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Ye J, Wang Y, Li Q, Hussain S, Chen S, Zhou X, Hou S, Feng Y. Phagocytosis in Marine Coccolithophore Gephyrocapsa huxleyi: Comparison between Calcified and Non-Calcified Strains. BIOLOGY 2024; 13:310. [PMID: 38785792 PMCID: PMC11117637 DOI: 10.3390/biology13050310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 04/19/2024] [Accepted: 04/25/2024] [Indexed: 05/25/2024]
Abstract
Coccolithophores play a significant role in marine calcium carbonate production and carbon cycles, attributing to their unique feature of producing calcareous plates, coccoliths. Coccolithophores also possess a haplo-diplontic life cycle, presenting distinct morphology types and calcification states. However, differences in nutrient acquisition strategies and mixotrophic behaviors of the two life phases remain unclear. In this study, we conducted a series of phagocytosis experiments of calcified diploid and non-calcified haploid strains of coccolithophore Gephyrocapsa huxleyi under light and dark conditions. The phagocytosis capability of each strain was examined based on characteristic fluorescent signals from ingested beads using flow cytometry and fluorescence microscopy. The results show a significantly higher phagocytosis percentage on fluorescent beads in the bacterial prey surrogates of the non-calcified haploid Gephyrocapsa huxleyi strain, than the calcified diploid strain with or without light. In addition, the non-calcified diploid cells seemingly to presented a much higher phagocytosis percentage in darkness than under light. The differential phagocytosis capacities between the calcified diploid and non-calcified haploid Gephyrocapsa huxleyi strains indicate potential distinct nutritional strategies at different coccolithophore life and calcifying stages, which may further shed light on the potential strategies that coccolithophore possesses in unfavorable environments such as twilight zones and the expanding coccolithophore niches in the natural marine environment under the climate change scenario.
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Affiliation(s)
- Jiayang Ye
- School of Oceanography, Shanghai Jiao Tong University, Shanghai 200030, China; (J.Y.); (Q.L.)
- Shanghai Key Laboratory of Polar Life and Environment Sciences, Shanghai Jiao Tong University, Shanghai 200030, China;
- Key Laboratory of Polar Ecosystem and Climate Change, Shanghai Jiao Tong University, Ministry of Education, Shanghai 200030, China
| | - Ying Wang
- School of Oceanography, Shanghai Jiao Tong University, Shanghai 200030, China; (J.Y.); (Q.L.)
| | - Qian Li
- School of Oceanography, Shanghai Jiao Tong University, Shanghai 200030, China; (J.Y.); (Q.L.)
| | - Sarfraz Hussain
- Department of Ocean Science & Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Songze Chen
- Shenzhen Ecological and Environmental Monitoring Center of Guangdong Province, Shenzhen 518049, China
| | - Xunying Zhou
- Department of Ocean Science & Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Shengwei Hou
- Shanghai Key Laboratory of Polar Life and Environment Sciences, Shanghai Jiao Tong University, Shanghai 200030, China;
- Key Laboratory of Polar Ecosystem and Climate Change, Shanghai Jiao Tong University, Ministry of Education, Shanghai 200030, China
- Department of Ocean Science & Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yuanyuan Feng
- School of Oceanography, Shanghai Jiao Tong University, Shanghai 200030, China; (J.Y.); (Q.L.)
