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Lapointe A, Kocademir M, Bergman P, Ragupathy IC, Laumann M, Underwood GJC, Zumbusch A, Spiteller D, Kroth PG. Characterization of polyphosphate dynamics in the widespread freshwater diatom Achnanthidium minutissimum under varying phosphorus supplies. JOURNAL OF PHYCOLOGY 2024; 60:624-638. [PMID: 38163284 DOI: 10.1111/jpy.13423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 11/11/2023] [Accepted: 12/01/2023] [Indexed: 01/03/2024]
Abstract
Polyphosphates (polyP) are ubiquitous biomolecules that play a multitude of physiological roles in many cells. We have studied the presence and role of polyP in a unicellular alga, the freshwater diatom Achnanthidium minutissimum. This diatom stores up to 2.0 pg·cell-1 of polyP, with chain lengths ranging from 130 to 500 inorganic phosphate units (Pi). We applied energy dispersive X-ray spectroscopy, Raman/fluorescence microscopy, and biochemical assays to localize and characterize the intracellular polyP granules that were present in large apical vacuoles. We investigated the fate of polyP in axenic A. minutissimum cells grown under phosphorus (P), replete (P(+)), or P deplete (P(-)) cultivation conditions and observed that in the absence of exogenous P, A. minutissimum rapidly utilizes their internal polyP reserves, maintaining their intrinsic growth rates for up to 8 days. PolyP-depleted A. minutissimum cells rapidly took up exogenous P a few hours after Pi resupply and generated polyP three times faster than cells that were not initially subjected to P limitation. Accordingly, we propose that A. minutissimum deploys a succession of acclimation strategies regarding polyP dynamics where the production or consumption of polyP plays a central role in the homeostasis of the diatom.
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Affiliation(s)
- Adrien Lapointe
- Department of Biology, University of Konstanz, Konstanz, Germany
| | | | - Paavo Bergman
- Electron-Microscopy Centre, University of Konstanz, Konstanz, Germany
| | | | - Michael Laumann
- Electron-Microscopy Centre, University of Konstanz, Konstanz, Germany
| | | | - Andreas Zumbusch
- Department of Chemistry, University of Konstanz, Konstanz, Germany
| | - Dieter Spiteller
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Peter G Kroth
- Department of Biology, University of Konstanz, Konstanz, Germany
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2
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Yang L, He X, Ru S, Zhang Y. Herbicide leakage into seawater impacts primary productivity and zooplankton globally. Nat Commun 2024; 15:1783. [PMID: 38413588 PMCID: PMC10899588 DOI: 10.1038/s41467-024-46059-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 02/13/2024] [Indexed: 02/29/2024] Open
Abstract
Predicting the magnitude of herbicide impacts on marine primary productivity remains challenging because the extent of worldwide herbicide pollution in coastal waters and the concentration-response relationships of phytoplankton communities to multiple herbicides are unclear. By analyzing the spatiotemporal distribution of herbicides at 661 bay and gulf stations worldwide from 1990 to 2022, we determined median, third quartile and maximum concentrations of 12 triazine herbicides of 0.18 nmol L-1, 1.27 nmol L-1 and 29.50 nmol L-1 (95%Confidence Interval: CI 1.06, 1.47), respectively. Under current herbicide stress, phytoplankton primary productivity was inhibited by more than 5% at 25% of the sites and by more than 10% at 10% of the sites (95%CI 3.67, 4.34), due to the inhibition of highly abundant sensitive species, community structure/particle size succession (from Bacillariophyta to Dinophyceae and from nano-phytoplankton to micro-phytoplankton), and resulting growth rate reduction. Concurrently, due to food chain cascade effects, the dominant micro-zooplankton population shifted from larger copepod larvae to smaller unicellular ciliates, which might prolong the transmission process in marine food chain and reduce the primary productivity transmission efficiency. As herbicide application rates on farmlands worldwide are correlated with residues in their adjacent seas, a continued future increase in herbicide input may seriously affect the stability of coastal waters.
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Affiliation(s)
- Liqiang Yang
- College of Marine Life Sciences, Ocean University of China, Qingdao, China
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong, 266101, China
| | - Xiaotong He
- College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Shaoguo Ru
- College of Marine Life Sciences, Ocean University of China, Qingdao, China.
| | - Yongyu Zhang
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong, 266101, China.
