Could oysters be the new corals of climate conservation?

Scientists Announce That The Great Barrier Reef Is Officially Terminal.” This is the jarring headline for a recent article citing some of Australia’s top coral researchers on the realities of one of the world’s most coveted natural systems. This type of prognosis has become eerily familiar in recent years as we’ve learned about the resounding effects of climate change in so many of our systems. As far as marine systems go, coral reefs are the face of marine conservation — and with good reason! Coral reefs are beautiful, diverse, and provide crucial ecosystem services for nearby communities. However, less sexy systems, like oyster reefs, fulfill all of these purposes as well (and even more!) and are being hit just as hard by climate change and overexploitation without receiving the same attention. Refreshingly, the outlook seems promising for these uncharismatic bivalves– initial restoration efforts are already paying off.

While local restoration has proven helpful for oyster reefs on a small scale, there is still much work to be done! With a bit of publicity and some good old TLC, we could save the oyster reefs in all their smelly glory!

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Oyster reef off the coast of Georgia, USA. Source: Daniel Harris, PhD student at UGA)

The Merits of Mud

Oyster reefs line both coasts of North America and occur mostly in coastal wetlands. Many of these reefs are intertidal, meaning they spend about half of their time above water and half below. This dual nature makes oyster reefs incredibly valuable to coastal ecology, stability, and economics.

Ecology: Oysters and corals are both ecosystem engineers because of their critical roles in structuring and maintaining their environments. Oyster reefs improve water quality by filtering excess nutrients out of the water column and depositing unused nutrients into the sediment underneath them. In fact, a single oyster is able to filter up to 50 gallons of water per day. A whole reef, comprised of thousands of oyster, provides an enormous amount of filtration that creates cleaner water that other organisms depend on for habitat.

In addition to improving water quality, the oyster reefs themselves serve as essential habitat for many marine invertebrate species. Their complex structure provides shade and refuge for mobile organisms and perfect settling conditions for sessile, or immobile, ones. This produces a highly diverse community on and around oysters, and attracts animals higher up in the food chain to come into the reefs to hunt for food.

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American oystercatcher feeding in an intertidal oyster reef in Texas, USA. Source.

Coastal Stability: Much like coral reefs, oyster reefs provide a physical buffer to nearby land, protecting it from erosion and flooding. As oysters grow vertically on top of one another they form a sort of bio-wall that absorbs wave energy moving inland. This is critical for preventing erosion damage from storms and boat wakes in coastal regions. They also protect other coastline stabilizing species, including sea grass and marsh grass, which grow in the nearby upper intertidal zone and depend on oyster reefs to slow down powerful waves.

Economics: Though not much fun to snorkel on, oysters reefs contribute heavily to coastal economies. The US consumed about 40 million lbs of oysters in 2010, the vast majority of which came from our own coasts. This high demand has created a new industry for oyster aquaculture, which translates into massive revenue in coastal communities and less harvesting pressure on naturally occurring oyster reefs. By increasing reliance on aquaculture oysters, wild populations have begun to recover from the overharvesting of previous centuries and sustainable harvesting has become a reality. Beyond the oysters themselves, the reef’s ecological appeal has economic payoffs.  Since a single reef can provide habitat for over a ton of fish and seafood, reefs also present excellent opportunities for recreational anglers to catch commercially valuable fish.

Successes in Conservation and Restoration

Because oysters have such a profound impact on their surrounding environment, conservation of coastal ecosystems often begins with oyster reef restoration. The National Oceanic and Atmospheric Association (NOAA) and The Nature Conservancy are two large-scale groups that have been working on spreading awareness and setting restoration plans in motion on US Coasts. But large scale change requires on-the-ground mobilization that starts in small coastal communities.

Several groups in the Southeastern US are working with state and national agencies to ramp up local awareness. Dr. Linda Walters, a professor at the University of Central Florida, has been working on oyster restoration for 15 years and has seen the improvement that can come from dedicated conservation and restoration efforts. Originally contracted to diagnose the cause of oyster habitat loss in Florida’s Indian River Lagoon (IRL), she now spends her weekends laying out foundational oyster material and monitoring restored reefs. Over a decade of records show the return of fish, birds, and crabs along with consistent oyster growth on restored reefs. In addition to her own lab team, Dr. Walters has recruited 57,000 people from nearby communities to help with monitoring and restoring oyster reefs in the lagoon. Having moved thousands of pounds of oyster shell and planted hundreds of mangrove seedlings, this ability to harness the excitement and energy of the public is the force behind her success. She has also created a mobile app that shows recreational boaters where to navigate around oyster and seagrass beds, protecting the established systems in the lagoon. A testament to the potential of an aware and involved community, Dr. Walters’ work is a glimpse at what could become of increased investment in oyster restoration.

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Oyster restoration sign in Virginia. Source.

Go Forth and Restore

Groups like Dr. Walters’ are popping up in communities all over the US coasts. With these efforts, we are beginning to see recovery in restored oyster reefs, seagrass meadows, and riverbanks. The importance of these ecosystems and the species interactions that drive them makes this job complicated and intricate, but all the more essential. Though these drab and jagged reefs lack the obvious aesthetic appeal of corals, there is an understated, smelly beauty to these brilliant coastal keepers and it merits protecting. So, next time you’ve got the weekend off, see if you can get your feet wet with a local reef monitoring group. You might be surprised by how beautiful oysters can be, and, hey, everyone loves a good mud fight!

About the author:

image03 Kaleigh Davis is a lab manager in the biology department at the University of Central Florida. She graduated from the Odum School of Ecology in 2015 and is a lover of all things aquatic. She is a student at the University of British Columbia pursuing a PhD in marine ecology. Other life goals of hers include beating Oprah’s marathon time and learning to do a headstand. For now you can find her sipping on coffee at all hours of the day or zigzagging around town watching birds overhead. Get in touch with Kaleigh at kaleighedavis@gmail.com. More from Kaleigh Davis.