- Shanghai Key Laboratory of Polar Life and Environment Sciences, Shanghai Jiao Tong University, Shanghai 200030, China;
- Key Laboratory of Polar Ecosystem and Climate Change, Shanghai Jiao Tong University, Ministry of Education, Shanghai 200030, China
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Balch WM, Drapeau DT, Poulton N, Archer SD, Cartisano C, Burnell C, Godrijan J. Osmotrophy of dissolved organic compounds by coccolithophore populations: Fixation into particulate organic and inorganic carbon. SCIENCE ADVANCES 2023; 9:eadf6973. [PMID: 37224255 DOI: 10.1126/sciadv.adf6973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 04/19/2023] [Indexed: 05/26/2023]
Abstract
Coccolithophores are typically thought of as photoautotrophs, yet a few genera inhabit sub-euphotic environments with insufficient light for photosynthesis, suggesting that other carbon acquisition strategies are likely. Field experiments were performed in the northwest Atlantic (a region with potentially abundant coccolithophores). Phytoplankton populations were incubated with 14C-labeled dissolved organic carbon (DOC) compounds, acetate, mannitol, and glycerol. Coccolithophores were sorted from these populations 24 hours later using flow cytometry, and DOC uptake was measured. DOC uptake rates were as high as 10-15 moles cell-1 day-1, slow relative to photosynthesis rates (10-12 moles cell-1 day-1). Growth rates on the organic compounds were low, suggesting that osmotrophy plays more of a survival strategy in low-light situations. Assimilated DOC was found in both particulate organic carbon and calcite coccoliths (particulate inorganic carbon), suggesting that osmotrophic uptake of DOC into coccolithophore calcite is a small but notable part of the biological carbon pump and alkalinity pump paradigms.
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Affiliation(s)
- William M Balch
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr., East Boothbay, ME 04544, USA
| | - David T Drapeau
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr., East Boothbay, ME 04544, USA
| | - Nicole Poulton
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr., East Boothbay, ME 04544, USA
| | - Stephen D Archer
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr., East Boothbay, ME 04544, USA
| | - Carmen Cartisano
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr., East Boothbay, ME 04544, USA
| | - Craig Burnell
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr., East Boothbay, ME 04544, USA
| | - Jelena Godrijan
- Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia
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Mitra A, Flynn KJ. Low rates of bacterivory enhances phototrophy and competitive advantage for mixoplankton growing in oligotrophic waters. Sci Rep 2023; 13:6900. [PMID: 37106077 PMCID: PMC10140275 DOI: 10.1038/s41598-023-33962-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 04/21/2023] [Indexed: 04/29/2023] Open
Abstract
With climate change, oceans are becoming increasingly nutrient limited, favouring growth of prokaryotic picoplankton at the expense of the larger protist plankton whose growth support higher trophic levels. Constitutive mixoplankton (CM), microalgal plankton with innate phototrophic capability coupled with phagotrophy, graze on these picoplankton, indirectly exploiting the excellent resource acquisition abilities of the prokaryotes. However, feeding rates can be very low (e.g., a few bacteria d-1). For the first time, the significance of such low consumption rates has been quantified. We find that while prokaryote-carbon (C) supply to CM grown at non-limiting light was so low that it may appear insignificant (< 10%), contributions of nitrogen (N) and phosphorus (P) from ingestions of 1-12 prokaryotes d-1 were significant. Under limiting light, contributions of ingested C increased, also raising the contributions of N and P. The order of nutritional importance for CM growth from predation was P > N > C. Further, provision of N through internal recycling of ingested prey-N stimulates C-fixation through photosynthesis. Importantly, coupled photo-phago-mixoplanktonic activity improved CM resource affinities for both inorganic and prey-bound nutrients, enhancing the nutritional status and competitiveness of mixoplankton. With warming oceans, with increased prokaryote abundance, we expect CM to exhibit more phagotrophy.
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Affiliation(s)
- Aditee Mitra
- School of Earth and Environmental Sciences, Cardiff University, Park Place, Cardiff, CF10 3AT, Wales, UK.
