Richard F. Dame

Robert Gardner, USC

Fred Holland, NOAA

US Forestry Service – Sewee Center

Acknowledgements

• In this presentation:(1) the prehistoric and modern oyster dominated systems will be examined and compared from a complex ecological systems perspective using literature data and simple reverse engineering techniques,

• (2) the relative uncertainties of the findings will be estimated and

• (3) lessons learned will be discussed.

From 4500 to 3000 B.P., oyster dominated estuarine ecosystems on the Southeastern Atlantic coasts of South Carolina, Georgia and Florida experienced a major change in state as evidenced by the presence and later abandonment of oyster shell rings.

Some properties of complex ecological systems

Intertidal reef during submergence

Connections

Hierarchical

Ecological Phase Shifts

From a management perspective, recognizing and predicting shifts between alternate regimes or states is probably among the most important aspects of ecological complexity.

What are some of these shifts or potential shifts in Southeastern estuaries?

Oyster Reef Phase or Regime

ShiftIntertidal Oyster Reef

Mudflat

CausesOver-harvestingHabitat

DestructionPollution DiseaseRapid Climate Change (RCC)

Benthic-Pelagic Shift

Subtidal Oyster Reef

CausesOver-

harvesting

EutrophicationPollution DiseaseRapid Climate

Change (RCC)

Pelagic

Salt Marsh Shift

Healthy Salt Marsh Marsh Converting to Mudflat

CausesDrought Flow Modification RCCFungiSnail Grazing

Native American Indian Shell Ring

after Trinkley (1997)

Shell Rings• Shell rings are circular or semi-circular

structures built mostly of oyster shells and are found along the coasts of South Carolina, Georgia and Florida.

• They were built by native Americans between 4600 to 3000 years B.P. and stood up to 10 m above the surrounding landscape.

• These constructs are the first indication of the end of the hunter-gathering period of Homo sapiens in North America.

• The relatively short functional duration of these structures is an issue of intense debate.

Natural Reef/Creek Shift

to Shell Ring System

CausesHigh

Ecosystem Production

Native American Indians

Shell Ring System Shift to

Natural Reef/Creek

CausesOver-

harvestingRCCIndians

Disperse

Location of Some Shell Rings on the South Carolina Coast

Sewee Shell Ring

• Size: 3.2 m high, 75 m diameter, 3900 m3 shell volume

• Age: 4120 to 3675 +/- 70 years B.P. • Major Threat: erosion due to sea level rise• Comments: Earliest shell ring in SC; Only

shell ring readily available for public viewing; site managed by US Forest Service, Francis Marion National Forest

Russo and Heide (2003)

Sewee Shell Ring

US 17

2nd or 3rd order tidal creek

Aerial Color IR of Sewee Area

Sewee Shell Ring Wall

Topographic Chart

Fig Island 1 Shell Ring (Botany Bay Plantation, Edisto Island)

• Size: 5.5 m high, 157 m diameter, 22,114 m3 shell volume

• Age: 3861 to 3816 +/- 70 years B.P.• Major Threats: Previous shell mining;

erosion due to sea level rise• Comments: Largest ring known; most

studied in SC; managed by SCDNR

Saunders and Russo (2002)

Aerial IR of Fig Island Shell Rings

2nd and 3rd order tidal creeks

Fig Island 1 aerial showing modern

damage

Fig Island 1 relative size

Fig Island 1 Inside Out

Topographic Chart

Environmental Change And Shell Rings

Climate ChangeCool Warm

Brooks Curve for South Carolina Coast

After Brooks et al. (1989)

RCC

Estuarine EcosystemsHigh Prod.

Low Prod.

Salt Marshes

Oyster Reefs Shift Shift ShiftDeltas

Coastal Native AmericansHunter Gathers

VillagesShell Ring Culture

Shell Rings Abandoned

Europeans

Were ecosystem services provided by oysters diminished by using oyster

shells to build shell rings?

• We can address this question by examining the density and size of the shells in the rings and in modern reefs.

• Then allometric models can be used to estimate biomass and physiological rates.

• It’s all a matter of size and scale.

SIZE

• Size is one of the most significant characteristics of individual organisms.

