1. West Side Story the context, causes, and consequences of the Pacific oyster introduction to Washington State Jennifer Ruesink University of Washington

2. Context –Ruesink, Lenihan, Trimble, Heiman, Micheli, Byers, Kay. 2005. Introduction of non-native oysters: ecosystem effects and restoration implications. Annu Rev Ecol Evol Syst 36:643-689 Causes –White, Ruesink, Trimble. History and management of native oysters (Ostrea conchaphila) in Washington State. In preparation for special issue of J Shellfish Res Consequences –Ruesink, Feist, Harvey, Hong, Trimble, Wisehart. 2006. Changes in productivity associated with four introduced species: Ecosystem transformation of a “pristine” estuary. Mar Ecol Prog Ser 311:203-215 –Trimble, Ruesink, Dumbauld. Factors preventing recovery of a historically overexploited shellfish species. In preparation. Outline

3. Context Oyster introductions have occurred frequently High establishment rate Vector for numerous other species Nearly complete replacement of native oyster production

4. Compilation of oyster introductions Introduction = movement of species from one country/ region to another where it was not previously present Sources = UN FAO, several earlier reviews (Eldredge 1994, NRC 2004), published papers, personal communications Number of introductions = _____ Number of recipient locations = ____ Number of species = ____

5. Compilation of oyster introductions Introduction = movement of species from one country/ region to another where it was not previously present Sources = UN FAO, several earlier reviews (Eldredge 1994, NRC 2004), published papers, personal communications Number of introductions = _164_ Number of recipient locations = _73_ Number of species = _16_

6. When did oyster introductions occur? Charles Elton fingered oyster introductions as the “greatest agency of all that spreads marine animals to new corners of the world”

7. Where have oysters been introduced? 18 61 6 19 9 6 41 3 4

8. Which oyster species have been introduced? O’Foighil & Taylor 2000 Molecular Phylogenetics & Evolution 15:301 C. virginica = 16 C. rhizophorae = 3 C. gigas = 64 + 6 C. ariakensis = 3 S. commercialis = 6 S. cucullata = 3 O. edulis = 11 T. chilensis = 3 C. densalamellosa = 1 O. conchaphila = 1 O. puelchana = 1 C. echinata = 5 C. sikamea = 3 C. iredalei = 2 C. belcheri = 1 C. cortezensis = 1

9. How well did they do?

10. Why were new oysters introduced? Replace native species Begin new product (Pacific islands) Research (12) Range expansion (4) By-product (3)

11. Introduced oysters have replaced native oyster production

12. Introduced oysters have vectored many other species

13. Context Oyster introductions have occurred frequently High establishment rate Vector for numerous other species Nearly complete replacement of native oyster production However, ecological impacts of introduced oysters are poorly studied: To what extent do introduced oysters replace “ecosystem function”? Is recovery of native oysters improved or impaired?

14. Causes Why were Pacific oysters (Crassostrea gigas) introduced to Washington State? –Harvesting native oysters was no longer economical… but therein lies a story

15. VANCOUVER SEATTLE PORTLAND Willapa Bay Puget Sound

16. Native oyster Baker 1995 Ostreola conchaphila (Carpenter, 1857) Historic Range: Sitka, AK to Mexico Maximum 6 cm Protandrous Hermaphrodite Brooding Females: ~250,000 larvae/adult Spawning above 12C for 3+ months/yr. Subtidal accumulations of shell

17. The way it used to be? Willapa Bay at low water, late 1800s

18. Willapa Bay – current population between 0 and -2’ MLLW is sparse in eelgrass

19. North Bay, Puget Sound – ~25 million oysters between 0 and -4’, newly recovered

20. Trimble, unpubl.

22. Willapa Bay timeline

23. First harvest restrictions

24. Native oysters described scientifically

25. Tideflat privatization

27. Marine Reserves

29. Collins, 1888 Oyster Reserves: Legislated ~1900 Almost perfect overlap with original native oyster beds

30. C. virginica introduction Subsequent introductions: C. gigas - established O. edulis C. sikamea C. ariakensis

31. Commercial interest shifted to Crassostrea gigas: Imports of spat to the west coast White, Ruesink, Trimble, unpubl.

32. Secondary production in Willapa Bay shifted from native to non-native shellfish (filtration too) Ruesink, Feist, Harvey, Hong, Trimble, Wisehart. 2006. Mar Ecol Prog Ser

33. Research efforts also shifted Number of holdings in the University of Washington library referring to each species Scientific literature includes <15 modern papers on O. conchaphila – but this will soon change!

34. Has C. gigas functionally replaced O. conchaphila? Native oyster –Brooding –Slow growth –Subtidal –Loose shell New oyster –Broadcasting –Rapid growth –Intertidal –Reef-building

35. Consequences What are the ecological impacts of Pacific oysters (Crassostrea gigas)? –Interactions with native oysters – directly and indirectly –Effects of shellfish and aquaculture practices on sediment properties, eelgrass, epibiota, fish and crabs are the focus of targeted research funded in part by the shellfish industry

36. Potential Factors Limiting Population Recovery - Reproductive Failure (no) ----------------------- - Settlement Habitat Change (yes) - Pollution and Sedimentation (yes) - Competition (space- yes) - Predation (yes) - Disease (limited)

37. Middle Sands Reserve Long Island Reserve Spatfall on Cinder Block Anchors (-10m) Native oyster recruitment remains high

38. Quantitative recruitment time series Weekly records of spatfall from 1947- 1987, 2002-2006 Native oyster usually > Pacific oyster

39. 1947-2006 Spatfall: O. conchaphila and C. gigas O.conchaphila C. gigas

40. But where do those larvae now settle? What native oyster beds used to be… maybe… perhaps?

41. Settlement Habitat Change C. gigas intertidal reefs

42. Settlement Habitat Change Increased sedimentation from logging in watershed

43. Quantitative assessment of recruitment across habitats

44. Recruitment rate across habitats Most available habitat

45. 2-factor experiment: 3 elevations, +/- competitors Tiles on mooring Day 0 (1 month old) Day 63 Day 304

46. MLLW (- 30cm) (+ 30cm) “HIGH” “LOW”

47. “MOORING” (-1 m)

48. F 8,112 = 2.8, P = 0.007 Survival declines when not submerged

49. Impacts of competitors Ectopleura crocea Botryllus spp. >45 introduced species reported in Willapa Bay Wonham & Carlton 2005 Biol Inv

50. F 1,112 = 42.4, P < 0.001 Competitors Reduce Survival

51. F 4,61 = 5.5, P = 0.001 Competitors Reduce Growth

52. Interactions between Washington’s native and non-native oysters Recruitment “sink”: Intertidal aquaculture Naturalized intertidal reefs Historical vector of non-native predators and competitors Recruitment, but poor intertidal survival - Overgrowth? High sustained recruitment indicates presence of core reproductive population

53. BareGravel Pacific shell Crushed Pacific shellNative shellLive natives May 2004

54. Recruitment improved at lower elevations and on natives

56. Unstable treatments washed away at most sites

57. Stable treatments were heavily fouled at most sites

58. Rosettes – natives grew and survived

59. Rosettes – buried at other sites

60. Shell on ground – not a functional replacement for natives