Elene Dorfmeier's presentation: How will a changing climate impact Vibrio tubiashii growth and pathogenicity to Pacific oyster larvae?

1. How will a changing climate impact
Vibrio tubiashii growth and pathogenicity
to Pacific oyster larvae?
Elene Dorfmeier, Steven Roberts, Carolyn Friedman
University of Washington | S A F S
PCSGA – NSA Joint Meeting 9-21-11

2. Aquaculture and Bivalve Larvae
Regional Problems
Ü Limited natural recruitment of
bivalve species
Ü Ocean chemistry changes
Ü Re-emergent disease
Photo: Norbert Dankers

3. Acidification of Northwest Waters
SUMMER 2009:
Dabob Bay
Totten Inlet
Map: R. Jacobsen Graphs: Simone Alin et al. NOAA

4. Environment
Impact of Acidification on C. gigas
Ü Effects of OA on calcifying marine
organisms:
• Growth and development
• Energy allocation
• Metabolic depression
Ü Pathogen – Host interaction?
Ü Disease susceptibility?

5. Pathogen
Vibrio tubiashii
Ü Gram-negative, facultative anaerobe
Ü Pathogenic to a variety of marine
invertebrate larvae, including Pacific oyster
Ü Re-emergent vibriosis in the Northwest
Photo: Phetsouvanh et al. 2008

6. Research Goals
Ü Investigate how environmental stressors will
influence Vibrio tubiashii growth
Ü Determine how elevated pCO2 impacts Pacific
oyster larval survival and disease susceptibility
Photo: Norbert Dankers

7. Research Goals
ü Investigate how environmental stressors will
influence Vibrio tubiashii growth
Ü Determine how elevated pCO2 impacts Pacific
oyster larval survival and disease susceptibility
Photo: Norbert Dankers

8. Vt growth experimental design
25°C 25°C
~380 750
ppm ppm
12°C 12°C
Vt strain RE22
Inoculation dose: 103 CFU/ml
3 days of growth

9. Results: 25°C Vt Growth
Error Bars = ± 1 SE

10. Results:
Vt Growth at elevated pCO2
Ü At 25°C, no detectable difference in
Vt growth at 750 ppm pCO2
Ü All stages of growth at 12°C not
captured within 72 hr experiment
Growth curves fit to Gompertz growth model: y = Ae(-b2*b3)^x

11. Research Goals
Ü Investigate how environmental stressors will
influence Vibrio tubiashii growth
ü Determine how elevated pCO2 impacts Pacific
oyster larval survival and disease susceptibility
Photo: Norbert Dankers

12. Larval Disease Challenge
Temperature:
16°C
pCO2:
~380 ppm = 8.0 pH Disease:
750 ppm = 7.8 pH V. tubiashii
2000 ppm = 7.4 pH
Ü Five Vt doses (102 – 106 CFU/ml), plus sterile control
Ü 40 larvae per well; 6 replicates per dose of Vt
Ü LD50 determination at 24, 48, and 72 hrs
Photo: Ghent University

13. Overview: Vt Disease Challenge
Early stage Late stage
D-veliger veliger
3 days old 10 days old
Photo: FAO

14. Results: Larval Disease Challenges
Larval Survival on Day 3
Early stage Late Stage
Error Bars: ± 95% CI
p-values > 0.05

15. LD50 Results
LD50 reported in CFU/ml of V. tubiashii

16. LD50 Results
LD50 reported in CFU/ml of V. tubiashii

17. LD50 Results
LD50 reported in CFU/ml of V. tubiashii

18. Larval Disease Challenge: Summary
No detectable difference in Pacific oyster
susceptibility to vibriosis at elevated pCO2.
Considerations:
Ø Larval population variation
Ø Length of exposure to low pH conditions
Ø Carbonate ion availability and saturation
states during spawning (Gazeau et al. 2011)
Ø Vt culture conditions

19. Conclusions
Ü Vt growth at 25°C was not significantly
different at elevated pCO2
Ü 12°C Vt growth to be performed again to
capture full growth curve at 750 ppm
Ü No significant differences in susceptibility
to vibriosis were detected at either larval
age or pCO2 level in Pacific oysters
Ø Important to consider factors that may
affect host susceptibility that are difficult to
account for

20. Next Step: Vt Gene Expression
VtpR
(Hasegawa & Hase 2009)
• Metalloprotease
Toxins (vtpA)
• Hemolysin
• Flagellar
Motility expression
Photo: NOAA NWFSC

21. THANK YOU!
Saltonstall-Kennedy Program (NOAA)
UW School of Aquatic & Fishery Sciences
Ed and Vicky Jones - Taylor Shellfish Hatchery
Joth Davis - Taylor Resources
Sam White
Richard Wilson – Bay Center Mariculture
Russell Rogers – WDFW
Generous student support provided by:
Chelsea Farms LLC, Little Skookum Shellfish
Growers, Rock Point Oyster Co., Seattle
Shellfish, and Taylor Shellfish Co.