{"id":8057,"date":"2014-06-03T15:31:59","date_gmt":"2014-06-03T20:31:59","guid":{"rendered":"http:\/\/college.unc.edu\/?p=8057"},"modified":"2024-07-02T14:38:13","modified_gmt":"2024-07-02T14:38:13","slug":"oysters","status":"publish","type":"post","link":"https:\/\/collegearchive.unc.edu\/?p=8057","title":{"rendered":"Oysters: Better than bulkheads"},"content":{"rendered":"
\"Oyster<\/a>
Oyster reefs could provide a cheaper alternative to bulkheads while also helping increase the number of fish in the water. (photo by Emily Woodward)<\/figcaption><\/figure>\n

Every time a wave hits the shore, it erodes a bit of sand or rock. Unless something like a river deposits new material faster than the waves can pick it up, the land disappears inch by\u00a0inch.<\/p>\n

Behind the thin (and thinning) protection of the Outer Banks, North Carolina\u2019s inner coast erodes between one and seven feet a year, says marine scientist Tony Rodriguez, who is based at the UNC Institute of Marine Sciences. We can\u2019t stop erosion, but Rodriguez thinks we can slow it down \u2014 with\u00a0oysters.<\/p>\n

Oyster reefs, which are piles of oysters attached to each other or to rocks and other hard material, were once plentiful in the sounds between the N.C. shoreline and the Outer Banks. They\u2019ve declined because of harvesting, disease, and runoff from human habitation. But there are still lots of oyster larvae out in the water, Rodriguez says. They just need something to latch on\u00a0to.<\/p>\n

More than 15 years ago, researchers at the Institute of Marine Sciences (IMS) built several reefs just six inches high in the waters near their facility in Morehead City, N.C. Other than taking some samples, the scientists left the reefs alone for more than 10\u00a0years.<\/p>\n

By then, Rodriguez had arrived at IMS. \u201cTwo researchers here said, \u2018Come out and let\u2019s look at these reefs \u2014 let\u2019s see how they\u2019ve done,\u2019\u201d he says. \u201cSo we spent a couple of days looking. And we noticed that some of the reefs had grown very large.\u201d Some had grown between one and two feet since they\u2019d been built in the late\u00a090s.<\/p>\n

Rodriguez, Niels Lindquist, and Joel Fodrie were fascinated \u2014 all the research they had read on oysters said that reefs just don\u2019t grow that quickly. So they built 32 new, small reefs in different parts of the water and made detailed maps of all the reefs, old and new. They left the reefs alone for two years, then came back and made new\u00a0measurements.<\/p>\n

\"From<\/a>
From left, Tony Rodriguez, Robin Matthues and Emily Elliott collect cores in Albemarle Sound. (Photo courtesy of UNC Institute of Marine Sciences)<\/figcaption><\/figure>\n

They found that reefs that were out of the water at low tide (in what\u2019s called the intertidal zone) grew much taller than reefs that were always underwater (the subtidal zone). \u201cYou would think that since oysters eat by filtering the water, they\u2019d want to be underwater all the time,\u201d Rodriguez says. \u201cBut they have predators in the water, and barnacles that want to attach to the reef, so being out of the water part of the time is good for\u00a0them.\u201d<\/p>\n

The newer reefs in the intertidal zone grew an average of more than four inches each year. \u201cThey grow really quickly until they reach the point where they\u2019re out of the water more than half the time,\u201d Rodriguez explains. \u201cIf they\u2019re exposed for too long, they dry\u00a0out.\u201d<\/p>\n

That\u2019s the great thing about oyster reefs as erosion protection \u2014 as the sea level rises, more of the reef is underwater for longer periods of time, Rodriguez says, giving it the opportunity to keep growing. This means that oyster reefs could be a lower-cost alternative to bulkheads, which have to be repaired or replaced as they\u00a0deteriorate.<\/p>\n

