1. IMPROVED RESOLUTION OF Filtration services FROM OCEANOGRAPHIC AND PHYSIOLOGICAL STUDIES of the native Olympia oyster (Ostrea lurida) and the introduced Pacific oyster (Crassostrea gigas)
Matthew Gray1, Philine ZU Ermgassen2, Jon GAIR3, Emily Lemagie4, Jim Lerczak4,
and Chris Langdon1
1. Hatfield Marine Science Center, Oregon State University, Newport, Oregon.
2. Department of Zoology, University of Cambridge, Cambridge U.K.
3. Institute of Astronomy, University of Cambridge, Cambridge U.K.
4. College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon
National
Estuaries Research Reserve
System

2. HISTORIC DISTRIBUTION OF O. LURIDA
(Peabody and Griffin, 2008)
Introduction
Traditional Models
Improved Model
Conclusions

3. HISTORIC DECLINE OF WEST COAST NATIVE OYSTERS
Populations of native oysters were rapidly exhausted in Willapa Bay and other coastal bays by the early 1900’s i.e. it too about years to reduce populations to a fraction of what they used to be before the arrival of the settlers. MORE THAN 5 BILLION REMOVED FROM 1850 TO 1915
In Puget Sound, there were attempts to farm the Native oyster, using a dyking system to impound the oysters and prevent them from being exposed to freezing conditions
However, deterioration in water quality due to the effluent from pulp mills has a serious negative effect and by the 1950’s populations were decimated.
Today, the Native oyster is listed as a Candidate species of concern (or equivalent) in the states of Washington and Oregon as well as Canada.
SOURCE: WHITE ET AL. 2009

4. ECOSYSTEM SERVICES PROVIDED BY OYSTER REEFS
Due to function
Filtration and clarification of overlying water
Benthic-pelagic coupling of food webs
Cycling of nutrients
Due to structure
Protection of beaches and coastlines
Reduction in marsh shoreline erosion
Stabilization of submerged land by trapping sediments
Habitat for invertebrates and food for higher trophic-level organisms
Nursery habitat for fish and shellfish – Essential Fish Habitat
THESE SERVICES DEPEND ON REEF STRUCTURE OR THE FEEDING ACTIVITIES OF THE OYSTERS
FILTRATION OF OVERLAYING WATER CLARIFIES THE WATER AND IMPROVES GROWTH OF EELGRASS.
FECES AND PSEUDOFECES TRANSFER NUTRIENTS FROM THE WATER COLUMN TO BENTHIC COMMUNITIES
THE STRUCTURAL BENEFITS OF OYSTER REEFS ARE DUE TO STABILIZATION OF COASTLINES DUE BUILD UP OF SHELL
SHELL ALSO PROVIDES HABITAT FOR A WIDE RANGE OF BENTHIC ORGANISMS
BOTH NATIVE AND PACIFIC OYSTER REEFS CAN PROVIDE THESE SERVICES

5. Desired Services/Estimates
INVESTING IN NATIVE OYSTER RESTORATION ON WEST COAST
Site
$ Invested
Organization
Desired Services/Estimates
Puget Sound, WA
$ 1.5 million
Puget Sound Restoration Fund
“Re-establish native oyster beds to provide natural filtration…..”
Netarts Bay, OR
$500,000
The Nature Conservancy
“ A native oyster that cleans water”  
“A single adult oyster can filter up to 15 gallons of water a day”
San Francisco, CA
$ 2 million
California Coastal Conservancy
“Oysters clean the water by filter feeding. oysters clean the water by filter feeding”
“A single oyster can filter up to 30 gallons of water a day”
Introduction
Traditional Models
Improved Model
Conclusions

6. TRADITIONAL APPROACH LABORATORY STUDIES ON FEEDING RATES COMBINED WITH SIMPLE MODELS OF ESTURINE HYDROLOGY
Clearance Rates (l/h/g)
C. gigas
O. lurida
C. GIGAS
O. LURIDA
SALINITY (ppm)
TEMPERATURE OC
TURBIDITY mg/l
Introduction
Traditional Models
Improved Model
Conclusions

