Enhanced CO2 concentrations change the structure of Antarctic marine microbial communities

Davidson, Andrew T.; McKinlay, John; Westwood, Karen J.; Thomson, Paul; Enden, Rick van den; Salas, Miguel de; Wright, Simon W.; Johnson, R. W.; Berry, Kate M.

doi:10.3354/meps11742

Cited by 41 publications

(90 citation statements)

References 99 publications

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“…Macronutrient samples were obtained from each minicosm following the protocol of Davidson et al (2016). Seawater was filtered through 0.45 µm Sartorius filters into 50 mL Falcon tubes and frozen at −20 • C for analysis in Australia.…”

Section: Nutrient Analysismentioning

confidence: 99%

“…Seawater was filtered through 0.45 µm Sartorius filters into 50 mL Falcon tubes and frozen at −20 • C for analysis in Australia. Concentrations of ammonia, nitrate plus nitrite (NO x ), soluble reactive phosphorus (SRP), and molybdate reactive silica (Silica) were determined using flow injection analysis by Analytical Services Tasmania following Davidson et al (2016).…”

Section: Nutrient Analysismentioning

confidence: 99%

“…These differing responses may be due to differences in community composition, nutrient supply, or ecological adaptations of the phytoplankton community in the region studied. They may also be due to differences in the experimental methods, especially the range of CO 2 concentrations employed (Hancock et al, 2017), the mechanism used to manipulate CO 2 concentrations, the duration of the acclimation and incubation, the nature and volume of the mesocosms used, and the extent to which higher trophic levels are screened from the mesocosm contents (see Davidson et al, 2016).…”

Section: Ocean Acidification Effects On Phytoplankton Productivitymentioning

confidence: 99%

“…Tolerance to CO 2 levels up to ∼ 800 µatm have been reported for natural coastal communities in the West Antarctic Peninsula and Prydz Bay, East Antarctica (Young et al, 2015;Davidson et al, 2016). Although in Prydz Bay, when CO 2 levels exceeded 780 µatm, primary productivity declined and community composition shifted toward smaller picoeukaryotes Thomson et al, 2016;Westwood et al, 2018).…”

mentioning

confidence: 93%

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Ocean acidification of a coastal Antarctic marine microbial community reveals a critical threshold for CO<sub>2</sub> tolerance in phytoplankton productivity

et al. 2018

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Abstract. High-latitude oceans are anticipated to be some of the first regions affected by ocean acidification. Despite this, the effect of ocean acidification on natural communities of Antarctic marine microbes is still not well understood. In this study we exposed an early spring, coastal marine microbial community in Prydz Bay to CO 2 levels ranging from ambient (343 µatm) to 1641 µatm in six 650 L minicosms. Productivity assays were performed to identify whether a CO 2 threshold existed that led to a change in primary productivity, bacterial productivity, and the accumulation of chlorophyll a (Chl a) and particulate organic matter (POM) in the minicosms. In addition, photophysiological measurements were performed to identify possible mechanisms driving changes in the phytoplankton community. A critical threshold for tolerance to ocean acidification was identified in the phytoplankton community between 953 and 1140 µatm. CO 2 levels ≥ 1140 µatm negatively affected photosynthetic performance and Chl a-normalised primary productivity (csGPP14 C ), causing significant reductions in gross primary production (GPP14 C ), Chl a accumulation, nutrient uptake, and POM production. However, there was no effect of CO 2 on C : N ratios. Over time, the phytoplankton community acclimated to high CO 2 conditions, showing a down-regulation of carbon concentrating mechanisms (CCMs) and likely adjusting other intracellular processes. Bacterial abundance initially increased in CO 2 treatments ≥ 953 µatm (days 3-5), yet gross bacterial production (GBP14 C ) remained unchanged and cell-specific bacterial productivity (csBP14 C ) was reduced. Towards the end of the experiment, GBP14 C and csBP14 C markedly increased across all treatments regardless of CO 2 availability. This coincided with increased organic matter availability (POC and PON) combined with improved efficiency of carbon uptake. Changes in phytoplankton community production could have negative effects on the Antarctic food web and the biological pump, resulting in negative feedbacks on anthropogenic CO 2 uptake. Increases in bacterial abundance under high CO 2 conditions may also increase the efficiency of the microbial loop, resulting in increased organic matter remineralisation and further declines in carbon sequestration.