- Shandong Energy Institute, No. 189 Songling Road, Qingdao, Shandong, 266101, China.
- Qingdao New Energy Shandong Laboratory, Qingdao, Shandong, 266101, China.
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3
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You Y, Sun X, Ma M, He J, Li L, Porto FW, Lin S. Trypsin is a coordinate regulator of N and P nutrients in marine phytoplankton. Nat Commun 2022; 13:4022. [PMID: 35821503 PMCID: PMC9276738 DOI: 10.1038/s41467-022-31802-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 07/05/2022] [Indexed: 11/30/2022] Open
Abstract
Trypsin is best known as a digestive enzyme in animals, but remains unexplored in phytoplankton, the major primary producers in the ocean. Here we report the prevalence of trypsin genes in global ocean phytoplankton and significant influences of environmental nitrogen (N) and phosphorus (P) on their expression. Using CRISPR/Cas9 mediated-knockout and overexpression analyses, we further reveal that a trypsin in Phaeodactylum tricornutum (PtTryp2) functions to repress N acquisition, but its expression decreases under N-deficiency to promote N acquisition. On the contrary, PtTryp2 promotes phosphate uptake per se, and its expression increases under P-deficiency to further reinforce P acquisition. Furthermore, PtTryp2 knockout led to amplitude magnification of the nitrate and phosphate uptake ‘seesaw’, whereas PtTryp2 overexpression dampened it, linking PtTryp2 to stabilizing N:P stoichiometry. Our data demonstrate that PtTryp2 is a coordinate regulator of N:P stoichiometric homeostasis. The study opens a window for deciphering how phytoplankton adapt to nutrient-variable marine environments. Using CRISPR-Cas9 mediated-knockout and overexpression analyses, this study shows that a trypsin in the diatom Phaeodactylum tricornutum promotes phosphorus uptake and inhibits nitrogen uptake but its expression is downregulated under nitrogen stress and upregulated under phosphorus stress. Together, the findings suggest this trypsin is a coordinate regulator of nutrient homeostasis.
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Affiliation(s)
- Yanchun You
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, 361102, China
| | - Xueqiong Sun
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, 361102, China
| | - Minglei Ma
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, 361102, China
| | - Jiamin He
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, 361102, China
| | - Ling Li
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, 361102, China
| | - Felipe Wendt Porto
- Department of Marine Sciences, University of Connecticut, Groton, CT, 06340, USA
| | - Senjie Lin
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, 361102, China. .,Department of Marine Sciences, University of Connecticut, Groton, CT, 06340, USA.
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4
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Xiao M, Burford MA, Wood SA, Aubriot L, Ibelings BW, Prentice MJ, Galvanese EF, Harris TD, Hamilton DP. Schindler's legacy: from eutrophic lakes to the phosphorus utilization strategies of cyanobacteria. FEMS Microbiol Rev 2022; 46:6617595. [PMID: 35749580 PMCID: PMC9629505 DOI: 10.1093/femsre/fuac029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 06/01/2022] [Accepted: 06/22/2022] [Indexed: 01/09/2023] Open
Abstract
David Schindler and his colleagues pioneered studies in the 1970s on the role of phosphorus in stimulating cyanobacterial blooms in North American lakes. Our understanding of the nuances of phosphorus utilization by cyanobacteria has evolved since that time. We review the phosphorus utilization strategies used by cyanobacteria, such as use of organic forms, alternation between passive and active uptake, and luxury storage. While many aspects of physiological responses to phosphorus of cyanobacteria have been measured, our understanding of the critical processes that drive species diversity, adaptation and competition remains limited. We identify persistent critical knowledge gaps, particularly on the adaptation of cyanobacteria to low nutrient concentrations. We propose that traditional discipline-specific studies be adapted and expanded to encompass innovative new methodologies and take advantage of interdisciplinary opportunities among physiologists, molecular biologists, and modellers, to advance our understanding and prediction of toxic cyanobacteria, and ultimately to mitigate the occurrence of blooms.
