Vibrio tubiashii and Pacific oyster disease susceptibility

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Vibrio tubiashii and Pacific oyster disease susceptibility

  1. 1. Vibrio tubiashii : disease and pathogenicity to Pacific oyster larvae Pacific Coast Shellfish Growers Association Annual Meeting September 26, 2012 Elene Dorfmeier, Carolyn Friedman, Steven Roberts University of Washington | School of Aquatic & Fishery Sciences
  2. 2. Pacific Northwest Shellfish Industry Photo: OSU• USD100 million industry (~3000 jobs)• Large-scale production reliant on shellfish hatcheries• Oysters account for ~76% of shellfish production Google Maps
  3. 3. Aquaculture and Bivalve Larvae Regional Problems  Declines in larval settlement  Re-emergent disease  Seawater chemistry changes Photo: Norbert Dankers
  4. 4. The Pathogen: Vibrio tubiashii (Vt) Gram-negative, facultative anaerobe Causative agent of vibriosis in early stage shellfish Pathogenic to a variety of marine invertebrates, including Pacific oyster Photo: Phetsouvanh et al. 2008
  5. 5. Disease Vibriosis:  Characterized by bacterial swarming, loss of motility, soft tissue necrosis, and mortality  Larval mortality within 24 hours of exposure to the most pathogenic strains  Management of bacterial disease has been historically problematic  Re-emergent in the Northwest Larvae Photo: Lisa Crosson Bacteria Photo: Dartmouth EM Facility
  6. 6. Environmental Change: Ocean AcidificationThe chemical changes associated with the increase of CO2 in the oceans. • increases aqueous CO2 • lower seawater pH • decreased carbonate ion (aragonite, calcite) availability
  7. 7. Acidification of Northwest Waters SUMMER 2009: Dabob Bay Totten InletMap: R. Jacobsen Graphs: Simone Alin et al. NOAA
  8. 8. Impact of Ocean Acidification on Marine Calcifiers Effects of ocean acidification on calcifying organisms:  Growth and development  Energy allocation  Metabolic depression Photo: Emma Timmons-Shiffman
  9. 9. Environmental Shifts and Shellfish Aquaculture 1. Re-emergent bacterial disease  Vibrio tubiashii 2. Host response to environmental shifts   high pCO2 and temperaturePhoto credit: Steve Ringman, Seattle Times
  10. 10. Research Goals Investigate the influence of elevated pCO2 on Vibrio tubiashii growth Determine the impact of elevated pCO2 on Pacific oyster larval susceptibility disease Photo: Norbert Dankers
  11. 11. Investigate the influence ofelevated pCO2 on Vibrio tubiashii growth Photo: Dartmouth Electron Microscope Facility
  12. 12. Vt Growth Curves pCO2:Ambient (7.9 pH)750 ppm (7.8 pH) Temperature:2000 ppm (7.4 pH) 16°C Establish growth curves Standard bacterial enumeration Photo: Ghent University
  13. 13. Growth RateError Bars = 95% CI
  14. 14. Growth RateError Bars = 95% CI
  15. 15. Growth Ratep = <0.001* p = 0.1 Error Bars = 95% CI
  16. 16. Total Abundance Error Bars = 95% CI
  17. 17. Total Abundance * * p = <0.001 * Error Bars = 95% CI Stationary Phase
  18. 18. Summary: Vt Growth At 16°C, Vt grew faster and reached higher abundance at elevated pCO2 Enhanced Vt growth under acidified conditions may lead to outbreaks of vibriosis in hatcheries Why? / How?  Enhanced gene expression of cell division when exposed to lower pH (cadA, toxR, rpoS)? Photo: Dartmouth Electron Microscope Facility
  19. 19. Determine the impact of elevated pCO2 on Pacific oyster larval susceptibility diseasePhoto: Virginia Sea Grant
  20. 20. Vt Disease Challenge Temperature: 16°C pCO2: DiseaseAmbient (7.9 pH) agent:750 ppm (7.8 pH) V. tubiashii2000 ppm (7.4 pH) RE22 Vt doses (102 – 106 CFU/ml) LD50 at 24, 48, and 72 hrs Photo: Ghent University
  21. 21. Overview: Vt Disease Challenge Early stage Prodissoconch I D-veliger veliger 3 days old 10 days oldPhoto: FAO
  22. 22. Results: Larval Disease Challenges Larval survival after 48 hours Vt exposure Late Stage Early stage ND ND Error Bars: 95% CI p-values >> 0.05
  23. 23. LD50 Results Early stage Late StageLD50 reported in CFU/ml of V. tubiashii Logistic curve: Pi = 1 / (1 + e –(a + b * x))
  24. 24. LD50 Results Early stage Late StageLD50 reported in CFU/ml of V. tubiashii Logistic curve: Pi = 1 / (1 + e –(a + b * x))
  25. 25. LD50 Results Early stage Late StageLD50 reported in CFU/ml of V. tubiashii Logistic curve: Pi = 1 / (1 + e –(a + b * x))
  26. 26. Larval Disease ChallengeNo detectable difference in Pacific oyster susceptibilityto vibriosis at elevated pCO2.Considerations: • Length of exposure to experimental conditions • Conditions throughout early shell development is important to overall survival • Vt culture conditions
  27. 27. Summary: Disease and OA Elevated pCO2 does not affect Vt pathogenicity, but Vt growth under acidified conditions may facilitate outbreaks of vibriosis  Higher temperature exacerbates growth  Still many unanswered questions Rearing oysters at lower temperatures when higher pCO2 levels exist may have lower risk of vibriosis  Trade-off  less disease / slower oyster growth
  28. 28. Saltonstall-Kennedy Program (NOAA) UW School of Aquatic & Fishery SciencesGenerous student support provided by NOAA NSA – Pacific Coast Section Ed and Vicky Jones Taylor Shellfish Hatchery Washington Sea Grant NOAA PMEL Joth Davis - Taylor Resources Emma Timmons-Shiffman Mackenzie Gavery Sammi Brombacker Robyn Strenge Alex Rutherford

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