Shows Promise for Carbon Capture

April 2024 Issue

Diver maintaining reef
Courtesy Curtis Hayungs

Thirteen miles off the coast of South Padre Island, the 1,650-acre Rio Grande Valley Reef is the largest and most complex artificial reef off the Texas coast. It has been constructed from sunken vessels, concrete rail ties and cinder blocks, and the variety of reef materials provides habitat for marine animals of all sizes and stages of life.

The reef is providing other benefits, too. It is capturing and storing carbon in significant amounts, illustrating the promise of artificial reefs as a tool to combat climate change, according to researchers at the University of Texas-Rio Grande Valley.

“The early data that we are seeing is delivering some encouraging results — the sponges and soft corals that cover the reef do contain high amounts of carbon,” says professor Richard Kline, who is conducting a two-year study to determine the carbon capture potential of artificial reefs.

The study, which is supported by Friends of the RGV Reef with a grant from Enbridge, is the first of its kind. “UTRGV's research is the most comprehensive study in the world to determine the ability of artificial reefs to capture or trap carbon and maybe provide a solution in dealing with our real-life climate challenges,” says Gary Glick, president of RGV Reef.

Over the last few years, the floor of the Gulf off South Padre has been transformed with the addition of decommissioned ships, concrete culverts, reefing pyramids and tens of thousands of cinder blocks. The goal is to create homes for fish and to improve Gulf fishing. The reef has already brought back substantial populations of fish and increased other sea life. The Texas Parks and Wildlife Department manages and oversees artificial reefs in Texas.

“There weren't very many fish here before we started putting this reef down,” Kline says. “Now we've got plenty. Every time we go out there we count thousands of fish.”

The reef has grown to about the same size as the town of South Padre. It has been built with graduated stepping stones of increasingly complex and taller habitat to carry multiple species of fish through their life cycles. By including complex materials of different sizes, the reef provides habitat for snapper of all ages and sizes, in addition to habitat for hundreds of other species that frequent the reef.

Once the reef was established and attracting fish and other creatures, researchers turned their attention to the prospect of carbon capture.

“The area has all this biomass that wasn't there before,” Kline says. “It's got carbon. All the bodies of the fish and all the bodies of the encrusting organisms such as sponges, sea fans, sea whips, barnacles, all those things actually derive all their energy from what's coming by the reef. And all of this is basically sun-derived energy that's pulling carbon dioxide out of the water column. So now we've developed this food chain that's actually bringing carbon into the reef and holding it there.”

Kline and his students are collecting samples to see how much carbon has built up on the reef.

“This is the so-called ‘blue carbon,’” Kline says, “which is the carbon held within the oceans.”

Carbon “sinks” such as seagrass beds and mangrove forests capture and hold carbon and thereby remove carbon dioxide from the atmosphere, helping combat climate change.

“Initial data shows that the reef's structure, the bottom or sediment, and the biomass, fish and other marine life in the water column are indeed capturing or trapping CO2, a known greenhouse gas, in some significant proportions,” Kline says.


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