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Wolf KKE, Hoppe CJM, Rehder L, Schaum E, John U, Rost B. Heatwave responses of Arctic phytoplankton communities are driven by combined impacts of warming and cooling. SCIENCE ADVANCES 2024; 10:eadl5904. [PMID: 38758795 PMCID: PMC11100554 DOI: 10.1126/sciadv.adl5904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 04/15/2024] [Indexed: 05/19/2024]
Abstract
Marine heatwaves are increasing in frequency and intensity as climate change progresses, especially in the highly productive Arctic regions. Although their effects on primary producers will largely determine the impacts on ecosystem services, mechanistic understanding on phytoplankton responses to these extreme events is still very limited. We experimentally exposed Arctic phytoplankton assemblages to stable warming, as well as to repeated heatwaves, and measured temporally resolved productivity, physiology, and composition. Our results show that even extreme stable warming increases productivity, while the response to heatwaves depends on the specific scenario applied and is not predictable from stable warming responses. This appears to be largely due to the underestimated impact of the cool phase following a heatwave, which can be at least as important as the warm phase for the overall response. We show that physiological and compositional adjustments to both warm and cool phases drive overall phytoplankton productivity and need to be considered mechanistically to predict overall ecosystem impacts.
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Affiliation(s)
- Klara K. E. Wolf
- Institute of Marine Ecosystem and Fishery Science, University of Hamburg, Hamburg, Germany
- Environmental Genomics, University of Konstanz, Konstanz, Germany
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Clara J. M. Hoppe
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Linda Rehder
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Elisa Schaum
- Institute of Marine Ecosystem and Fishery Science, University of Hamburg, Hamburg, Germany
| | - Uwe John
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
- Helmholtz Institute for Functional Marine Biodiversity (HIFMB), Oldenburg, Germany
| | - Björn Rost
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
- FB2, University of Bremen, Bremen, Germany
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Biswas H. A story of resilience: Arctic diatom Chaetoceros gelidus exhibited high physiological plasticity to changing CO 2 and light levels. FRONTIERS IN PLANT SCIENCE 2022; 13:1028544. [PMID: 36438134 PMCID: PMC9692007 DOI: 10.3389/fpls.2022.1028544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
Arctic phytoplankton are experiencing multifaceted stresses due to climate warming, ocean acidification, retreating sea ice, and associated changes in light availability, and that may have large ecological consequences. Multiple stressor studies on Arctic phytoplankton, particularly on the bloom-forming species, may help understand their fitness in response to future climate change, however, such studies are scarce. In the present study, a laboratory experiment was conducted on the bloom-forming Arctic diatom Chaetoceros gelidus (earlier C. socialis) under variable CO2 (240 and 900 µatm) and light (50 and 100 µmol photons m-2 s-1) levels. The growth response was documented using the pre-acclimatized culture at 2°C in a closed batch system over 12 days until the dissolved inorganic nitrogen was depleted. Particulate organic carbon and nitrogen (POC and PON), pigments, cell density, and the maximum quantum yield of photosystem II (Fv/Fm) were measured on day 4 (D4), 6 (D6), 10 (D10), and 12 (D12). The overall growth response suggested that C. gelidus maintained a steady-state carboxylation rate with subsequent conversion to macromolecules as reflected in the per-cell POC contents under variable CO2 and light levels. A substantial amount of POC buildup at the low CO2 level (comparable to the high CO2 treatment) indicated the possibility of existing carbon dioxide concentration mechanisms (CCMs) that needs further investigation. Pigment signatures revealed a high level of adaptability to variable irradiance in this species without any major CO2 effect. PON contents per cell increased initially but decreased irrespective of CO2 levels when nitrogen was limited (D6 onward) possibly to recycle intracellular nitrogen resources resulting in enhanced C: N ratios. On D12 the decreased dissolved organic nitrogen levels could be attributed to consumption under nitrogen starvation. Such physiological plasticity could make C. gelidus "ecologically resilient" in the future Arctic.