| | - Kevin J Flynn
- Plymouth Marine Laboratory, Prospect Place, West Hoe, Plymouth, PL1 3DH, UK
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Endo H, Umezawa Y, Takeda S, Suzuki K. Haptophyte communities along the Kuroshio current reveal their geographical sources and ecological traits. Mol Ecol 2023; 32:110-123. [PMID: 36221794 DOI: 10.1111/mec.16734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/27/2022] [Accepted: 09/29/2022] [Indexed: 12/29/2022]
Abstract
Haptophytes are one of the most ecologically successful phytoplankton groups in the modern ocean and tend to maintain balanced and stable communities across various environments. However, little is known about the mechanisms that enable community stability and ecological success. To reveal the community characteristics and interactions among haptophytes, we conducted comprehensive observations from the upstream to downstream regions of the Kuroshio Current. Haptophyte abundance and taxonomy were assessed using quantitative polymerase chain reaction and metabarcoding of 18S rRNA sequences, respectively. The haptophyte community structure changed abruptly at sites on the shelf-slope of the East China Sea, indicating the strong influence of shelf waters with high phytoplankton biomass on downstream communities. Correlation network analysis combined with the phylogeny suggested that haptophytes can coexist with their close relatives, possibly owing to their nutritional flexibility, thereby escaping from resource competition. Consistently, some noncalcifying haptophyte genera with high mixotrophic capacities such as Chrysochromulina constituted a major component of the co-occurrence network, whereas coccolithophores such as Emiliania/Gephyrocapsa were rarely observed. Our study findings suggest that noncalcifying haptophytes play crucial roles in community diversity and stability, and in sustaining the food web structure in the Kuroshio ecosystems.
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Affiliation(s)
- Hisashi Endo
- Bioinformatics Center, Institute for Chemical Research, Kyoto University, Kyoto, Japan
| | - Yu Umezawa
- Department of Environmental Science on Biosphere, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Shigenobu Takeda
- Faculty of Environmental Earth Science, Hokkaido University, Hokkaido, Sapporo, Japan
| | - Koji Suzuki
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki, Japan
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John U, Šupraha L, Gran-Stadniczeñko S, Bunse C, Cembella A, Eikrem W, Janouškovec J, Klemm K, Kühne N, Naustvoll L, Voss D, Wohlrab S, Edvardsen B. Spatial and biological oceanographic insights into the massive fish-killing bloom of the haptophyte Chrysochromulina leadbeateri in northern Norway. HARMFUL ALGAE 2022; 118:102287. [PMID: 36195411 DOI: 10.1016/j.hal.2022.102287] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 05/04/2022] [Accepted: 07/03/2022] [Indexed: 06/16/2023]
Abstract
A bloom of the fish-killing haptophyte Chrysochromulina leadbeateri in northern Norway during May and June 2019 was the most harmful algal event ever recorded in the region, causing massive mortalities of farmed salmon. Accordingly, oceanographic and biodiversity aspects of the bloom were studied in unprecedented detail, based on metabarcoding and physico-chemical and biotic factors related with the dynamics and distribution of the bloom. Light- and electron-microscopical observations of nanoplankton samples from diverse locations confirmed that C. leadbeateri was dominant in the bloom and the primary cause of associated fish mortalities. Cell counts by light microscopy and flow cytometry were obtained throughout the regional bloom within and adjacent to five fjord systems. Metabarcoding sequences of the V4 region of the 18S rRNA gene from field material collected during the bloom and a cultured isolate from offshore of Tromsøy island confirmed the species identification. Sequences from three genetic markers (18S, 28S rRNA gene and ITS region) verified the close if not identical genetic similarity to C. leadbeateri from a previous massive fish-killing bloom in 1991 in northern Norway. The distribution and cell abundance of C. leadbeateri and related Chrysochromulina species in the recent incident were tracked by integrating observations from metabarcoding sequences of the V4 region of the 18S rRNA gene. Metabarcoding revealed at least 14 distinct Chrysochromulina variants, including putative cryptic species. C. leadbeateri was by far the most abundant of these species, but with high intraspecific genetic variability. Highest cell abundance of up to 2.7 × 107 cells L - 1 of C. leadbeateri was found in Balsfjorden; the high cell densities were associated with stratification near the pycnocline (at ca. 12 m depth) within the fjord. The cell abundance of C. leadbeateri showed positive correlations with temperature, negative correlation with salinity, and a slightly positive correlation with ambient phosphate and nitrate concentrations. The spatio-temporal succession of the C. leadbeateri bloom suggests independent initiation from existing pre-bloom populations in local zones, perhaps sustained and supplemented over time by northeastward advection of the bloom from the fjords.
