Restoring the “Coral Reefs” of the Chesapeake
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(See notes below) Four hundred years ago, the Chesapeake Bay that the English colonists found here was lined with huge oyster reefs that grew up from the bottom in waters both deep and shallow. Those reefs provided the base for much of the life in the Bay and its rivers, from worms and barnacles through mud crabs and tiny fish to big blue crabs and predators like sheepshead, drum, and rockfish (striped bass). The oyster reefs weren’t as “pretty” (to us humans) as the coral reefs further south, but in terms of ecosystem richness, they were just as important. One key to their strength was their three-dimensional structure, which successive generations built gradually on the shells of their predecessors over several thousands of years. The structures placed the oysters up in the water column, away from gill-choking bottom sediments, where dissolved oxygen was plentiful and currents brought food in the form of algae cells seeking sunlight. This PowerPoint presentation, developed by the Chesapeake Bay Foundation’s Fisheries Program Director Bill Goldsborough, tells the story of those reefs and what has happened to them over the past four hundred years. It is not a pretty story, but it offers a hopeful conclusion, as we learn more each year about how to restore these essential elements in the Chesapeake ecosystem. Anglers have as much to gain as anyone in restoring the Chesapeake’s oysters. The presentation closes with suggestions for how to get involved in oyster restoration, and how to incorporate the restoration reefs into your 2015 angling season. To participate in CBF’s oyster restoration programs in Virginia and Maryland, visit http://www.cbf.org/oysters.
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Restoring the “Coral Reefs” of the Chesapeake
- 1. Bill Goldsborough/John Page Williams CCA/MD Anglers’ Night Out March 31, 2015 Restoring the “Coral Reefs” of the Chesapeake
- 2. “The abundance of oysters is incredible. There are whole banks of them so that the ships must avoid them…” - Francis Louis Michel, 1701 “Chesapiooc” Great Shellfish Bay
- 3. Oysters are communal animals Reef section showing vertical growth (Bureau of Commercial Fisheries 1964)
- 4. 3-D reefs, “an organizing force for the estuarine system” - Dr. Jerry McCormick-Ray, UVA, 2005
- 5. The introduction of the oyster dredge in 1810 Laws prohibiting dredging: VA – 1811 MD - 1820 “…well-grounded apprehensions are entertained of the utter extinction of oysters in the state.”
- 6. Darling Oyster Company Hampton, Virginia, circa 1900 Harper’s Weekly March 1, 1884 Post-Civil War Legalization of dredging led to an Oyster Boom and the “Oyster Wars”
- 7. “We have wasted our inheritance by improvidence and mismanagement and blind confidence.” - Dr. William Brooks, JHU, 1891 “Today destruction of the oyster’s prime habitat in the Chesapeake, the natural, self-renewing upthrusting oyster reefs, is nearing completion. When they are gone it will have taken somewhat less than two centuries to destroy some 6,000 to 7,000 years of nature’s works.” - Dr. William J. Hargis, VIMS, 1999 Oyster harvest peaked in 1884 and has declined since
- 8. 2 hrs. In the 1980s scientists determined: •only 1% of oysters were left in the Bay •oysters are critical to the ecosystem One oyster can filter 50 gallons per day
- 9. Sheepshead: a fish that has been “…extinct in the Chesapeake since about 1900.”
- 10. BBA Typical MD oyster bar with 1 or 2 oysters per square meter and heavy siltation Restored bar with >50 oysters per sq. meter and oysters outgrowing siltation: •more than ten times the # of organisms •more than twenty times the N-removal
- 11. Increasing oyster density from 2/m² (typical density on harvest bars) to 50/m² (target restoration density) increases the fertilization rate tenfold
- 12. Restored tributary reef networks designed to maximize spawning and export larvae to other bars UMD larval transport model simulation Day 1: restored reefs in Harris Creek spawn Day 15: larvae have spread miles with the tide Day 27: bars where spat have attached
- 13. “Three-dimensional reefs, standing substantially above the bottom, are essential for oyster reproductive success, for predator protection and to create habitat for other organisms.” - Chesapeake Research Consortium report, 1999
- 14. Virginia Marine Resources Commission shellpile reefs to restore vertical relief
- 15. MD Artificial Reef Initiative (MARI)
- 16. Healthy System Eutrophic System Minimal Nutrient Inputs Excessive Nutrient Inputs Water Quality Limitation Low oxygen in deep water and vertical clearance rules mean only a narrow band of vertical reefs can support oysters
- 17. Reef Substrate “The lack of suitable oyster habitat is the principal impediment to… recovery. As it takes decades to create an oyster bar naturally, engineering replacement habitat with artificial structures… seems to represent a viable alternative.” - Dr. Brian Rothschild, UMD, 1994
- 18. Concrete “Reef Balls” for re-creating vertical relief Cost per reef ball = $182.28 8 vol. hrs @ $22.55= 180.40 Total = $362.68
- 19. over 5 years, 1213 reef balls with 6.8 million spat and 21.9 million spat-on-shell were planted on 8 acres Cook’s Point Sanctuary, Choptank River, MD
- 20. Cook’s Point reef: “…the best fishing hole in the river.”
