1. Settlement of Olympia Oysters onto Shell Strings Suspended
at Varying Distances from the Ocean Floor
Karla P. Arriaga, and Danielle Zacherl
Department of Biological Science, California State University, Fullerton
References
Results
Discussion
Acknowledgments
ResultsMethodsIntroduction
Objective and Hypothesis
Figure 4. Dock where shell strings were
suspended from located at JDMR in
Alamitos Bay, California.
Figure 5. Sample
shell string.
Figure 6. Karla Arriaga deploying shell strings at JDMR.
Figure 3. Olympia oyster settler.
• Determine whether suspending shell strings at varying distances from
the substrate affects oyster settlement. Determine which distance is
the most successful at recruiting oyster settlement.
• We hypothesized that the shell strings closer to the bottom of the
ocean floor would have higher settlement rates than the shell strings
suspended above the ocean floor.
• Twenty shell strings were suspended from a floating dock at Jack Dunster
Marine Reserve (JDMR) in Alamitos Bay, CA (Fig. 4).
• Strings consisted of 15 shells stacked on an 18-inch wire rope (Fig 5.) and
were tied (with polypropylene rope) to eyebolts that were screwed to
the side of a floating dock at JDMR and deployed into the water (Fig 6.).
• Shell strings were suspended at 4 different distances from the bottom
substrate so that each treatment group rested on the mud when the low
tide reached 0, -1, -2, or -3 ft. MLLW.
• Shell strings were collected after 24 days (Figs. 7 and 8), were individually
rinsed through a 300μm sieve, and shells were examined under
dissecting microscopes for settlement of native and non-native oysters,
the tube worm Spirorbis bifurcatus and the bryozoan Watersipora
subtorquata.
• McGraw, K. A. 2009. The Olympia oyster, Ostrea lurida Carpenter 1864
along the west coast of North America. Journal of Shellfish Research.
28: 5-10.
• Baker, P (1995) Review of Ecology and Fishery of the Olympia Oyster,
Ostrea lurida with Annotated Bibliography. Journal of Shellfish Research
2:501-518.
• Coen, L. D, Brumbaugh, R. D, Bushek, D., Grizzle, R., Luckenbach, M. W,
Posey, M. H, Powers, S. P, Tolley, S. G (2007) Ecosystem Services Related
to Oyster Restoration. Marine Ecology Progress Series 341:303-307.
Future Studies
Figure 10. Settlement of Spirorbis bifurcatus per shell string as a function treatment
during a 24 day deployment (ANOVA, n=5, p=0.53). Error bars=1 SE
Figure 11. Settlement of Watersipora subtorquata per shell string as a function
treatment during a 24 day deployment (ANOVA, n=5, p=0.92). Error bars= 1SE
Figure 9. Native Olympia oyster, Ostrea lurida, settlers per shell string as function of
treatment during a 24 day deployment (ANOVA, n=5, p=0.11). Error bars= 1 SE.
• Settlement of oysters (O. lurida), Spirorbis bifurcatus, and Watersipora
subtorquata were not affected by the distance the shell strings were
suspended above the substratum.
• Shell strings were buoyant enough (due to the polypropylene rope) that
during tidal exchange they did not sink to the bottom and so did not
hang vertically nor sit at the bottom of the mudflat as long as we
anticipated.
• Shells strings should be weighted down into a vertical position so that
tidal currents do not affect positioning.
http://farm6.static.flickr.com/5014/5431076083_52aa9a3966.jpg
Figure 2. Watersipora
subtorquata.
Figure 1. Spirorbis
bifurcatus.
http://content60.eol.org/content/2010/11/27/14/48236_580_360.jpg
• Thanks to all of the Zacherl lab members, the city of Long Beach, Lenny
Arkinstall, CSUF Department of Biology, STEM2, and the Dean Scholar
Program. Funds were provided by Department of Education Grant #
P031C110116 and NOAA-RCC Project # 11-058-01.
• The Olympia Oyster, Ostrea lurida, is the only oyster species native to
western North America and is present in southern California estuaries
(McGraw, 2009). It was once abundant from Alaska down to Baja
California (Baker, 1995).
• The Olympia oyster experienced overexploitation that resulted in
ecological extinction before 1930 (Trimble et al., 2009).
• Oysters provide complex habitat for other organisms (Figs. 1 and 2), as
their beds support rich epifaunal communities (Coen et al., 2007).
• A restoration project in Alamitos Bay, California is using dead oyster
shell to build a bed on the mudflat to increase the amount of hard
substrate available for recruiting young oyster settlers (Fig. 3) .
• In addition, community members will “garden” oysters using shell
strings suspended from docks throughout the bay. Oysters recruited to
shell strings will be concentrated onto the restored bed.
Figure 7. Karla Arriaga collecting the shell
strings after 24 days.
Figure 8. Sample shell string after
collection.
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