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Affiliation(s)
- Uwe John
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany; Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Ammerländer Heersstraße 231, 26129 Oldenburg, Germany.
| | - Luka Šupraha
- Section for Aquatic Biology and Toxicology, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway
| | - Sandra Gran-Stadniczeñko
- Section for Aquatic Biology and Toxicology, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway
| | - Carina Bunse
- Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Ammerländer Heersstraße 231, 26129 Oldenburg, Germany; ICBM: Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Allan Cembella
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Wenche Eikrem
- Section for Aquatic Biology and Toxicology, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway
| | - Jan Janouškovec
- Section for Aquatic Biology and Toxicology, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway
| | - Kerstin Klemm
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Nancy Kühne
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Lars Naustvoll
- Institute of Marine Research, P.O box 1871 Nordnes, NO-5817 Bergen, Norway
| | - Daniela Voss
- ICBM: Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
| | - Sylke Wohlrab
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany; Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Ammerländer Heersstraße 231, 26129 Oldenburg, Germany
| | - Bente Edvardsen
- Section for Aquatic Biology and Toxicology, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway
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Koppelle S, López-Escardó D, Brussaard CPD, Huisman J, Philippart CJM, Massana R, Wilken S. Mixotrophy in the bloom-forming genus Phaeocystis and other haptophytes. HARMFUL ALGAE 2022; 117:102292. [PMID: 35944956 DOI: 10.1016/j.hal.2022.102292] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/11/2022] [Accepted: 07/13/2022] [Indexed: 05/13/2023]
Abstract
Phaeocystis is a globally widespread marine phytoplankton genus, best known for its colony-forming species that can form large blooms and odorous foam during bloom decline. In the North Sea, Phaeocystis globosa typically becomes abundant towards the end of the spring bloom, when nutrients are depleted and the share of mixotrophic protists increases. Although mixotrophy is widespread across the eukaryotic tree of life and is also found amongst haptophytes, a mixotrophic nutrition has not yet been demonstrated in Phaeocystis. Here, we sampled two consecutive Phaeocystis globosa spring blooms in the coastal North Sea. In both years, bacterial cells were observed inside 0.6 - 2% of P. globosa cells using double CARD-FISH hybridizations in combination with laser scanning confocal microscopy. Incubation experiments manipulating light and nutrient availability showed a trend towards higher occurrence of intracellular bacteria under P-deplete conditions. Based on counts of bacteria inside P. globosa cells in combination with theoretical values of prey digestion times, maximum ingestion rates of up to 0.08 bacteria cell-1 h-1 were estimated. In addition, a gene-based predictive model was applied to the transcriptome assemblies of seven Phaeocystis strains and 24 other haptophytes to assess their trophic mode. This model predicted a phago-mixotrophic feeding strategy in several (but not all) strains of P. globosa, P. antarctica and other haptophytes that were previously assumed to be autotrophic. The observation of bacterial cells inside P. globosa and the gene-based model predictions strongly suggest that the phago-mixotrophic feeding strategy is widespread among members of the Phaeocystis genus and other haptophytes, and might contribute to their remarkable success to form nuisance blooms under nutrient-limiting conditions.
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Affiliation(s)
- Sebastiaan Koppelle
- Department of Freshwater and Marine Ecology (FAME), Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94920, 1090 XH, Amsterdam, The Netherlands.
| | - David López-Escardó
- Ecology of Marine Microbes, Institut de Ciènces del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Catalonia, Spain
| | - Corina P D Brussaard
- Department of Freshwater and Marine Ecology (FAME), Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94920, 1090 XH, Amsterdam, The Netherlands; Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB, Den Burg, Texel, The Netherlands
| | - Jef Huisman
- Department of Freshwater and Marine Ecology (FAME), Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94920, 1090 XH, Amsterdam, The Netherlands
| | - Catharina J M Philippart
- Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB, Den Burg, Texel, The Netherlands; Department of Physical Geography, Utrecht University, P.O. Box 80115, 3508 TC, Utrecht, The Netherlands
| | - Ramon Massana
- Ecology of Marine Microbes, Institut de Ciènces del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Catalonia, Spain
| | - Susanne Wilken
- Department of Freshwater and Marine Ecology (FAME), Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94920, 1090 XH, Amsterdam, The Netherlands.
