improving siting and construction criteria for oyster reef

ImprImprImprImprImproving Siting and Constructionoving Siting and Constructionoving Siting and Constructionoving Siting and Constructionoving Siting and ConstructionCriteria for Oyster Reef RestorationCriteria for Oyster Reef RestorationCriteria for Oyster Reef RestorationCriteria for Oyster Reef RestorationCriteria for Oyster Reef Restoration

Center for Coastal Resources ManagementVirginia Institute of Marine Science

Gloucester Point, VA 23062

Helen WoodsWilliam J. Hargis Jr.

Carl H. HershnerPam Mason

&WILLIAM MARY Center forCoastal Resources Management

Virginia Institute of Marine Science

VIMS Special Report in Applied MarineScience and Ocean Engineering

(SRAMSOE) # 387

20042004200420042004

Figure 1. Study sites within the Chesapeake Bay. A. The Potomac River; B. Tangier and PocomokeSounds; C. The Rappahannock River; D. The York River; E. The James River

Cover photos by Jim Wesson

IntroductionThe Chesapeake Bay, named Chesepiooc, the “greatshellfish bay,” by the Algonquin speaking nativeAmericans of the region, was once one of the mostproductive oyster (Crassostrea virginica) producingestuaries in the world. With the advent of canningand the development of the railroad system, hugenational and international markets were establishedfor Chesapeake Bay oysters (United States Secre-tary of the Interior 1866,Wennerston 1981). From1894 to 1912 annual oyster harvests in Virginia aloneranged from 5 to 7.5 million bushels (Hargis andHaven 1988). Shells from harvested oysters werenot replaced on oyster grounds but sold for a varietyof commercial purposes ranging from road projectsto chicken feed. This tremendous, largely unregu-lated, harvest of oysters and shell, wreaked havoc onoysters and their habitat (Wennerston 1981,Rothschild et al 1994).

In recent years, considerable attention has been paidto the historical anecdotal reports of mariners whoreported that Chesapeake Bay oysters once grew inlarge reef-like colonies. These stories suggest thatChesapeake Bay oyster reefs were once threedimensional structures which breached the surfaceof the water at low tide. It is believed that the threedimensional structure of these reefs favorably alteredthe environment for oysters by raising oysters off thebottom into the more favorable upper water columnwhich increased oxygen, water temperature, andfood availability for the oysters.

Based upon these reports and beliefs, three dimen-sional oyster reef habitat restoration efforts inVirginia began in 1993. Studies by the VirginiaInstitute of Marine Science indicated that the great-est oyster survival rates could be found on reefscreated from oyster shell and thus reef restorationfocused upon the deployment of large mounds ofoyster shell. These shell mounds, or reconstructedreefs, were primarily situated upon areas surveyed inthe 1970s (Haven and Whitcomb 1978 & 1983)

which were classified as hard oyster bottom. Thesehard oyster bottom areas were considered to be“reef footprints.” Reconstructed reef shape andorientation was based upon the shape and orientationof these “footprints” as well as knowledge of thelocal site, history of reefs in the area, and naviga-tional and social issues that are unique to the localarea. These siting procedures have changed littlesince 1993.

While the application of these concepts has contin-ued in the field with the aim of increasing viableoyster habitat while decreasing the costs of restora-tion, research has also continued examining optionsand techniques for increasing oyster reef success.Much of this research has focused upon understand-ing the natural function of oyster reefs as theyhistorically existed in hope of applying this knowledgeto restoration efforts. This paper outlines some ofthe things which have been learned through theseendeavors and ways which these lessons can beapplied to continuing restoration efforts to increaserestoration success.