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Affiliation(s)
- Man Xiao
- Corresponding author: Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing, Jiangsu, China. E-mail:
| | - Michele A Burford
- Australian Rivers Institute, Griffith University, Nathan, QLD 4111, Australia
| | - Susanna A Wood
- Coastal and Freshwater Group, Cawthron Institute, Nelson, 7010, New Zealand
| | - Luis Aubriot
- Phytoplankton Physiology and Ecology Group, Sección Limnología, Instituto de Ecología y Ciencias Ambientales, Facultad de Ciencias; Universidad de la República, Montevideo, 11400, Uruguay
| | - Bas W Ibelings
- Department F.-A. Forel for Aquatic and Environmental Sciences and Institute for Environmental Sciences, University of Geneva, Geneva, 1290, Switzerland
| | - Matthew J Prentice
- Australian Rivers Institute, Griffith University, Nathan, QLD 4111, Australia
| | - Elena F Galvanese
- Laboratório de Análise e Síntese em Biodiversidade, Departamento de Botânica, Setor de Ciências Biológicas, Universidade Federal do Paraná, Curitiba-PR, 81531-998, Brazil,Programa de Pós-graduação em Ecologia e Conservação, Setor de Ciências Biológicas, Universidade Federal do Paraná, Curitiba-PR, 80060-140, Brazil
| | - Ted D Harris
- Kansas Biological Survey and Center for Ecological Research, Lawrence, KS, 66047, United States
| | - David P Hamilton
- Australian Rivers Institute, Griffith University, Nathan, QLD 4111, Australia
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5
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Bonachela JA, Choua M, Heath MR. Unconstrained coevolution of bacterial size and the latent period of plastic phage. PLoS One 2022; 17:e0268596. [PMID: 35617195 PMCID: PMC9135238 DOI: 10.1371/journal.pone.0268596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 05/02/2022] [Indexed: 11/19/2022] Open
Abstract
Viruses play critical roles in the dynamics of microbial communities. Lytic viruses, for example, kill significant fractions of autotrophic and heterotrophic microbes daily. The dynamic interplay between viruses and microbes results from an overlap of physiological, ecological, and evolutionary responses: environmental changes trigger host physiological changes, affecting the ecological interactions of host and virus and, ultimately, the evolutionary pressures influencing the two populations. Recent theoretical work studied how the dependence of viral traits on host physiology (viral plasticity) affects the evolutionarily stable host cell size and viral infection time emerging from coevolution. Here, we broaden the scope of the framework to consider any coevolutionary outcome, including potential evolutionary collapses of the system. We used the case study of Escherichia coli and T-like viruses under chemostat conditions, but the framework can be adapted to any microbe-virus system. Oligotrophic conditions led to smaller, lower-quality but more abundant hosts, and infections that were longer but produced a reduced viral offspring. Conversely, eutrophic conditions resulted in fewer but larger higher-quality hosts, and shorter but more productive infections. The virus influenced host evolution decreasing host size more noticeably for low than for high dilution rates, and for high than for low nutrient input concentration. For low dilution rates, the emergent infection time minimized host need/use, but higher dilution led to an opportunistic strategy that shortened the duration of infections. System collapses driven by evolution resulted from host failure to adapt quickly enough to the evolving virus. Our results contribute to understanding the eco-evolutionary dynamics of microbes and virus, and to improving the predictability of current models for host-virus interactions. The large quantitative and qualitative differences observed with respect to a classic description (in which viral traits are assumed to be constant) highlights the importance of including viral plasticity in theories describing short- and long-term host-virus dynamics.