- 21. May 6, 2014 Tangier Sound reef ball retrieved and examined after 11 years in the water www.cbf.org/reefballvideo
- 23. 3-D reefs as coastal resilience
- 24. Final Programmatic Environmental Impact Statement for Oyster Restoration in Chesapeake Bay Including the Use of a Native and/or Nonnative Oyster Six-year EIS rejects the Asian oyster & endorses native oyster restoration President’s Executive Order calls for focused effort to restore self- sustaining networks of reefs. 2009 – a turning point year Lafayette Piankatank Harris Creek Lynnhaven Tred Avon Little Choptank MD adopts a targeted plan
- 25. Harris Creek targeted tributary oyster restoration: user conflicts with alternative material for reefs
- 26. “UPDATE: Watermen Protest Md. Oyster Project in Dorchester County” WBOC-TV 16, Delmarva's News Leader – May 01, 2014 Little Choptank River targeted tributary oyster restoration: Dispute over fossil shell
- 27. What can you do? 1. Spread the word about oysters to friends and neighbors 2. Share your support for oyster restoration by writing letters to local papers or state officials 3. Volunteer for oyster programs at CBF oyster center in Shady Side 4. Become an oyster gardener 5. Help recycle oyster shells
- 28. Conclusions 3-D oyster reefs, once common in Chesapeake Bay, were a key part of the estuarine system, very much like the coral reefs of the tropics The Bay’s 3-D reefs were destroyed historically Bay users have grown accustomed to a flat Bay, but vertical relief should be part of oyster restoration Reef balls are a viable option for 3-D reefs: Oysters appear to grow better than on the surrounding bottom Spat-set reef balls provide suitable reef habitat for fish
- 29. Questions? For more information, visit CBF’s Anglers for Clean Water, www.cbf.org/anglers
Notas do Editor
- Slide 1: No, the Chesapeake never actually had coral reefs, but it did have an ecological equivalent that was lost, with great repercussions for the ecosystem.
- Slide 2: The early colonists found a very different Bay from the one we have today. Many early records like this seventeenth century woodcut attest to the existence of massive 3-D reefs throughout the estuary. No surprise the Native American name Chesapeake meant “Great Shellfish Bay.”
- Slide 3: The Eastern Oyster is a reef-building oyster due to its unique life cycle. Males and females must be set in close proximity for reproduction, and larvae need a hard substrate on which to set. Their vertical growth means that over many generations they form 3-D reefs.
- Slide 4: The Eastern Oyster is a reef-building oyster due to its unique life cycle. Males and females must be set in close proximity for reproduction, and larvae need a hard substrate on which to set. Their vertical growth means that over many generations they form 3-D reefs.
- Slide 5: After exhausting their beds further north, New England schooners arrived in the Chesapeake in 1810 to introduce the dredge, a very efficient gear type for harvesting oysters, in an attempt to satisfy their well-developed northern markets. Great concern about overharvesting here in the Bay, where hand tongs were the primary gear in use, led to both states outlawing the gear.
- Slide 6: Apparently due to a different political climate in the post-Civil War era, dredging was legalized, and this efficient harvesting led to an oyster boom that spawned a huge industry. A period known as the “Oyster Wars” ensued in which dredgers fought with tongers, MD oystermen fought with Virginians, and everyone fought with the nascent “Oyster Navies” of both states. These predecessors today’s marine police were created to stem the gold rush era mentality enough to preserve the resource. Those efforts failed, in large part due to the political influence of the oyster industry in both states.
