Andrew McMinn

Short note: extracellular export and consumption of glucose in Antarctic sea ice

Publisher: Springer Science and Business Media LLC

Date: 11-03-2022

DOI: 10.1007/S00300-022-03031-6

Abstract: Extracellular carbohydrate production is widespread in sea ice microbial communities, being produced by both algae and bacteria. Under stressful conditions, including nutrient limitation and high light, cells may export excess fixed carbon as glucose. Glucose microsensors were used to measure extracellular glucose exudation and consumption in a sea ice algal community. Glucose export increased with increasing irradiance between 15 and 512 µmol photons m −2 s −1 . This export correlated with declining F v F m values and increasing NPQ values, implying that glucose export resulted from exposure to above optimal irradiances. Glucose concentrations in s les treated with DCMU to block photosynthesis, declined at all irradiances. Bacterial consumption of glucose was between 6 and 34% of extracellular export per hour. There have been very few measurements of DOC/glucose in sea ice and the data presented here make an important contribution to our understanding of sea ice microbial processes.

Characterization and Genome Analysis of a Novel Alteromonas Phage JH01 Isolated from the Qingdao Coast of China

Publisher: Springer Science and Business Media LLC

Date: 08-2019

DOI: 10.1007/S00284-019-01751-3

Abstract: A novel Alteromonas phage JH01, with the host strain identified to be Alteromonas marina SW-47(T), was isolated from the Qingdao coast during the summer of 2017. Transmission electron microscopy analysis showed that phage JH01 can be categorized into the Siphoviridae family, with an icosahedral head of 62 ± 5 nm and a long contractile tail of 254 ± 10 nm. The bioinformatic analysis shows that this phage consists of a linear, double-stranded 46,500 bp DNA molecule with a GC content of 44.39%, and 58 ORFs with no tRNA genes. The ORFs are classified into four groups, including phage packaging, phage structure, DNA replication and regulation, and hypothetical protein. The phylogenetic tree, constructed using neighbor-joining analysis, shows that phage JH01 has altitudinal homology with some Vibrio and Pseudoalteromonas phage B8b. Comparative analysis reveals the high similarity between phage JH01 and phage B8b. Additionally, our study of phage JH01 provides useful information for further research on the interaction between Alteromonas phages and their hosts.

Using picoeukaryote communities to indicate the spatial heterogeneity of the Nordic Seas

Publisher: Elsevier BV

Date: 12-2019

DOI: 10.1016/J.ECOLIND.2019.105582

Rapid changes in spectral composition after darkness influences nitric oxide, glucose and hydrogen peroxide production in the Antarctic diatom Fragilariopsis cylindrus

Publisher: Springer Science and Business Media LLC

Date: 18-05-2021

DOI: 10.1007/S00300-021-02867-8

Minireview: The role of viruses in marine photosynthetic biofilms

Publisher: Springer Science and Business Media LLC

Date: 09-06-2020

DOI: 10.1007/S42995-020-00042-2

Abstract: Microphytobenthos and sea ice algae comprise globally significant photosynthetic biofilms. While their microalgal and bacterial constituents are well characterized, there is very little information on their viral communities or on the virus–bacteria and virus–algae interactions within them. While high levels of interaction might be expected because of the high density of cells, infection rates, particularly of microalgae, have been found to be low. It remains unclear whether this is a result of environment characteristics, developed resistance or because of the small number of studies.

The effects of hydrocarbons on meiofauna in marine sediments in Antarctica

Publisher: Elsevier BV

Date: 11-2017

DOI: 10.1016/J.JEMBE.2017.07.009

Viral Characteristics of the Warm Atlantic and Cold Arctic Water Masses in the Nordic Seas

Publisher: American Society for Microbiology

Date: 28-10-2021

DOI: 10.1128/AEM.01160-21

Abstract: This is a systematic study of Nordic Sea viromes using metagenomic analysis. The viral ersity, community structure, and their relationships with host cells and the complex water masses from both the cool Arctic and the warm Atlantic oceans were illustrated.

Effects of ocean acidification on Antarctic marine organisms: A meta‐analysis

Publisher: Wiley

Date: 16-04-2020

DOI: 10.1002/ECE3.6205

<p><strong><em>Sabbea</em></strong><strong> gen. nov., a new diatom genus (Bacillariophyta) from continental Antarctica</strong></p>

Publisher: Magnolia Press

Date: 23-09-2019

DOI: 10.11646/PHYTOTAXA.418.1.2

Abstract: The non-marine diatom flora of the Antarctic Continent includes several endemic taxa recorded over the past 100 years. One of these taxa, Navicula adminensis D.Roberts & McMinn, was described from the Vestfold Hills, East Antarctica. Detailed light and scanning electron microscopy observations have shown that based on its morphological features, the species does not belong to the genus Navicula sensu stricto. To determine the most closely related genera to N. adminensis, the morphological features of Adlafia, Kobayasiella, Envekadea, Stenoneis, Berkeleya, Climaconeis, and Parlibellus were compared with those of N. adminensis. Although each of these genera shows one or more similar features, none of them accommodates the salient morphological characteristics of N. adminensis. Therefore, a new genus, Sabbea gen. nov., is herein described, and Navicula adminensis is formally transferred to the new genus as Sabbea adminensis comb. nov. The genus Sabbea is characterized by uniseriate striae composed of small, rounded areolae occluded externally by in idual hymenes, a rather simple raphe structure with straight, short proximal ends and short terminal raphe fissures, open girdle bands with double perforation and a very shallow mantle.

Novel D-glutamate catabolic pathway in marine Proteobacteria and halophilic archaea

Publisher: Springer Science and Business Media LLC

Date: 23-01-2023

DOI: 10.1038/S41396-023-01364-6

Psychrobacter Phage Encoding an Antibiotics Resistance Gene Represents a Novel Caudoviral Family

Publisher: American Society for Microbiology

Date: 17-08-2023

DOI: 10.1128/SPECTRUM.05335-22

Abstract: Although Psychrobacter is a well-known and important bacterial genus that is widespread in Antarctic and marine environments, genetic characterization of its phages is still rare. This study describes a novel Psychrobacter phage containing an uncharacterized antibiotic resistance gene and representing a new virus family, Minviridae . The characterization provided here will bolster current understanding of genomes, ersity, evolution, and phage-host interactions in Psychrobacter populations.