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Affiliation(s)
- Juan A. Bonachela
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, NJ, United States of America
- * E-mail:
| | - Melinda Choua
- Blue Remediation Ltd., Glasgow, Scotland, United Kingdom
| | - Michael R. Heath
- Marine Population Modelling Group, Department of Mathematics and Statistics, University of Strathclyde, Glasgow, Scotland, United Kingdom
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6
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Apostolopoulou NG, Smeti E, Lamorgese M, Varkitzi I, Whitfield P, Regnault C, Spatharis S. Microalgae show a range of responses to exometabolites of foreign species. ALGAL RES 2022; 62:None. [PMID: 35311224 PMCID: PMC8924005 DOI: 10.1016/j.algal.2021.102627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 10/14/2021] [Accepted: 12/23/2021] [Indexed: 12/01/2022]
Abstract
Studies on microalgae interspecific interactions have so far focused either on nutrient competition or allelopathic effects due to excreted substances from Harmful Algal Bloom (HAB) species. Evidence from plants, bacteria and specific microalgae groups, point to a range of responses mediated by sensing or direct chemical impact of exometabolites from foreign species. Such processes remain under-investigated, especially in non-HAB microalgae, despite the importance of such knowledge in ecology and industrial applications. Here, we study the directional effect of exometabolites of 4 "foreign" species Heterosigma akashiwo, Phaeocystis sp., Tetraselmis sp. and Thalassiosira sp. to each of three "target" species across a total of 12 treatments. We disentangle these effects from nutrient competition by adding cell free medium of each "foreign" species into our treatment cultures. We measured the biomass response, to the foreign exometabolites, as cell number and photosynthetic biomass (Chla), whereas nutrient use was measured as residual phosphorus (PO4) and intracellular phosphorus (P). Exometabolites from filtrate of foreign species were putatively annotated by untargeted metabolomics analysis and were discussed in association to observed responses of target species. Among others, these metabolites included L-histidinal, Tiliacorine and dimethylsulfoniopropionate (DMSP). Our findings show that species show a range of responses with the most common being biomass suppression, and less frequent biomass enhancement and intracellular P storage. Filtrate from the green microalgae Tetraselmis caused the most pronounced negative effects suggesting that non-HAB species can also cause negative chemical interference. A candidate metabolite inducing this response is L-histidinal which was measured in high abundance uniquely in Tetraselmis and its L-histidine form derived from bacteria was previously confirmed as a microalgal algicidal. H. akashiwo also induced biomass suppression on other microalgae and a candidate metabolite for this response is Tiliacorine, a plant-derived alkaloid with confirmed cytotoxic activity.
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Affiliation(s)
- Natalia G. Apostolopoulou
- Department of Ecology and Systematics, National and Kapodistrian University of Athens, 10679, Greece
- School of Life Sciences, University of Glasgow, G12 8QQ, UK
| | - Evangelia Smeti
- Institute of Marine Biological Resources and Inland Waters, HCMR Hellenic Centre for Marine Research, PO Box 713, Anavyssos 19013, Greece
| | | | - Ioanna Varkitzi
- Institute of Oceanography, HCMR Hellenic Centre for Marine Research, PO Box 713, Anavyssos 19013, Greece
| | | | | | - Sofie Spatharis
- School of Life Sciences, University of Glasgow, G12 8QQ, UK
- Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, G12 8QQ, UK
- Corresponding author at: School of Life Sciences, University of Glasgow, G12 8QQ, UK.
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7
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Konopáčová E, Nedoma J, Čapková K, Čapek P, Znachor P, Pouzar M, Říha M, Řeháková K. Low Specific Phosphorus Uptake Affinity of Epilithon in Three Oligo- to Mesotrophic Post-mining Lakes. Front Microbiol 2021; 12:735498. [PMID: 34690974 PMCID: PMC8527014 DOI: 10.3389/fmicb.2021.735498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/10/2021] [Indexed: 11/13/2022] Open
Abstract
Epilithon contributes to phosphorus (P) cycling in lakes, but its P uptake traits have been rarely studied. We measured the chemical composition of epilithon and its inorganic P uptake kinetics using isotope 33P in three deep oligo- to mesotrophic post-mining lakes in April, July, and October 2019. Over the sampling period, epilithon biomass doubled, while the P content in biomass dropped to 60% of the April values, and the seasonal changes in P content expressed per epilithon area were only marginal and statistically not significant. High epilithic C:P molar ratios (677 on average) suggested strong P deficiency in all investigated lakes. Regarding the kinetic parameters of phosphorus uptake, maximum uptake velocity (Vmax, seasonal range 1.9–129 mg P g OM–1 h–1) decreased by an order of magnitude from April to October, while half-saturation constant (KS, seasonal range 3.9–135 mg P L–1) did not show any consistent temporal trend. Values of epilithic specific P uptake affinity (SPUAE, seasonal range 0.08–3.1 L g OM–1 h–1) decreased from spring to autumn and were two to four orders of magnitude lower than the corresponding values for seston (SPUAsest), which showed an opposite trend. Considering our results, we suggest a possible mechanism underlying a stable coexistence of planktonic and epilithic microorganisms, with plankton prospering mostly in summer and autumn and epilithon in winter and spring season. Additionally, a phenomenon of reversible abiotic P adsorption on epilithon was observed.
