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Rapid manipulation in irradiance induces oxidative free-radical release in a fast-ice algal community (McMurdo Sound, Antarctica)


Kennedy, F and Martin, A and Castrisios, K and Cimoli, E and McMinn, A and Ryan, KG, Rapid manipulation in irradiance induces oxidative free-radical release in a fast-ice algal community (McMurdo Sound, Antarctica), Frontiers in Plant Science, 11 Article 588005. ISSN 1664-462X (2020) [Refereed Article]

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DOI: doi:10.3389/fpls.2020.588005


Sea ice supports a unique assemblage of microorganisms that underpin Antarctic coastal food-webs, but reduced ice thickness coupled with increased snow cover will modify energy flow and could lead to photodamage in ice-associated microalgae. In this study, microsensors were used to examine the influence of rapid shifts in irradiance on extracellular oxidative free radicals produced by sea-ice algae. Bottom-ice algal communities were exposed to one of three levels of incident light for 10 days: low (0.5 μmol photons m−2 s−1, 30 cm snow cover), mid-range (5 μmol photons m−2 s−1, 10 cm snow), or high light (13 μmol photons m−2 s−1, no snow). After 10 days, the snow cover was reversed (either removed or added), resulting in a rapid change in irradiance at the ice-water interface. In treatments acclimated to low light, the subsequent exposure to high irradiance resulted in a ~400 increase in the production of hydrogen peroxide (H2O2) and a 10 increase in nitric oxide (NO) concentration after 24 h. The observed increase in oxidative free radicals also resulted in significant changes in photosynthetic electron flow, RNA-oxidative damage, and community structural dynamics. In contrast, there was no significant response in sea-ice algae acclimated to high light and then exposed to a significantly lower irradiance at either 24 or 72 h. Our results demonstrate that microsensors can be used to track real-time in-situ stress in sea-ice microbial communities. Extrapolating to ecologically relevant spatiotemporal scales remains a significant challenge, but this approach offers a fundamentally enhanced level of resolution for quantifying the microbial response to global change.

Item Details

Item Type:Refereed Article
Keywords:oxidative stress, Antarctica, sea-ice algae, hydrogen peroxide (H2O2), nitric oxide (NO), microelectrodes, snow, photophysiology
Research Division:Biological Sciences
Research Group:Biochemistry and cell biology
Research Field:Cell metabolism
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Effects of climate change on Antarctic and sub-Antarctic environments (excl. social impacts)
UTAS Author:Kennedy, F (Dr Fraser Kennedy)
UTAS Author:Martin, A (Dr Andrew Martin)
UTAS Author:Castrisios, K (Miss Katerina Castrisios)
UTAS Author:Cimoli, E (Mr Emiliano Cimoli)
UTAS Author:McMinn, A (Professor Andrew McMinn)
ID Code:141884
Year Published:2020
Deposited By:Ecology and Biodiversity
Deposited On:2020-12-01
Last Modified:2021-02-22

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