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Juchem DP, Schimani K, Holzinger A, Permann C, Abarca N, Skibbe O, Zimmermann J, Graeve M, Karsten U. Lipid degradation and photosynthetic traits after prolonged darkness in four Antarctic benthic diatoms, including the newly described species Planothidium wetzelii sp. nov. Front Microbiol 2023; 14:1241826. [PMID: 37720158 PMCID: PMC10500929 DOI: 10.3389/fmicb.2023.1241826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 08/08/2023] [Indexed: 09/19/2023] Open
Abstract
In polar regions, the microphytobenthos has important ecological functions in shallow-water habitats, such as on top of coastal sediments. This community is dominated by benthic diatoms, which contribute significantly to primary production and biogeochemical cycling while also being an important component of polar food webs. Polar diatoms are able to cope with markedly changing light conditions and prolonged periods of darkness during the polar night in Antarctica. However, the underlying mechanisms are poorly understood. In this study, five strains of Antarctic benthic diatoms were isolated in the field, and the resulting unialgal cultures were identified as four distinct species, of which one is described as a new species, Planothidium wetzelii sp. nov. All four species were thoroughly examined using physiological, cell biological, and biochemical methods over a fully controlled dark period of 3 months. The results showed that the utilization of storage lipids is one of the key mechanisms in Antarctic benthic diatoms to survive the polar night, although different fatty acids were involved in the investigated taxa. In all tested species, the storage lipid content declined significantly, along with an ultrastructurally observable degradation of the chloroplasts. Surprisingly, photosynthetic performance did not change significantly despite chloroplasts decreasing in thylakoid membranes and an increased number of plastoglobules. Thus, a combination of biochemical and cell biological mechanisms allows Antarctic benthic diatoms to survive the polar night.
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Affiliation(s)
- Desirée P. Juchem
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Katherina Schimani
- Botanischer Garten und Botanisches Museum Berlin, Freie Universität Berlin, Berlin, Germany
| | - Andreas Holzinger
- Department of Botany, Functional Plant Biology, University of Innsbruck, Innsbruck, Austria
| | - Charlotte Permann
- Department of Botany, Functional Plant Biology, University of Innsbruck, Innsbruck, Austria
| | - Nélida Abarca
- Botanischer Garten und Botanisches Museum Berlin, Freie Universität Berlin, Berlin, Germany
| | - Oliver Skibbe
- Botanischer Garten und Botanisches Museum Berlin, Freie Universität Berlin, Berlin, Germany
| | - Jonas Zimmermann
- Botanischer Garten und Botanisches Museum Berlin, Freie Universität Berlin, Berlin, Germany
| | - Martin Graeve
- Alfred-Wegener-Institute Helmholtz-Center for Polar and Marine Research, Ecological Chemistry, Bremerhaven, Germany
| | - Ulf Karsten
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
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Prelle LR, Schmidt I, Schimani K, Zimmermann J, Abarca N, Skibbe O, Juchem D, Karsten U. Photosynthetic, Respirational, and Growth Responses of Six Benthic Diatoms from the Antarctic Peninsula as Functions of Salinity and Temperature Variations. Genes (Basel) 2022; 13:genes13071264. [PMID: 35886047 PMCID: PMC9324188 DOI: 10.3390/genes13071264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 07/12/2022] [Accepted: 07/13/2022] [Indexed: 02/04/2023] Open
Abstract
Temperature and salinity are some of the most influential abiotic parameters shaping biota in aquatic ecosystems. In recent decades, climate change has had a crucial impact on both factors—especially around the Antarctic Peninsula—with increasing air and water temperature leading to glacial melting and the accompanying freshwater increase in coastal areas. Antarctic soft and hard bottoms are typically inhabited by microphytobenthic communities, which are often dominated by benthic diatoms. Their physiology and primary production are assumed to be negatively affected by increased temperatures and lower salinity. In this study, six representative benthic diatom strains were isolated from different aquatic habitats at King George Island, Antarctic Peninsula, and comprehensively identified based on molecular markers and morphological traits. Photosynthesis, respiration, and growth response patterns were investigated as functions of varying light availability, temperature, and salinity. Photosynthesis−irradiance curve measurements pointed to low light requirements, as light-saturated photosynthesis was reached at <70 µmol photons m−2 s−1. The marine isolates exhibited the highest effective quantum yield between 25 and 45 SA (absolute salinity), but also tolerance to lower and higher salinities at 1 SA and 55 SA, respectively, and in a few cases even <100 SA. In contrast, the limnic isolates showed the highest effective quantum yield at salinities ranging from 1 SA to 20 SA. Almost all isolates exhibited high effective quantum yields between 1.5 °C and 25 °C, pointing to a broad temperature tolerance, which was supported by measurements of the short-term temperature-dependent photosynthesis. All studied Antarctic benthic diatoms showed activity patterns over a broader environmental range than they usually experience in situ. Therefore, it is likely that their high ecophysiological plasticity represents an important trait to cope with climate change in the Antarctic Peninsula.