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Evolutionary Rates in the Haptophyta: Exploring Molecular and Phenotypic Diversity. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2022. [DOI: 10.3390/jmse10060798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Haptophytes are photosynthetic protists found in both freshwater and marine environments with an origin possibly dating back to the Neoproterozoic era. The most recent molecular phylogeny reveals several haptophyte “mystery clades” that await morphological verification, but it is otherwise highly consistent with morphology-based phylogenies, including that of the coccolithophores (calcifying haptophytes). The fossil coccolith record offers unique insights into extinct lineages, including the adaptive radiations that produced extant descendant species. By combining molecular data of extant coccolithophores and phenotype-based studies of their ancestral lineages, it has become possible to probe the modes and rates of speciation in more detail, although this approach is still limited to only few taxa because of the lack of whole-genome datasets. The evolution of calcification likely involved several steps, but its origin can be traced back to an early association with organic scales typical for all haptophytes. Other key haptophyte traits, including the haplo-diplontic life cycle, are herein mapped upon the coccolithophorid phylogeny to help navigate a discussion of their ecological benefits and trade-offs in a rapidly changing ocean.
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The dynamic trophic architecture of open-ocean protist communities revealed through machine-guided metatranscriptomics. Proc Natl Acad Sci U S A 2022; 119:2100916119. [PMID: 35145022 PMCID: PMC8851463 DOI: 10.1073/pnas.2100916119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2021] [Indexed: 12/25/2022] Open
Abstract
Mixotrophy is a ubiquitous nutritional strategy in marine ecosystems. Although our understanding of the distribution and abundance of mixotrophic plankton has improved significantly, the functional roles of mixotrophs are difficult to pinpoint, as mixotroph nutritional strategies are flexible and form a continuum between heterotrophy and phototrophy. We developed a machine learning–based method to assess the nutritional strategies of in situ planktonic populations based on metatranscriptomic profiles. We demonstrate that mixotrophic populations play varying functional roles along physicochemical gradients in the North Pacific Ocean, revealing a degree of physiological plasticity unique to aquatic mixotrophs. Our results highlight mechanisms that may dictate the flow of biogeochemical elements and ecology of the North Pacific Ocean, one of Earth's largest biogeographical provinces. Intricate networks of single-celled eukaryotes (protists) dominate carbon flow in the ocean. Their growth, demise, and interactions with other microorganisms drive the fluxes of biogeochemical elements through marine ecosystems. Mixotrophic protists are capable of both photosynthesis and ingestion of prey and are dominant components of open-ocean planktonic communities. Yet the role of mixotrophs in elemental cycling is obscured by their capacity to act as primary producers or heterotrophic consumers depending on factors that remain largely uncharacterized. Here, we develop and apply a machine learning model that predicts the in situ trophic mode of aquatic protists based on their patterns of gene expression. This approach leverages a public collection of protist transcriptomes as a training set to identify a subset of gene families whose transcriptional profiles predict trophic mode. We applied our model to nearly 100 metatranscriptomes obtained during two oceanographic cruises in the North Pacific and found community-level and population-specific evidence that abundant open-ocean mixotrophic populations shift their predominant mode of nutrient and carbon acquisition in response to natural gradients in nutrient supply and sea surface temperature. Metatranscriptomic data from ship-board incubation experiments revealed that abundant mixotrophic prymnesiophytes from the oligotrophic North Pacific subtropical gyre rapidly remodeled their transcriptome to enhance photosynthesis when supplied with limiting nutrients. Coupling this approach with experiments designed to reveal the mechanisms driving mixotroph physiology provides an avenue toward understanding the ecology of mixotrophy in the natural environment.