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Affiliation(s)
- Eliška Konopáčová
- Institute of Environmental and Chemical Engineering, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czechia.,Institute of Hydrobiology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia
| | - Jiří Nedoma
- Institute of Hydrobiology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia
| | - Kateřina Čapková
- Institute of Hydrobiology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia
| | - Petr Čapek
- Faculty of Sciences, University of South Bohemia, České Budějovice, Czechia
| | - Petr Znachor
- Institute of Hydrobiology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia.,Faculty of Sciences, University of South Bohemia, České Budějovice, Czechia
| | - Miloslav Pouzar
- Institute of Environmental and Chemical Engineering, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czechia.,Center of Materials and Nanotechnologies, University of Pardubice, Pardubice, Czechia
| | - Milan Říha
- Institute of Hydrobiology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia
| | - Klára Řeháková
- Institute of Hydrobiology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia
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8
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Xu D, Wang H, Han D, Chen A, Niu Y. Phytoplankton community structural reshaping as response to the thermal effect of cooling water discharged from power plant. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 285:117517. [PMID: 34380219 DOI: 10.1016/j.envpol.2021.117517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/24/2021] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
The increase of water temperature caused by the thermal effect of cooling water discharged from power plants has become a major environmental problem, especially its influence on phytoplankton community. The change of water temperature usually reshapes the structure of phytoplankton community. A research combining phytoplankton community and thermal discharge of power plants was conducted to identify the potential influences. Results indicated the average annual water temperature of the reservoir increased gradually by 5-11 °C because of the thermal discharge. Through annual diversity analysis, 139 species or taxa from 6 phyla (i.e., Bacillariophyta, Chlorophyta, Cyanobacteria, Euglenophyta, Dinoflagellata, and Cryptophyta) were found in different sampling sites, among which Bacillariophyta was the dominant community. Preliminary experimental results revealed the increasing temperature completely reshaped the phytoplankton community structure, especially during the cold season, and this was confirmed by the results of redundancy analysis. In addition, lots of thermophilic genera (i.e., Synedra, Nitzschia, and Navicula) were detected at sampling station 1 (Spt1) and sampling station 2 (Spt2) where the effect of thermal discharge was the most obvious. The increase in biomass and cell count of Bacillariophyta was the result of thermal effect, especially in cold season. Besides, consequences also revealed some environmental parameters (i.e., dissolved oxygen concentration, chlorophyll a concentration, and transparency) were affected by the thermal discharge. Chlorophyll a concentration exhibited a slow rising trend while dissolved oxygen concentration and transparency gradually decreased.
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Affiliation(s)
- Duo Xu
- College of Civil and Architectural Engineering, North China University of Science and Technology, Tangshan, PR China; College of Natural Resources and Environment, Northwest A&F University, Yangling, PR China
| | - Hao Wang
- College of Civil and Architectural Engineering, North China University of Science and Technology, Tangshan, PR China
| | - Dongyun Han
- College of Chemical Engineering, North China University of Science and Technology, Tangshan, PR China.
