Influence of seasonally variable hypoxia on epibenthic communities in a coastal ecosystem, British Columbia, Canada

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dc.contributor.authorChu, Jackson Wing Four
dc.contributor.supervisorTunnicliffe, Verena
dc.date.accessioned2016-04-25T14:40:40Z
dc.date.available2017-04-02T11:22:05Z
dc.date.copyright2016en_US
dc.date.issued2016-04-25
dc.degree.departmentDepartment of Biology
dc.degree.levelDoctor of Philosophy Ph.D.en_US
dc.description.abstractNatural cycles of environmental variability and long-term deoxygenation in the ocean impose oxygen deficiency (hypoxia) on marine communities. My research exploits a naturally occurring hypoxia cycle in Saanich Inlet, British Columbia, Canada where I combined spatial surveys with remotely operated vehicles, ecological time-series from the subsea cabled observatory VENUS, and lab-based respirometry experiments to examine the influence of seasonally variable oxygen conditions on epibenthic communities. In situ oxygen thresholds established for dozens of fish and invertebrate species in this system show they naturally occur in lower oxygen levels than what general lethal and sublethal thresholds would predict. Expansion of hypoxic waters induced a loss of community structure which was previously characterized by disjunct distributions among species. Communities in variable hypoxia also have scale-dependent structure across a range of time scales but are primarily synchronized to a seasonal oscillation between two phases. Time-series revealed timing of diurnal movement in the slender sole Lyopsetta exilis and reproductive behavior of squat lobster Munida quadrispina in the hypoxia cycle. Hypoxia-induced mortality of sessile species slowed the rate of community recovery after deoxygenation. The 10-year oxygen time-series from VENUS, revealed a significant increase in the annual low-oxygen period in Saanich Inlet and that deoxygenation has occurred in this system since 2006. Differences in the critical oxygen thresholds (O2crit) and standard metabolic rates of key species (spot prawn Pandalus platyceros, slender sole, and squat lobster) determined the lowest in situ oxygen at which populations occurred and explained disproportionate shifts in distributions and community respiration. Finally, a meta-analysis on global O2crit reported for crustaceans showed that hypoxia tolerance differs among major ocean basins. Long-term trends of deoxygenation suggest a future regime shift may occur when the duration at which a system remains below critical oxygen levels exceeds the time needed for communities to recover. Species-specific traits will determine the critical threshold and the nature of the community response in systems influenced by variable states of oxygen deficiency. However, oceanographic and evolutionary history provides context when determining the regional response of benthic communities influenced by rapidly changing environments.en_US
dc.description.proquestcode0329en_US
dc.description.proquestcode0416en_US
dc.description.proquestcode0433en_US
dc.description.proquestemailjwfchu@gmail.comen_US
dc.description.scholarlevelGraduateen_US
dc.identifier.urihttp://hdl.handle.net/1828/7182
dc.languageEnglisheng
dc.language.isoenen_US
dc.rightsAvailable to the World Wide Weben_US
dc.subjectoceanographyen_US
dc.subjecthypoxiaen_US
dc.subjectbenthic ecologyen_US
dc.subjectmarine biologyen_US
dc.subjectremotely operated vehiclesen_US
dc.subjectdeep sea biologyen_US
dc.subjectmarine ecologyen_US
dc.subjectocean networks canadaen_US
dc.subjectVENUSen_US
dc.subjectcabled observatoryen_US
dc.subjectecological time-seriesen_US
dc.subjectecophysiologyen_US
dc.subjectslender sole Lyopsetta exilisen_US
dc.subjectsquat lobster Munida quadrispinaen_US
dc.subjectspot prawn Pandalus platycerosen_US
dc.subjectrespirometryen_US
dc.subjectoxygenen_US
dc.subjectcritical oxygen tensionen_US
dc.titleInfluence of seasonally variable hypoxia on epibenthic communities in a coastal ecosystem, British Columbia, Canadaen_US
dc.typeThesisen_US

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