Phytoplankton photoacclimation in the Southern Ocean and Arctic Ocean
Abstract/Contents
- Abstract
- Polar regions are undergoing rapid and dramatic changes. Substantial shifts in the extent and thickness of sea ice have cascading effects on marine primary production and polar ecosystems. Primary production is closely tied to environmental variables such as light and nutrient availability, which are sensitive to these climate-induced changes. Climate change-induced shifts in phytoplankton communities can have far-reaching effects on nutrient cycling, carbon drawdown and export, higher trophic levels, and benthic-pelagic coupling. In the spring, light increases from wintertime lows and sea ice begins to retreat. During this time, phytoplankton can experience both very high light (when mixed to the surface) and very low light (when under sea ice or at the base of the mixed layer). To acclimate to this variable light field, phytoplankton must optimize carbon fixation while minimizing photodamage due to periods of excessive light. Determining how phytoplankton photoacclimate will help us understand how phytoplankton might adapt to future changing environmental conditions. My dissertation aims to understand how phytoplankton photoacclimate in spring in both the Southern Ocean and the Arctic Ocean. I employ field experiments investigating how phytoplankton respond to changes in light and, in one chapter, the interactive effects of both light and iron (in much of the Southern Ocean, iron can limit phytoplankton growth). Results from my Southern Ocean (western Antarctic Peninsula) field experiments showed that at moderate light exposure, phytoplankton experienced little photodamage or changes in net primary production, and high light exposure stimulated Phaeocystis antarctica growth (but not diatom growth). My combined light and iron experiments demonstrated that light limits phytoplankton growth, whereas iron does not, despite overall low iron concentrations and evidence of iron stress. In the Arctic Ocean (Baffin Bay), both my in situ measurements and experiments demonstrate that phytoplankton under the ice, in the marginal ice zone, and in open water are photoacclimated similarly. I observed high photoprotective pigments in phytoplankton in all three irradiance regimes, as well as high rates of photosynthesis. These findings lend support to the hypothesis that Arctic phytoplankton under sea ice are primed to bloom once they have access to sufficient light. Both the Southern Ocean and Arctic Ocean results provide evidence that early season polar phytoplankton are acclimated to higher light than they are experiencing and are thus prepared to manage rapid changes in light. As sea ice thins and retreats earlier in the season, phytoplankton will be exposed to light earlier, enabling them to bloom earlier. These findings further our ability to understand the impacts of climate-driven changes on phytoplankton communities.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2021; ©2021 |
| Publication date | 2021; 2021 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Joy-Warren, Hannah Louise |
|---|---|
| Degree committee member | Arrigo, Kevin R |
| Degree committee member | Casciotti, Karen Lynn, 1974- |
| Degree committee member | Thomas, Leif N |
| Thesis advisor | Arrigo, Kevin R |
| Thesis advisor | Casciotti, Karen Lynn, 1974- |
| Thesis advisor | Thomas, Leif N |
| Associated with | Stanford University, Department of Earth System Science |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Hannah Louise Joy-Warren. |
|---|---|
| Note | Submitted to the Department of Earth System Science. |
| Thesis | Thesis Ph.D. Stanford University 2021. |
| Location | https://purl.stanford.edu/xn110cg7121 |
Access conditions
- Copyright
- © 2021 by Hannah Louise Joy-Warren
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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