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Transitioning global change experiments on Southern Ocean phytoplankton from lab to field settings: insights and challenges

Citation

Boyd, PW and Doney, SC and Eggins, S and Ellwood, MJ and Fourquez, M and Nunn, BL and Strzepek, R and Timmins-Schiffman, E, Transitioning global change experiments on Southern Ocean phytoplankton from lab to field settings: insights and challenges, Limnology and Oceanography pp. 1-20. ISSN 0024-3590 (2022) [Refereed Article]


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Copyright Statement

Copyright (2022) The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License, (https://creativecommons.org/licenses/by-nc/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

DOI: doi:10.1002/lno.12175

Abstract

The influence of global change on Southern Ocean productivity will have major ramifications for future management of polar life. A prior laboratory study investigated the response of a batch-cultured subantarctic diatom to projected change simulating conditions for 2100 (increased temperature/CO2/irradiance/iron; decreased macronutrients), showed a twofold higher chlorophyll-derived growth rate driven mainly by temperature and iron. We translated this design to the field to understand the phytoplankton community response, within a subantarctic foodweb, to 2100 conditions. A 7-d shipboard study utilizing 250-liter mesocosms was conducted in March 2016. The outcome mirrors lab-culture experiments, yielding twofold higher chlorophyll in the 2100 treatment relative to the control. This trend was also evident for intrinsic metrics including nutrient depletion. Unlike the lab-culture study, photosynthetic competence revealed a transient effect in the 2100 mesocosm, peaking on day 3 then declining. Metaproteomics revealed significant differences in protein profiles between treatments by day 7. The control proteome was enriched for photosynthetic processes (c.f. 2100) and exhibited iron-limitation signatures; the 2100 proteome exposed a shift in cellular energy production. Our findings of enhanced phytoplankton growth are comparable to model simulations, but underlying mechanisms (temperature, iron, and/or light) differ between experiments and models. Batch-culture approaches hinder cross-comparison of mesocosm findings to model simulations (the latter are akin to "continuous-culture chemostats"). However, chemostat techniques are problematic to use with mesocosms, as mesozooplankton will evade seawater flow-through, thereby accumulating. Thus, laboratory, field, and modeling approaches reveal challenges to be addressed to better understand how global change will alter Southern Ocean productivity.

Item Details

Item Type:Refereed Article
Keywords:global change, Southern Ocean, phytoplankton productivity, omics, physiology
Research Division:Environmental Sciences
Research Group:Climate change impacts and adaptation
Research Field:Ecological impacts of climate change and ecological adaptation
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Antarctic and Southern Ocean oceanic processes
UTAS Author:Boyd, PW (Professor Philip Boyd)
UTAS Author:Fourquez, M (Dr Marion Fourquez)
UTAS Author:Strzepek, R (Dr Robert Strzepek)
ID Code:150901
Year Published:2022
Deposited By:Australian Antarctic Program Partnership
Deposited On:2022-07-04
Last Modified:2022-08-08
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