Effect of elevated CO 2 concentration on microalgal communities in Antarctic pack ice

Publisher: Elsevier BV

Date: 09-2016

DOI: 10.1016/J.DSR2.2016.01.005

Spatio-temporal variation of bacterial community structure in two intertidal sediment types of Jiaozhou Bay

Publisher: Elsevier BV

Date: 11-2023

DOI: 10.1016/J.ENVRES.2023.116743

Spatiotemporal Dynamics of Coastal Viral Community Structure and Potential Biogeochemical Roles Affected by an Ulva prolifera Green Tide

Publisher: American Society for Microbiology

Date: 27-04-2023

DOI: 10.1128/MSYSTEMS.01211-22

Abstract: To the best of our knowledge, this study is the first to investigate the responses of viruses to the world’s largest macroalgal green tide. It revealed the spatiotemporal dynamics of the unique viral assemblages and auxiliary metabolic genes (AMGs) following the variation and degradation of Ulva prolifera . These findings demonstrate a tight coupling between viral assemblages, and prokaryotic and eukaryotic abundances were influenced by the green tide.

Lack of N-Terminal Segment of the Flagellin Protein Results in the Production of a Shortened Polar Flagellum in the Deep-Sea Sedimentary Bacterium Pseudoalteromonas sp.

Publisher: American Society for Microbiology

Date: 14-10-2021

DOI: 10.1128/AEM.01527-21

Abstract: Polar flagella, which are essential organelles for bacterial motility, are comprised of multiple flagellin subunits. A flagellin molecule contains an N-terminal segment, a core segment, and a C-terminal segment.

McMinn's response to RC2

Publisher: Copernicus GmbH

Date: 03-07-2017

DOI: 10.5194/BG-2017-111-AC2

McMinn's response to RC3

Publisher: Copernicus GmbH

Date: 03-07-2017

DOI: 10.5194/BG-2017-111-AC3

Complete genomic sequence of bacteriophage P23: a novel Vibrio phage isolated from the Yellow Sea, China

Publisher: Springer Science and Business Media LLC

Date: 16-08-2019

DOI: 10.1007/S11262-019-01699-3

Abstract: A novel Vibrio phage, P23, belonging to the family Siphoviridae was isolated from the surface water of the Yellow Sea, China. The complete genome of this phage was determined. A one-step growth curve showed that the latent period was approximately 30 min, the burst size was 24 PFU/cell, and the rise period was 20 min. The phage is host specific and is stable over a range of pH (5-10) and temperatures (4-65 °C). Transmission electron microscopy showed that phage P23 can be categorized into the Siphoviridae family, with an icosahedral head of 60 nm and a long noncontractile tail of 144 nm. The genome consisted of a linear, double-stranded 40.063 kb DNA molecule with 42.5% G+C content and 72 putative open reading frames (ORFs) without tRNA. The predicted ORFs were classified into six functional groups, including DNA replication, regulation and nucleotide metabolism, transcription, phage packaging, phage structure, lysis, and hypothetical proteins. The Vibrio phage P23 genome is a new marine Siphoviridae-family phage genome that provides basic information for further molecular research on interaction mechanisms between bacteriophages and their hosts.

McMinn's RESPONSE to RC1

Publisher: Copernicus GmbH

Date: 03-07-2017

DOI: 10.5194/BG-2017-111-AC1

Response of tropical marine benthic diatoms exposed to elevated irradiance and temperature

Publisher: Copernicus GmbH

Date: 22-02-2021

DOI: 10.5194/BG-2021-18

Abstract: Abstract. Shallow tropical marine environments are likely to experience future water temperatures that will challenge the ability of life to survive. Changes in temperature and irradiance during tidal cycles in the Tanjung Rhu estuary, Langkawi, Malaysia in 2007 did not significantly affect the benthic diatom communities, although, higher photosynthetic parameters, such as maximum relative electron transport rate (rETRmax), photosynthetic efficiency (α), maximum quantum yield (Fv/Fm) and effective quantum yield (∆F/Fm'), were recorded at high tide when the temperatures were lower. However, when benthic diatoms were experimentally exposed to irradiances of 1800 µmol photons m−2 s−1, they were only able to photosynthesize at temperatures

Reviews and syntheses: Ice acidification, the effects of ocean acidification on sea ice microbial communities

Publisher: Copernicus GmbH

Date: 08-09-2017

DOI: 10.5194/BG-14-3927-2017

Abstract: Abstract. Sea ice algae, like some coastal and estuarine phytoplankton, are naturally exposed to a wider range of pH and CO2 concentrations than those in open marine seas. While climate change and ocean acidification (OA) will impact pelagic communities, their effects on sea ice microbial communities remain unclear. Sea ice contains several distinct microbial communities, which are exposed to differing environmental conditions depending on their depth within the ice. Bottom communities mostly experience relatively benign bulk ocean properties, while interior brine and surface (infiltration) communities experience much greater extremes. Most OA studies have examined the impacts on single sea ice algae species in culture. Although some studies examined the effects of OA alone, most examined the effects of OA and either light, nutrients or temperature. With few exceptions, increased CO2 concentration caused either no change or an increase in growth and/or photosynthesis. In situ studies on brine and surface algae also demonstrated a wide tolerance to increased and decreased pH and showed increased growth at higher CO2 concentrations. The short time period of most experiments ( 10 days), together with limited genetic ersity (i.e. use of only a single strain), however, has been identified as a limitation to a broader interpretation of the results. While there have been few studies on the effects of OA on the growth of marine bacterial communities in general, impacts appear to be minimal. In sea ice also, the few reports available suggest no negative impacts on bacterial growth or community richness. Sea ice ecosystems are ephemeral, melting and re-forming each year. Thus, for some part of each year organisms inhabiting the ice must also survive outside of the ice, either as part of the phytoplankton or as resting spores on the bottom. During these times, they will be exposed to the full range of co-stressors that pelagic organisms experience. Their ability to continue to make a major contribution to sea ice productivity will depend not only on their ability to survive in the ice but also on their ability to survive the increasing seawater temperatures, changing distribution of nutrients and declining pH forecast for the water column over the next centuries.