Natural Oyster Reefs in theChesapeake BayThe Center for Coastal Resources Management atthe Virginia Institute of Marine Science has recentlydigitized and analyzed the data from numeroushistoric hydrographic surveys from around theChesapeake Bay. These surveys primarily date fromthe mid to late 1800’s before extreme harvestpressure had decimated the Chesapeake oysterpopulations. Areas studied included the PotomacRiver, the Rappahannock River, the York River, theJames River, and Pocomoke and Tangier Soundsarea (Figure 1). Oyster bottom survey data indicat-ing areas of high oyster concentration were overlaidupon these data. Oyster bottom data varied in agebut it was assumed that areas of dense oyster fromlater surveys would approximate areas of denseoyster during the survey time as well. The end result

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of this work was a series of three dimensional digitalimages which clearly showed the contours of thebottom as they related to dense oyster areas.

The results of this work varied between sites and canbe roughly divided by latitude into northern andsouthern style reef formations. Historic literature onthe subject suggests that the Chesapeake Bay wasthe northern latitudinal extent for southern styleoysters reefs and the overall dividing line between thedominance of these two styles of reef formation. It isinteresting to note that the 1860 United States Censusdivided the Eastern Oyster into two species, theVirginia Oyster and the New York Oyster, with theChesapeake Bay as the primary dividing line (Secre-tary of the Interior 1866). While speculation, it ispossible that the two different styles of reef formationcontributed to experts dividing the Eastern Oyster intotwo species at that time.

The northern study areas Tangier/Pocomoke Sounds,the Potomac River, Rappahannock River, and YorkRiver predominantly demonstrated northern style reefdevelopment. These northern style oyster reefsappeared along channel edge terraces at the begin-ning of the shoals. What little relief was present inthese reefs ran parallel to and bordered the edge ofthe channel (Figure 2). No significant biogenic reliefwas detectable in many of these reefs. Up-thrustingfeatures of bottom, such as points extending fromland and the ridges between paleo-channels were,however, covered with dense oyster aggregations(Figure 3). The literature suggests that oyster reefs inestuaries north of the Chesapeake Bay demonstratethis same type of reef formation.

The southern study area, the James River, predomi-nantly demonstrated southern-style reef formations.While some mostly flat, northern-style, channel edgereefs were present, large upthrusting oyster reefsdominated the system. Many of these upthrustingreefs actually breached the surface of the water atlow tide and the largest of these reefs extended some3 km in length (Figure 4). Upthrusting reefs werelocated along the shoals near the channel edge andwere oriented perpendicular to the main flow of thecurrent. Many of these reefs extended from thechannel edge towards, but not touching, the shoreline(Figure 5).

Although a few upthrusting reefs were alsopresent in the Potomac and York Rivers, thesereefs were few and the systems were dominatedby northern style reef development. It is interest-ing to note that in all three of these systemsupthrusting reef formations were limited to theupper, lower salinity portions of the oyster produc-ing reaches and the shallower areas (2 meters orless).

Understanding Natural OysterReefs

The Biological Needs of Oysters

Oysters require relatively few things to survive.These include oxygen-rich water of the propersalinity and suitable phytoplankton as a foodsource.

However, the requirements for an oyster popula-tion to survive are somewhat greater. This isbecause a population needs to be self-sustainingthrough reproductive success which outpacesmortality. To be so, an oyster population alsorequires suitable proximity of male and femalegametes and hard clean substrate upon which toset.

A number of other factors can be outlined whichwill increase the success of an oyster population.These factors include:

• Increased abundance of male and femalegametes

• Increased abundance of clean hardsubstrate for spat set

• Increased abundance of phytoplankton• Extended warm water growing and

breeding season• Decreased sediment concentrations in

water to increase feeding efficiency andfouling substrate rate

By adjusting these factors accordingly, an oysterpopulation will not only survive but flourish.

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Figure 2. Tangier Sound.*. Oysters, outlined in red,clustered along the edges of the channel. What littlerelief exists runs parallel to the channel.

Figure 3. The Rappahannock River, Virginia.*Oysters, outlined in red, are clustered along the edgesof channels and in areas of geologic relief.

Figure 5. Evenly spaced southern-style reefs of Burwell’sBay, James River, Virginia.* Red indicates emergentfeatures.

