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Dive into the research topics where Nina Schuback is active.

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Featured researches published by Nina Schuback.


PLOS ONE | 2015

Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton.

Nina Schuback; Christina Schallenberg; Carolyn Duckham; Maria T. Maldonado; Philippe D. Tortell

Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETRRCII, mol e- mol RCII-1 s-1) increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal – oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETRRCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements.


Frontiers in Marine Science | 2017

Functional Redundancy Facilitates Resilience of Subarctic Phytoplankton Assemblages toward Ocean Acidification and High Irradiance

Clara Jule Marie Hoppe; Nina Schuback; David M. Semeniuk; Maria T. Maldonado; Björn Rost

In order to understand how ocean acidification (OA) and enhanced irradiance levels might alter phytoplankton eco-physiology, productivity and species composition, we conducted an incubation experiment with a natural plankton assemblage from subsurface Subarctic waters (Davis Strait, 63°N). The phytoplankton assemblage was exposed to 380 and 1000 µatm pCO2 at both 15% and 35% surface irradiance over two weeks. The incubations were monitored and characterized in terms of their photo-physiology, biomass stoichiometry, primary production and dominant phytoplankton species. We found that the phytoplankton assemblage exhibited pronounced high-light stress in the first days of the experiment (20-30% reduction in photosynthetic efficiency, Fv/Fm). This stress signal was more pronounced under OA and high light, indicating interactive effects of these environmental variables. Primary production in the high light treatments was reduced by 20% under OA compared to ambient pCO2 levels. Over the course of the experiment, the assemblage fully acclimated to the applied treatments, achieving similar bulk characteristics (e.g. net primary production and elemental stoichiometry) under all conditions. We did, however, observe a pCO2-dependent shift in the dominant diatom species, with Pseudonitzschia sp. dominating under low and Fragilariopsis sp. under high pCO2 levels. Our results indicate an unexpectedly high level of resilience of Subarctic phytoplankton to OA and enhanced irradiance levels. The co-occurring shift in dominant species suggests functional redundancy to be an important, but so-far largely overlooked mechanism for resilience towards climate change.


Nature Climate Change | 2018

Compensation of ocean acidification effects in Arctic phytoplankton assemblages

Clara Jule Marie Hoppe; Klara Wolf; Nina Schuback; Philippe D. Tortell; Björn Rost

The Arctic and subarctic shelf seas, which sustain large fisheries and contribute to global biogeochemical cycling, are particularly sensitive to ongoing ocean acidification (that is, decreasing seawater pH due to anthropogenic CO2 emissions). Yet, little information is available on the effects of ocean acidification on natural phytoplankton assemblages, which are the main primary producers in high-latitude waters. Here we show that coastal Arctic and subarctic primary production is largely insensitive to ocean acidification over a large range of light and temperature levels in different experimental designs. Out of ten CO2-manipulation treatments, significant ocean acidification effects on primary productivity were observed only once (at temperatures below 2 °C), and shifts in the species composition occurred only three times (without correlation to specific experimental conditions). These results imply a high capacity to compensate for environmental variability, which can be understood in light of the environmental history, tolerance ranges and intraspecific diversity of the dominant phytoplankton species.The effects of projected ocean acidification on primary productivity of the Arctic and subarctic shelf seas are found to be minimal, with the phytoplankton communities showing a high capacity to compensate for environmental change.


PLOS ONE | 2017

Contrasting effects of copper limitation on the photosynthetic apparatus in two strains of the open ocean diatom Thalassiosira oceanica

Anna A. Hippmann; Nina Schuback; Kyung-Mee Moon; John P. McCrow; Andrew E. Allen; Leonard J. Foster; Beverley R. Green; Maria T. Maldonado; Paul A. Cobine