Supplementary material to Sea ice and productivity changes over the last glacial cycle in the Adélie Land region, East Antarctica, based on diatom assemblage variability

Publisher: Copernicus GmbH

Date: 04-10-2022

DOI: 10.5194/EGUSPHERE-2022-1009-SUPPLEMENT

Diaminopimelic Acid Metabolism by Pseudomonadota in the Ocean

Publisher: American Society for Microbiology

Date: 26-10-2022

DOI: 10.1128/SPECTRUM.00691-22

Abstract: DAP is a unique component of peptidoglycan in Gram-negative bacterial cell walls. Due to the large number of marine Gram-negative bacteria, DAP is an important component of marine organic matter.

Ocean acidification changes the structure of an Antarctic coastal protistan community

Publisher: Copernicus GmbH

Date: 07-06-2017

DOI: 10.5194/BG-2017-224

Abstract: Abstract. Antarctic near-shore waters are amongst of the most vulnerable in the world to ocean acidification. Microbes occupying these waters are critical drivers of ecosystem productivity, elemental cycling and ocean biogeochemistry, yet little is known about their sensitivity to ocean acidification. An unreplicated, six-level dose-response experiment was conducted using 650 L incubation tanks (minicosms) adjusted to fugacity of carbon dioxide (ƒCO2) from 343 to 11 641 μatm. The minicosms were filled with near-shore water from Prydz Bay, East Antarctica and the protistan composition and abundance was determined by microscopy analysis of s les collected during the 18 day incubation. No CO2-related change in the protistan community composition was observed during the initial 8 day acclimation period under low light. Thereafter, the response of protists to ƒCO2 were species-specific for both heterotrophic and autotrophic protists. The response by diatoms was related to cell size, large cells increasing in abundance with low to moderate ƒCO2 (634–953 μatm). Similarly, the abundance of Phaeocystis antarctica increased with increasing ƒCO2 peaking at a ƒCO2 of 634 μatm. Above this threshold the abundances of large diatoms and Phaeocystis antarctica fell dramatically, and small diatoms dominated, therefore culminating in a significant shift in the composition of the protistan community. The threshold CO2 level at which the composition changed agreed with that previously measured at this location, indicating it remains consistent among seasons. This suggests that near-shore microbial communities are likely to change significantly near the end of this century if anthropogenic CO2 release continues unabated, with profound ramifications for near-shore Antarctic ecosystems.

Discovery of an Abundant Viral Genus in Polar Regions through the Isolation and Genomic Characterization of a New Virus against Oceanospirillaceae

Publisher: American Society for Microbiology

Date: 26-04-2023

DOI: 10.1128/AEM.01896-22

Abstract: Oceanospirillum phage vB_OsaM_PD0307 is the first myovirus found to infect Oceanospirillaceae , and it represents a novel abundant viral genus in polar regions. This study provides insights into the genomic, phylogenetic, and ecological characteristics of the new viral genus, namely Oceanospimyovirus .

Sea ice and productivity changes over the last glacial cycle in the Adélie Land region, East Antarctica, based on diatom assemblage variability

Publisher: Copernicus GmbH

Date: 14-02-2023

DOI: 10.5194/CP-19-419-2023

Abstract: Abstract. Although diatoms can provide important palaeoenvironmental information about seasonal sea ice extent productivity, sea surface temperature, and ocean circulation variability, there are still relatively few studies analysing the last glacial cycle near the Antarctic continent. This study examines diatom assemblages over the last glacial cycle from core TAN1302-44, offshore Adélie Land, East Antarctica. Two distinct diatom assemblages were identified using principal component analysis (PC 1–PC 2). The PC 1 assemblage is characterised by Thalassiosira lentiginosa, Actinocyclus actinochilus, Euc ia antarctica, Azpeitia tabularis and Asteromphalus hyalinus and is associated with the interglacial, sedimentary Facies 1, suggesting that the MIS 5e and Holocene interglacials were characterised by seasonal sea ice environments with similar ocean temperature and circulation. The PC 2 assemblage is characterised by Fragilariopsis obliquecostata, Asteromphalus parvulus and Thalassiosira tumida and is associated with the glacial Facies 2. The variability of PC 2 indicates that, during the MIS 4–2 glacial and the last glaciation, there was an increase in the length of the sea ice season compared with that of the interglacial period, yet there was still no permanent sea ice cover. The initial increase of PC 2 at the start of the glaciation stage and then the gradual increase throughout late MIS 4–2 suggest that sea ice cover steadily increased, reaching a maximum towards the end of MIS 2. The increase in sea ice during glaciation and MIS 4–2 glacial is further supported by the increase in the Euc ia index (terminal/intercalary valve ratio), an additional proxy for sea ice, which coincides with increases in PC 2. Aside from the statistical results, the increase in the relative abundance of Thalassiothrix antarctica at 40 and 270 cm suggests that, during the last two deglacials, there was a period of enhanced nutrient delivery, which is inferred to reflect an increase in upwelling of Circumpolar Deep Water. Interestingly, the diatom data suggest that, during the last deglacial, the onset of increased Circumpolar Deep Water occurred after the loss of a prolonged sea ice season (decrease in PC 2) but before the ice sheet started to retreat (increase in IRD). Together, these results suggest the changes in sea ice season potentially influenced the ocean's thermohaline circulation and were important factors in driving the climate transitions. The results contribute to our understanding of the sea ice extent and ocean circulation changes proximal to East Antarctica over the last glacial cycle.

Characterization and Genomic Analysis of ssDNA Vibriophage vB_VpaM_PG19 within Microviridae , Representing a Novel Viral Genus

Publisher: American Society for Microbiology

Date: 31-08-2022

DOI: 10.1128/SPECTRUM.00585-22

Abstract: Vibriophage vB_VpaM_PG19 was distant from other isolated microviruses in the phylogenetic tree and network analysis and represents a novel microviral genus, named Vimicrovirus . Our report describes the genomic and phylogenetic features of vB_VpaM_PG19 and provides a potential antimicrobial candidate for pathogenic V. parahaemolyticus .

Referee Report

Publisher: Copernicus GmbH

Date: 04-04-2017

DOI: 10.5194/BG-2017-18-RC3

The Southern Annular Mode (SAM) influences phytoplankton communities in the seasonal ice zone of the Southern Ocean

Publisher: Copernicus GmbH

Date: 23-07-2020

DOI: 10.5194/BG-17-3815-2020

Abstract: Abstract. Ozone depletion and climate change are causing the Southern Annular Mode (SAM) to become increasingly positive, driving stronger winds southward in the Southern Ocean (SO), with likely effects on phytoplankton habitat due to possible changes in ocean mixing, nutrient upwelling, and sea ice characteristics. This study examined the effect of the SAM and 12 other environmental variables on the abundance of siliceous and calcareous phytoplankton in the seasonal ice zone (SIZ) of the SO. A total of 52 surface-water s les were collected during repeat resupply voyages between Hobart, Australia, and Dumont d'Urville, Antarctica, centred around longitude 142∘ E, over 11 consecutive austral spring–summer seasons (2002–2012), and spanning 131 d in the spring–summer from 20 October to 28 February. A total of 22 taxa groups, comprised of in idual species, groups of species, genera, or higher taxonomic groups, were analysed using CAP analysis (constrained analysis of principal coordinates), cluster analysis, and correlation. Overall, satellite-derived estimates of total chlorophyll and measured depletion of macronutrients both indicated a more positive SAM was associated with greater productivity in the SIZ. The greatest effect of the SAM on phytoplankton communities was the average value of the SAM across 57 d in the previous austral autumn centred around 11 March, which explained 13.3 % of the variance in community composition in the following spring–summer. This autumn SAM index was significantly correlated pair-wise (p .05) with the relative abundance of 12 of the 22 taxa groups resolved. A more positive SAM favoured increases in the relative abundance of large Chaetoceros spp. that predominated later in the spring–summer and reductions in small diatom taxa and siliceous and calcareous flagellates that predominated earlier in the spring–summer. In idual species belonging to the abundant Fragilariopsis genera responded differently to the SAM, indicating the importance of species-level observation in detecting SAM-induced changes in phytoplankton communities. The day through the spring–summer on which a s le was collected explained a significant and larger proportion (15.4 %) of the variance in the phytoplankton community composition than the SAM, yet this covariate was a proxy for such environmental factors as ice cover and sea surface temperature, factors that are regarded as drivers of the extreme seasonal variability in phytoplankton communities in Antarctic waters. The impacts of SAM on phytoplankton, which are the pasture of the SO and principal energy source for Antarctic life, would have ramifications for both carbon export and food availability for higher trophic levels in the SIZ of the SO.

Differences in diversity and photoprotection capability between ice algae and under-ice phytoplankton in Saroma-Ko Lagoon, Japan: a comparative taxonomic diatom analysis with microscopy and DNA barcod

Publisher: Springer Science and Business Media LLC

Date: 25-09-2020

DOI: 10.1007/S00300-020-02751-X

Use of glucose biosensors to measure extracellular glucose exudation by intertidal microphytobenthos in southern Tasmania

Publisher: Wiley

Date: 19-04-2018

DOI: 10.1111/JPY.12641

Abstract: Micro glucose biosensors were used to measure net extracellular glucose produced by natural microphytobenthos and three diatom cultures (Amphora coffeaeformis, Navicula menisculus, Nitzschia longissima) from southern Tasmania, Australia. They were exposed to a light gradient in either nutrient-replete or nutrient-limiting conditions. Glucose exudation in the natural communities increased with increased light but the response in the cultures was variable. Similarly, nutrient-replete conditions elicited lower rates of glucose exudation in the natural communities but produced variable species-specific responses in the cultures. Increased glucose exudation mostly correlated with a reduction in maximum quantum yield (F

Environmental gradients shape microbiome assembly and stability in the East China sea

Publisher: Elsevier BV

Date: 12-2023

DOI: 10.1016/J.ENVRES.2023.117197

In-situ behavioural and physiological responses of Antarctic microphytobenthos to ocean acidification

Publisher: Springer Science and Business Media LLC

Date: 13-02-2019

DOI: 10.1038/S41598-018-36233-2

Abstract: Ocean acidification (OA) is predicted to alter benthic marine community structure and function, however, there is a paucity of field experiments in benthic soft sediment communities and ecosystems. Benthic diatoms are important components of Antarctic coastal ecosystems, however very little is known of how they will respond to ocean acidification. Ocean acidification conditions were maintained by incremental computer controlled addition of high f CO 2 seawater representing OA conditions predicted for the year 2100. Respiration chambers and PAM fluorescence techniques were used to investigate acute behavioural, photosynthetic and net production responses of benthic microalgae communities to OA in in-situ field experiments. We demonstrate how OA can modify behavioural ecology, which changes photo-physiology and net production of benthic microalgae. Ocean acidification treatments significantly altered behavioural ecology, which in turn altered photo-physiology. The ecological trends presented here have the potential to manifest into significant ecological change over longer time periods.

Ice Acidification: A review of the effects of ocean acidification on sea ice microbial communities

Publisher: Copernicus GmbH

Date: 20-04-2017

DOI: 10.5194/BG-2017-111

Abstract: Abstract. Sea ice algae are naturally exposed to a wider range of pH and CO2 concentrations than marine phytoplankton. While climate change and ocean acidification (OA) will impact pelagic communities, their effects on sea ice microbial communities remains unclear. Sea ice contains several distinct microbial communities, which are exposed to differing environmental conditions depending on their depth within the ice. Bottom communities mostly experience relatively benign bulk ocean properties, while interior brine and surface communities experience much greater extremes. Most OA studies have examined the impacts on single sea ice algae species in culture. Although some studies examined the effects of OA alone, most also examined the effects of OA and either light, nutrients or temperature. With few exceptions, increased CO2 concentration caused either no change or an increase in growth and/or photosynthesis. In situ studies of brine and surface algae also demonstrated a wide tolerance to increased and decreased pH and showed increased growth at higher CO2 concentrations. The short time period of most experiments (

Reconstruction of the Functional Ecosystem in the High Light, Low Temperature Union Glacier Region, Antarctica

Publisher: Frontiers Media SA

Date: 18-10-2019

DOI: 10.3389/FMICB.2019.02408

The Southern Annular Mode (SAM) influences phytoplankton communities in the seasonal ice zone of the Southern Ocean

Publisher: Copernicus GmbH

Date: 21-10-2019

DOI: 10.5194/BG-2019-402

Abstract: Abstract. Ozone depletion and climate change are causing the Southern Annular Mode (SAM) to become increasingly positive, driving stronger winds southward in the Southern Ocean (SO), with likely effects on phytoplankton habitat due to changes in ocean mixing, nutrient upwelling, and sea ice. This study examined the effect of the SAM and other environmental variables on the abundance of siliceous and calcareous phytoplankton in the seasonal ice zone (SIZ) of the SO. S les were collected during repeat transects between Hobart, Australia, and Dumont d'Urville, Antarctica, centred around longitude 142° E, over 11 consecutive austral spring-summers (2002–2012). Twenty-two taxa, comprised of species, genera or higher taxonomic groups, were analysed using CAP analysis, cluster analysis and correlation. The SAM significantly affected phytoplankton community composition, with the greatest influence exerted by a SAM index averaged across 57 days centred on 11th March in the preceding autumn, explaining 13.3 % of the variance of taxa composition during the following spring–summer, and showing correlation with the relative abundance of 12 of the 22 taxa resolved. The day through the spring-summer that a s le was collected exerted the greatest influence on phytoplankton community structure (15.4 % of variance explained), reflecting the extreme seasonal variation in the physical environment in the SIZ that drives phytoplankton community succession. The response of different species of Fragilariopsis spp. and Chaetoceros spp. differed over the spring–summer and with the SAM, indicating the importance of species-level observation in detecting subtle changes in pelagic ecosystems. This study indicated that higher SAM favoured increases in the relative-abundance of large Chaetoceros spp. that predominated later in the spring–summer and reductions in small diatom taxa and siliceous and calcareous flagellates that predominated earlier in the spring–summer. Such changes in the taxonomic composition of phytoplankton, the pasture of the SO and principal energy source for Antarctic life, may alter both carbon sequestration and composition of higher tropic levels of the SIZ region of the SO.

Tolerance of tropical marine microphytobenthos exposed to elevated irradiance and temperature

Publisher: Copernicus GmbH

Date: 10-2021

DOI: 10.5194/BG-18-5313-2021

Abstract: Abstract. The photosynthetic productivity of tropical microphytobenthos (MPB) is largely driven by changes in light intensities and temperature at the surface of sediment flats during emersion. Here, the response of the MPB community to temperature and light was examined. Changes in temperature and irradiance during tidal cycles in the Tanjung Rhu estuary, Langkawi, Malaysia, in 2007 significantly affected the photosynthetic capacities of the MPB. Higher photosynthetic parameters, such as the maximum relative electron transport rate (rETRmax), photosynthetic efficiency (α), maximum quantum yield (Fv/Fm), and effective quantum yield (ΔF/Fm′), were recorded at high tide when the temperatures were lower. However, when the community was experimentally exposed to irradiances of 1800 µmol photons m−2 s−1, it was only able to photosynthesize at temperatures 50 ∘C. Above this temperature, no photosynthetic activity was observed. Not only did high temperatures at high irradiance affect the algal communities, but limited photosynthetic activity was also observed in s les when exposed to limited irradiance. Recovery rates were highest at the lowest temperatures and decreased as the temperature increased. The recovery rates for s les exposed to temperatures of 40 ∘C were 4.01×10-3±0.002 s−1 and decreased to 1.01×10-5±0.001 s−1 at 60 ∘C, indicating irreversible damage to Photosystem II (PSII). These characteristics suggest that the MPB communities in this estuary were able to adapt to temperature variation. However, enhanced photoinhibition would result if exposed to elevated temperatures, especially during low tide where in situ temperature was already 43 ∘C. Hence, if in situ temperature were to further increase during tidal emersion, 50 ∘C could be a temperature threshold for photosynthetic performance of tropical estuarine benthic microalgal communities.