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Ferreira GD, Figueira J, Marques SC, Hansen PJ, Calbet A. The strengths and weaknesses of Live Fluorescently Labelled Algae (LFLA) to estimate herbivory in protozooplankton and mixoplankton. MARINE ENVIRONMENTAL RESEARCH 2022; 174:105558. [PMID: 34998128 DOI: 10.1016/j.marenvres.2022.105558] [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: 08/09/2021] [Revised: 12/21/2021] [Accepted: 01/01/2022] [Indexed: 06/14/2023]
Abstract
The Live Fluorescently Labelled Algae (LFLA) technique has been used numerous times to estimate microzooplankton herbivory. Yet, it is unknown how mixoplankton (i.e., single-cell organisms that can combine phototrophy and phagotrophy) affect the outcome of this technique. Hence, we conducted a broad-spectrum assessment of the strengths and weaknesses of the LFLA technique, using several mixoplanktonic and protozooplanktonic grazers. Species from different taxonomic groups and different feeding mechanisms were tested in short-term experiments (ca. 5 h) in the laboratory, at different prey concentrations and during light and dark periods of the day. Overall, our findings suggest that the LFLA technique, due to its short-term nature, is an effective tracker of diel ingestion and digestion rates, and can detect new mixoplanktonic predators. We recommend that, irrespective of the prey concentration, incubations to measure grazing rates with this technique should generally be concluded within 1 h (adaptable to the environmental temperature). Nevertheless, our results also call for caution whenever using LFLA in the field: feeding mechanisms other than direct engulfment (like peduncle feeding) may provide severely biased ingestion rates. Furthermore, size and species selectivity are very hard to circumvent. To reduce the effects of selectivity, we propose the combined use of two distinctly coloured fluorochromes (i.e., distinct emission spectra). With this modification, one could either label different size ranges of prey or account for species-specific interactions in the food web.
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Affiliation(s)
- Guilherme Duarte Ferreira
- Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain; Marine Biological Section, University of Copenhagen, DK-3000, Helsingør, Denmark
| | - Joana Figueira
- MARE - Marine and Environmental Science Centre, Polytechnic of Leiria, Peniche, Portugal
| | - Sónia Cotrim Marques
- MARE - Marine and Environmental Science Centre, Polytechnic of Leiria, Peniche, Portugal
| | - Per Juel Hansen
- Marine Biological Section, University of Copenhagen, DK-3000, Helsingør, Denmark
| | - Albert Calbet
- Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain.
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Godrijan J, Drapeau DT, Balch WM. Osmotrophy of dissolved organic carbon by coccolithophores in darkness. THE NEW PHYTOLOGIST 2022; 233:781-794. [PMID: 34784058 PMCID: PMC9298845 DOI: 10.1111/nph.17819] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 10/18/2021] [Indexed: 05/12/2023]
Abstract
The evolutionary and ecological story of coccolithophores poses questions about their heterotrophy, surviving darkness after the end-Cretaceous asteroid impact as well as survival in the deep ocean twilight zone. Uptake of dissolved organic carbon might be an alternative nutritional strategy for supply of energy and carbon molecules. Using long-term batch culture experiments, we examined coccolithophore growth and maintenance on organic compounds in darkness. Radiolabelled experiments were performed to study the uptake kinetics. Pulse-chase experiments were used to examine the uptake into unassimilated, exchangeable pools vs assimilated, nonexchangeable pools. We found that coccolithophores were able to survive and maintain their metabolism for up to 30 d in darkness, accomplishing about one cell division. The concentration dependence for uptake was similar to the concentration dependence for growth in Cruciplacolithus neohelis, suggesting that it was taking up carbon compounds and immediately incorporating them into biomass. We recorded net incorporation of radioactivity into the particulate inorganic fraction. We conclude that osmotrophy provides nutritional flexibility and supports long-term survival in light intensities well below threshold for photosynthesis. The incorporation of dissolved organic matter into particulate inorganic carbon, raises fundamental questions about the role of the alkalinity pump and the alkalinity balance in the sea.
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Affiliation(s)
- Jelena Godrijan
- Bigelow Laboratory for Ocean SciencesEast BoothbayME04544USA
- Division for Marine and Environmental ResearchRuđer Bošković InstituteZagreb10000Croatia
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