- Slide 7: The catch peaked by 1884 and dropped way off by the turn of the 20th century, even as the number of harvesting vessels grew – a classic case of overcapitalization, resource depletion, and tragedy of the commons. Scientists of the day lamented the loss, a sentiment still echoed by their successors today. (Focus on the tail end of this graph when going to the next slide…)
- Slide 8: When diseases hit in the 1960s, the resource was already a shadow of its former glory (although today’s watermen think diseases are the primary cause of depletion, since that is all they have known in their lives). After a wet decade pushed back the diseases for the MD fishery in the 1970s, a drought in the 1980s allowed them to knock it down for good. At that time, two key things happened: scientists estimated the Bay’s oysters were at 1% of their former abundance, and accumulating evidence painted a clear picture that the Eastern oyster was a key part of the Chesapeake ecosystem. Its ability to filter Bay waters got the most initial attention.
- Slide 9: Not as widely recognized initially was the habitat role that 3-D reefs played in the Chesapeake system. This display in the St. Mary’s City museum shows sheepshead bones as the most common of fish species found in the trash pits of early colonial archeological sites. It notes the sheepshead has been “extinct” in MD since about 1900. That is not exactly the right use of the word extinct, but it is definitely true that sheepshead are rarely found in MD waters of the Bay now. They are a reef species, and when we destroyed their habitat, we lost that previously important fishery. (It’s worth noting that what brought sheepshead back to Virginia was the construction of the rocky 3-D structure covering the traffic lane tubes of the Chesapeake Bay Bridge-Tunnel at the Bay’s mouth. Could restoration oyster reefs bring these hard-fighting, great-tasting fish back to the mouth of the Potomac and the upper Bay?)
- Slide 10: These two images show an unrestored oyster bar on the left (low oyster density and high siltation) and a “restored” one to the right that meets the target density of 50 oysters per square meter or more. Visibility is poor, but you can see the higher density of oysters as they assume the vertical growth that over many generations will build 3-D reefs. At this restored density, more than ten times the number of other reef organisms and twenty times the nitrogen removal has been documented (in separate studies).
- Slide 11: Perhaps even more important for restoring oysters is that this higher density increases the fertilization of oyster eggs tenfold for individual pairs of oysters. Multiply that by the increased number of potential pairs at this density, and the production of oyster larvae could be as much as 250 times greater per area for a restored reef. “Spat-on-shell,” produced with hatchery-spawned larvae in huge tanks where larvae and shell are mixed, is the currency of oyster restoration. When planted on good substrate and provided good water quality, they can blossom into clusters that cumulatively make 3-D reefs.
- Slide 12: Since oyster larvae are planktonic for about two weeks, they can be distributed by currents miles from their spawned site. This computer simulation of spawning at the planned acreage of restored sites in Harris Creek suggests that spatset in the entire lower Choptank River and adjoining Bay area could be enhanced. Thus, sanctuary areas maintained at high densities can act as reproductive engines repopulating wide areas, including harvest bars.
- Slide 13: Recognizing all these reef attributes, the scientific community released this guidance for restoration in 1999 that specifically stated the value of 3-D reefs.
- Slide 14: Well aware of this building documentation, the VA Marine Resources Commission began building 3-D reefs using piles of oyster shell in the early 1990s. While new insights have been learned about reef design since then, this was a dramatic recognition of the value of 3-D reefs.
- Slide 15: “Fishing reef” programs in both states have been attempting to create 3-D habitat using materials of opportunity. While well-intentioned for restoring 3-D reefs, these projects are not always built to encourage colonization by oysters. These large materials are not conducive to planting seed oysters, and they typically are not allowed on natural oyster bars where natural spatset might occur.
- Slide 16: In addition, there is often a water quality limitation at the deeper water sites usually used for fishing reefs. Nutrient pollution that causes the low dissolved oxygen “Dead Zones” seasonally renders the lower parts of such reefs uninhabitable, as illustrated by this sounder image. In addition, the vertical clearance required by the Coast Guard limits how much of the oxygenated part of the water column can be used for reef habitat.
- Slide 17: While natural shell is the preferred reef material, severe shortages of shell require the use of alternative materials. Granite or recycled concrete (crushed and screened to size) are being used, as is fossilized shell mined in FL. Both can provide a suitable substrate for planting spat-on-shell. Cast concrete reef modules like “reef balls,” upon which oysters can set either in tanks or in the wild, can also be used to start rebuilding three-dimensionality.