\u201cThere are lots of predictions of where the level of the sea will be in 2100,\u201d Rodriguez says. \u201cSome of the highest predictions are about six and a half feet. A lot of predictions are about three feet, and then some predictions are lower than that. Our reefs have the potential to grow four inches a year.\u201d Four inches each year is more than enough growth to keep up with even the highest predictions of how much the sea will rise by\u00a02100.<\/p>\n

Rodriguez especially wants to see more reefs in areas like Back Sound, North Carolina, where the shoreline is eroding about three feet a year. \u201cThere are a lot of boat wakes, and that increases erosion,\u201d he says. \u201cOyster reefs could provide\u00a0stabilization.\u201d<\/p>\n

\"Rodriguez<\/a>
Rodriguez and a team of researchers found out that reefs can grow four inches a year\u2014fast enough to protect against erosion and keep pace with sea level rise. (photo by Emily Woodward)<\/figcaption><\/figure>\n

Some parts of North Carolina\u2019s inner coastline that are protected by the Outer Banks will see more erosion with time, Rodriguez says. \u201cRight now, Pamlico Sound has almost no tides. But the Outer Banks are narrowing \u2014 eventually they\u2019ll breach in a storm because they\u2019re so narrow, and suddenly the sound will become more tidal.\u201d One silver lining: the increasing tides might make the habitat even better for\u00a0oysters.<\/p>\n

Oyster reefs are good for more than just shoreline protection. They also provide shelter for the fish and shrimp that North Carolinians catch, sell, and eat.<\/p>\n

Rodriguez and his team are trying to find just the right distance to build oyster reefs from shore. Build too close to land, and the reefs don\u2019t grow well \u2014 maybe because the oysters don\u2019t have enough water flowing over them, or maybe because crabs eat them. \u201cIf you build at the right distance, the reef will still grow, and it will still protect the shoreline from erosion,\u201d Rodriguez says. \u201cWe\u2019re trying to find that magic distance so we can make a set of guidelines on how to protect the\u00a0shoreline.\u201d<\/p>\n

IMS builds its reefs out of piles of oyster shell. \u201cCanneries shuck oysters and discard the shells,\u201d Rodriguez says. \u201cWe buy these piles of shell from them, it\u2019s delivered in trucks, and we haul it out to the site and spread it in these areas that we\u2019ve mapped out. Once that dead shell is out there, the oyster larvae are just in the water, and they settle on the shell. Then the next year, they\u2019re fairly large oysters.\u201d Oyster reefs can also be made more cheaply from concrete topped with a layer of shell, Rodriguez\u00a0says.<\/p>\n

Another part of the oyster habitat Rodriguez wants to figure out is how marshes help, and hurt, oyster reefs. IMS and other organizations promote planting marshes to prevent shorelines from eroding<\/a>. Oyster reefs, in turn, can protect the\u00a0marshes.<\/p>\n

\u201cIt\u2019s difficult for us to grow oyster reefs next to marshes,\u201d Rodriguez says, \u201cbut we see oyster reefs growing that way naturally. We\u2019re trying to figure out why that is. Maybe the reef established itself and grew big, and then the marsh established itself later?\u201d The researchers are studying how to grow healthy marshes and oyster reefs side by\u00a0side.<\/p>\n

\u201cI\u2019d like to see us build fewer bulkheads and try some of these more natural solutions,\u201d Rodriguez says. \u201cIf you\u2019re building a house in low-elevation land and you\u2019re worried about shoreline erosion\u2014think about constructing an oyster\u00a0reef.\u201d<\/p>\n

Story by Susan Hardy, <\/em>Endeavors magazine<\/em><\/a><\/div>\n
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Learn more:<\/strong><\/p>\n

\n
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“Oyster reefs can outpace sea-level rise”<\/a><\/div>\n
Rodriguez Lab<\/a><\/div>\n
Tony Rodriguez on Public Radio East<\/a><\/div>\n
<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

North Carolina\u2019s inner coast erodes between one and seven feet a year, says marine scientist Tony Rodriguez. We can\u2019t stop erosion, but Rodriguez thinks we can slow it down \u2014 with 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