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Affiliation(s)
- Haimanti Biswas
- National Institute of Oceanography - CSIR (Council of Scientific and Industrial Research), Biological Oceanography Division, Goa, India
- Polar Biological Oceanography, Alfred Wegener Institute of Polar and Marine Research, Bremerhaven, Germany
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Bozzato D, Jakob T, Wilhelm C, Trimborn S. Effects of iron limitation on carbon balance and photophysiology of the Antarctic diatom Chaetoceros cf. simplex. Polar Biol 2021. [DOI: 10.1007/s00300-020-02785-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
AbstractIn the Southern Ocean (SO), iron (Fe) limitation strongly inhibits phytoplankton growth and generally decreases their primary productivity. Diatoms are a key component in the carbon (C) cycle, by taking up large amounts of anthropogenic CO2 through the biological carbon pump. In this study, we investigated the effects of Fe availability (no Fe and 4 nM FeCl3 addition) on the physiology of Chaetoceros cf. simplex, an ecologically relevant SO diatom. Our results are the first combining oxygen evolution and uptake rates with particulate organic carbon (POC) build up, pigments, photophysiological parameters and intracellular trace metal (TM) quotas in an Fe-deficient Antarctic diatom. Decreases in both oxygen evolution (through photosynthesis, P) and uptake (respiration, R) coincided with a lowered growth rate of Fe-deficient cells. In addition, cells displayed reduced electron transport rates (ETR) and chlorophyll a (Chla) content, resulting in reduced cellular POC formation. Interestingly, no differences were observed in non-photochemical quenching (NPQ) or in the ratio of gross photosynthesis to respiration (GP:R). Furthermore, TM quotas were measured, which represent an important and rarely quantified parameter in previous studies. Cellular quotas of manganese, zinc, cobalt and copper remained unchanged while Fe quotas of Fe-deficient cells were reduced by 60% compared with High Fe cells. Based on our data, Fe-deficient Chaetoceros cf. simplex cells were able to efficiently acclimate to low Fe conditions, reducing their intracellular Fe concentrations, the number of functional reaction centers of photosystem II (RCII) and photosynthetic rates, thus avoiding light absorption rather than dissipating the energy through NPQ. Our results demonstrate how Chaetoceros cf. simplex can adapt their physiology to lowered assimilatory metabolism by decreasing respiratory losses.
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Pierella Karlusich JJ, Bowler C, Biswas H. Carbon Dioxide Concentration Mechanisms in Natural Populations of Marine Diatoms: Insights From Tara Oceans. FRONTIERS IN PLANT SCIENCE 2021; 12:657821. [PMID: 33995455 PMCID: PMC8119650 DOI: 10.3389/fpls.2021.657821] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 03/23/2021] [Indexed: 05/08/2023]
Abstract
Marine diatoms, the most successful photoautotrophs in the ocean, efficiently sequester a significant part of atmospheric CO2 to the ocean interior through their participation in the biological carbon pump. However, it is poorly understood how marine diatoms fix such a considerable amount of CO2, which is vital information toward modeling their response to future CO2 levels. The Tara Oceans expeditions generated molecular data coupled with in situ biogeochemical measurements across the main ocean regions, and thus provides a framework to compare diatom genetic and transcriptional flexibility under natural CO2 variability. The current study investigates the interlink between the environmental variability of CO2 and other physicochemical parameters with the gene and transcript copy numbers of five key enzymes of diatom CO2 concentration mechanisms (CCMs): Rubisco activase and carbonic anhydrase (CA) as part of the physical pathway, together with phosphoenolpyruvate carboxylase, phosphoenolpyruvate carboxykinase, and malic enzyme as part of the potential C4 biochemical pathway. Toward this aim, we mined >200 metagenomes and >220 metatranscriptomes generated from samples of the surface layer of 66 globally distributed sampling sites and corresponding to the four main size fractions in which diatoms can be found: 0.8-5 μm, 5-20 μm, 20-180 μm, and 180-2,000 μm. Our analyses revealed that the transcripts for the enzymes of the putative C4 biochemical CCM did not in general display co-occurring profiles. The transcripts for CAs were the most abundant, with an order of magnitude higher values than the other enzymes, thus implying the importance of physical CCMs in diatom natural communities. Among the different classes of this enzyme, the most prevalent was the recently characterized iota class. Consequently, very little information is available from natural diatom assemblages about the distribution of this class. Biogeographic distributions for all the enzymes show different abundance hotspots according to the size fraction, pointing to the influence of cell size and aggregation in CCMs. Environmental correlations showed a complex pattern of responses to CO2 levels, total phytoplankton biomass, temperature, and nutrient concentrations. In conclusion, we propose that biophysical CCMs are prevalent in natural diatom communities.