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Section: Nutrient Analysismentioning

confidence: 99%

Section: Nutrient Analysismentioning

confidence: 99%

Section: Ocean Acidification Effects On Phytoplankton Productivitymentioning

confidence: 99%

mentioning

confidence: 93%

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Ocean acidification of a coastal Antarctic marine microbial community reveals a critical threshold for CO<sub>2</sub> tolerance in phytoplankton productivity

et al. 2018

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“…Overall, differences in competitive fitness among phytoplankton functional groups indicate that exposure to elevated pCO 2 could alter the phytoplankton community in coming decades (Dutkiewicz et al, 2015). Responses by natural coastal communities of Antarctic marine microbes within and among seasons suggest that moderate increases in CO 2 concentrations may enhance phytoplankton productivity and growth, but by the end of this century CO 2 concentrations may have risen sufficiently that they could alter the species composition, reduce rates of biomass accumulation and enhance the relative abundance of small phytoplankton taxa (Davidson et al, 2016).…”

Section: Climate-driven Changes To the Southern Oceanmentioning

confidence: 99%

Southern Ocean phytoplankton physiology in a changing climate

Petrou

Kranz

Trimborn

et al. 2016

Journal of Plant Physiology

114

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Please cite this article in press as: Petrou, K., et al., Southern Ocean phytoplankton physiology in a changing climate. J Plant Physiol (2016), http://dx.doi.org/10.1016/j.jplph.2016.05.004 ARTICLE IN PRESS a b s t r a c tThe Southern Ocean (SO) is a major sink for anthropogenic atmospheric carbon dioxide (CO 2 ), potentially harbouring even greater potential for additional sequestration of CO 2 through enhanced phytoplankton productivity. In the SO, primary productivity is primarily driven by bottom up processes (physical and chemical conditions) which are spatially and temporally heterogeneous. Due to a paucity of trace metals (such as iron) and high variability in light, much of the SO is characterised by an ecological paradox of high macronutrient concentrations yet uncharacteristically low chlorophyll concentrations. It is expected that with increased anthropogenic CO 2 emissions and the coincident warming, the major physical and chemical process that govern the SO will alter, influencing the biological capacity and functioning of the ecosystem. This review focuses on the SO primary producers and the bottom up processes that underpin their health and productivity. It looks at the major physico-chemical drivers of change in the SO, and based on current physiological knowledge, explores how these changes will likely manifest in phytoplankton, specifically, what are the physiological changes and floristic shifts that are likely to ensue and how this may translate into changes in the carbon sink capacity, net primary productivity and functionality of the SO.

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Plankton Assemblage Estimated with BGC‐Argo Floats in the Southern Ocean: Implications for Seasonal Successions and Particle Export

et al. 2017

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The Southern Ocean (SO) hosts plankton communities that impact the biogeochemical cycles of the global ocean. However, weather conditions in the SO restrict mainly in situ observations of plankton communities to spring and summer, preventing the description of biological successions at an annual scale. Here, we use shipboard observations collected in the Indian sector of the SO to develop a multivariate relationship between physical and bio‐optical data, and, the composition and carbon content of the plankton community. Then we apply this multivariate relationship to five biogeochemical Argo (BGC‐Argo) floats deployed within the same bio‐geographical zone as the ship‐board observations to describe spatial and seasonal changes in plankton assemblage. The floats reveal a high contribution of bacteria below the mixed layer, an overall low abundance of picoplankton and a seasonal succession from nano‐ to microplankton during the spring bloom. Both naturally iron‐fertilized waters downstream of the Crozet and Kerguelen Plateaus show elevated phytoplankton biomass in spring and summer but they differ by a nano‐ or microplankton dominance at Crozet and Kerguelen, respectively. The estimated plankton group successions appear consistent with independent estimations of particle diameter based on the optical signals. Furthermore, the comparison of the plankton community composition in the surface layer with the presence of large mesopelagic particles diagnosed by spikes of optical signals provides insight into the nature and temporal changes of ecological vectors that drive particle export. This study emphasizes the power of BGC‐Argo floats for investigating important biogeochemical processes at high temporal and spatial resolution.

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Enhanced CO2 concentrations change the structure of Antarctic marine microbial communities

Cited by 41 publications

References 99 publications

Ocean acidification of a coastal Antarctic marine microbial community reveals a critical threshold for CO<sub>2</sub> tolerance in phytoplankton productivity

Ocean acidification of a coastal Antarctic marine microbial community reveals a critical threshold for CO<sub>2</sub> tolerance in phytoplankton productivity

Southern Ocean phytoplankton physiology in a changing climate

Plankton Assemblage Estimated with BGC‐Argo Floats in the Southern Ocean: Implications for Seasonal Successions and Particle Export

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Enhanced CO2 concentrations change the structure of Antarctic marine microbial communities

Cited by 41 publications

References 99 publications

Ocean acidification of a coastal Antarctic marine microbial community reveals a critical threshold for CO&lt;sub&gt;2&lt;/sub&gt; tolerance in phytoplankton productivity

Ocean acidification of a coastal Antarctic marine microbial community reveals a critical threshold for CO&lt;sub&gt;2&lt;/sub&gt; tolerance in phytoplankton productivity

Southern Ocean phytoplankton physiology in a changing climate

Plankton Assemblage Estimated with BGC‐Argo Floats in the Southern Ocean: Implications for Seasonal Successions and Particle Export

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Ocean acidification of a coastal Antarctic marine microbial community reveals a critical threshold for CO<sub>2</sub> tolerance in phytoplankton productivity

Ocean acidification of a coastal Antarctic marine microbial community reveals a critical threshold for CO<sub>2</sub> tolerance in phytoplankton productivity