7. Models based on traditional methods suggest historical
1908 map of historic
Native oyster grounds
in Yaquina Bay
Models based on traditional
methods suggest historical
populations of O. lurida
contributed limited
filtration services in West
coast estuaries
(zu Ermgassen et al. 2013)
Native oyster beds
Introduction
Traditional Models
Improved Model
Conclusions

8. TRADITIONAL VERSUS IMPROVED METHOD
Traditional Model
Improved Model
Laboratory Feeding Rates
Constant Conditions
Constant Food
In situ Feeding Rates
Variable conditions across seasons
Residence Times
Tidal Prism Method
Circulation models
Introduction
Traditional Models
Improved Model
Conclusions

9. TRADITIONAL VERSUS IMPROVED METHOD
Traditional Model
Improved Model
Laboratory Feeding Rates
Constant Conditions
Constant Food
High maximum laboratory clearance rates
In situ Feeding Rates
Variable conditions across seasons
Variable and lower rates
Residence Times
Tidal Prism Method
High exchange rates (<1 day)
Circulation models
Localized retention (>20 days)
Introduction
Traditional Models
Improved Model
Conclusions

10. PREDICTED CLEARANCE RATES (l/h/g)
IN SITU MEASUREMENTS OF FEEDING ACTIVITY AND ENVIRONMENTAL PARAMETERS RESULTS IN MORE ACCURATE PREDICTIVE MODELS TO OF CLEARANCE RATES
C.GIGAS
O. LURIDA
IN SITU-BASED
DRY SEASON
WET SEASON
PREDICTED CLEARANCE RATES (l/h/g)
LAB-BASED
r2= 0.01
P=0.49
Slope 0.01
r2= 0.56
P<0.001
Slope 0.03
ACTUAL CLEARANCE RATES (l/h/g)

11. PREDICTED CLEARANCE RATES (l/h/g)
IN SITU MEASUREMENTS OF FEEDING ACTIVITY AND ENVIRONMENTAL PARAMETERS RESULTS IN MORE ACCURATE PREDICTIVE MODELS TO OF CLEARANCE RATES
C.GIGAS
O. LURIDA
IN SITU-BASED
DRY SEASON
r2= 0.19
P<0.001
Slope 0.19
r2= 0.61
P<0.001
Slope 0.61
WET SEASON
PREDICTED CLEARANCE RATES (l/h/g)
LAB-BASED
r2= 0.01
P=0.49
Slope 0.01
r2= 0.56
P<0.001
Slope 0.03
ACTUAL CLEARANCE RATES (l/h/g)

12. (Summer residence times > 4 days)
MODELED RESIDENCE TIMES IN YAQUINA BAY, OR
Prime Oyster Habitat
(Summer residence times > 4 days)
Residence Time (Days)
Lemagie and Lerczak (2014)
Introduction
Traditional Models
Improved Model
Conclusions

13. Oyster shell length = 35 mm; density = 360 oysters m-2
Model to estimate filtration services of historic populations of O. lurida in Yaquina Bay, Oregon. Parameters and Assumptions
Oysters and environmental conditions
Oyster shell length = 35 mm; density = 360 oysters m-2
Oyster distribution based on 1908 survey of O. lurida in Yaquina Bay
Clearance rates determined under wet and dry seasons
Average seasonal environmental conditions applied to each season’s estimates of clearance rates

14. Model to estimate filtration services of historic populations of O
Model to estimate filtration services of historic populations of O. lurida in Yaquina Bay, Oregon. Parameters and Assumptions
Oysters and environmental conditions
Oyster shell length = 35 mm; density = 360 oysters m-2
Oyster distribution based on 1908 survey of O. lurida in Yaquina Bay
Clearance rates determined under wet and dry seasons
Average seasonal environmental conditions applied to each season’s estimates of clearance rates
Model characteristics
Models were started with an even distribution of seston
Water column was modeled as well mixed
Oysters filtered each parcel of water after entering cell
Oysters in downstream cells filtered the same parcel at a later time step.
Filtration services expressed as the % of estuary volume filtered during 1 residence period

