Success Targets for Oyster Restoration Deriving Benchmarks from Natural Populations Nancy Hadley, Loren Coen, Michael Hodges, Dara Wilber and Keith Walters

SCORE Community-Based Oyster Restoration Program 28 sites constructed between 2001 and 2006

18 of 28 sites have reefs of multiple ages.

Success measures must be matched to restoration goals RESTORATION GOAL METRICHabitatShorelineWQHarvestingBroodstockEducation Reef SizeXXXXX Reef Condition Oyster DensityXXXXXX Oyster Size FrequencyXXXXX? Associated FaunaX X Reef ArchitectureXX?X X Reef FragmentationXX?XX SalinityX XXXX DOX (s) XXXX Chlorophyll X Turbidity/TSS X X TemperatureX X X

When can/should success be determined? What constitutes success? Sustainability Multiple year classes Size/density comparable to natural populations How do you establish the targets? Habitat functioning When can/should success be determined? What constitutes success? Sustainability Multiple year classes Size/density comparable to natural populations How do you establish the targets? Habitat functioning EVALUATING SUCCESS

Size Frequencies on 1 and 3 Year Old Reefs Fall 2004

Size Frequencies on 2 and 3 Year Old Reefs Fall 2004 Could success be evaluated at 2 years?

Size Frequency of Oysters on 2 and 3 Year Old Reefs Fall 2005

When can/should success be determined? 3 years or more at most sites What constitutes success? Multiple year classes Most 3 year old (and some 2 year old) SCORE sites have multiple year classes Size/density comparable to natural populations How do you establish the targets? Mean values from long-term datasets Habitat functioning EVALUATING SUCCESS

Data spans 9 years with different sites sampled each year, covering the spectrum of natural oyster reefs in the state.

Metrics Considered (Natural Population Mean) Mean Shell Height (31 mm) Total density (2,350/m 2 ) Density of small oysters (<20 mm=YoY) (1,100/m 2 ) Density of large oysters (>60 mm) (240/m 2 ) Percent of population consisting of small oysters (45%) Percent large oysters (10%) Good = population mean or greater Fair = within 1 SD of population mean Poor = more than 1 SD less than population mean

3 “good”, 7 “fair”. All 1 year old reefs “fair”.

5 “good”, 2 “fair”, 1 “poor”.

Shortcomings of Using Population Means Site rankings all similar No definition for “Excellent” Even one year old sites rank fair

When can/should success be determined? 3 years or more at most sites What constitutes success? Multiple year classes Most 3 year old (and some 2 year old) SCORE sites have multiple year classes Size/density comparable to natural populations How do you establish the targets? Mean values from long-term datasets Classify natural reefs (= stratify) Habitat functioning EVALUATING SUCCESS

Fair Good Strata C Fair Strata A Very good Strata G Good Strata E Excellent?

Note: Very few large oysters on any strata

Total Beds in Each Strata from Statewide Survey Ben Dyar 12 June 2006 Total beds classified: 2519 Very few Strata A or E

Metrics Evaluated Mean Size Total oyster abundance Oyster abundance minus YoY Abundance of YoY (<20 mm) Abundance of large (>60 mm) Percent small Percent large Ratio large:small Live bushels/m 2 Within 25% of strata mean = “match” Iterative matching starting with best strata Best match determined by assigned ranks (0,1,2,3,4) to the strata

1 “Excellent”, 4 “Very good”, 3 “Good”, 2 “Fair”

When can/should success be determined? 3 years or more at most sites What constitutes success? Multiple year classes Most 3 year old (and some 2 year old) SCORE sites have multiple year classes Size/density comparable to natural populations How do you establish the targets? Mean values from long-term datasets Classify natural reefs (= stratify) Compare restored reefs to specific strata Habitat functioning EVALUATING SUCCESS

Palmetto 3 Years Population means: Good Strata Means: Excellent Strata Convergence:E Strata A Very good Strata G Good Strata E Excellent?

Dataw - 3 Years Population means: Fair Strata means: Good Strata Convergence: Between C and G Strata G Good Strata C Fair

Pinckney 3 Years Population mean: Fair Strata Mean: Fair Fair Not yet converging Strata C Fair

Trask 3 Years Population means: Good Strata Means: Very Good Similar to G, may reach A Strata A Very good Strata G Good

Edisto 3 Years Fair Population means: Poor Strata Means: Fair Different from all defined strata Strata C Fair Strata E Excellent?

When can/should success be determined? 3 years or more at most sites What constitutes success? Multiple year classes Most 3 year old (and some 2 year old) SCORE sites have multiple year classes Size/density comparable to natural populations How do you establish the targets? Mean values from long-term datasets Classify natural reefs (= stratify) Compare restored reefs to specific strata Habitat functioning EVALUATING SUCCESS

Associate Fauna Targets based on Population Means 4 “Good”, 6 “Fair”

2 Excellent 3 Very Good 3 Good 1 Poor 1 Unknown 6 Good 4 Fair 3 Good 2 Fair 1 Excellent 4 Very Good 3 Good 2 Fair

CONCLUSIONS Success can be evaluated at 3 years of age at most sites. Sites should continue to develop and it may take many years to resemble a complex habitat like Stratas E and A. 2 and 3 year old SCORE sites have multiple size classes. Using population means as targets may be striving for mediocrity. Stratifying natural populations may provide more meaningful targets. Classifying restored sites by strata characteristics sets site- specific goals. Is this a valid tool? Most SCORE sites appear to be on a convergence path with some natural strata. Even 1 year old reefs score well for habitat function (?)

Future Directions % vertical coverage Confidence limits Test at older restored sites Validation at natural sites Test targets in other geographic areas Habitat functioning –Diversity indices –Transient fauna Weighting of metrics Relate success to site characteristics

Acknowledgements Shellfish Research Section, past and present, particularly Steve Roth, Andrew Hollis, Ben Dyar, Julie Nelson, Meghan Ward, Amanda Powers, Donnia Richardson, Yvonne Bobo, Virginia Shervette, Claudia Jendron, Lee Taylor, Darin Jones and Emma Gerald. All the volunteers who helped build and sample the reefs! Funded by: