scholarly journals Genomic evidence for inter-class host transition between abundant streamlined heterotrophs by a novel and ubiquitous marine Methylophage

2021 ◽  
Author(s):  
Holger Heiko Buchholz ◽  
Luis M Bolaños ◽  
Ashley G Bell ◽  
Michelle L Michelsen ◽  
Mike Allen ◽  
...  
Keyword(s):  
Global Ocean ◽  
Sargasso Sea ◽  
English Channel ◽  
Free Living ◽  
Host Abundance ◽  
Marine Biogeochemistry ◽  
Transition Event ◽  
Ocean Gyre ◽  
Sar11 Clade ◽  
Marine Primary Production

The methylotrophic OM43 clade are Gammaproteobacteria that comprise some of the smallest free-living cells known with highly streamlined genomes. OM43 represents an important microbial link between marine primary production and return of carbon back to the atmosphere. Bacteriophages shape microbial communities and are major drivers of mortality and global marine biogeochemistry. Recent cultivation efforts have brought the first viruses infecting members of the OM43 clade into culture. Here we characterize a novel myophage infecting OM43, called Melnitz. Melnitz was isolated independently on three separate occasions (with isolates sharing >99.95% average nucleotide identity) from water samples from a subtropical ocean gyre (Sargasso Sea) and temperate coastal (Western English Channel) systems. Metagenomic recruitment from global ocean viromes confirmed that Melnitz is globally ubiquitous, congruent with patterns of host abundance. Bacteria with streamlined genomes such as OM43 and the globally dominant SAR11 clade use riboswitches as an efficient method to regulate metabolism. Melnitz encodes a two-piece tmRNA (ssrA), controlled by a glutamine riboswitch, providing evidence that riboswitch use also occurs for regulation during phage infection of streamlined heterotrophs. Virally encoded tRNAs and ssrA found in Melnitz were phylogenetically more closely related to those found within the alphaproteobacterial SAR11 clade and their associated myophages than those within their gammaproteobacterial hosts. This suggests the possibility of an ancestral inter-class host transition event between SAR11 and OM43. Melnitz and a related myophage that infects SAR11 were unable to infect hosts of the SAR11 and OM43, respectively, suggesting host transition rather than a broadening of host range.

Effects of light and phosphorus on summer DMS dynamics in subtropical waters using a global ocean biogeochemical model

2016 ◽  
Vol 13 (2) ◽  
pp. 379 ◽  
Author(s):  
Italo Masotti ◽  
Sauveur Belviso ◽  
Laurent Bopp ◽  
Alessandro Tagliabue ◽  
Eva Bucciarelli
Keyword(s):  
General Circulation ◽  
North Atlantic Ocean ◽  
Model Simulation ◽  
Global Ocean ◽  
Longitudinal Distribution ◽  
Biogeochemical Model ◽  
Relative Role ◽  
Sargasso Sea ◽  
Ecological Processes ◽  
Climatological Data

Environmental context Models are needed to predict the importance of the changes in marine emissions of dimethylsulfide (DMS) in response to ocean warming, increased stratification and acidification, and to evaluate the potential effects on the Earth’s climate. We use complementary simulations to further our understanding of the marine cycle of DMS in subtropical waters, and show that a lack of phosphorus may exert a more important control on surface DMS concentrations than an excess of light. Abstract The occurrence of a summer DMS paradox in the vast subtropical gyres is a strong matter of debate because approaches using discrete measurements, climatological data and model simulations yielded contradictory results. The major conclusion of the first appraisal of prognostic ocean DMS models was that such models need to give more weight to the direct effect of environmental forcings (e.g. irradiance) on DMS dynamics to decouple them from ecological processes. Here, the relative role of light and phosphorus on summer DMS dynamics in subtropical waters is assessed using the ocean general circulation and biogeochemistry model NEMO-PISCES in which macronutrient concentrations were restored to monthly climatological data values to improve the representation of phosphate concentrations. Results show that the vertical and temporal decoupling between chlorophyll and DMS concentrations observed in the Sargasso Sea during the summer months is captured by the model. Additional sensitivity tests show that the simulated control of phosphorus on surface DMS concentrations in the Sargasso Sea is much more important than that of light. By extending the analysis to the whole North Atlantic Ocean, we show that the longitudinal distribution of DMS during summer is asymmetrical and that a correlation between the solar radiation dose and DMS concentrations only occurs in the Sargasso Sea. The lack of a widespread summer DMS paradox in our model simulation as well as in the comparison of discrete and climatological data could be due to the limited occurrence of phosphorus limitation in the global ocean.

scholarly journals A Parasitic Arsenic Cycle That Shuttles Energy from Phytoplankton to Heterotrophic Bacterioplankton

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Stephen J. Giovannoni ◽  
Kimberly H. Halsey ◽  
Jimmy Saw ◽  
Omran Muslin ◽  
Christopher P. Suffridge ◽  
...  
Keyword(s):  
Field Experiments ◽  
Standing Stock ◽  
Methyl Groups ◽  
Sargasso Sea ◽  
Arsenic Compounds ◽  
Transfer Energy ◽  
Oxidation Rates ◽  
Arsenate Resistance ◽  
Abundant Phytoplankton ◽  
Ocean Gyre

ABSTRACTIn many regions of the world oceans, phytoplankton face the problem of discriminating between phosphate, an essential nutrient, and arsenate, a toxic analogue. Many phytoplankton, including the most abundant phytoplankton group known,Prochlorococcus, detoxify arsenate (AsV) by reduction to arsenite (AsIII), followed by methylation and excretion of the methylated arsenic products. We synthesized [14C]dimethyl arsenate (DMA) and used it to show that culturedPelagibacterstrain HTCC7211 (SAR11) cells oxidize the methyl group carbons of DMA, producing14CO2and ATP. We measured [14C]DMA oxidation rates in the P-depleted surface waters of the Sargasso Sea, a subtropical ocean gyre. [14C]DMA was oxidized to14CO2by Sargasso Sea plankton communities at a rate that would cause turnover of the estimated DMA standing stock every 8.1 days. SAR11 strain HTCC7211, which was isolated from the Sargasso Sea, has a pair of arsenate resistance genes and was resistant to arsenate, showing no growth inhibition at As/P ratios of >65:1. Across the global oceans, there was a strong inverse relationship between the frequency of the arsenate reductase (LMWPc_ArsC) inPelagibactergenomes and phosphate concentrations. We propose that the demethylation of methylated arsenic compounds byPelagibacterand possibly other bacterioplankton, coupled with arsenate resistance, results in the transfer of energy from phytoplankton to bacteria. We dub this a parasitic cycle because the release of arsenate byPelagibacterin principle creates a positive-feedback loop that forces phytoplankton to continually regenerate arsenate detoxification products, producing a flow of energy to P-limited ocean regions.IMPORTANCEIn vast, warm regions of the oceans, phytoplankton face the problem of arsenic poisoning. Arsenate is toxic because it is chemically similar to phosphate, a scarce nutrient that phytoplankton cells need for growth. Many phytoplankton, including the commonest phytoplankton type in warm oceans,Prochlorococcus, detoxify arsenate by adding methyl groups. Here we show that the most abundant non-photosynthetic plankton in the oceans, SAR11 bacteria, remove the methyl groups, releasing poisonous forms of arsenic back into the water. We postulate that the methylation and demethylation of arsenic compounds creates a cycle in which the phytoplankton can never get ahead and must continually transfer energy to the SAR11 bacteria. We dub this a parasitic process and suggest that it might help explain why SAR11 bacteria are so successful, surpassing all other plankton in their numbers. Field experiments were done in the Sargasso Sea, a subtropical ocean gyre that is sometimes called an ocean desert because, throughout much of the year, there is not enough phosphorous in the water to support large blooms of phytoplankton. Ocean deserts are expanding as the oceans absorb heat and grow warmer.

Rapid Determination of Organic Matter Fractions by Ozonation Chemiluminescence

2012 ◽  
Vol 468-471 ◽  
pp. 2842-2848 ◽  
Author(s):  
Yan Liu ◽  
Ping Ping Fan ◽  
Guang Li Hou ◽  
Ji Chang Sun ◽  
Yan Cheng ◽  
...  
Keyword(s):  
Organic Matter ◽  
Rapid Determination ◽  
In Situ Monitoring ◽  
Global Ocean ◽  
Sediment Chemistry ◽  
Marine Biogeochemistry ◽  
Organic Matter Fractions ◽  
Soluble Fractions

Understanding marine biogeochemistry requires a network of global ocean in situ monitoring of various parameters on different scales in time and space. Among the various parameters involved in marine biogeochemistry, sediment chemistry is most important, and the organic matter fractions are the dominate factor in this parameter. However, classical methods of determining organic matter fractions consume a great deal of time and labor. In addition, some of these methods can produce high levels of pollution and are therefore not suitable for in situ studies. This study explored a method of rapid determination of organic matter fractions by ozonation chemiluminescence. In this method, the organic matter was separated into extractives, acid soluble fractions and acid insoluble fractions (AIF) using the classical method and then oxidized by ozone. The ozonation chemiluminescence characteristics of eight samples were subsequently used to set up a model to predict the concentrations of organic matter fractions. The model was tested using nine other organic samples and the results showed that it provided a better fit for the predicted acid soluble fractions. This study is the first to demonstrate the use of ozonation chemiluminescence for rapid determination of organic matter fractions; however, further study is required to enable its universal use.

scholarly journals Argon as a Tracer of Cross-Isopycnal Mixing in the Thermocline

2006 ◽  
Vol 36 (11) ◽  
pp. 2090-2105 ◽  
Author(s):  
Cara C. Henning ◽  
David Archer ◽  
Inez Fung
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Vertical Mixing ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Global Ocean ◽  
Equatorial Pacific Ocean ◽  
Subsurface Waters ◽  
Different Temperatures ◽  
Ocean Gyre

Abstract Noble gases such as argon are unaffected by chemical reactions in the ocean interior, but a number of physical mechanisms can lead to measurable sea level atmospheric disequilibrium in subsurface waters of the ocean. One such mechanism is the mixing of waters of different temperatures, which can lead to supersaturation in the ocean interior. The authors simulate the supersaturation mixing signature in the thermocline in a global ocean general circulation model, Parallel Ocean Program model, version 1.4 (POP 1.4). In contrast to existing mixing diagnostics such as dye tracers or microstructure measurements, which yield the local, recent rate of diabatic mixing, argon disequilibrium traces an integrated lifetime history of subsurface mixing. A theoretical model of the subtropical Atlantic Ocean gyre is built, based on the competing time scales of horizontal and vertical mixing, that agrees well with the full general circulation model argon supersaturation gradient in the thermocline. These results suggest that gyre-scale argon data from the real ocean could be similarly interpreted. The variation of the argon supersaturation with diffusivity in the equatorial Pacific Ocean is also investigated.

scholarly journals The Indonesian Throughflow and its Impact on Biogeochemistry in the Indonesian Seas

2020 ◽  
Vol 37 (1) ◽  
Author(s):  
Edwards Taufiqurrahman ◽  
A’an J. Wahyudi ◽  
Yukio Masumoto
Keyword(s):  
Global Ocean ◽  
Physical Parameters ◽  
Indonesian Throughflow ◽  
Mixing Processes ◽  
Indonesian Seas ◽  
Marine Biogeochemistry ◽  
Strong Relation ◽  
Climate Systems ◽  
Critical Aspects

It has been widely known that the Indonesian Throughflow (ITF) is an important inter-ocean connection with unique and complex oceanographic and geographic conditions, as well as a strong relation to both regional and global ocean currents and climate systems. Many studies on characteristics, mechanisms, and impacts of the ITF have been conducted, mainly focusing on the ITF pathways, transport, water mass mixing processes, and their variability in connection with monsoons and climate systems. In this paper, we summarize some of the critical aspects related to ocean conditions within the Indonesian Seas and the Indonesian Throughflow, with the main focus on studies of marine biogeochemistry in a region affected by the ITF. Although the biogeochemical cycle is one of the key research topics that are needed to advance our ocean understanding, studies on marine biogeochemistry within the Indonesian Seas are quite limited due to less observed data compared to the physical parameters. Further studies on biogeochemistry and efforts to conduct in situ and remotely sensed observations in this region are strongly required. Here, we propose several biogeochemical observations correlated to the ITF.

