Waite, Anya
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Waite, Anya
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Waite, Anya
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Waite, Anya M.
Waite, A.
Waite, A. M.
ORCID
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Item type:Publication, Microbial processes and element cycling from micro- to meso-scale : from single cells and aggregates to the whole water column perspective.(2019-04-01); ; ; Marine microorganisms are important drivers of the C-, N- and S- cycles on earth. They can adapt to various substrates and, thus, inhabit extreme environments, such as sub- and anoxic or even sulfidic waters or micro-zones within sinking particles. The latter still represent a major black box in microbial ecology due to their fragile nature, which makes them inaccessible for detailed micro-scale observations. Moreover, sinking particles and their complex communities represent a biogeochemical link between small- and large-scale processes because they are shaped by a wide variety of physical and biological processes ranging from the micro- to meso-scale. In this thesis, cutting-edge methodologies were applied to investigate microbial processes of free-living and particle-associated organisms at the micro-scale, and to build strategies to integrate these processes into a broader understanding of microbial dynamics at oceanographic scales of relevance to the global ocean.doctoral thesis466 136 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Morphometrics of Southern Ocean diatoms using high throughput imaging and semi-automated image analysisSince the ADIAC project, which ended more than 15 years ago, not much progress in automating morphometric analysis of diatoms from slide-mounted material has been published, and no ready-to-use system has become available. This thesis work is the first to implement such a system completely, covering all aspects of the underlying imaging and image processing pipeline, by combining a commercially available slide scanning microscope with my diatom morphometry software SHERPA. I was able to show the applicability as well as the potential of this approach by executing a series of smaller and two large-scale morphometry projects. The extensive sampling sizes, which were made possible only by the new workflow, enabled the first observations of life cycle related size distribution changes of Fragilariopsis kerguelensis in its natural habitat, leading to hypotheses on influences of reproduction, grazing and environmental changes in one of the most important diatom species of the Southern Ocean. In a second large-scale investigation, SHERPA's precise morphometric measurements revealed a second F. kerguelensis morphotype, which has not been recognized before, even though the species, as well as the very material I analyzed, have been investigated intensely before by experienced diatomists; a result not disqualifying their work, but rather underlining that explicit and precise quantification of morphological information has a strong potential to generate novel scientific insights. This new morphotype has implications on the utilization of paleo-proxies which are based on geometrical valve features of F. kerguelensis. Differentiating both morphotypes might improve established methods and possibly provides a new proxy for summer sea surface temperature.doctoral thesis430 177