| | - Aiting Chen
- School of Chemical and Environmental Engineering, China University of Mining and Technology Beijing, Beijing, PR China
| | - Yunxia Niu
- College of Civil and Architectural Engineering, North China University of Science and Technology, Tangshan, PR China
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9
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Cyanobacteria and Cyanotoxins in a Changing Environment: Concepts, Controversies, Challenges. WATER 2021. [DOI: 10.3390/w13182463] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Concern is widely being published that the occurrence of toxic cyanobacteria is increasing in consequence of climate change and eutrophication, substantially threatening human health. Here, we review evidence and pertinent publications to explore in which types of waterbodies climate change is likely to exacerbate cyanobacterial blooms; whether controlling blooms and toxin concentrations requires a balanced approach of reducing not only the concentrations of phosphorus (P) but also those of nitrogen (N); how trophic and climatic changes affect health risks caused by toxic cyanobacteria. We propose the following for further discussion: (i) Climate change is likely to promote blooms in some waterbodies—not in those with low concentrations of P or N stringently limiting biomass, and more so in shallow than in stratified waterbodies. Particularly in the latter, it can work both ways—rendering conditions for cyanobacterial proliferation more favourable or less favourable. (ii) While N emissions to the environment need to be reduced for a number of reasons, controlling blooms can definitely be successful by reducing only P, provided concentrations of P can be brought down to levels sufficiently low to stringently limit biomass. Not the N:P ratio, but the absolute concentration of the limiting nutrient determines the maximum possible biomass of phytoplankton and thus of cyanobacteria. The absolute concentrations of N or P show which of the two nutrients is currently limiting biomass. N can be the nutrient of choice to reduce if achieving sufficiently low concentrations has chances of success. (iii) Where trophic and climate change cause longer, stronger and more frequent blooms, they increase risks of exposure, and health risks depend on the amount by which concentrations exceed those of current WHO cyanotoxin guideline values for the respective exposure situation. Where trophic change reduces phytoplankton biomass in the epilimnion, thus increasing transparency, cyanobacterial species composition may shift to those that reside on benthic surfaces or in the metalimnion, changing risks of exposure. We conclude that studying how environmental changes affect the genotype composition of cyanobacterial populations is a relatively new and exciting research field, holding promises for understanding the biological function of the wide range of metabolites found in cyanobacteria, of which only a small fraction is toxic to humans. Overall, management needs case-by-case assessments focusing on the impacts of environmental change on the respective waterbody, rather than generalisations.
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10
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Osburn FS, Wagner ND, Scott JT. Biological stoichiometry and growth dynamics of a diazotrophic cyanobacteria in nitrogen sufficient and deficient conditions. HARMFUL ALGAE 2021; 103:102011. [PMID: 33980450 PMCID: PMC8119935 DOI: 10.1016/j.hal.2021.102011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 03/08/2021] [Accepted: 03/11/2021] [Indexed: 06/12/2023]
Abstract
The role of nitrogen (N) fixation in determining the frequency, magnitude, and extent of harmful algal blooms (HABs) has not been well studied. Dolichospermum is a common HAB species that is diazotrophic (capable of N fixation) and thus growth is often considered never to be limited by low combined N sources. However, N fixation is energetically expensive and its cost during bloom formation has not been quantified. Additionally, it is unknown how acclimation to differing nutrient ratios affects growth and cellular carbon (C):N stoichiometry. Here, we test the hypotheses that diazotrophic cyanobacteria are homeostatic for N because of their ability to fix atmospheric N2 and that previous acclimation to low N environments will result in more fixed N and lower C:N stoichiometry. Briefly, cultures that varied in resource N:phosphorus (P) ranging from 0.01 to 100 (atom), were seeded with Dolichospermum which were previously acclimated to low and high N:P conditions and then sampled temporally for growth and C:N stoichiometry. We found that Dolichospermum was not homeostatic for N and displayed classic signs of N limitation and elevated C:N stoichiometry, highlighting the necessary growth trade-off within cells when expending energy to fix N. Acclimation to N limited conditions caused differences in both C:N and fixed N at various time points in the experiment. These results highlight the importance of environmentally available N to a diazotrophic bloom, as well as how previous growth conditions can influence population growth during blooms experiencing variable N:P.
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Affiliation(s)
- Felicia S Osburn
- Department of Biology, Baylor University, One Bear Place 97388, Waco, TX 76798, USA; Center for Reservoir and Aquatic Systems Research, Baylor University, One Bear Place 97178, Waco, TX 76798, USA.