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Affiliation(s)
- Juan José Pierella Karlusich
- Institut de Biologie de l’ENS, Département de Biologie, École Normale Supérieure, CNRS, INSERM, Université PSL, Paris, France
- CNRS Research Federation for the study of Global Ocean Systems Ecology and Evolution, FR2022/Tara Oceans GOSEE, Paris, France
| | - Chris Bowler
- Institut de Biologie de l’ENS, Département de Biologie, École Normale Supérieure, CNRS, INSERM, Université PSL, Paris, France
- CNRS Research Federation for the study of Global Ocean Systems Ecology and Evolution, FR2022/Tara Oceans GOSEE, Paris, France
| | - Haimanti Biswas
- CSIR National Institute of Oceanography, Biological Oceanography Division, Dona Paula, India
- *Correspondence: Haimanti Biswas,
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Seifert M, Rost B, Trimborn S, Hauck J. Meta-analysis of multiple driver effects on marine phytoplankton highlights modulating role of pCO 2. GLOBAL CHANGE BIOLOGY 2020; 26:6787-6804. [PMID: 32905664 DOI: 10.1111/gcb.15341] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/26/2020] [Accepted: 08/26/2020] [Indexed: 06/11/2023]
Abstract
Responses of marine primary production to a changing climate are determined by a concert of multiple environmental changes, for example in temperature, light, pCO2 , nutrients, and grazing. To make robust projections of future global marine primary production, it is crucial to understand multiple driver effects on phytoplankton. This meta-analysis quantifies individual and interactive effects of dual driver combinations on marine phytoplankton growth rates. Almost 50% of the single-species laboratory studies were excluded because central data and metadata (growth rates, carbonate system, experimental treatments) were insufficiently reported. The remaining data (42 studies) allowed for the analysis of interactions of pCO2 with temperature, light, and nutrients, respectively. Growth rates mostly respond non-additively, whereby the interaction with increased pCO2 profusely dampens growth-enhancing effects of high temperature and high light. Multiple and single driver effects on coccolithophores differ from other phytoplankton groups, especially in their high sensitivity to increasing pCO2 . Polar species decrease their growth rate in response to high pCO2 , while temperate and tropical species benefit under these conditions. Based on the observed interactions and projected changes, we anticipate primary productivity to: (a) first increase but eventually decrease in the Arctic Ocean once nutrient limitation outweighs the benefits of higher light availability; (b) decrease in the tropics and mid-latitudes due to intensifying nutrient limitation, possibly amplified by elevated pCO2 ; and (c) increase in the Southern Ocean in view of higher nutrient availability and synergistic interaction with increasing pCO2 . Growth-enhancing effect of high light and warming to coccolithophores, mainly Emiliania huxleyi, might increase their relative abundance as long as not offset by acidification. Dinoflagellates are expected to increase their relative abundance due to their positive growth response to increasing pCO2 and light levels. Our analysis reveals gaps in the knowledge on multiple driver responses and provides recommendations for future work on phytoplankton.
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Affiliation(s)
- Miriam Seifert
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
| | - Björn Rost
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
- Universität Bremen, Bremen, Germany
| | - Scarlett Trimborn
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
- Universität Bremen, Bremen, Germany
| | - Judith Hauck
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
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