• Size is important because along with temperature it governs many physiological rates.

• Bivalve size is measured linearly as height and as biomass or body weight .

• The two measures are related allometrically and provide a method to estimate biomass on archaeological samples.

• An example for intertidal oysters is:

Wt = -2.38 H2.21

Allometric Model for Oyster Clearance Rate

CR = 0.120 Wt0.75

210LargestPristineSantee Delta

200LargestShell MoundSewee

166AverageShell MoundSewee

120LargestPristineSewee

98AveragePristineSewee

89AveragePollutedAshley River

Height (mm)CategoryEnvironmentLocation

Sizes of Crassostrea virginica in SC

Lunz (1938); Dame (unpublished)

( 2.71 x 107 m3/d)1.21 x 108 m3/d6.60 x 104 m3/dTotal Clearance

Rate

(0.10 m3/d)0.10 m3/d0.04 m3/dClearance Rate/Ind

(0.82 gdb)0.82 gdb0.20 gdbAvg. Biomass/ind

(2.21 x 108)1.26 x 1092.59 x 105Total pop. Biomass

(2.71 x 108)1.54 x 1091.65 x 106Total pop. Density

(56,848 gdb/m3)56,848 gdb/m3345 gdb/ m2Biomass

(69,538/ m3)69,538/ m32200/ m2Density

4120 +/- 70 B.P.3820 +/- 70 B.P.LiveAge

Crassostrea

virginica

Crassostrea virginica

Crassostrea virginica

Species

(0.025 m3 )0.025 m30.25 m2Sample Size

3,900 m322,114 m3NAVolume (shell)

4416 m217,427 m2750 m2Area

SeweeFig Island 1NI Live ReefCharacteristic

Is it possible that the removal of oysters from the tidal creeks caused a phase shift?

• Direct Effects of Overfishing: fewer and smaller oysters available to main oyster consumer, Native American Indians, and oysters were the main item in their diet.

• Effects may be amplified by RCC, particularly declining sea level and increased exposure with cooling conditions.

• Modern phase shifts almost always involve multiple forces.

• With declining food availability, Native Americans had to choose between staying and starving or returning to the hunter-gatherer mode.

Evidence Uncertainty

• Native American Indians built the Fig Island 1 shell ring using over a billion oyster shells from the surrounding creeks, thus establishing a new more complex state.

• Implies over-fishing as an anthropomorphic stress on the ecosystem.

• Prehistoric and modern oysters may or may not be similar in size.

• Contradictory evidence from different sites suggests that size is the result of fishing intensity and food availability, i.e., habitat specific.

• Oysters from polluted environments are smaller than those from pristine locations.

• The loss of oyster clearance capacity due to shell ring building may have had an impact on the tidal creek system.

• Reduced clearance capacity due to over-harvesting does seem to occur in modern systems.

+/+

+/-

+/+

+/-

Evidence Uncertainty

• Sea level decline and rapid climate cooling were coincidental with the abandonment of shell rings.

• The error of up to (+/-) 150 years and the scarcity of replication in radiocarbon analysis increases uncertainty.

• The Native Americans abandoned the shell rings and never reestablished their use, i.e., changed state of the ecosystem.

• Some archaeological evidence suggests a lack of quantity and quality of food for the Indians.

• By 3000 B.P. (+/-) 150 yr, all shell rings were abandoned.

• Oysters still flourish in the creeks surrounding Fig Island 1 and Sewee.

• Archaeological and modern evidence from Sapelo Island, GA suggests that today’s oyster reefs are at least as productive as those of the shell ring era.

+/-

+/-

+/-

+/+

Conclusions

• Like today, the prehistoric system probably collapsed or shifted to another state due to a combination of anthropogenic and climatic stresses.

• The oysters returned to at least the same levels of production as in pristine areas today and that production is similar to that of the pre-shell ring era.

• The Native American shell ring culture was abandoned and eventually replaced by a culture that did not focus on oysters as their major food and feasting source, as well as building material.