Survival of the endophytic sporophyte of Acrosiphonia (Codiolales, Chlorophyta)

2005 ◽  
Vol 85 (1) ◽  
pp. 49-58 ◽  
Author(s):  
Andrea V. Sussmann ◽  
Robert E. DeWreede
Keyword(s):  
Net Primary Productivity ◽  
Red Alga ◽  
Close Approximation ◽  
Mortality Factors ◽  
Free Living ◽  
Winter Storms ◽  
Host Abundance ◽  
Zoospore Release ◽  
Study Sites ◽  
Germination And Growth

The unicellular sporophyte phase of the filamentous green alga, Acrosiphonia (Codiolales), is endophytic in the bladed red alga, Mazzaella splendens in southern British Columbia, Canada. Since endophyte maturity coincides with decreased host abundance (winter storms dislodge Mazzaella blades), many endophytes lose their host before zoospore release has occurred. We investigated whether the endophytes can reach reproductive maturity within decaying host tissue (drift blades) or as free-living entities once their host has disappeared. We demonstrate that both occur. Suspension of M. splendens blades, colonized by the endophyte phase of Acrosiphonia, in seawater tanks in winter, resulted in the germination and growth of filamentous Acrosiphonia plants (gametophytes) in spring. Net primary productivity of 132·2 g dry wt/m2/mo was estimated by harvesting total Acrosiphonia biomass after a one-month growing season. An estimate of Acrosiphonia survivorship from zoospore to macroscopic adult gametophyte (0·01–0·89%), is in close approximation with kelp spore survivorship to microscopic gametophyte (0·005–0·1%), but is 102–105 times higher than kelp survivorship from spore to macroscopic adult sporophyte. Differential survivorship in the field and in experimental tanks and among different study sites can be explained by variable mortality factors for spores and germlings and Acrosiphonia's success in colonizing highly disturbed environments.

scholarly journals Photosynthetic oxygen production in a warmer ocean: the Sargasso Sea as a case study

2017 ◽  
Vol 375 (2102) ◽  
pp. 20160329 ◽  
Author(s):  
Katherine Richardson ◽  
Jørgen Bendtsen
Keyword(s):  
Water Column ◽  
Vertical Mixing ◽  
Global Ocean ◽  
Sargasso Sea ◽  
Surface Oxygen ◽  
Oxygen Production ◽  
Food Web Structure ◽  
Oxygen Conditions ◽  
Photosynthetic Oxygen ◽  
Warming World

Photosynthetic O 2 production can be an important source of oxygen in sub-surface ocean waters especially in permanently stratified oligotrophic regions of the ocean where O 2 produced in deep chlorophyll maxima (DCM) is not likely to be outgassed. Today, permanently stratified regions extend across approximately 40% of the global ocean and their extent is expected to increase in a warmer ocean. Thus, predicting future ocean oxygen conditions requires a better understanding of the potential response of photosynthetic oxygen production to a warmer ocean. Based on our own and published observations of water column processes in oligotrophic regions, we develop a one-dimensional water column model describing photosynthetic oxygen production in the Sargasso Sea to quantify the importance of photosynthesis for the downward flux of O 2 and examine how it may be influenced in a warmer ocean. Photosynthesis is driven in the model by vertical mixing of nutrients (including eddy-induced mixing) and diazotrophy and is found to substantially increase the downward O 2 flux relative to physical–chemical processes alone. Warming (2°C) surface waters does not significantly change oxygen production at the DCM. Nor does a 15% increase in re-mineralization rate (assuming Q 10  = 2; 2°C warming) have significant effect on net sub-surface oxygen accumulation. However, changes in the relative production of particulate (POM) and dissolved organic material (DOM) generate relatively large changes in net sub-surface oxygen production. As POM/DOM production is a function of plankton community composition, this implies plankton biodiversity and food web structure may be important factors influencing O 2 production in a warmer ocean. This article is part of the themed issue ‘Ocean ventilation and deoxygenation in a warming world’.

scholarly journals SPEAD 1.0 – A model for Simulating Plankton Evolution with Adaptive Dynamics in a two-trait continuous fitness landscape applied to the Sargasso Sea

2020 ◽  
Author(s):  
Guillaume Le Gland ◽  
Sergio M. Vallina ◽  
S. Lan Smith ◽  
Pedro Cermeño
Keyword(s):  
General Circulation ◽  
Environmental Changes ◽  
Adaptive Dynamics ◽  
Computational Cost ◽  
Circulation Model ◽  
Global Ocean ◽  
Mutation Rates ◽  
Sargasso Sea ◽  
Continuous Trait ◽  
Trait Diversity