Metagenomic characterization of the viral community of the South Scotia Ridge

Publisher: Cold Spring Harbor Laboratory

Date: 24-10-2018

DOI: 10.1101/451732

Abstract: Viruses are the most abundant biological entities in aquatic ecosystems and harbor an enormous genetic ersity. While their great influence on the marine ecosystems is widely acknowledged, current information about their ersity remains scarce. Aviral metagenomic analysis of two surfaces and one bottom water s le was conducted from sites on the South Scotia Ridge (SSR) near the Antarctic Peninsula, during the austral summer 2016. The taxonomic composition and ersity of the viral communities were investigated and a functional assessment of the sequences was determined. Phylotypic analysis showed that most viruses belonging to the order Caudovirales, in particular, the family Podoviridae (41.92-48.7%), which is similar to the viral communities from the Pacific Ocean. Functional analysis revealed a relatively high frequency of phage-associated and metabolism genes. Phylogenetic analyses of phage TerL and Capsid_NCLDV (nucleocytoplasmic large DNA viruses) marker genes indicated that many of the sequences associated with Caudovirales and NCLDV were novel and distinct from known complete phage genomes. High Phaeocystis globosa virus virophage (Pgvv) signatures were found in SSR area and complete and partial Pgvv-like were obtained which may have an influence on host-virus interactions in the area during summer. Our study expands the existing knowledge of viral communities and their ersities from the Antarctic region and provides basic data for further exploring polar microbiomes. In this study, we used high-throughput sequencing and bioinformatics analysis to analyze the viral community structure and bio ersity of SSR in the open sea near the Antarctic Peninsula. The results showed that the SSR viromes are novel, oceanic-related viromes and a high proportion of sequence reads was classified as unknown. Among known virus counterparts, members of the order Caudovirales were most abundant which is consistent with viromes from the Pacific Ocean. In addition, phylogenetic analyses based on the viral marker genes (TerL and MCP) illustrate the high ersity among Caudovirales and NCLDV. Combining deep sequencing and a random subs ling assembly approach, a new Pgvv-like group was also found in this region, which may a signification factor regulating virus-host interactions.

A re-investigation of lake sediment diatoms from the Vestfold Hills, Antarctica, using an updated, fine-grained taxonomy

Publisher: Informa UK Limited

Date: 02-07-2020

DOI: 10.1080/0269249X.2020.1794982

Supplementary material to &quot;The Southern Annular Mode (SAM) influences phytoplankton communities in the seasonal ice zone of the Southern Ocean&quot;

Publisher: Copernicus GmbH

Date: 21-10-2019

DOI: 10.5194/BG-2019-402-SUPPLEMENT

Insights into the Production and Role of Nitric Oxide in the Antarctic Sea‐ice Diatom Fragilariopsis cylindrus

Publisher: Wiley

Date: 23-06-2020

DOI: 10.1111/JPY.13027

Abstract: Nitric oxide (NO) is widely recognized as an important transmitter molecule in biological systems, from animals to plants and microbes. However, the role of NO in marine photosynthetic microbes remains unclear and even less is known about the role of this metabolite in Antarctic sea‐ice diatoms. Using a combination of microsensors, microfluidic chambers, and artificial sea‐ice tanks, a basic mechanistic insight into NO's dynamics within the Antarctic sea‐ice diatom Fragilariopsis cylindrus was obtained. Results suggest that NO production in F. cylindrus is nitrite‐dependent via nitrate reductase. NO production was abolished upon exposure to light but could be induced in the light when normal photosynthetic electron flow was disrupted. The addition of exogenous NO to cellular suspensions of F. cylindrus negatively influenced growth, disrupted photosynthesis, and altered non‐photochemical dissipation mechanisms. NO production was also observed when cells were exposed to stressful salinity and temperature regimes. These results suggest that during periods of environmental stress, NO could be produced in F. cylindrus as a “stress signa” molecule.

Antarctic landfast sea ice: Physical, biogeochemical and ecological significance

Publisher: Wiley

Date: 24-10-2022

DOI: 10.1002/ESSOAR.10512682.1

Effects of CO2 concentration on a late summer surface sea ice community

Publisher: Springer Science and Business Media LLC

Date: 21-03-2017

DOI: 10.1007/S00227-017-3102-4

Genomic and phylogenetic analysis of the first myovirus isolated from Oceanospirillaceae, representing a novel viral cluster prevalent in polar oceans

Publisher: Cold Spring Harbor Laboratory

Date: 28-01-2022

DOI: 10.1101/2022.01.27.478124

Abstract: The marine bacterial family Oceanospirillaceae , which is abundant in the deep-seas and polar oceans, is closely associated with algal blooms and petroleum hydrocarbons degradation. However, only a few Oceanospirillaceae -infecting phages have so far been reported. Here we report on a novel Oceanospirillum phage, vB_OsaM_PD0307, which is the first myovirus to be found that infects Oceanospirillaceae . vB_OsaM_PD0307 with a 44,421 bp linear dsDNA genome. Phylogenetic analysis and average nucleotide sequence identities suggest that vB_OsaM_PD0307 is different from other phage isolates and represents a novel genus-level myoviral cluster with two high-quality uncultured viral genomes, designed as Oceanospimyovirus . Additionally, the biogeographical distribution of the vB_OsaM_PD0307 cluster suggests that they are widespread in the oceans and abundant in polar areas. In summary, our findings expand the current understanding of the phylogenetic ersity, genomic characteristic and function of Oceanospimyovirus phages, and highlight the role of the vB_OsaM_PD0307 phage as a major ecological agent that can infect certain key bacterial groups associated with polar algal blooms. Oceanospirillumphage vB_OsaM_PD0307 is the first myovirus found to infect Oceanospirillaceae and represents a novel viral genus, Oceanospimyovirus . This study provides insights into the genomic, phylogenetic, and ecological characteristics of myoviruses infecting Oceanospirillaceae and improves our understanding of the interactions between Oceanospirillaceae and their phages in the oceans.

Dark metabolism: a molecular insight into how the Antarctic sea‐ice diatom Fragilariopsis cylindrus survives long‐term darkness

Publisher: Wiley

Date: 07-05-2019

DOI: 10.1111/NPH.15843

Mechanistic Insights into Substrate Recognition and Catalysis of a New Ulvan Lyase of Polysaccharide Lyase Family 24

Publisher: American Society for Microbiology

Date: 26-05-2021

DOI: 10.1128/AEM.00412-21

Abstract: Ulvan is a major cell wall component of green algae of the genus Ulva. Many marine heterotrophic bacteria can produce extracellular ulvan lyases to degrade ulvan for a carbon nutrient. In addition, ulvan has a range of physiological bioactivities based on its specific chemical structure.

