Interactive effects of iron and temperature on the growth of <scp><i>Fragilariopsis cylindrus</i></scp>

Jabre, Loay; Bertrand, Erin M.

doi:10.1002/lol2.10158

Cited by 20 publications

(22 citation statements)

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“…Upregulation of Lhcf and Lhcr groups contributes to increased light harvesting efficiency, and alleviates photosynthetic iron demand by reducing the number of iron-containing photosynthetic components required to process light energy (Schuback et al 2015). Increased light harvesting cross section under warming has been detected in iron-stressed F. cylindrus under laboratory conditions (Jabre and Bertrand, 2020), and these environmental data indicate that Pseudo-nitzschia may be even better equipped to use this mechanism to support growth under low iron in the SO. Several Lhcf and Lhcr clusters were also upregulated in both Fragilariopsis and Pseudo-nitzschia after iron addition.…”

Section: Resultsmentioning

confidence: 91%

“…Several Lhcf and Lhcr clusters were also upregulated in both Fragilariopsis and Pseudo-nitzschia after iron addition. Given that iron addition is expected to reduce light harvesting cross section (Greene et al 1992; Jabre and Bertrand 2020) it might be expected that Fe addition could decrease demand for Lhcf and Lhcr expression. However, this impact appears to be overridden by increased demand for LHC expression as a result of Fe-induced increases in PSU abundance.…”

Section: Resultsmentioning

confidence: 99%

“…Increased temperature (up to a critical threshold) improves cellular iron use efficiency (Sunda and Huntsman 2011; Jiang et al 2018) and may cause a reduction in the amount of enzymes -and iron-needed to carry out metabolic functions. Antarctic diatoms also exhibit reduced cell size under elevated temperature, which can increase surface area to volume ratios and facilitate nutrient uptake and growth (Zhu et al 2016; Jabre and Bertrand 2020). Additionally, concurrent increases in temperature and iron have a much larger effect on growth compared to the individual effects of each factor (Rose et al 2009; Zhu et al 2016; Hutchins and Boyd 2016), with some species like Fragilariopsis cylindrus requiring iron supplementation to benefit from warming (Jabre and Bertrand 2020).…”

Section: Main Textmentioning

confidence: 99%

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Molecular underpinnings and biogeochemical consequences of enhanced diatom growth in a warming Southern Ocean

Jabre¹,

Allen

McCain³

et al. 2020

Preprint

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AbstractThe Southern Ocean (SO) harbours some of the most intense phytoplankton blooms on Earth. Changes in temperature and iron availability are expected to alter the intensity of SO phytoplankton blooms, but little is known about how environmental change will influence community composition and downstream biogeochemical processes. We performed experimental manipulations on surface ocean microbial communities from McMurdo Sound in the Ross Sea, with and without iron addition, at −0.5 °C, 3 °C, and 6 °C. We then examined nutrient uptake patterns as well as the growth and molecular responses of two dominant diatoms, Fragilariopsis and Pseudo-nitzschia, to these conditions. We found that nitrate uptake and primary productivity were elevated at increased temperature in the absence of iron addition, and were even greater at high temperature with added iron. Pseudo-nitzschia became more abundant under increased temperature without added iron, while Fragilariopsis required additional iron to benefit from warming. We attribute the apparent advantage Pseudo-nitzschia shows under warming to upregulation of iron-conserving photosynthetic processes, utilization of iron-economic nitrogen assimilation mechanisms, and increased iron uptake and storage. These data identify important molecular and physiological differences between dominant diatom groups and add to the growing body of evidence for Pseudo-nitzschia’s increasingly important role in warming SO ecosystems. This study also suggests that temperature-driven shifts in SO phytoplankton assemblages may increase utilization of the vast pool of excess nutrients in iron-limited SO surface waters, and thereby influence global nutrient distributions and carbon cycle.Significance StatementPhytoplankton assemblages contribute to the Southern Ocean’s ability to absorb atmospheric CO2, form the base of marine food webs, and shape the global distribution of macronutrients. Anthropogenic climate change is altering the SO environment, yet we do not fully understand how resident phytoplankton will react to this change. By comparing the responses of two prominent SO diatom groups to changes in temperature and iron in a natural community, we find that one group, Pseudo-nitzschia, grows better under warmer low-iron conditions by managing cellular iron demand and efficiently increasing photosynthetic capacity. This ability to grow and draw down nutrients in the face of warming, regardless of iron availability, may have major implications for ocean ecosystems and global nutrient and carbon cycles.

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Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Main Textmentioning

confidence: 99%

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Molecular underpinnings and biogeochemical consequences of enhanced diatom growth in a warming Southern Ocean

Jabre¹,

Allen

McCain³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…facilitate photosynthesis (13,14). Diatoms may also use iron-free rhodopsin to supplement photosynthetic energy capture (15), have transport mechanisms that can be up-regulated to maximize iron acquisition (16)(17)(18), and some species contain iron storage proteins (ferritin) to buffer the sporadic availability of this micronutrient (19).…”

Section: Significancementioning

confidence: 99%

Molecular underpinnings and biogeochemical consequences of enhanced diatom growth in a warming Southern Ocean