Figure 4. Point of Shoals reef system in the JamesRiver.* Long Shoal reef extended above water fornearly 3km. Red indicates emergent features.

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Southern-Style Reefs

• Present only from the Chesapeake Bay southward• A lot of relief, often emergent, although many more shoal-like

than concept models• Biogenic lumps and groin-like ridges perpendicular to current• Often extend from near-shore to channel edge• Shallow water

Northern-Style Reefs

• Present along the entire coast although dominant from the Chesapeake Bay north• Terrace tops, channel edges, geologic relief• Follow bottom contours• Large patches, often parallel to channel• Deeper water• Little relief• Relief centered along and parallel to channel edge

* All images vertically exaggerated by a factor of ten.

IntertidalMean Low Water0m - 1.5m

Legend: Depths

1.5m - 3m3m - 4.5m4.5m - 6m6m - 7.5m7.5m - 9m9m and Below


Legend: Depths




Legend: Depths

1.5m - 3m3m - 4.5m4.5m - 6m


6m - 7.5m7.5m - 9m9m and Below

The Success of the Natural Reef System

By placing the results of our work into the contextof research on the subject of oysters and oysterreefs we can see that the natural Chesapeakeoyster reefsystemsdeveloped inlocations andforms whichcapitalized onmany of thefactors listedabove andthereforemaximized thesuccess of thereefs. Byunderstanding theevolution of thesesystems, we mightbetter understandthe factors leadingto the success ofoyster reefcommunities andhence betterformulate anddirect restorationefforts.

Southern-Style Reefs

A review of historic literature of southern estuariesindicates that large, upthrusting, and emergentoyster reefs, like those in the James River, wereonce quite prevalent in the shallow waters of manysouthern estuaries. These reefs were long,relatively narrow and were situated in the shallowshoal areas running perpendicular to the flow ofcurrent. (Figure 6; Figure 7) Writings by late 19th

and early 20th century scientists, often referring tothis sort of reef formation as a “long reef” or“string reef,” suggest that the controlling factor inthe development and success of these reefs waswater flow (Grave 1905, Moore 1907).

One of the most informative reports on this subjectwas written by Caswell Grave, Ph.D., in his 1903report to the United States Fish Commission on thecondition of the oyster industry of North Carolina.Grave describes these reefs as a, “long narrow

Figure 6. A typical southern style reef - Limekiln Rock, NewportRiver, North Carolina (Grave 1905).

ridge of mud and shells, the tops usually coveredwith a dense growth of badly shaped oysters knownas ‘coons’” (Figure 8). The elongated and thin-shelled coon oysters resulted from the massiveovercrowding of oysters. In these aggregations,

oysters are forcedto grow rapidlyupward, competingfor food and spacewith neighboringoysters. Sedimentsettling on the reef,falls between theoysters leaving thetops of the oystersclean. Youngoysters often set onthe tips of theseliving oysters withthe original oystersbeing smothered bysuccessive genera-tions. Grave notesthat, “...although notfavorable to thegrowth of adultoysters, the condi-tions on the reefsare most favorable

for the attachment of spat.” (Grave 1905) This isimportant to note in the context of reef restoration asit shows that optimizing conditions for individualoysters is not nearly as critical as is optimizing

Figure 7. A typical southern-style reef, Long Shoal Reef,1885, James River, Virginia.(Photo courtesy of TheMariners’ Museum of Virginia)

Figure 8. Coon oysters. Extreme crowdingand competition for space caused this typicalmalformation of shape (Grave 1905).

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conditions for the reproductive success of thecommunity.

