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dc.contributor.advisorDonald M. Anderson.en_US
dc.contributor.authorFischer, Alexis Dalen_US
dc.contributor.otherWoods Hole Oceanographic Institution.en_US
dc.date.accessioned2017-09-15T15:30:41Z
dc.date.available2017-09-15T15:30:41Z
dc.date.copyright2017en_US
dc.date.issued2017en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/111359
dc.descriptionThesis: Ph. D., Massachusetts Institute of Technology, Department of Biology, 2017.en_US
dc.descriptionThesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution), 2017.en_US
dc.descriptionCataloged from PDF version of thesis.en_US
dc.descriptionIncludes bibliographical references.en_US
dc.description.abstractBlooms of the dinoflagellate Alexandrium catenella cause paralytic shellfish poisoning syndrome and present an expanding public health threat. They are inoculated through the germination of benthic cysts, a process regulated by internal and environmental factors, most importantly temperature. Less understood is the effect of temperature conditioning on cyst dormancy cycling, which inhibits germination for long periods. This thesis characterizes the temperature-dependence of both dormancy and germination in natural A. catenella cyst populations from Nauset Marsh (Cape Cod, MA, USA), a small estuarine embayment, and relates these processes to the phenology of blooms there. Through laboratory germination assays, it is shown that dormant A. catenella cysts require a quantifiable amount of chilling to exit dormancy and attain quiescence (i.e. become germinable). A series of experiments compares germination rates of quiescent cysts across a range of temperatures through laboratory experiments and field incubations of raw sediment using plankton emergence traps (PETs). Emergence rates of A. catenella germlings measured by PETs increased linearly with temperature and were comparable to germination under constant laboratory conditions. Total emergence fluxes were much lower than expected, suggesting that germination occurs in a much shallower layer of sediments than typically assumed. The results are synthesized to develop a temperature-dependent model to examine the sensitivity of A. catenella bloom phenology to dormancy-breaking by winter chilling. Notably, the chilling-alleviated dormancy model accurately predicted the timing of quiescence (January) and the variable bloom phenology from multiple blooms in Nauset. Once cysts became quiescent and began to germinate, however, temperatures were typically too cold for growth to exceed losses so there was a several-week lag until bloom development. Years with warmer winters and springs had shorter lag periods and thus significantly earlier blooms. Ecologically, dormancy-breaking by a chilling threshold is advantageous because it prevents the mismatch between conditions that are favorable for germination but not for the formation of large blooms. Synchronized germination after winter chilling also promotes promotes efficient conversion from the cyst seedbed to the spring bloom inoculum. The dormancy mechanism characterized here may be present in other cyst-forming dinoflagellates, but there is likely plasticity that reflects the temperature regime of each habitat.en_US
dc.description.statementofresponsibilityby Alexis Dal Fischer.en_US
dc.format.extent165 pagesen_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsMIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectJoint Program in Oceanography/Applied Ocean Science and Engineering.en_US
dc.subjectBiology.en_US
dc.subjectWoods Hole Oceanographic Institution.en_US
dc.subject.lcshMarine biologyen_US
dc.subject.lcshDinoflagellatesen_US
dc.subject.lcshAlexandrium catenellaen_US
dc.subject.lcshTemperatureen_US
dc.subject.lcshHibernationen_US
dc.titleAlexandrium catenella cyst dynamics in a coastal embayment : temperature dependence of dormancy, germination, and bloom initiationen_US
dc.typeThesisen_US
dc.description.degreePh. D.en_US
dc.contributor.departmentJoint Program in Oceanography/Applied Ocean Science and Engineering.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Biology.en_US
dc.contributor.departmentWoods Hole Oceanographic Institution.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Biology
dc.identifier.oclc1003291128en_US


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