Restoring the “Coral Reefs” of the Chesapeake Bay

Restoring the “Coral Reefs” of the Chesapeake Bay Rebuilding the Reefs Support Efforts to Restore Three-Dimensional Reefs to the Bay cbf.org/oysters The Benefits of Oyster Reefs Structure and Flow Habitat and Diversity Clean Water Number of Organisms in One Square Meter of Oyster Reef Three-dimensional reef Oyster reefs are more than When oysters and other Un- systems affect the physical just mounds that change reef species feed in the Restored Restored environment within the water flow. The intricate currents, they filter the water Black-clawed 108 3 Bay in the same way that latticework of shells provides for small particles, usually Mud Crab mountain ranges affect diverse habitats for many microscopic plants called weather patterns. Reefs small plants and animals phytoplankton. A single Flat Mud Crab 90 1 interrupt currents, speeding that make their homes on oyster can filter up to fifty them up and creating reefs. Some attached gallons of Bay water a day. Grass Shrimp 40 1 turbulence behind the reefs. animals, such as barnacles, They remove algae, bacteria, Many reef organisms have mussels, and bryozoans, lie and bits of decayed material. Scud 43 2 evolved to take advantage flat against the oyster shell. Oyster feces and the other of such currents and Others like redbeard sponges, matter they discard fuel Soft Shell Clam 122 42 are less abundant or non- flower-like anemones, and the reef community where existent in a flat habitat. We feathery hydroids branch out bacteria convert the nitrogen Barnacle 3040 89 know that oysters thrive at into the water. Mobile it contains into a harmless the tops of three-dimen- invertebrates such as mud form. It has been estimated White Anenome 74 24 sional reefs where faster crabs, oyster drills, and grass that the filtering ability of currents bring more food, shrimp inhabit the nooks the Bay’s oysters was Sites restored with high and mud and silt can’t bury and crannies. Small fish— diminished by 99 percent densities of oysters can them. Reefs also increase including blennies, gobies, due to their depletion and have ten or twenty times as many organisms as oxygen levels as the currents and skillet-fish—are also the destruction of their unrestored sites. Three- flowing around them mix common on reefs. The reefs. The loss of this major dimensional substrates oxygen down into the water abundance of life draws natural filter compounds like reef balls can double column. One scientist called larger animals such as the problems caused by or triple the surface area for oysters and the reef vertical reefs striped bass and blue crabs nitrogen and phosphorus community to inhabit “an organizing force for that come to the reefs pollution and the over- compared with flat bottom. the estuarine system.” to feed. Oyster reefs are like abundance of phytoplankton Chart adapted from W.S. Rodney coral reefs in the way they it causes. and K.T Paynter 2006 support a diversity of life. Black sea bass, reef-dependent fish not seen in the Choptank River “ The abundance of in generations, now frequent the oyster-covered reef balls that were placed in the Cook’s Point Sanctuary in the lower river. wo hundred years oysters is incredible. ago a journey up the Chesapeake Bay There are whole required more careful navigation. Instead of a flat banks of them so sandy surface, the bottom that the ships must was rich with oyster reefs extending to the surface. It avoid them.” was common for these reefs Francis Louis Michel, a visitor to to pierce the surface at low the Chesapeake Bay in 1701. tide. Although memories of these reefs are gone, it wasn’t very long ago that When the colonists first these great reefs, like the arrived, a massive reef barrier reefs of Australia, system extended throughout dominated the underwater most of the Bay and its landscape in the Bay. tidal tributaries. Then modern technology came along Unfortunately, we have and scraped them away. Trying to Turn the Tide: Bringing grown accustomed to Most of the reefs are now Back the Beds is Not Enough thinking of a largely flat gone. What was once a bottom beneath the Bay’s three- dimensional aquatic Most often, oyster resto- Today, alternative materials surface. We talk of “oyster jungle, is now a flat desert ration involves spreading like concrete, granite, beds” and “bars.” But this is by comparison. Increased a layer six to 12 inches thick and fossilized oyster shell not the natural state. Oysters harvesting began to shrink of shell or other material must also be used to grow vertically, one on top of the reef system about two on which