| | - Nicole D Wagner
- Center for Reservoir and Aquatic Systems Research, Baylor University, One Bear Place 97178, Waco, TX 76798, USA
| | - J Thad Scott
- Department of Biology, Baylor University, One Bear Place 97388, Waco, TX 76798, USA; Center for Reservoir and Aquatic Systems Research, Baylor University, One Bear Place 97178, Waco, TX 76798, USA
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11
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Helliwell KE, Harrison EL, Christie-Oleza JA, Rees AP, Kleiner FH, Gaikwad T, Downe J, Aguilo-Ferretjans MM, Al-Moosawi L, Brownlee C, Wheeler GL. A Novel Ca 2+ Signaling Pathway Coordinates Environmental Phosphorus Sensing and Nitrogen Metabolism in Marine Diatoms. Curr Biol 2020; 31:978-989.e4. [PMID: 33373640 DOI: 10.1016/j.cub.2020.11.073] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/26/2020] [Accepted: 11/30/2020] [Indexed: 10/22/2022]
Abstract
Diatoms are a diverse and globally important phytoplankton group, responsible for an estimated 20% of carbon fixation on Earth. They frequently form spatially extensive phytoplankton blooms, responding rapidly to increased availability of nutrients, including phosphorus (P) and nitrogen (N). Although it is well established that diatoms are common first responders to nutrient influxes in aquatic ecosystems, little is known of the sensory mechanisms that they employ for nutrient perception. Here, we show that P-limited diatoms use a Ca2+-dependent signaling pathway, not previously described in eukaryotes, to sense and respond to the critical macronutrient P. We demonstrate that P-Ca2+ signaling is conserved between a representative pennate (Phaeodactylum tricornutum) and centric (Thalassiosira pseudonana) diatom. Moreover, this pathway is ecologically relevant, being sensitive to sub-micromolar concentrations of inorganic phosphate and a range of environmentally abundant P forms. Notably, we show that diatom recovery from P limitation requires rapid and substantial increases in N assimilation and demonstrate that this process is dependent on P-Ca2+ signaling. P-Ca2+ signaling thus governs the capacity of diatoms to rapidly sense and respond to P resupply, mediating fundamental cross-talk between the vital nutrients P and N and maximizing diatom resource competition in regions of pulsed nutrient supply.
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Affiliation(s)
- Katherine E Helliwell
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK; Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK.
| | - Ellen L Harrison
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
| | | | - Andrew P Rees
- Plymouth Marine Laboratory, Plymouth, Devon PL1 3DH, UK
| | - Friedrich H Kleiner
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
| | - Trupti Gaikwad
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
| | - Joshua Downe
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
| | | | | | - Colin Brownlee
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK; School of Ocean and Earth Science, University of Southampton, Southampton SO14 3ZH, UK
| | - Glen L Wheeler
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
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12
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Dell'Aquila G, Maier UG. Specific acclimations to phosphorus limitation in the marine diatom Phaeodactylum tricornutum. Biol Chem 2020; 401:1495-1501. [PMID: 32845857 DOI: 10.1515/hsz-2020-0197] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/19/2020] [Indexed: 11/15/2022]
Abstract
Phosphorus (P) is a crucial element and diatoms, unicellular phototrophic organisms, evolved efficient strategies to handle limiting phosphorus concentrations in the oceans. In the last decade, several groups investigated the model diatom Phaeodactylum tricornutum concerning phosphate homeostasis mechanisms. Here, we summarize the actual status of knowledge by linking the available data sets, thereby indicating experimental limits but also future research directions.
