Historically, oysters were plentiful throughout the east coast of the United States. Folklore of New York Harbor or the Chesapeake Bay tells of specimens as big as dinner plates. Reefs of oysters counting in the hundreds of thousands, and even millions, were common from Maine to Florida to Texas. Today that is not the story. Most of these populations have disappeared.
That’s a shame. These invertebrates possess an ability to remediate water quality problems within estuaries, tidal rivers and basins, inlets and other coastal zones like no other organism – or human technology. Moreover, oysters are a keystone species, meaning that when present within a habitat or ecosystem, they provide the basis for healthy biodiversity. This in turn, offers even more positive attributes to society such as carbon sequestration by aquatic flora, fisheries for game fish, surge protection from storms and climate change protection.
Many reasons caused oysters to vanished, however two major issues contributed to their demise – namely pollution and overharvesting. Other factors played a role such as channelization of waterways and ineffective stormwater management that uses natural estuarine areas as catch basins for runoff. All of these engineered elements of the natural landscape need to be reversed to get back to the plate-sized bivalves.
Even in some of the worse conditions, if they are given a footing to repopulate, these little creatures will colonize into populations in the size of tens of thousands. Colonies of oysters of 10,000 to 60,000 can have an incredibly positive effect on water because each oyster can filter around four gallons of water every hour. For a reef of 50,000 oysters that would mean nearly five million gallons of water per day. With estimates that almost 50 percent of estuarine areas having impaired water quality, man-assisted “oyster-tecture” can be a solution that is low cost with high return. If done correctly, a reef with the measurements of 10 to 20 feet long and 5 to 10 feet wide could be built and installed for the price of….well, almost nothing.
I’ve been involved with a project in Myrtle Beach, South Carolina call Withers Estuary. We have installed two reefs at those dimensions and it cost us not one cent. We had to get the community engaged, and we had to collect oyster shells from local restaurants….and we had to get volunteers to help us install the reef. But that’s good business when community involvement spells community improvement. The tricky part isn’t the final steps of building a reef – it’s getting to the point of making sure an oyster reef is the best way to solve problems. So, out of the success of the Withers Estuary project, I’ve put together a “how to” on oyster-tecture so more people and communities can build green and ecological solutions that will improve property values, enhance water quality, and create other unforeseen benefits at a fraction of the costs of more technological solutions.
The first thing you have to do is determine if the water body is connected to the ocean. Oysters need a very specific level of salinity to survive. Salinity is the amount of dissolved salt within the water measured as parts per thousand. For oysters, the water has to be, at least, brackish –simply saltwater that has mixed with freshwater. If you are not a scientist or an oyster expert, you may be at a loss for how to test salinity levels. For the Withers project, we partnered with Dr. Keith Walters at Coastal Carolina University to help figure this out. Strategic partnerships are essential for community and technical engagement. Oyster restoration is essentially habitat restoration. And though, it is as much an art as a science, the number of factors needing to be understood will take scientific methods.
Once you have discovered that the salinity levels are adequate, the next critical factor is to find a reliable spot within the estuary to plant the reef. Many tidal areas are highly engineered and used as part of the stormwater management plan. This results in large amount of sedimentation and pollutants. The buildup of sediment over time means that the bed of an estuary could be caked with decades of mud. In South Carolina, the estuaries have a special kind of mud called Pluff Mud – which is a kind of airy, lightly packed mud that acts neither as solid ground nor liquid. If you run into this, you will need to make sure the bottom is strong enough to support a reef…if not, the reef will sink. We learned this the hard way. Good ol’ field research is the best way to determine whether a location will support or not support the weight of a reef. During a low-tide event, you and your renewal recruited scientist friend should go to sites for the reef, put on waders armed with poles. You’ll need to wade into the water (if safe) and poke around with your stick. If at low-tide you sink and the pole never really finds the bottom…you can guess that it is not a good spot. It may take you several visits to find an adequate location for installing a reef depending on the size and soupiness of the estuary you are working.
The reef itself can be made of many different materials. Oyster spat (aka, oyster larvae) will attach to just about anything as long as the object is strong enough to support them. During field trips to Withers Estuary, Walters and I found oysters growing on discarded beer bottles, concrete blocks and pieces of wood. An ideal material for a reef is recycled oyster shell. They are coarse, sturdy and when placed in mess bags create innumerous niches for spat to attach and grow. For the Withers project, we coordinate our efforts with recycling programs that work with local restaurants to collect used shells. The shell is free, and reusing a product that is intended for harsh conditions of salty water will allow for longevity for the reefs. There is one catch – over the last several years, a pathogen has been introduced to oyster populations throughout the east coast. Known as Haplosporidium nelsoni, or commonly called MSX, this protozoan has been responsible for periodic, large-scale oyster mortality in estuaries. South Carolina has strict rules about not allowing outside living oysters to be planted in its native waters. To guarantee that efforts to restore the oysters is not inadvertently killing them off, you have to make 100 percent sure the shell is exposed to the sun and weather, away from water, for 6 to 12 months. This will make them safe for building reefs.
The last step is the easiest. Now that you know where to put the shell, you have sanitized them, and you have bagged them in mess bags. You need only gather 10 to 12 people to place the bags into the estuary. We’ve enlisted local volunteers and Boy Scout troops to help us in the past. It’s a great way to introduce the community to a worthwhile activity. Once the bags are stacked in a rectangular shape in the water, the only thing to do is wait for the spat to attaching and grow. It takes about a year, after which you should look for small adolescent oyster that resemble fingernails. It’s best to develop a community program that installs a new reef every spring to continue engaging the community and make sure your spot is working. Overtime, you will need to investigate other ways to improve the water quality and ecological health of your local estuary. These natural eco-zones are critical for providing community-based climate change adaptation, strong tourism and biodiversity. Oyster-tecture can be the foundation in which we rebuild a thriving natural landscape that is good for people and the planet.
This guest post was written by Neil Chambers, LEED AP, Founder and CEO of Chambers Design. His oyster-tecture project was highlighted at The Economist magazine’s conference on “Intelligent Infrastructure.” His new book, “Urban Green: Architecture for the Future,” will be released in July.
Image credits: (1) Withers Estuary oyster reef, (2) Measuring water salinity, (3) Oysters in the grass / Dr. Keith Walters