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Affiliation(s)
- Lara R. Prelle
- Applied Ecology and Phycology, Institute of Biological Sciences, Albert-Einstein-Strasse 3, University of Rostock, 18057 Rostock, Germany; (L.R.P.); (I.S.); (D.J.)
| | - Ina Schmidt
- Applied Ecology and Phycology, Institute of Biological Sciences, Albert-Einstein-Strasse 3, University of Rostock, 18057 Rostock, Germany; (L.R.P.); (I.S.); (D.J.)
| | - Katherina Schimani
- Botanic Garden and Botanical Museum Berlin-Dahlem, Freie Universität Berlin, 14163 Berlin, Germany; (K.S.); (J.Z.); (N.A.); (O.S.)
| | - Jonas Zimmermann
- Botanic Garden and Botanical Museum Berlin-Dahlem, Freie Universität Berlin, 14163 Berlin, Germany; (K.S.); (J.Z.); (N.A.); (O.S.)
| | - Nelida Abarca
- Botanic Garden and Botanical Museum Berlin-Dahlem, Freie Universität Berlin, 14163 Berlin, Germany; (K.S.); (J.Z.); (N.A.); (O.S.)
| | - Oliver Skibbe
- Botanic Garden and Botanical Museum Berlin-Dahlem, Freie Universität Berlin, 14163 Berlin, Germany; (K.S.); (J.Z.); (N.A.); (O.S.)
| | - Desiree Juchem
- Applied Ecology and Phycology, Institute of Biological Sciences, Albert-Einstein-Strasse 3, University of Rostock, 18057 Rostock, Germany; (L.R.P.); (I.S.); (D.J.)
| | - Ulf Karsten
- Applied Ecology and Phycology, Institute of Biological Sciences, Albert-Einstein-Strasse 3, University of Rostock, 18057 Rostock, Germany; (L.R.P.); (I.S.); (D.J.)
- Correspondence:
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Prelle LR, Albrecht M, Karsten U, Damer P, Giese T, Jähns J, Müller S, Schulz L, Viertel L, Glaser K. Ecophysiological and Cell Biological Traits of Benthic Diatoms From Coastal Wetlands of the Southern Baltic Sea. Front Microbiol 2021; 12:642811. [PMID: 33912148 PMCID: PMC8072133 DOI: 10.3389/fmicb.2021.642811] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/19/2021] [Indexed: 11/13/2022] Open
Abstract
The German Baltic Sea coastline is characterized by sea-land transitions zones, specifically coastal peatlands. Such transition zones exhibit highly fluctuating environmental parameters and dynamic gradients that affect physiological processes of inhabiting organisms such as microphytobenthic communities. In the present study four representative and abundant benthic diatom strains [Melosira nummuloides, Nitzschia filiformis, Planothidium sp. (st. 1) and Planothidium sp. (st.2)] were isolated from a Baltic Sea beach and three peatlands that are irregularly affected by Baltic Sea water intrusion. Ecophysiological and cell biological traits of the strains were investigated for the first time as function of light, temperature and salinity. The four strains exhibited euryhaline growth over a range of 1–39 SA, surpassing in situ salinity of the respective brackish habitats. Furthermore, they showed eurythermal growth over a temperature range from 5 to 30°C with an optimum temperature between 15 and 20°C. Growth rates did not exhibit any differences between the peatland and Baltic Sea strains. The photosynthetic temperature optimum of the peatland diatom isolates, however, was much higher (20–35°C) compared to the Baltic Sea one (10°C). All strains exhibited light saturation points ranging between 29.8 and 72.6 μmol photons m–2 s–1. The lipid content did not change in response to the tested abiotic factors. All data point to wide physiological tolerances in these benthic diatoms along the respective sea-land transitions zones. This study could serve as a baseline for future studies on microphytobenthic communities and their key functions, like primary production, under fluctuating environmental stressors along terrestrial-marine gradients.
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Affiliation(s)
- Lara R Prelle
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Martin Albrecht
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Ulf Karsten
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Pauline Damer
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Tabea Giese
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Jessica Jähns
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Simon Müller
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Louisa Schulz
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Lennard Viertel
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Karin Glaser
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
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Wolf KKE, Romanelli E, Rost B, John U, Collins S, Weigand H, Hoppe CJM. Company matters: The presence of other genotypes alters traits and intraspecific selection in an Arctic diatom under climate change. GLOBAL CHANGE BIOLOGY 2019; 25:2869-2884. [PMID: 31058393 PMCID: PMC6852494 DOI: 10.1111/gcb.14675] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 05/11/2023]
Abstract
Arctic phytoplankton and their response to future conditions shape one of the most rapidly changing ecosystems on the planet. We tested how much the phenotypic responses of strains from the same Arctic diatom population diverge and whether the physiology and intraspecific composition of multistrain populations differs from expectations based on single strain traits. To this end, we conducted incubation experiments with the diatom Thalassiosira hyalina under present-day and future temperature and pCO2 treatments. Six fresh isolates from the same Svalbard population were incubated as mono- and multistrain cultures. For the first time, we were able to closely follow intraspecific selection within an artificial population using microsatellites and allele-specific quantitative PCR. Our results showed not only that there is substantial variation in how strains of the same species cope with the tested environments but also that changes in genotype composition, production rates, and cellular quotas in the multistrain cultures are not predictable from monoculture performance. Nevertheless, the physiological responses as well as strain composition of the artificial populations were highly reproducible within each environment. Interestingly, we only detected significant strain sorting in those populations exposed to the future treatment. This study illustrates that the genetic composition of populations can change on very short timescales through selection from the intraspecific standing stock, indicating the potential for rapid population level adaptation to climate change. We further show that individuals adjust their phenotype not only in response to their physicochemical but also to their biological surroundings. Such intraspecific interactions need to be understood in order to realistically predict ecosystem responses to global change.