15. Wet Season Filtration Services of O. lurida
Contribution by Historic Populations: 0.5% of Bay Filtered
Fraction of Bay Filtered by Oysters Within Cells
Introduction
Traditional Models
Improved Model
Conclusions

16. Wet Season Filtration Services of C. gigas
Equal coverage and size to that for O. lurda : 13.4 % of Bay Filtered
Fraction of Bay Filtered by Oysters Within Cells
Introduction
Traditional Models
Improved Model
Conclusions

17. Dry Season Filtration Services of O. lurida
Contributions by Historic Populations: 27.9 % of Bay Filtered
Fraction of Bay Filtered by Oysters Within Cells
Introduction
Traditional Models
Improved Model
Conclusions

18. Dry Season Filtration Services of C. gigas
Equal coverage and size to that of O. lurda: 33.1% of Bay Filtered
Fraction of Bay Filtered by Oysters Within Cells
Introduction
Traditional Models
Improved Model
Conclusions

19. Conclusions
Traditional estimates based on lab-based clearance rate measurements and simple hydrological models indicated that historic populations of O. lurida filtered less than 1% of Yaquina Bay, Oregon
Estimates of clearance rates based on in situ measurements of oyster feeding activity and environmental conditions together with more sophisticated hydrological models resulted in estimates that historic populations of O. lurida filtered up to 27.7% of Yaquina Bay in the dry season
Predicted filtration services of C. gigas were greater than those for O. lurida, but models for predicting its in situ clearance rates were less accurate than for O. lurida

20. ACKNOWLEDGEMENTS Funding agencies:
South Slough NERRS/NOAA
Markham Award, Hatfield Marine Science Center, OSU
Pacific Coast Shellfish Growers Assoc.
USDA-ARS
Oregon Society of Conchologists
Additional support provided by staff of the Molluscan Broodstock
Program
Greg Hutchinson
Marileen ReavIs
Blaine Schoolfield
Javan Bailey
National
Estuaries Research Reserve
System
Introduction
Traditional Models
Improved Model
Conclusions

21. Oysters in San Francisco fetched high prices – up to $20 a bushel
From 1870 to 1876, over a billion exported from Willapa Bay
Large numbers also exported from Yaquina Bay and Puget Sound
QUESTIONS?

23. OYSTER REEFS ARE IN GLOBAL DECLINE 85% LOSS OF OYSTER REEFS GLOBALLY
(BECK ET AL. 2009)
50% LOSS OF MARSHES AND MANGROVES
(ZEDLER AND KERCHER 2005)
20% LOSS OF CORAL REEFS
(WILKINSON 2002)
OYSTER REEFS ARE
IN GLOBAL DECLINE
GLOBALLY THERE HAS BEEN A HUGE LOSS OF OYSTER REEFS – 85% LOSS ACCORDING TO A STUDY SUPPORTED BY THE NATURE CONSERVANCY.
THIS EXCEEDS THE LOSS OF MARSHES AND WETLANDS AS WELL AS CORALS BY A WIDE MARGIN
SOURCE: BECK ET AL. 2009

24. OF WEST COAST ESTUARIES WERE FILTERED BY NATIVE OYSTERS?
WHAT PROPORTION OF
THE RESIDENCE VOLUME
OF WEST COAST ESTUARIES
WERE FILTERED BY NATIVE
OYSTERS?
RESIDENCE TIME IS THE AVERAGE TRANSIT TIME OF FRESHWATER THROUGH THE ESTUARY
NATIVE OYSTERS LIKLEY DID NOT FILTER MORE THAN ABOUT 50% OF WEST COAST BAYS AND ESTUARIES AND IN MOST CASES FILTERED LESS THAN 20 % OF THE RESIDENCE VOLUME
THESE LOW VALUES ARE DUE TO THE HIGH FLUSHING RATES FOR WEST COAST ESTUARIES AND THE LOW CLEARANCE RATES OF NATIVE OYSTERS
SOURCE: zu Ermgassen et al.
(Aquatic Ecology, accepted)