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Affiliation(s)
- Gianluca Dell'Aquila
- Cell Biology Laboratory, Philipps Universität Marburg, Karl-von-Frisch Strasse 8, D-35043Marburg, Germany
| | - Uwe G Maier
- SYNMIKRO Research Center, Hans-Meerwein-Str. 6, D-35032Marburg, Germany
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13
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Tagliabue A, Barrier N, Du Pontavice H, Kwiatkowski L, Aumont O, Bopp L, Cheung WWL, Gascuel D, Maury O. An iron cycle cascade governs the response of equatorial Pacific ecosystems to climate change. GLOBAL CHANGE BIOLOGY 2020; 26:6168-6179. [PMID: 32970390 DOI: 10.1111/gcb.15316] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/07/2020] [Accepted: 08/09/2020] [Indexed: 05/24/2023]
Abstract
Earth System Models project that global climate change will reduce ocean net primary production (NPP), upper trophic level biota biomass and potential fisheries catches in the future, especially in the eastern equatorial Pacific. However, projections from Earth System Models are undermined by poorly constrained assumptions regarding the biological cycling of iron, which is the main limiting resource for NPP over large parts of the ocean. In this study, we show that the climate change trends in NPP and the biomass of upper trophic levels are strongly affected by modifying assumptions associated with phytoplankton iron uptake. Using a suite of model experiments, we find 21st century climate change impacts on regional NPP range from -12.3% to +2.4% under a high emissions climate change scenario. This wide range arises from variations in the efficiency of iron retention in the upper ocean in the eastern equatorial Pacific across different scenarios of biological iron uptake, which affect the strength of regional iron limitation. Those scenarios where nitrogen limitation replaced iron limitation showed the largest projected NPP declines, while those where iron limitation was more resilient displayed little future change. All model scenarios have similar skill in reproducing past inter-annual variations in regional ocean NPP, largely due to limited change in the historical period. Ultimately, projections of end of century upper trophic level biomass change are altered by 50%-80% across all plausible scenarios. Overall, we find that uncertainties in the biological iron cycle cascade through open ocean pelagic ecosystems, from plankton to fish, affecting their evolution under climate change. This highlights additional challenges to developing effective conservation and fisheries management policies under climate change.
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Affiliation(s)
| | - Nicolas Barrier
- MARBEC (IRD, Univ. Montpellier, CNRS, Ifremer), Sète, France
| | - Hubert Du Pontavice
- ESE, Ecology and Ecosystem Health, Institut Agro, Rennes, France
- Nippon Foundation-Nereus Program, Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, BC, Canada
| | | | - Olivier Aumont
- LOCEAN, Sorbonne Université-CNRS-IRD-MNHN, Paris, France
| | | | - William W L Cheung
- Nippon Foundation-Nereus Program, Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, BC, Canada
| | - Didier Gascuel
- ESE, Ecology and Ecosystem Health, Institut Agro, Rennes, France
| | - Olivier Maury
- MARBEC (IRD, Univ. Montpellier, CNRS, Ifremer), Sète, France
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14
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Eckford-Soper LK, Canfield DE. The global explosion of eukaryotic algae: The potential role of phosphorus? PLoS One 2020; 15:e0234372. [PMID: 33091058 PMCID: PMC7580907 DOI: 10.1371/journal.pone.0234372] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 10/04/2020] [Indexed: 11/24/2022] Open
Abstract
There arose one of the most important ecological transitions in Earth’s history approximately 750 million years ago during the middle Neoproterozoic Era (1000 to 541 million years ago, Ma). Biomarker evidence suggests that around this time there was a rapid shift from a predominantly bacterial-dominated world to more complex ecosystems governed by eukaryotic primary productivity. The resulting ‘Rise of the algae’ led to dramatically altered food webs that were much more efficient in terms of nutrient and energy transfer. Yet, what triggered this ecological shift? In this study we examined the theory that it was the alleviation of phosphorus (P) deficiency that gave eukaryotic alga the prime opportunity to flourish. We performed laboratory experiments on the cyanobacterium Synechocystis salina and the eukaryotic algae Tetraselmis suecica and examined their ability to compete for phosphorus. Both these organisms co-occur in modern European coastal waters and are not known to have any allelopathic capabilities. The strains were cultured in mono and mixed cultures in chemostats across a range of dissolved inorganic phosphorus (DIP) concentrations to reflect modern and ancient oceanic conditions of 2 μM P and 0.2 μM P, respectively. Our results show that the cyanobacteria outcompete the algae at the low input (0.2 μM P) treatment, yet the eukaryotic algae were not completely excluded and remained a constant background component in the mixed-culture experiments. Also, despite their relatively large cell size, the algae T. suecica had a high affinity for DIP. With DIP input concentrations resembling modern-day levels (2 μM), the eukaryotic algae could effectively compete against the cyanobacteria in terms of total biomass production. These results suggest that the availability of phosphorus could have influenced the global expansion of eukaryotic algae. However, P limitation does not seem to explain the complete absence of eukaryotic algae in the biomarker record before ca. 750 Ma.
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Affiliation(s)
| | - Donald E. Canfield
- Nordcee, Department of Biology, University of Southern Denmark, Odense M, Denmark
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