Characterising southern ocean phytoplankton community variability and environmental coupling: zonal, sectoral, and seasonal perspectives

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dc.contributor.advisorFietz, Susanneen_ZA
dc.contributor.authorQuinlan, Liam Bodleyen_ZA
dc.contributor.otherStellenbosch University. Faculty of Science. Dept. of Earth Sciences.en_ZA
dc.date.accessioned2024-03-04T10:48:33Z
dc.date.accessioned2024-04-26T21:26:20Z
dc.date.available2024-03-04T10:48:33Z
dc.date.available2024-04-26T21:26:20Z
dc.date.issued2024-03
dc.descriptionThesis (MSc)--Stellenbosch University, 2024. en_ZA
dc.description.abstractENGLISH ABSTRACT: Marine phytoplankton communities vary in functional groups prevalence across the Southern Ocean. The variability of phytoplankton groups, some drivers of important biogeochemical processes, is intricately linked to their adaptation to specific environmental conditions. Community group composition will thus vary as the surface water environment does. In the southern Ocean, different latitudes (ocean zones), longitudes (ocean sectors), and times of year (seasons) support distinct community profiles. In characterising the relationships that exist between specific phytoplankton groups and major environmental drivers, we can contribute to the baseline understanding of the Southern Ocean ecosystem, with implications for the biogeochemical processes its phytoplankton support and the trophic food web these primary producers underpin. Phytoplankton community structure was determined by chemotaxonomic pigment reconstruction (CHEMTAX) for historically under-surveyed austral spring and winter voyages to the Indian and Atlantic Ocean sectors of the Southern Ocean. Complimented by ship-board environmental monitoring of the physical sea surface environment (temperature, salinity, and light) and macronutrient parameters (nitrate, phosphate, silicate), the relationships between phytoplankton groups and major environmental drivers were explored using Canonical Correlation Analysis (CCA). From this analysis we determined group-environment associations that promote similar community structures three broad zonal regions: northernmost temperate, transitional sub-Antarctic, and southernmost polar. Phytoplankton communities across these regions appear to become increasingly dominated by fewer groups placing greater importance on key functional groups further south. Some group-environments associations appear independent of ocean zone, sector, or season, emphasizing the coupling between major groups components of Southern Ocean phytoplankton communities and their environment. The consistency of positive coupling relationships falls within two classifications: physical environment associated groups (phaeocystis cryptophytes, chlorophytes, coccolithophores, cyanobacteria, and pelagophytes) and nutrient associated groups (diatoms, dinoflagellates, and prasinophytes). These relationships suggest that changes to the Southern Ocean physical environment and nutrient regimes will drive group-specific community restructuring to either favor or hinder some groups over others, with knock-on consequences for the biogeochemical processes those groups drive and the trophic chains they support.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Geen opsomming beskikbaar.af_ZA
dc.description.versionMastersen_ZA
dc.format.extent103 pages : illustrations (some color)en_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130543
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshMarine phytoplankton -- South Atlantic Oceanen_ZA
dc.subject.lcshMarine phytoplankton -- Environmental aspectsen_ZA
dc.subject.lcshChemotaxonomyen_ZA
dc.subject.lcshPhytoplankton -- Effect of temperature onen_ZA
dc.subject.lcshEnvironmental monitoringen_ZA
dc.subject.lcshPhytoplankton -- Geographical distribution -- Effect of temperature onen_ZA
dc.subject.lcshNutrient cycles -- Environmental aspectsen_ZA
dc.subject.nameUCTDen_ZA
dc.titleCharacterising southern ocean phytoplankton community variability and environmental coupling: zonal, sectoral, and seasonal perspectivesen_ZA
dc.typeThesisen_ZA
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