Genome and Ecology of a NovelAlteromonasPodovirus, ZP6, Representing a New Viral Genus,Mareflavirus

Publisher: American Society for Microbiology

Date: 31-10-2021

DOI: 10.1128/SPECTRUM.00463-21

Abstract: Alteromonas is an important symbiotic bacterium of phytoplankton, but research on its bacteriophages is still at an elementary level. Our isolation and genome characterization of a novel Alteromonas podovirus, ZP6, identified a new viral genus of podovirus and Gammaproteobacteria phages, namely, Mareflavirus .

Ocean acidification changes the structure of an Antarctic coastal protistan community

Publisher: Copernicus GmbH

Date: 20-04-2018

DOI: 10.5194/BG-15-2393-2018

Abstract: Abstract. Antarctic near-shore waters are amongst the most sensitive in the world to ocean acidification. Microbes occupying these waters are critical drivers of ecosystem productivity, elemental cycling and ocean biogeochemistry, yet little is known about their sensitivity to ocean acidification. A six-level, dose–response experiment was conducted using 650 L incubation tanks (minicosms) adjusted to a gradient in fugacity of carbon dioxide (fCO2) from 343 to 1641 µatm. The six minicosms were filled with near-shore water from Prydz Bay, East Antarctica, and the protistan composition and abundance was determined by microscopy during 18 days of incubation. No CO2-related change in the protistan community composition was observed during the initial 8 day acclimation period under low light. Thereafter, the response of both autotrophic and heterotrophic protists to fCO2 was species-specific. The response of diatoms was mainly cell size related microplanktonic diatoms ( 20 µm) increased in abundance with low to moderate fCO2 (343–634 µatm) but decreased at fCO2 ≥ 953 µatm. Similarly, the abundance of Phaeocystis antarctica increased with increasing fCO2 peaking at 634 µatm. Above this threshold the abundance of micro-sized diatoms and P. antarctica fell dramatically, and nanoplanktonic diatoms (≤ 20 µm) dominated, therefore culminating in a significant change in the protistan community composition. Comparisons of these results with previous experiments conducted at this site show that the fCO2 thresholds are similar, despite seasonal and interannual differences in the physical and biotic environment. This suggests that near-shore microbial communities are likely to change significantly near the end of this century if anthropogenic CO2 release continues unabated, with profound ramifications for near-shore Antarctic ecosystem food webs and biogeochemical cycling.

Chlorophyll‐a in Antarctic Landfast Sea Ice: A First Synthesis of Historical Ice Core Data

Publisher: American Geophysical Union (AGU)

Date: 11-2018

DOI: 10.1029/2018JC014245

Extracellular Enzyme Activity and Its Implications for Organic Matter Cycling in Northern Chinese Marginal Seas

Publisher: Frontiers Media SA

Date: 13-09-2019

DOI: 10.3389/FMICB.2019.02137

Sea ice and productivity changes over the last glacial cycle in the Adélie Land region, East Antarctica, based on diatom assemblage variability

Publisher: Copernicus GmbH

Date: 04-10-2022

DOI: 10.5194/EGUSPHERE-2022-1009

Abstract: Abstract. Diatoms can provide important paleoenvironmental information about seasonal sea ice extent, productivity, sea surface temperature and ocean circulation variability, yet there are relatively few studies analysing the last glacial cycle near the Antarctic continent. This study examines diatom assemblages over the last glacial cycle from core TAN1302-44, from off Adélie Land, East Antarctica. Four distinct diatom assemblages were identified using principal components analyses. The PC 1 assemblage is associated with the interglacial, sedimentary facies, Facies 1, and comprises Thalassiosira lentiginosa, Actinocyclus actinochilus, Euc ia antarctica, Azpeitia tabularis and Asteromphalus hyalinus, suggesting that MIS 5e and Holocene interglacial time periods were characterised by seasonal sea ice environments with similar ocean temperature and circulation. The PC 2 assemblage is associated with the glacial, Facies 2, and comprises Fragilariopsis obliquecostata, Asteromphalus parvulus, Rhizosolenia styliformis, Thalassiosira tumida, Chaetoceros dichaeta, and a Euc ia antarctica terminal/intercalary ratio. This indicates that, during the MIS 4-2 glacial there was an increase in the length of the sea ice season compared with the interglacial period, yet still no permanent sea ice cover. The PC 2 assemblage is also associated with the glaciation and deglacial facies. There is an initial increase of PC 2 at the start of MIS 5d-a glaciation stage and then a gradual increase throughout late MIS 4-2, suggests that sea ice cover steadily increased reaching a maximum at the end of MIS 2. The PC 3 assemblage is associated with all four facies and comprises Actinocyclus ingens, Actinocyclus actinochilus, Thalassiosira oliverana and Fragilariopsis kerguelensis, suggesting that reworking of sediments and an influx of older sediments occurred throughout the last glacial cycle. Finally, the PC 4 assemblage is associated with the deglacial, glaciation, and glacial facies and comprises Fragilariopsis kerguelensis, Thalassiothrix antarctica, Chaetoceros bulbosum and Euc ia antarctica, suggesting that during the last glaciation, the last two deglacials, and the early glacial, there was a period of enhanced upwelling of nutrient-rich, warmer water, which is inferred to reflect an increase in Circumpolar Deep Water. Interestingly, the diatom data suggest the onset of increased Circumpolar Deep Water during the last deglacial occurred after the rapid loss of a prolonged sea ice season at the end of last glacial. Together, these results suggest changes in ocean circulation and sea ice season were important factors during climate transitions. The results fill a gap in our understanding of the sea ice extent and ocean circulation changes proximal to East Antarctica over the last glacial cycle.