Addendum

• Height to dry body weight spreadsheet model

• Clearance rate spreadsheet model

• Bibliography

Height to Dry Body Weight ConvertorCrassostrea virginica

Log W = Log a + b Log HDame (1972)

Log a b H Log H b*Log H Log W Wcm g db

-2.383 2.214 0.5 -0.3010 -0.6665 -3.0495 0.0009-2.383 2.214 1.0 0.0000 0.0000 -2.3830 0.0041-2.383 2.214 2.0 0.3010 0.6665 -1.7165 0.0192-2.383 2.214 3.0 0.4771 1.0563 -1.3267 0.0471-2.383 2.214 4.0 0.6021 1.3330 -1.0500 0.0891-2.383 2.214 5.0 0.6990 1.5475 -0.8355 0.1461-2.383 2.214 6.0 0.7782 1.7228 -0.6602 0.2187-2.383 2.214 7.0 0.8451 1.8710 -0.5120 0.3076-2.383 2.214 8.0 0.9031 1.9994 -0.3836 0.4135-2.383 2.214 9.0 0.9542 2.1127 -0.2703 0.5367-2.383 2.214 10.0 1.0000 2.2140 -0.1690 0.6776-2.383 2.214 11.0 1.0414 2.3056 -0.0774 0.8368-2.383 2.214 12.0 1.0792 2.3893 0.0063 1.0146-2.383 2.214 13.0 1.1139 2.4663 0.0833 1.2114-2.383 2.214 14.0 1.1461 2.5375 0.1545 1.4273-2.383 2.214 15.0 1.1761 2.6039 0.2209 1.6629-2.383 2.214 16.0 1.2041 2.6659 0.2829 1.9183

Individual Bivalve Clearance Rate (CR) Model Young PopulationGeneral Case

CR=aW b

CR = 0.120 W 0.75 (Gerritsen et al. 1994)

W a b Wb CR n size class wt size class clearance

gdb m3 Ind -1 d -1 Ind m -2gdb m3 d -1

0.10 0.12 0.75 0.18 0.02 100 10.00 2.130.20 0.12 0.75 0.30 0.04 90 18.00 3.230.30 0.12 0.75 0.41 0.05 50 15.00 2.430.40 0.12 0.75 0.50 0.06 20 8.00 1.210.50 0.12 0.75 0.59 0.07 5 2.50 0.360.60 0.12 0.75 0.68 0.08 7 4.20 0.570.70 0.12 0.75 0.77 0.09 8 5.60 0.730.80 0.12 0.75 0.85 0.10 3 2.40 0.300.90 0.12 0.75 0.92 0.11 2 1.80 0.221.00 0.12 0.75 1.00 0.12 1 1.00 0.12