Abstract. Diversity plays a key role in the adaptive capacities of marine ecosystems to environmental changes. However, modeling phytoplankton trait diversity remains challenging due to the strength of the competitive exclusion of sub-optimal phenotypes. Trait diffusion (TD) is a recently developed approach to sustain diversity in plankton models by allowing the evolution of functional traits at ecological timescales. In this study, we present a model for Simulating Plankton Evolution with Adaptive Dynamics (SPEAD), where phytoplankton phenotypes characterized by two traits, nitrogen half-saturation constant and optimal temperature, can mutate at each generation using the TD mechanism. SPEAD does not resolve the different phenotypes as discrete entities, computing instead six aggregate properties: total phytoplankton biomass, mean value of each trait, trait variances, and inter-trait covariance of a single population in a continuous trait space. Therefore SPEAD resolves the dynamics of the population's continuous trait distribution by solving its statistical moments, where the variances of trait values represent the diversity of ecotypes. The ecological model is coupled to a vertically-resolved (1D) physical environment, and therefore the adaptive dynamics of the simulated phytoplankton population are driven by seasonal variations in vertical mixing, nutrient concentration, water temperature, and solar irradiance. The simulated bulk properties are validated by observations from BATS in the Sargasso Sea. We find that moderate mutation rates sustain trait diversity at decadal timescales and soften the almost total inter-trait correlation induced by the environment alone, without reducing the annual primary production or promoting permanently maladapted phenotypes, as occur with high mutation rates. As a way to evaluate the performance of the continuous-trait approximation, we also compare the solutions of SPEAD to the solutions of a classical discrete entities approach, both approaches including TD as a mechanism to sustain trait variance. We only find minor discrepancies between the continuous model SPEAD and the discrete model, the computational cost of SPEAD being lower by two orders of magnitude. Therefore SPEAD should be an ideal eco-evolutionary plankton model to be coupled to a general circulation model (GCM) at the global ocean.

scholarly journals Evidence for aggregation and export of cyanobacteria and nano-eukaryotes from the Sargasso Sea euphotic zone

2010 ◽  
Vol 7 (5) ◽  
pp. 7173-7206 ◽  
Author(s):  
M. W. Lomas ◽  
S. B. Moran
Keyword(s):  
Particle Size ◽  
Net Primary Production ◽  
Euphotic Zone ◽  
Sargasso Sea ◽  
Particle Size Fractions ◽  
Poc Export ◽  
Chlorophyll Precursor ◽  
Autotrophic Biomass ◽  
Ocean Gyre

Abstract. Pico-plankton and nano-plankton are generally thought to represent a negligible fraction of the total particulate organic carbon (POC) export flux in oligotrophic gyres due to their small size, slow individual sinking rates, and tight grazer control that leads to high rates of recycling in the euphotic zone. Based upon recent inverse modeling and network analysis however, it has been hypothesized that pico-plankton, including the cyanobacteria Synechococcus and Prochlorococcus, and nano-plankton contribute significantly to POC export, via formation of aggregates and consumption of those aggregates by mesozooplankton, in proportion to their contribution to net primary production. This study presents total suspended particulate (> 0.7 μm) and particle size-fractionated (10–20 μm, 20–53 μm, > 53 μm) pigment concentrations from within and below the euphotic zone in the oligotrophic subtropical North Atlantic, collected using Niskin bottles and large volume in-situ pumps, respectively. Results show the indicator pigments for Synechococcus, Prochlorococcus and nano-eukaryotes are; (1) found at depths down to 500 m, and; (2) essentially constant, relative to the sum of all indicator pigments, across particle size fractions ranging from 10 μm to > 53 μm. Based upon the presence of chlorophyll precursor and degradation pigments, and that in-situ pumps do not effectively sample fecal pellets, it is concluded that these pigments were redistributed to deeper waters on larger, more rapidly sinking aggregates. Using available pigment data and ancillary cruise data, these Synechococcus, Prochlorococcus and nano-plankton derived aggregates are estimated to contribute 2–13% (5 ± 4%), 1–20% (5 ± 7%), and 6–43% (23 ± 14%) of the total sediment trap POC flux measured on the same cruises, respectively. Furthermore, nano-eukaryotes contribute equally to POC export and autotrophic biomass, while cyanobacteria contributions to POC export are one-tenth of their contribution to autotrophic biomass. These field observations provide direct evidence that pico- and nano-plankton represent a significant contribution to the total POC export in this oligotrophic ocean gyre. We suggest that this pathway should be included in ecosystem models, particularly as oligotrophic regions are hypothesized to expand in areal extent with warming and increased stratification in the future.

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