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Affiliation(s)
- Klara K. E. Wolf
- Marine BiogeosciencesAlfred Wegener Institut – Helmholtz‐Zentrum für Polar‐ und MeeresforschungBremerhavenGermany
| | - Elisa Romanelli
- Marine BiogeosciencesAlfred Wegener Institut – Helmholtz‐Zentrum für Polar‐ und MeeresforschungBremerhavenGermany
- Marine Science InstituteUniversity of CaliforniaSanta BarbaraCalifornia
| | - Björn Rost
- Marine BiogeosciencesAlfred Wegener Institut – Helmholtz‐Zentrum für Polar‐ und MeeresforschungBremerhavenGermany
- University of BremenBremenGermany
| | - Uwe John
- Marine BiogeosciencesAlfred Wegener Institut – Helmholtz‐Zentrum für Polar‐ und MeeresforschungBremerhavenGermany
- Helmholtz Institute for Functional Marine Biodiversity (HIFMB)OldenburgGermany
| | - Sinead Collins
- Institute of Evolutionary Biology, School of Biological SciencesUniversity of EdinburghEdinburghUK
| | - Hannah Weigand
- Aquatic Ecosystem Research, Faculty of BiologyUniversity of Duisburg‐EssenEssenGermany
| | - Clara J. M. Hoppe
- Marine BiogeosciencesAlfred Wegener Institut – Helmholtz‐Zentrum für Polar‐ und MeeresforschungBremerhavenGermany
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Broman E, Sachpazidou V, Dopson M, Hylander S. Diatoms dominate the eukaryotic metatranscriptome during spring in coastal 'dead zone' sediments. Proc Biol Sci 2018; 284:rspb.2017.1617. [PMID: 28978732 DOI: 10.1098/rspb.2017.1617] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 09/04/2017] [Indexed: 01/05/2023] Open
Abstract
An important characteristic of marine sediments is the oxygen concentration that affects many central metabolic processes. There has been a widespread increase in hypoxia in coastal systems (referred to as 'dead zones') mainly caused by eutrophication. Hence, it is central to understand the metabolism and ecology of eukaryotic life in sediments during changing oxygen conditions. Therefore, we sampled coastal 'dead zone' Baltic Sea sediment during autumn and spring, and analysed the eukaryotic metatranscriptome from field samples and after incubation in the dark under oxic or anoxic conditions. Bacillariophyta (diatoms) dominated the eukaryotic metatranscriptome in spring and were also abundant during autumn. A large fraction of the diatom RNA reads was associated with the photosystems suggesting a constitutive expression in darkness. Microscope observation showed intact diatom cells and these would, if hatched, represent a significant part of the pelagic phytoplankton biomass. Oxygenation did not significantly change the relative proportion of diatoms nor resulted in any major shifts in metabolic 'signatures'. By contrast, diatoms rapidly responded when exposed to light suggesting that light is limiting diatom development in hypoxic sediments. Hence, it is suggested that diatoms in hypoxic sediments are on 'standby' to exploit the environment if they reach suitable habitats.
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Affiliation(s)
- Elias Broman
- Centre for Ecology and Evolution in Microbial model Systems - EEMiS, Linnaeus University, 39182 Kalmar, Sweden
| | - Varvara Sachpazidou
- Centre for Ecology and Evolution in Microbial model Systems - EEMiS, Linnaeus University, 39182 Kalmar, Sweden
| | - Mark Dopson
- Centre for Ecology and Evolution in Microbial model Systems - EEMiS, Linnaeus University, 39182 Kalmar, Sweden
| | - Samuel Hylander
- Centre for Ecology and Evolution in Microbial model Systems - EEMiS, Linnaeus University, 39182 Kalmar, Sweden
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Schaub I, Wagner H, Graeve M, Karsten U. Effects of prolonged darkness and temperature on the lipid metabolism in the benthic diatom Navicula perminuta from the Arctic Adventfjorden, Svalbard. Polar Biol 2017. [DOI: 10.1007/s00300-016-2067-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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