hatchery-produced provide enough substrate the next, reaching upward hundred years ago, and baby oysters are planted. for reef restoration. through the water. When little is left of it today. The This approach is successful they spawn, they produce widespread use of oyster at establishing high den- Reefs as Part of tiny larvae that drift with the dredges during the post-Civil sities of oysters and a a Network currents for a few weeks War oyster boom hauled community of asso ciated Piling up alternative material and then settle and attach so many oysters from the organisms. But it does not or placing concrete reef to other oysters. Over bottom that the Chesapeake create the very important balls or other reef structures thousands of years, these supplied two-thirds of all vertical structure that is a practice often used “communal” animals that the oysters eaten around restores the bottom topog - for building artificial reefs cluster together in colonies the world. raphy and reef habitat to attract fish. They may created a mountainous that once was common in provide hard surfaces for landscape that lined the the Bay and its tributaries. oysters, but they’re usually Bay’s channels and spread not located or built with toward its shores. We Need Scaffolding oyster habitat in mind. For The scale of the once-booming It took thousands of years instance, if there are no oyster fishery is evident from for the Bay’s reefs to grow existing oyster reefs nearby, this shell pile of a Virginia oyster processing plant (circa 1900). naturally. Fully restoring there will be no supply of reefs will require us to create oyster larvae to populate a vertical structure on the reef. In the natural state, bottom where oysters can oyster reefs form networks grow in an optimal habitat. of complex habitats that When available, shell has feed one another as currents been used to create vertical move larvae and small relief, especially in Virginia. organisms throughout But oyster shell is in short the system. supply. For centuries it was used for making mortar and roads before its value to the Bay was understood. The Chesapeake Bay Foundation, “ Three-dimensional reefs, the Maryland Environmental Service, the U.S. Army Corps of Engineers, standing substantially and others are now using concrete reef structures, like reef balls, above the bottom, to restore vertical structure. are essential for oyster reproductive success, for predator protection, and to create habitat Rebuilding the Reefs for other organisms.” State and Federal agencies may interfere with some Chesapeake Research Consortium report, 1999. are committing millions of harvest techniques, Chesapeake Bay Oyster Restoration: Consensus of a meeting of scientific experts. dollars annually to restore such as trotlining for crabs, oysters to the Bay and its and navigation. tributaries. They are focusing their efforts in targeted This mindset disregards areas that are off-limits to the fact that large oyster oyster harvesting. reefs once pervaded the Bay and shows little As we move forward in appreciation for the our efforts to restore a immense value of these healthy oyster population, live structures. Unfortunately, we must consider the people have grown accus- important role that vertical tomed to a flat-bottomed structure plays in a healthy Chesapeake Bay. History reef system. However, some tells us that three-dimen- approaches to restoring sional oyster reefs belong vertical structure aren’t in the Bay. It’s time to always popular. Opposition jog our collective memory has come from certain and do what’s needed stakeholders, concerned that to recreate this vital reef balls or other materials habitat for oysters and for a healthier Bay. PHOTO CREDITS: Page 1: Dave Harp; Page 3: Michael Eversmier; National Archives; Page 4: Top to bottom, CBF Staff; Bill Goldsborough/CBF Staff; Tanner Council/CBF Staff Support Efforts to Restore Three-Dimensional Reefs to the Bay SPREAD the word SHARE your support VOLUNTEER with to your neighbors and for oyster recovery— CBF’s active oyster friends about how and especially the restoration program important oysters are unique value of vertical by building reef to the health of the reefs—by writing a balls, cleaning shells, waters and wildlife of letter to your local or becoming an the Bay. paper or to state oyster gardener. officials responsible Visit cbf.org/oysters for oyster restoration. for more info. Baltimore students volunteered their time after school to count and release about 3,680 baby oysters cbf.org on a small man-made reef in their local river. .

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