TX - Texas's largest artificial reef could help capture carbon
The 1,650-acre Rio Grande Valley Reef has helped to restore the waterways off the coast of Texas. Could it help capture carbon, too? Researchers from the University of Texas Rio Grande Valley have been studying the largest artificial reef off the Texas coast. A year in, the results are promising.
Twelve miles off the coast of Texas, an intricate arrangement of 76 million tons of man-made material rests on the ocean floor. Known as the Rio Grande Valley Reef (RGV Reef), the artificial reef spans 1,650 acres and is the largest such reef off the Texas Coast. It’s made up of half a dozen sunken vessels that range from 100-foot tugboats to decommissioned shrimp haulers, cinder blocks, and about 7 miles’ worth of used concrete railroad ties donated by BNSF railway, which operates one of the largest freight railroad networks in North America.
Over the past year, the reef has been the subject of an ambitious, first-of-its-kind study. Artificial reefs have been vaunted for decades: They can help increase fish populations by restoring natural habitat that’s been lost to climate change; they can promote conservation efforts; and in the right conditions, they can double as natural breakwaters and help fight coastal erosion. In the U.S. in particular, they are also a magnet for recreational fishing, which in 2011 generated $15 billion in state and federal taxes.
Could they sequester carbon, too?
The two-year study, which is currently at the halfway mark, points to a yes. Over the past 12 months, researchers from the University of Texas Rio Grande Valley have found that the RGV reef is indeed sequestering carbon. The exact amount, and whether it is enough to make a significant impact, will have to wait until the study complete next year. But if the findings are conclusive, they could lead to the building of more artificial reefs—provided they’re not made of subway cars, because that most definitely failed.
Artificial reefs are complex underwater cities. They have to be made of the right materials and placed in the right locations to attract the right kinds of marine species. They also have to resist water currents and the constant threat of corrosion, making old vessels, shipwrecks, and objects made of concrete and steel (which are heavy and don’t rust) much better contenders than stainless steel subway cars—or even worse: tires.
Curtis Hayungs, who is the director of the non-profit Friends of RGV Reef, remembers “not one fish in sight” when his team sank the first vessel back in 2015. Just two days later, he told me he found himself taking videos of “thousands of fish and 15 to 20 species.” Over the next eight years, the wasteland he first encountered has metamorphosed into a thriving ecosystem with more than 100 species of fish and 300,000 red snappers in just one of the many micro-habitats within the reef. (Various teams have attempted to count fish over the past two years, but the process is far more complex than your typical bouncer with a tally counter.)
To understand how reefs capture carbon, it’s important to take a step back and understand the role that fish and other marine species play in the carbon cycle. Like plants and trees, which capture carbon through photosynthesis then store it in their biomass, fish store carbon in their tissues. The process starts on the surface, usually with phytoplankton. Then, as small fish eat the plankton, and bigger fish eat the smaller fish, the carbon is transferred from one organism to another.
When a fish dies, their organic matter sinks to the ocean floor in a process that bears the oddly poetic name of “marine snow.” There, the carbon is locked into ocean floor sediments “for as long as we can imagine,” says Richard Kline, a professor of environmental and marine sciences at the University of Texas Rio Grande Valley, who is leading the study.