286 68.5 11.31 Total Clearance/m 2

gdb = grams dry body 0.24 Avg Wt gdbInd = individual 8.22

Brooks et al. 1989. Sea-level change, estuarine development and temporal variability during the Woodland Period . In: Goodyear and Hansen, Studies in South Carolina ArchaeologyBrown, JH, Gillooly, JF, Allen, AP, Savage, VM, West, GB. 2004. Towards a metabolic theory of ecology. Ecology 85:1771-1785.Carbotte, SM, Bell, RE, Ryan, WBF, McHugh, C, Slagle, A, Nitsche, F, and Rubenstone, J. 2004. Environmental change and oyster colonization within the Hudson River estuary linked to Holocene climate. Geo-Mar Letters 24:212-224.Claassen, C. 1998. Shells. Cambridge University Press, Cambridge. 266 pages.Crook, MR. 1992. Oyster sources and their prehistoric use on the Georgia coast. Journal of Archaeological Science 19:483-396. Crook, MR. 2007. Prehistoric pile dwellers within an emergent ecosystem: An archaeological case of hunters and gatherers at the mouth of the Savannah River during the mid-Holocene. Human Ecology 33:223-237. Dame RF. 1972a. Comparison of various allometric relationships in intertidal and subtidal American oysters. Fishery Bulletin 70:1121-1126.Dame, RF. 2005. Oyster reefs as complex systems. In: The Comparative Roles of Suspension-Feeders in Ecosystems, RF Dame S Olenin (Eds), Kluwer Academic Publishers, Dordrecht.Dame, RF. and 10 other authors. 2000. Estuaries of the South Atlantic coast of North America: Their geographical signatures. Estuaries 23:793-819.Dame, RF, Childers, D, and Koepfler, E. 1992. A geohydrologic continuum theory for the spatial and temporal evolution of marsh-estuarine ecosystems. Netherlands Journal of Sea Research 30:63-72.DePratter, CB, and Howard, JD. 1981. Evidence for a sea level lowstand between 4500 and 2400 B.P. on the southeast coast of the United States. Journal of Sedimentary Petrology 51:1287-1295.Gardner, LR, and Porter, DE. 2001. Stratigraphy and geologic history of a southeastern salt marsh basin, North Inlet, South Carolina, USA. Wetlands Ecology and Management 9:371-385.Grattan, J. 2006. Aspects of Armageddon: An exploration of the role of volcanic eruptions in human history and civilization. Quaternary International 151:10-18.Jackson, JBC, & 18 others. 2001. Historical overfishing and the recent collapse of coastal ecosystems. Science 293:629-638.Keith, WJ, and Gracie, RC. 1972. History of the South Carolina Oyster. SC Wildlife Resources Department. Educational Rept. No. 1, 20 pages.Lunz, GR. 1938. Comparison between pre-colonial and present-day oysters. Science 87: 367.Manning, S. 1999(with update). A Test of Time: the volcano of Thera (Santorini). Oxbow, Oxford.Mannino, MA, and Thomas, KD. 2002. Depletion of a resource? The impact of prehistoric human foraging on intertidal mollusc communities and its significance for human settlement, mobility and dispersal. World Archaeology 33(3):452-474.

Mayewski, PA. and 15 others. 2004. Holocene climate variability. Quaternary Research 62:243-255.Newell, R. 1988. Ecological changes in Chesapeake Bay: are they the result of overharvesting the American oyster, Crassostrea virginica? In: Understanding the estuary: advances in Chesapeake Bay research, Lynch MP Krome EC (Eds), Chesapeake Bay Research Consortium, Solomon’s Maryland. pp 536-546.Reitz, EJ, and Wing, ES. 2008. Zooarchaeology, 2nd Edition. Cambridge University Press, Cambridge. 533 pages.Russo, M. 1991. A method for the measurement of season and duration of oyster collection: Two case studies from the prehistoric South-East U.S. coast. Journal of Archaeological Science 18:137-158.Russo, M. 2002. Faunal analysis at Fig Island. In: Saunders, R. (Ed.) 2002. The Fig Island ring complex: Coastal adaptation and the question of ring function in the Late Archaic. Report to the South Carolina Department of Archives and History, Columbia, SC. Pages 141-153/Russo, M. 2004. Notes on South Carolina and Florida shell rings. NPS.Russo, M, and Heide, G. 2001. Shell rings of the southeast. Antiquity 75:491-492.Sadler, JP and Grattan, JP. 1999. Volcanoes as agents for past environmental change. Global and Planetary Change 21:181-196.Sanger, D, and Sanger, MJ. 1986. Boom or bust on the river: The story of the Damariscotta oyster shell heaps. Archaeology of Eastern North America 14:65-78.Saunders, R. (Ed.) 2002. The Fig Island ring complex: Coastal adaptation and the question of ring function in the Late Archaic. Report to the South Carolina Department of Archives and History, Columbia, SC.Scott, DB, Gayes, PT and Collins, ES. 1995. Mid-Holocene precedent for a future rise in sea-level along the Atlantic coast of North America. Journal of Coastal Research 11:6150-622.Surge, DM, Lohmann, KC, and Goodfriend, GA. 2003. Restructuring estuarine conditions: oyster shells as recorders of environmental change. Estuarine, Coastal and Shelf Science 57:737-756.Trinkley, M. 1985. Form and function in South Carolina’s early Woodland shell rings. In: Dickens, R, and Ward, T. (Eds.), Structure and Process in Southeastern Archaeology. University of Alabama Press, Tuscaloosa. Pages 102-118.Wood, R. 2000. Reef Evolution. Oxford University Press, Oxford. 414 pages.