The conditions for the attachment of spat areimproved through a remarkable feat of naturalselection which dictates the reef location and shape.Grave notes that reefs such as these begin asclusters of oysters attached to a shoreline. Theoysters protrude into the water where the currentruns more swiftly. The swifter currents removesediment and fouling from the tips of the oystersproviding a clean surface on which other oysters canset. The swift currents also bring more food for theyoung oysters to consume, allowing for healthieranimals. As thiscycle is repeated, thewater currents areforced around andover the oysters.The Bernoulli Effectcauses the currentsto increase invelocity, thus creat-ing an even morefavorable environ-ment for the oystersat the tip and on thetop of the youngreef. The result isthe reef growing inlength and heightand, “The long axesof the reefs areusually at rightangles to the shore-line...” Graveexplains that theshape, position and orientation of the reef, “showsthat their position depends upon the direction not ofthe shoreline but of the currents which flowed pastthem during their growth, the formations alwaysmaking right angles with the direction of flow.”(Grave 1905)

While the growth of the long reef increases watervelocity along the reef tip and crest, it stifles waterflow along the shoreline and downstream of the reef.As a consequence of this suppressed water flow, the

reef begins to die landward and become detachedfrom the shoreline. Smaller reefs and outcroppingsof oysters which may have begun to grow downstream, are stifled and begin to die as well. Not untilwater velocity has increased again downstream cananother reef begin to grow. (Grave 1905) Thisexplains the even spacing of reefs in the James andother southern estuaries. Eventually the reef reachesthe channel where the water flowing around the reefcauses a new channel to be cut further out. Theflow direction is no longer 90 degrees to the reef andthe reef begins to branch at its end.

The reef also reaches a maximum height. At acritical point, oysterson the top centerridge of the reef areexposed betweentidal cycles to such apoint that they cannotfeed long enough tosurvive. The top-mostoysters die and sand,shell, and other debriscollect on these dead“islands” or “hog-backs” on top of theliving reefs (Grave1905, Hedgpeth1953) (Figure 9).

H. F. Moore, in his1907 Survey ofOyster Bottoms inMatagorda Bay,Texas, expresses thesame theory as

Grave to explain the long reefs he surveyed there.Moore, however, also describes smaller scale reefmorphology and the condition of the oysters on thesereefs. “The margin of the bed facing up the bay iscomparatively close to this crest, abrupt in its risefrom the bottom and continuous in its contour, whilethe opposite margin is farther removed from thecrest, merging more gradually with the adjacent barebottom and broken up into long projecting ridges orspurs separated by narrow, muddy indentations andsloughs.” Observing the condition of the oysters

a.

b.

c.

d.

e.

f.

Figure 9. The evolution of a southern-style long reef from clustersalong a marsh to a detached reef-like formation as hypothesizedby Grave (1905). Figure reproduced from Kennedy and Sanford,1999.

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themselves on the reef Moore notes, “In all of thesereefs, also, the upper side is the only one resorted toby the oystermen, as there only are large oysters ofquality to be found in quantities sufficient to makeremunerative tonging. On the lower sides of thereefs not only is the density of all sizes of oystersless, but among those that are found there is apreponderance of small ones, and all are inferior infatness to those just across the crest.” Mooreattributes these observations to the superior condi-tions for spat set and supply of food on the up-baymargins of the reef caused by the greater velocity ofwater over the reef in this area, “...it is a generalcondition of oyster growth that, other things beingequal, the set of spat, the rate of growth, and theproduction of fat are greatest in those parts of reefswhere the water flows with greatest velocity.”Moore continues, “...the flowing surface water isexerting a scouring action on the top of the reefnortheast [upstream side] of the crest. The prepon-derance of oyster growth is therefore at the top ofthe reef and toward the upper margin of that side,with the result that the margin in question tends tomaintain a uniform outline and an abrupt face. Thecrest itself lies closer to the northeast margin,because it, too, tends to grow in that direction fromthe same causes - the superior scouring action andfood carrying capacity of the currents on that side ofthe reef” (Moore 1907).