Jabre

Allen

McCain

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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The Southern Ocean (SO) harbors some of the most intense phytoplankton blooms on Earth. Changes in temperature and iron availability are expected to alter the intensity of SO phytoplankton blooms, but little is known about how these changes will influence community composition and downstream biogeochemical processes. We performed light-saturated experimental manipulations on surface ocean microbial communities from McMurdo Sound in the Ross Sea to examine the effects of increased iron availability (+2 nM) and warming (+3 and +6 °C) on nutrient uptake, as well as the growth and transcriptional responses of two dominant diatoms, Fragilariopsis and Pseudo-nitzschia. We found that community nutrient uptake and primary productivity were elevated under both warming conditions without iron addition (relative to ambient −0.5 °C). This effect was greater than additive under concurrent iron addition and warming. Pseudo-nitzschia became more abundant under warming without added iron (especially at 6 °C), while Fragilariopsis only became more abundant under warming in the iron-added treatments. We attribute the apparent advantage Pseudo-nitzschia shows under warming to up-regulation of iron-conserving photosynthetic processes, utilization of iron-economic nitrogen assimilation mechanisms, and increased iron uptake and storage. These data identify important molecular and physiological differences between dominant diatom groups and add to the growing body of evidence for Pseudo-nitzschia’s increasingly important role in warming SO ecosystems. This study also suggests that temperature-driven shifts in SO phytoplankton assemblages may increase utilization of the vast pool of excess nutrients in iron-limited SO surface waters and thereby influence global nutrient distribution and carbon cycling.

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“…Although several studies on the individual or interactive roles of iron and light have been conducted (Boyd et al., 2015; Feng et al., 2010; Sedwick et al., 2007; Strzepek et al., 2019; Sunda & Huntsman, 1997), there is a lack of consensus regarding the dynamics that govern the productivity in this area. Moreover, still the observations and laboratory incubation experiments on the roles of temperature, grazing rate by predators, and acidification are deficient (e.g., Jabre & Bertrand, 2020). Hence, predicting the responses of ecosystems to environmental changes is not straightforward currently.…”

Section: Introductionmentioning

confidence: 99%

Exploring the Roles of Iron and Irradiance in Dynamics of Diatoms and Phaeocystis in the Amundsen Sea Continental Shelf Water

Kwon

Jung

et al. 2021

JGR Oceans

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The Southern Ocean, generally defined as the waters occurring south of 60°S and encircling Antarctica, plays a disproportionate role in control of atmospheric carbon by contributing ∼40% of the total oceanic uptake of anthropogenic carbon dioxide (CO 2) emissions (Frölicher et al., 2015; Khatiwala et al., 2009; Takahashi et al., 2009, 2012). In particular, the Antarctic continental shelf areas show substantial carbon uptake capacity due to efficient biological pump through primary production (Arrigo et al., 2008) during the summertime when sea ice retreat allows solar irradiance penetration into the upper ocean. However, the reason for the low efficiency of carbon export into the deep ocean despite the high productivity in the upper Abstract The Amundsen Sea continental shelf (ACS) water ecosystem is expected to undergo changes since increasing melt rate of glacier and decreasing sea ice extent by global warming would lead to the mitigation of iron and light limitation. We investigated how diatoms and Phaeocystis, two dominant taxa, and primary production in the ACS water would respond to variations in iron and light availabilities by using a 1-D pelagic ecosystem model. In the model, we added sea ice effects that reduce light penetration and optimized model parameters for diatoms and Phaeocystis. The results from our model showed good agreement with 20-year observations of Chl-a as well as the biomass proportion of diatoms and Phaeocystis and nutrient distributions during the growing season. Our model experimental results suggest that the current moderate iron and high light conditions favor the growth of Phaeocystis over diatoms. Moreover, as iron increases, the organic carbon exudation by phytoplankton increases more rapidly than net primary production (NPP), leading to a decline in phytoplankton biomass. On the other hand, irradiance plays a role in controlling NPP in terms of photoinhibition which is reduced by increasing iron. Increases in both iron and irradiance lead to an advance in the timing of the bloom peak (surface Chl-a maximum) due to increases in phytoplankton carbon loss and photoinhibition. Our results imply that the dominance of Phaeocystis can continue and that the carbon uptake capacity of the ACS in the summer seasons might increase given that iron availability will increase with future climate change. Plain Language Summary We firmly believe that this research based on an optimum biogeochemical model developed for the Amundsen Sea continental shelf water is of sufficiently broad interest for the public as well as the scientific community, since it advances the study of phytoplankton ecology and carbon uptake in the Antarctic coastal area. A complex coupled ocean-ecosystem model was developed to investigate dynamics of the two dominant species (diatoms and Phaeocystis) in the ACS water, one of the most rapidly warming regions on Earth with extremely high primary productivity. These two groups are particularly important as they could significantly contribute to the carbon export into the dee...

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Interactive effects of iron and temperature on the growth of Fragilariopsis cylindrus

Cited by 20 publications

References 35 publications

Molecular underpinnings and biogeochemical consequences of enhanced diatom growth in a warming Southern Ocean

Molecular underpinnings and biogeochemical consequences of enhanced diatom growth in a warming Southern Ocean

Molecular underpinnings and biogeochemical consequences of enhanced diatom growth in a warming Southern Ocean

Exploring the Roles of Iron and Irradiance in Dynamics of Diatoms and Phaeocystis in the Amundsen Sea Continental Shelf Water

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