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The effects of biomechanical and ecological factors on population and community structure of wave-exposed, intertidal macroalgae

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dc.contributor.advisor Menge, Bruce
dc.contributor.advisor Lubchenco, Jane
dc.creator Blanchette, Carol A.
dc.date.accessioned 2012-11-07T22:34:11Z
dc.date.available 2012-11-07T22:34:11Z
dc.date.copyright 1994-08-29
dc.date.issued 1994-08-29
dc.identifier.uri http://hdl.handle.net/1957/34956
dc.description Graduation date: 1995 en_US
dc.description.abstract I examined the biomechanical factors that influence the sizes of intertidal macroalgae by studying a population of Fucus gardneri at Fogarty Creek Point, OR. I constructed a mathematical model to predict optimal sizes and probabilities of survival for Fucus under conditions of high and low wave exposure. Predicted optimal sizes of Fucus closely matched the mean observed sizes of plants collected from wave-exposed and protected locations. To test this hypothesis in the field, I reciprocally transplanted Fucus between wave-exposed and wave-protected sites and found that the degree of wave exposure did not affect survival, but did influence size. Large Fucus were tattered by waves at exposed sites, and small Fucus grew at protected sites. These results support the hypothesis that wave forces can set mechanical limits to size in Fucus. I experimentally examined the relative influences of wave-induced disturbance, competition and predation on the sea palm, Postelsia palmaeformis and its understory community at a wave-exposed site at Depoe Bay, OR. Postelsia recruitment was affected by seasonal variations in disturbance and was greatest in areas disturbed in winter. Postelsia were most abundant at mid-zone, wave-exposed sites, and their restriction to wave-exposed sites seems to be due both to; 1) the occurrence of predictable winter disturbances at these sites which remove mussels, thereby stimulating sea palm growth from the underlying rock, and 2) high water motion which enhances sea palm growth by increasing nutrient exchange and photosynthesis and preventing desiccation at low tide. Competition, disturbance and grazing were all important factors in structuring the Postelsia understory community. Postelsia were dominant competitors and their holdfasts overgrew low-lying plants which were torn loose with Postelsia when this kelp was dislodged by winter storm surf. In the absence of this predictable, seasonal disturbance, competitive understory species, such as Corallina dominated primary space. Intermediate levels of disturbance allowed for the highest understory species diversity. Limpets played a keystone role by grazing Postelsia, the competitive dominant during most of the year, and maintained high levels of species diversity in the algal understory. en_US
dc.language.iso en_US en_US
dc.subject.lcsh Fucus -- Ecology -- Oregon en_US
dc.subject.lcsh Laminariales -- Ecology -- Oregon en_US
dc.subject.lcsh Intertidal ecology -- Oregon en_US
dc.subject.lcsh Ocean waves en_US
dc.title The effects of biomechanical and ecological factors on population and community structure of wave-exposed, intertidal macroalgae en_US
dc.type Thesis/Dissertation en_US
dc.degree.name Doctor of Philosophy (Ph. D.) in Zoology en_US
dc.degree.level Doctoral en_US
dc.degree.discipline Science en_US
dc.degree.grantor Oregon State University en_US
dc.contributor.committeemember Denny, Mark
dc.contributor.committeemember Derryberry, Doug
dc.contributor.committeemember Gregory, Stan
dc.contributor.committeemember Hixon, Mark
dc.description.digitization File scanned at 300 ppi (Monochrome) using Capture Perfect 3.0 on a Canon DR-9050C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR. en_US
dc.description.peerreview no en_us
dc.description.graduationdate 1995


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