- Slide 18: CBF’s work building 500 reef balls per year depends heavily on volunteer labor (about half the total cost, which, using the federal rate, we are able to apply as match for grants supporting the program).
- Slide 19: Our largest reef ball project to date, in the mouth of the Choptank River off Cook’s Point, has been a collaboration with the Maryland Artificial Reef Initiative and the Dorchester Chapter of the Maryland Saltwater Sportfishing Association. Over five years, it has produced areas of different reef ball densities that we are evaluating over time (starting initially with a current study being conducted by a scientist at the University of Maryland’s Horn Point Laboratory under contract to CBF). The left-hand image is an acoustic survey by NOAA that indicates depth by color and shows four shell-pile hills built by DNR around 2000. Each of the little dark spots around the shell-piles is a cluster of four reef balls.
- Slide 20: By all accounts, the site has been transformed into excellent fish habitat. MSSA’s Clint Waters caught a 72 pound black drum there, and one day’s fishing yielded 6 species – unusually high diversity in this part of the Bay. This view of a mature reef ball at the Cook’s Point site tells the story with proof of use by black sea bass, a reef-dependent species rarely seen in this part of the Bay due to lack of reef habitat. “Build it, and they will come!”
- Slide 21: In another attempt to document the value of reef balls, CBF hired biologists and divers to retrieve a reef ball place in Tangier Sound by Maryland Environmental Services in 2003. It had not been set with spat when deployed. When brought to the surface, it looked like a piece of the Chesapeake’s natural reefs as Dr. William Brooks described them in the 1890s. Data collected on the reef ball, in the area of bottom next to it, and out a distance away showed clearly that oysters of all sizes were more numerous on the reef ball. Check the website link just below this presentation for a 4-minute video from that day.
- Slide 22: Here’s a screen shot from the Cook’s Point reef ball field taken on June 6, 2012. It speaks for itself. The fish are schoolie rockfish and large white perch (see the article “Chesapeake Fish Love Live Bottom” just below). BTW, the dissolved oxygen that day dropped into stressful levels at 7 meters (23 feet). Note the open space on the lower right side of the 200 kHz screen where the bottom drops off to that level.
- Slide 23: Finally, the role of 3-D reefs as coastal resilience features can be very important. They dissipate wave energy and protect shallow water and shoreline habitats and structures. The project to the right was undertaken by a Calvert Cliffs (MD) community to protect its shoreline. Below in a lower energy site, smaller reef structures can buffer wetlands. CBF has a new project in Norfolk’s Lafayette River that is testing this hypothesis. More work needs to be done to document the role of 3-D reefs and develop Best Management Practices for applying them to it.
- Slide 24: 2009 was a turning point year for oyster restoration when the federal/state Environmental Impact Statement rejected the proposal to introduce non-native oysters to the Bay and endorsed scaling up native oyster restoration. Also, a President’s Executive Order that year set in motion a new collaborative strategy to focus resources on targeted tributaries and restore whole networks of self-sustaining reefs. MD’s subsequent Ten-Point Plan embraced this strategy and established harvest sanctuaries in 24% of MD’s productive areas to implement it.
- Slide 25: Harris Creek was MD’s first targeted tributary with specific bars surveyed and categorized. Unfortunately, conflicts with watermen arose due to their view that reef materials could serve as snags for trotlines used for crabbing. Those conflicts pose a clear indication that society has become used to a flat Bay and doesn’t appreciate the value of restored oyster reefs.
- Slide 26: In the Little Choptank River, the 2nd targeted tributary in MD, watermen actually staged a blockade of a barge deploying fossilized shell as reef material. While their expressed concern of siltation from sediment mixed with the shell was resolved, the fundamental objection to reef restoration remains. Ultimately, watermen want the sanctuaries to be open to direct harvest, which would destroy the accumulating reef structure, reduce oyster densities back to 1 or 2 per square meter, and diminish spawning, filtering, and habitat.
- Slide 27: Here’s what you can do to help (and improve your knowledge of where healthy, 3-D restoration reefs are located).
- Learn more about oysters and what you can do to help at www.cbf.org
- Slide 29: Questions? Contact: Capt. John Page Williams Senior Naturalist Chesapeake Bay Foundation 6 Herndon Avenue Annapolis, MD 21403 410-268-8816, x2041 410-279-1385 (cell) [email_address] Visit CBF’s new Anglers for Clean Water Program: www.cbf.org/anglers