Conversely, Moore correlates areas of low oysterabundance and areas with poor oyster quality to lowwater flow and associated sediment deposition. Henotes that on the up-bay side of the reef, the waterstagnates at the foot of the reef, which prevents thereef foot from growing outward on that side. Simi-larly, on the down-bay side of the reef, the waterslows and silt is deposited along the entire back sideof the reef, with highest quantity of silt being depos-ited between the ridges. This in part accounts forthe general poor performance of oysters on the backof the reef, and , “that the original oyster clumps ...eventually develop into tongue like ridges at rightangles to the general tend of the reef, with muddysilted sloughs between them.” Moore also notes thatthis small scale morphology, while present in all ofthe reefs, is most prevalent in the largest and upper-most reef (Moore 1907).

Recently, Hunter Lenihan published the findings ofhis own 1999 North Carolina study where he ex-plored these factors in detail. Lenihan created aseries of experimental reefs of different heightswhere he tested the recruitment, growth, and survivalof oysters on different parts of these reefs, withrelation to water flow. His work validated the earlierobservations by Grave and Moore and found that astaggering 81% of variability in oyster growth andmortality could be linked to variations in water flow.After 10 months the shell growth and condition indexwere greatest on the crests of tall and short reefs,where flow speed and quality of suspended foodmaterial were highest and sediment deposition waslowest. Additionally, the two lowest reef forms in hisexperiment were nearly completely buried by mudafter 16 months (Lenihan 1999).

While not depicted on bathymetric surveys, oyster“ledges” or “fringing reefs” which covered theintertidal portions of the shoreline were also quitecommon in southern estuaries (Bahr and Lanier1981, Oemler 1894). Such reefs would form on theconcave outer banks of meander loops, in areasimmediately adjacent to smaller tidal tributaries andat points of tidal stream confluence (Bahr and Lanier1981). In other words, like long reefs, these oysterledge reefs also formed in areas of increased waterflow.

Northern-Style Reefs

The northern-style reefs occurred and still occurthroughout the range of the eastern oyster. How-ever, in the absence of southern-style reefs, theydominated estuarine systems from the middleChesapeake Bay northward. These reefs, which areactually rather flat and bed-like, tend to be locatedalong the bottom of rivers in areas of abrupt changein relief, often oriented parallel to the current (Figure10). Gary Smith and his colleagues in Maryland usedsubbottom profiling to examine many of these oysterreefs in detail. In their 2003 paper, they found thatnorthern-style reefs almost always grow in areaswith a sudden change of bottom relief such as theedge of a channel, a terrace, lump, or an erodedisland. Reefs which appeared to be isolated inexpanses of flat bottom were actually channel edgereefs at a late state of development where the

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Figure 10. Core stratigraphy indicates that the strong acoustic reflector on the scarp was a thin layer of oystershells forming a northern-style reef. This reef originally developed along the edge of a channel which has sincefilled in. An area of biogenic relief running parallel to the original channel is still present along the edge of theterrace (Smith et al., 2003).

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Oyster Shell and Shell Bits

Fine Gray Mud

Shell layer ~ 1801 BP

Agricultural horizon line 1850-1900

Coarse Gray Sand

Seafloor

Cen

timet

ers

original channel filled in, becoming flush with the topof the adjacent oyster bed (Figure 11). They alsofound many reefs which had been completely buriedby the continual deposition of sediment after thechannel had been completely filled. In such in-stances, new channels formed elsewhere and newoyster beds formed along the edges of the newchannels. They concluded that northern-style ofoyster beds were therefore ephemeral and transitoryon a geologic time scale (Smith et al. 2003).

Gary Smith’s work also indicates that scouringcurrents are at work along the scarps which maintainsediment free oysters and likely bring increased foodto the oyster bed. (Smith et al. 2003) The impor-tance of strong currents for northern-style oyster bedformation was noted as early as 1891 by Dr. WilliamKeith Brooks of the John’s Hopkins Laboratory inMaryland. In his book, The Oyster, which concen-trated upon northern-style oyster reefs and aquacul-ture techniques, he noted that in many places aroundthe Bay, oysters grew in dense patches while otherareas were completely devoid of oysters. To helpexplain this observation, Brooks quotes Ingersol’saccount of the origin of American oyster farming.Ingersol reports that oyster farming using naturalspawn was simple to establish once farmers realizedthat the water was not spat limited but substratelimited due to the rapid rate at which slimy filmdevelops on submerged objects. This slimy “half-sedimentary, half-vegetable” film, as well as the

