1. Inter-site and inter-specific differences in rates of survival and growth of C. ariakensis and C. virginica: A collaborative on-bottom study in Virginia and Maryland Kingsley-Smith, P. R., Harwell, H. D, Kellogg, M. L., Allen, S. K. Jr., Meritt, D. W., Paynter, K. T. Jr. & Luckenbach, M. W. 9 th International Conference on Shellfish Restoration Charleston, South Carolina, USA November 15 th -19 th 2006

2. FUNDING SOURCES COLLABORATORS University of Maryland Center for Environmental Science (UMCES) Horn Point Laboratory

3. Current knowledge of C. ariakensis survival and growth rates is based upon 1) field trials using triploids in off-bottom, caged aquaculture, and 2) quarantined studies using diploids. Predicting rates of survival and growth of C. ariakensis in natural bottom habitats is critical to a pending decision on an intentional introduction. Accurate determination of these rates will improve parameterization of a developing demographic model. This study is the first to grow C. virginica and C. ariakensis (in VA and MD) side-by-side on the bottom in an effort to gather survival and growth data in a more naturalistic setting. I. INTRODUCTION

4. Triploid C. ariakensis and C. virginica were set on shell in May 2005 and planted at ~400 oysters m -2 in late Oct–Nov 2005 at 4 sites in VA and MD. II. METHODS

5. Oysters were planted in 2’ x 2’ bread trays in 5 x 5 arrays in late Oct-Nov 2005. II. METHODS

6. Cages were placed around the trays to prevent disturbances by large epibenthic predators (e.g., cownose rays) and humans, while allowing access to small predators (e.g., xanthid crabs). II. METHODS Machipongo River Virginia

7. Treatments (single treatment per cage): C. virginica onlyC. virginica only C. ariakensis onlyC. ariakensis only C. virginica and C. ariakensis in a 50 : 50 mixC. virginica and C. ariakensis in a 50 : 50 mix Shell only (no live oysters)Shell only (no live oysters) Experimental design: 2 replicate cages (blocks 1 and 2) per treatment (4) at each field site. 4 sites (2 sites in Virginia; 2 sites in Maryland). Sites were chosen to cover a range of salinities, water depths, disease pressures and relative predator abundances. II. METHODS

8. Atlantic Ocean Delaware Bay Chesapeake Bay 25 km Patuxent River York River Severn River Machipongo River II. METHODS

9. MACHIPONGO RIVER, VA Intertidal Salinity: ~30 psu Predation pressure: High High Dermo & High MSX II. METHODS

10. YORK RIVER, VA Subtidal (1-2m) Salinity: 20-25 psu Predation pressure: High High Dermo & High MSX II. METHODS

11. PATUXENT RIVER, MD Subtidal (3-4m) Salinity: 8-10 psu Predation pressure: Moderate Low Dermo & No MSX SEVERN RIVER, MD Subtidal (3-4m) Salinity: 5-8 psu Predation pressure: Low No Dermo & No MSX II. METHODS Courtesy of Paynter Lab

12. Sampling = removal of 3 trays from each cage and replacement of sampled trays with those containing only clean shell. Cages were sampled one month after deployment (i.e., Nov-Dec 2005) to assess handling and early post-deployment mortality. Quarterly sampling thereafter: Apr 2006, July 2006 and Oct 2006. Future sampling: Apr 2007, July 2007 and Oct 2007. II. METHODS

13. This study will provide data on the following parameters: oyster survival (# live oysters) oyster growth (shell height mm) oyster biomass (ash-free dry weight) ploidy/reversion (biosecurity) disease (RFTM & histology) gametogenesis (histology) comparisons of habitat complexity between treatments (spp.) and its relationship to associated free-living and attached faunal assemblages. (Poster by Heather Harwell et al.). II. METHODS

14. This study will provide data on the following parameters: oyster survival (# live oysters) oyster growth (shell height mm) oyster biomass (ash-free dry weight) ploidy/reversion (biosecurity) disease (RFTM & histology) gametogenesis (histology) comparisons of habitat complexity between treatments (spp.) and its relationship to associated free-living and attached faunal assemblages. (Poster by Heather Harwell et al.). II. METHODS July 2006

15. SURVIVAL III. RESULTS – SURVIVAL MACHIPONGO RIVERYORK RIVER PATUXENT RIVERSEVERN RIVER 140 120 100 80 60 40 20 0 140 120 100 80 60 40 20 0 140 120 100 80 60 40 20 0 140 120 100 80 60 40 20 0 Oct Nov DecJanFebMarAprMayJunJulOct Nov DecJanFebMarAprMayJunJul Oct Nov DecJanFebMarAprMayJunJulOct Nov DecJanFebMarAprMayJunJul 20062005 20062005 20062005 20062005 Mean no. oyster tray -1 C. virginica C. ariakensis Single spp. cages only Error bars are S.D.s (n = 6)

16. Error bars are S.E.s III. RESULTS – SURVIVAL - Within site comparisons 100 80 60 40 20 0 Mean # live oysters per tray 12121212 MachipongoYorkPatuxentSevern C. virginica C. ariakensis

17. 100 80 60 40 20 0 Mean # live oysters per tray 12121212 MachipongoYorkPatuxentSevern C. virginica C. ariakensis BLOCKS & SPP. NOT SIGNIFICANTLY DIFFERENT SIGNIFICANT BLOCK & SPP. EFFECTS III. RESULTS – SURVIVAL - Within site comparisons

