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Iron availability influences the tolerance of Southern Ocean phytoplankton to warming and elevated irradiance

Citation

Andrew, SM and Morell, HT and Strzepek, R and Boyd, PW and Ellwood, MJ, Iron availability influences the tolerance of Southern Ocean phytoplankton to warming and elevated irradiance, Frontiers in Marine Science, 6, (NOV) Article 681. ISSN 2296-7745 (2019) [Refereed Article]


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Copyright Statement

Copyright © 2019 Andrew, Morell, Strzepek, Boyd and Ellwood. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) http://creativecommons.org/licenses/by/4.0/

DOI: doi:10.3389/fmars.2019.00681

Abstract

The Southern Ocean is responsible for approximately 40% of oceanic carbon uptake through biological and physical processes. In the Southern Ocean, phytoplankton growth is limited by low iron (Fe) and light supply. Climate model projections for the Southern Ocean indicate that temperature, underwater irradiance and Fe supply are likely to change simultaneously in the future due to increasing anthropogenic carbon dioxide emissions. The individual effects of these environmental properties on phytoplankton physiology have been extensively researched, and culturing studies using Southern Ocean phytoplankton have shown that temperature and Fe will play a key role on setting growth under future conditions. To explore the potential responses of Southern Ocean phytoplankton to these environmental changes, we cultured the haptophyte Phaeocystis antarctica and the diatoms Chaetoceros flexuosus, Proboscia inermis, and Thalassiosira antarctica under two light and iron combinations and over a range of temperatures. Our study revealed that the thermal response curves of key Southern Ocean phytoplankton are diverse, with the highest growth rates measured at 5°C (the annual temperature range at the isolation sites is currently 1–4°C). Warming had species-specific effects on the photochemical efficiency of photosystem II (PSII; Fv/Fm), the functional absorption cross-section of PSII (σPSII), carbon:nitrogen ratio and cellular Chlorophyll a concentrations. Iron availability increased species’ ability to tolerate warmer conditions by increasing the upper limit for growth and subsequently increasing the thermal niche that each species inhabit.

Item Details

Item Type:Refereed Article
Keywords:temperature, climate change, photosynthesis, evolution, multiple stressors, carbon
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological Oceanography
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Climate Change Mitigation Strategies
UTAS Author:Strzepek, R (Dr Robert Strzepek)
UTAS Author:Boyd, PW (Professor Philip Boyd)
ID Code:137722
Year Published:2019
Deposited By:Oceans and Cryosphere
Deposited On:2020-02-28
Last Modified:2020-04-02
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