muddy bottom sediments are lethal to young oysters.“The first thing found out was that the floating spawnwould not attach itself to or ‘set’ upon anythingwhich had not a clean surface...” Ingersol also noted,“It was evident that the swifter the current the less... chance of rapid fouling. Planters, therefore, chosetheir ground in the swiftest tideways they could find.”(Brooks 1891)

It is also important to note that the location of thenorthern-style oyster reefs along the edges of the

channel and tops of upthrusting areas of bottom is notjust a remnant artifact of conditions present at lowerstands of water. The existence of these reefs isdirectly attributable to conditions present at thecurrent time. This is documented in the work of EricPowell and his colleagues in Galveston Bay. Powelldocuments over 1000 acres of dramatic new oysterreef growth along the Houston Ship channel - arecent man made feature in this bay (Figure 12).Powell also attributes the reef formation to changesin salinity and the increase water velocity caused bythe dredging of the channel. The result was the rapiddevelopment of northern-style oyster reefs coveringthe spoil banks paralleling the edges of the channel.Powell notes that the reefs were most dominantalong the channel side and crest of the spoil banks.Few oysters exist on the outer sides of the spoilbanks (Powell 1995).

Figure 11. Further evidence that northern-style oyster reefs almost always form along the edges of channels,scarps, and emergent terraces which protrude into the current flow. Sub bottom profiling suggests that theoyster reef to the right which appears isolated in the center of a broad shoal, actually originated along theedges of a now buried channel. Dark areas indicate gases trapped in soft sediments of depositional and buriedchannels (Smith et al., 2003).

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Figure 12. The oyster reefs of Galveston Bay proper (Powell 1995). Areas in black indicate dense oyster.Within a few years of the creation of the northeastern shipping channel, oysters had colonized the edges of thenew channel (arrow). This suggests that northern-style reef formation and placement along channel edges isnot a remnant artifact of earlier low stands of water, but is caused by conditions now present along channeledges.

Implications of andRecommendations forIncreasing Restoration SuccessIt is certain that a variety of factors such as watertemperature, salinity, bottom hardness, food availabil-ity, spat availability, etc, interact to dictate thesuccess or failure of an oyster reef. However, areview of modern and historic literature for bothnorthern and southern style oyster reefs indicatesthat the major controlling factor dictating oyster reefsuccess is water flow. Both northern and southernstyle oyster reefs and their variations form in areaswith a strong scouring current. The exact reason forthis is unclear but food supply, substrate cleaning, andspat delivery are all likely enhanced in these areas ofhigh water flow. It should also be noted, that in thesouthern style long reef, arguably one of the mostproductive reef forms, the reef development actuallycontrols and enhances the flow of water over thereef thus improving the quality of its own habitat.

These observations have implications for restorationprojects. This work strongly suggests that siting offuture reef restoration projects should center aroundselecting sites with high current flow. Additionalwork will be needed to determine the exact param-eters of optimal water flow for an oyster reefcommunity (as opposed to single oysters); however, astarting point might be suggested by selecting siteswith the highest possible current flow which stillafford low flow during slack tides to allow for spatset. In many cases these areas may occur alongchannel edges and atop submerged terraces. His-toric and modern observations suggest that restora-tion success may be further enhanced by carefullydesigning reef shape and orientation with the objec-tive of maximizing current flow over and around thereef.

An oyster reef restoration project in Long Creek, Lynnhaven River,Virginia. Photo courtesy of Erik Moleen, First Landing State Park.

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Yancey Powell and Tommy Leggett of the Chesapeake Bay Foundation add brood stock toa restored oyster reef. Photo courtesy of Chesapeake Bay Foundation.