18. 100 80 60 40 20 0 Mean # live oysters per tray 12 MachipongoYorkPatuxentSevern C. virginica C. ariakensis III. RESULTS – SURVIVAL - Within site comparisons combined Error bars are S.E.s

19. 100 80 60 40 20 0 Mean # live oysters per tray 12 MachipongoYorkPatuxentSevern C. virginica C. ariakensis III. RESULTS – SURVIVAL - Within site comparisons combined ns Error bars are S.E.s

20. 100 80 60 40 20 0 Mean # live oysters per tray 12 MachipongoYorkPatuxentSevern C. virginica C. ariakensis Intertidal Subtidal ns III. RESULTS – SURVIVAL - Within site comparisons combined Error bars are S.E.s

21. 100 80 60 40 20 0 Mean # live oysters per tray 12 MachipongoYorkPatuxentSevern C. virginica C. ariakensis MLW MLW + 1ft Intertidal Subtidal ns III. RESULTS – SURVIVAL - Within site comparisons combined Error bars are S.E.s

22. Machipongo River Virginia

23. BLOCK 1

24. BLOCK 2 Machipongo River Virginia

25. 100 80 60 40 20 0 Mean # live oysters per tray 12 MachipongoYorkPatuxentSevern C. virginica C. ariakensis MLW MLW + 1ft Intertidal Subtidal (p = 0.06) ns III. RESULTS – SURVIVAL - Within site comparisons combined MSX? predation? Error bars are S.E.s

26. 100 80 60 40 20 0 Mean # live oysters per tray MachipongoYorkPatuxentSevern C. virginica C. ariakensis III. RESULTS – SURVIVAL – Across site comparisons combined Error bars are S.E.s

27. III. RESULTS – SURVIVAL – Across site comparisons 100 80 60 40 20 0 Mean # live oysters per tray MachipongoYorkPatuxentSevern A ABBCC C. virginica across site comparisons combined Error bars are S.E.s

28. III. RESULTS – SURVIVAL – Across site comparisons 100 80 60 40 20 0 Mean # live oysters per tray MachipongoYorkPatuxentSevern A ABBCC C. virginica across site comparisons combined Error bars are S.E.s

29. III. RESULTS – SURVIVAL – Across site comparisons 100 80 60 40 20 0 Mean # live oysters per tray MachipongoYorkPatuxentSevern A ABBCC C. virginica across site comparisons combined Error bars are S.E.s

30. III. RESULTS – SURVIVAL – Across site comparisons 100 80 60 40 20 0 Mean # live oysters per tray MachipongoYorkPatuxentSevern A ABBCC C. virginica across site comparisons combined increasing survival decreasing salinity Error bars are S.E.s

31. III. RESULTS – SURVIVAL – Across site comparisons 100 80 60 40 20 0 Mean # live oysters per tray MachipongoYorkPatuxentSevern C. virginica across site comparisons combined Machipongo represents suitable habitat for C. virginica (survival comparable with York River)…. A ABBCC Error bars are S.E.s

32. 100 80 60 40 20 0 Mean # live oysters per tray MachipongoYorkPatuxentSevern a b C. ariakensis across site comparisons b b III. RESULTS – SURVIVAL – Across site comparisons combined …but less suitable habitat for C. ariakensis Error bars are S.E.s

33. MACHIPONGO RIVER, VA JULY 5 TH 2006 YORK RIVER, VA JULY 24 TH 2006 PATUXENT RIVER, MD JULY 10 TH 2006 SEVERN RIVER, MD JULY 17 TH 2006 Shell height (mm) # oysters C. virginica C. ariakensis GROWTH III. RESULTS – GROWTH (Data include oysters from both single and mixed spp. cages.)

34. Survival and growth data are now available for triploid C. ariakensis and C. virginica from several bottom habitats ranging in salinity, depth, disease pressure and relative predator abundance. Significant interactions were observed between sites and species for both survival and growth. Lowest survival of both species was observed at the intertidal Machipongo River site, with C. ariakensis survival especially low. Highest growth rates of C. ariakensis were observed at the York River (site characteristics: subtidal & high salinity). Both species (particularly C. virginica) show a trend of increased survival with decreasing salinity across sites. Growth rates of C. virginica and C. ariakensis were most similar at the low salinity Severn River site. IV. CONCLUSIONS

35. Eastern Shore Lab Reade Bonniwell PG Ross Sean Fate Alan Birch Edward Smith Jamie Wheatley Al Curry Stephanie Bonniwell Rochelle Brown University of Maryland (sampling help) Jake Goodwin Mark Sherman Steve Allen Marcy Chen Nancy Ward VIMS ABC Shane Bonnot Ryan Gill Karen Hudson ESL Summer aides Raija Bushnell Sarah Mallette Matt Foley Andrew Wilson Andrew Matkin VIMS Shellfish Pathology Lab Ryan Carnegie Rita Crockett Susan Denny V. ACKNOWLEDGEMENTS

37. 2 4 6 8 10 % frequency shell height (mm) 5101520253035 40 Pre-deployment shell height distributions C. ariakensis(mean SH = 13.85mm, n = 1272) C. virginica(mean SH = 12.80mm, n = 1362)