There is an intricate interaction between iron (Fe) and copper (Cu) physiology in diatoms. However, strategies to cope with low Cu are largely unknown. This study unveils the comprehensive restructuring of the photosynthetic apparatus in the diatom Thalassiosira oceanica (CCMP1003) in response to low Cu, at the physiological and proteomic level. The restructuring results in a shift from light harvesting for photochemistry—and ultimately for carbon fixation—to photoprotection, reducing carbon fixation and oxygen evolution. The observed decreases in the physiological parameters Fv/Fm, carbon fixation, and oxygen evolution, concomitant with increases in the antennae absorption cross section (σPSII), non-photochemical quenching (NPQ) and the conversion factor (φe:C/ηPSII) are in agreement with well documented cellular responses to low Fe. However, the underlying proteomic changes due to low Cu are very different from those elicited by low Fe. Low Cu induces a significant four-fold reduction in the Cu-containing photosynthetic electron carrier plastocyanin. The decrease in plastocyanin causes a bottleneck within the photosynthetic electron transport chain (ETC), ultimately leading to substantial stoichiometric changes. Namely, 2-fold reduction in both cytochrome b6f complex (cytb6f) and photosystem II (PSII), no change in the Fe-rich PSI and a 40- and 2-fold increase in proteins potentially involved in detoxification of reactive oxygen species (ferredoxin and ferredoxin:NADP+ reductase, respectively). Furthermore, we identify 48 light harvesting complex (LHC) proteins in the publicly available genome of T. oceanica and provide proteomic evidence for 33 of these. The change in the LHC composition within the antennae in response to low Cu underlines the shift from photochemistry to photoprotection in T. oceanica (CCMP1003). Interestingly, we also reveal very significant intra-specific strain differences. Another strain of T. oceanica (CCMP 1005) requires significantly higher Cu concentrations to sustain both its maximal and minimal growth rate compared to CCMP 1003. Under low Cu, CCMP 1005 decreases its growth rate, cell size, Chla and total protein per cell. We argue that the reduction in protein per cell is the main strategy to decrease its cellular Cu requirement, as none of the other parameters tested are affected. Differences between the two strains, as well as differences between the well documented responses to low Fe and those presented here in response to low Cu are discussed.


Biogeosciences | 2016

Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific

Nina Schuback; Mirkko Flecken; Maria T. Maldonado; Philippe D. Tortell


Limnology and Oceanography | 2017

Primary productivity and the coupling of photosynthetic electron transport and carbon fixation in the Arctic Ocean

Nina Schuback; Clara Jule Marie Hoppe; Jean-Éric Tremblay; Maria T. Maldonado; Philippe D. Tortell


Biogeosciences | 2016

Impact of ocean acidification on Arctic phytoplankton blooms and dimethyl sulfide concentration under simulated ice-free and under-ice conditions

Rachel Hussherr; Maurice Levasseur; Martine Lizotte; Jean-Éric Tremblay; Jacoba Mol; Helmuth Thomas; Michel Gosselin; Michel Starr; Lisa A. Miller; Tereza Jarníková; Nina Schuback; Alfonso Mucci


Polar Biology | 2018

Resistance of Arctic phytoplankton to ocean acidification and enhanced irradiance

Clara Jule Marie Hoppe; Nina Schuback; David M. Semeniuk; K. Giesbrecht; J. Mol; Helmuth Thomas; Maria T. Maldonado; Björn Rost; D. E. Varela; Philippe D. Tortell


Polar Biology | 2018

Correction to: Resistance of Arctic phytoplankton to ocean acidification and enhanced irradiance

Clara Jule Marie Hoppe; Nina Schuback; David M. Semeniuk; K. Giesbrecht; J. Mol; Helmuth Thomas; Maria T. Maldonado; Bjoern Rost; D. E. Varela; Philippe D. Tortell


EPIC3Arctic Frontiers Conference, Tromsø, Norway, 2017-01-23-2017-01-27 | 2017

Resisting climate change - multiple stressors do not alter Arctic primary production

Clara Jule Marie Hoppe; Klara Wolf; Nina Schuback; Philippe D. Tortell; Bjoern Rost

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Maria T. Maldonado

University of British Columbia

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Clara Jule Marie Hoppe

University of British Columbia

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Philippe D. Tortell

University of British Columbia

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David M. Semeniuk

University of British Columbia

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Björn Rost

Alfred Wegener Institute for Polar and Marine Research

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Bjoern Rost

University of British Columbia

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J. Mol

Dalhousie University

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