AcknowledgmentsSupport for the project was provided by the Centerfor Coast Resources Management and the VirginiaInstitute of Marine Science. Partial support for themaps included in this report was provided by theVirginia Sea Grant Program, Virginia Department ofEnvironmental Quality Coastal Program, and theVirginia Marine Resources Commission. Scientificsuggestions and guidance were provided by DexterHaven.

Technical assistance for this work was provided bymembers of the Center for Coastal ResourceManagement and the Department of InformationTechnology at the Virginia Institute of MarineScience. The librarians at the Hargis Library of theVirginia Institute of Marine Science greatly assistedin locating obscure references.

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ReferencesBahr, L.M. and W. P. Lanier. 1981. The ecology of

intertidal oyster reefs of the South Atlantic coast:a community profile. U.S. Fish and WildlifeFWS/OBS/81.15. Washington DC. 105 pp.

Brooks, W.K. 1891. The oyster. The JohnsHopkins Press, Baltimore MD. 230 p.

Grave, C. 1905. Investigations for the promotion ofthe oyster industry of North Carolina. In:Report of the United States Fish Commission,1903, Washington, D.C. pp. 247-315.

Hargis, W. J., Jr. & D. S. Haven. 1988. Rehabilita-tion of the troubled oyster industry of the lowerChesapeake Bay. Journal of Shellfish Re-search, 7:271-279

Haven, D. S., W. J. Hargis, Jr., & P. C. Kendall.1978. The oyster industry of Virginia: Its status,problems and promise. VIMS Special Papersin Marine Science, Virginia Institute of ScienceSea Grant Program, Gloucester Point, Virginia.No. 4

Haven, D. S. & J. P. Whitcomb. 1983. The originand extent of oyster reefs in the James RiverVirginia. Journal of Shellfish Research.3:141-151.

Hedgpeth, J.W. 1953. An introduction to thezoogeography of the northwestern Gulf ofMexico with reference to the invertebrate fauna.Publications of the Institute of Marine Sci-ence Unviversity of Texas. 3: 107-224.

Kennedy, V. S. & L. P. Sanford. 1999. Characteris-tics of relatively unexploited beds of the easternoyster, Crassostrea virginica, and early restora-tion programs. In: M. W. Luckenbach, R. Mann& J. A. Wesson, editors. Oyster Reef HabitatRestoration: A Synopsis and Synthesis of Ap-

proaches. Gloucester Point, VA: VirginiaInstitute of Marine Science Press. pp. 25-46.

Lenihan, H. S. 1999. Physical-biological coupling onoyster reefs: how habitat structure influencesindividual performance. Ecological Mono-graphs, 69:251-275

Moore, H.F. 1907. Survey of oyster bottoms inMatagorda Bay, Texas. Bureau of FisheriesDocument, 610:1-87

Oemler, A. 1894. The past, present, and future ofthe oyster industry in Georgia. Bulletin of theUnited States Fish Commission. 13:263-272

Powell, E.N., J. Song, M.S. Ellis & E.A. Wilson-Ormond. 1995. The status and long-term trendsof oyster reefs in Galviston Bay, Texas. Journalof Shellfish Research, 14:439-457

Rothschild, B. J., J. S. Ault & M. Heral. 1994.Decline of the Chesapeake Bay oyster popula-tion: a century of habitat destruction and over-fishing. Marine Ecology Progress Series,111:29-39

Smith, G.H., E.B. Roach & D.G. Bruce. 2003. Thelocation, composition, and origin of oyster bars inmesohaline Chesapeake Bay. EstuarineCoastal and Shelf Science, 56:391-409

United States Secretary of the Interior. 1866.Statistics of the United States in 1860 of theEight Census. pp. 539-542. Washington:Government Printing Office.

Wennerston, J. R. 1981. The oyster wars of theChesapeake Bay, Centerville, Md: TidewaterPublishers. pp. 1-147

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improving siting and construction criteria for oyster reef

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