Identification of hidden N4-like viruses and their interactions with hosts

Publisher: American Society for Microbiology

Date: 26-10-2023

DOI: 10.1128/MSYSTEMS.00197-23

Ancient DNA and microfossils reveal dynamics of three harmful dinoflagellate species off Eastern Tasmania, Australia, over the last 9,000 years

Publisher: Cold Spring Harbor Laboratory

Date: 18-02-2021

DOI: 10.1101/2021.02.18.431790

Abstract: Harmful algal blooms (HABs) have significantly impacted the seafood industry along the Tasmanian east coast over the past three decades, and are expected to change in frequency and magnitude due to climate change induced changing oceanographic conditions. To investigate the long-term history of regional HABs, a combination of palynological and sedimentary ancient DNA ( sed aDNA) analyses was applied to marine sediment cores from inshore (up to 145 years old) and offshore (up to ~9,000 years) sites at Maria Island, southeast Tasmania. Analyses focused Paralytic Shellfish Toxin (PST) producing dinoflagellates Alexandrium catenella and Gymnodinium catenatum , and the red-tide dinoflagellate Noctiluca scintillans , which were specifically targeted using a hybridization capture sed aDNA technique. Identification of primulin-stained A. catenella cysts throughout the inshore sediment core, together with sed aDNA evidence of a bloom-phase of Alexandrium ~15 years ago, indicates recent stimulation of a cryptic endemic population. Morphologically similar but unstained Alexandrium cysts were observed throughout the offshore core, with sed aDNA confirming the presence of A. catenella from ~8,300 years ago to present. Gymnodinium catenatum cysts were detected only in inshore surface sediments from 30 years ago to present, supporting previous evidence of a 1970s introduction via shipping ballast water. sed aDNA confirmed the presence of G. catenatum -related sequences in the inshore and offshore cores, however, unambiguous species identification could not be achieved due to limited reference sequence coverage of Gymnodinium . Our hybridization capture sed aDNA data also confirmed the historically recent dispersal of the non-fossilizing dinoflagellate Noctiluca scintillans , detected inshore from ~30 years ago, matching first observations of this species in Tasmanian waters in 1994. At the offshore site, N. scintillans sed aDNA was detected only in surface sediments, confirming a recent climate-driven range expansion this species. This study provides new insights into the distribution and abundance of three HAB species in the Tasmanian region, including clues to past bloom phases. Further research into paleo-environmental conditions and paleo-community structure are required to identify the factors driving bloom phases through time and predict plankton community responses under different future climate scenarios. Dinocyst and sed aDNA analyses were applied to marine sediments off Tasmania Alexandrium catenella has been endemic to Australia for at least ~9,000 years Recent A. catenella blooms are likely induced by climate and oceanographic change Gymnodinium catenatum cysts in recent (~30y) sediments confirm a 1970s introduction Noctiluca scintillans sed aDNAin recent (~30y) sediments matches a 1994 introduction

Ice Melting Can Change DMSP Production and Photosynthetic Activity of the Haptophyte Phaeocystis antarctica¹

Publisher: Wiley

Date: 02-04-2020

DOI: 10.1111/JPY.12985

Diverse, abundant and stable coastal RNA viruses identified by spatiotemporal metatranscriptomics

Publisher: Research Square Platform LLC

Date: 30-11-2022

DOI: 10.21203/RS.3.RS-2282285/V1

Abstract: The ersity and spatiotemporal dynamics of a coastal RNA virus community, was investigated focusing on the effects of a bloom of the macroalgae U. prolifera through a metatranscriptomic reconstruction of ~ 880Gb of Qingdao Coastal RNA sequences from May 2019 to December 2020. 6,079 RNA viral contigs were identified and these generated 2,351 viral operational taxonomic units within known orders. The analysis found that structural components of the coastal marine RNA virus community are erse, abundant and stable. The viruses were mainly associated with eukaryotes from Intramacronucleata, Chlorophyta, Bacillariophyta and Dinophyceae, bacteria from Flavobacteriales and Rhodobacterales and MGII and Nitrosopumilales from archaea. The viral auxiliary metabolic genes indicate that coastal RNA viruses manipulate reprogramming of erse host metabolisms, including carbon cycling, signaling pathways, membrane transport, transcription and translation. Together these results provide critical insights for incorporating RNA viruses into marine ecological and epidemiological models.

Freezing, Melting, and Light Stress on the Photophysiology of Ice Algae: Ex Situ Incubation of the Ice Algal diatom Fragilariopsis cylindrus (Bacillariophyceae) Using an Ice Tank

Publisher: Wiley

Date: 07-07-2020

DOI: 10.1111/JPY.13036

Abstract: Sea ice algae contribute up to 25% of the primary productivity of polar seas and seed large‐scale ice‐edge blooms. Fluctuations in temperature, salinity, and light associated with the freeze/thaw cycle can significantly impact the photophysiology of ice‐associated taxa. The effects of multiple co‐stressors (i.e., freezing temperature and high brine salinity or sudden high light exposure) on the photophysiology of ice algae were investigated in a series of ice tank experiments with the polar diatom Fragilariopsis cylindrus under different light intensities. When algal cells were frozen into the ice, the maximum quantum yield of photosystem II photochemistry (PSII F v / F m ) decreased possibly due to the damage of PSII reaction centers and/or high brine salinity stress suppressing the reduction capacity downstream of PSII. Expression of the rbc L gene was highly up‐regulated, suggesting that cells initiated strategies to enhance survival upon freezing in. Algae contained within the ice‐matrix displayed similar levels of F v / F m regardless of the light treatments. Upon melting out, cells were exposed to high light (800 μmol photons · m −2 · s −1 ), resulting in a rapid decline in F v / F m and significant up‐regulation of non‐photochemical quenching (NPQ). These results suggest that ice algae employed safety valves (i.e., NPQ) to maintain their photosynthetic capability during the sudden environmental changes. Our results infer that sea ice algae are highly adaptable when exposed to multiple co‐stressors and that their success can, in part, be explained by the ability to rapidly modify their photosynthetic competence – a key factor contributing to algal bloom formation in the polar seas.

Antarctic Landfast Sea Ice: A Review of Its Physics, Biogeochemistry and Ecology

Publisher: American Geophysical Union (AGU)

Date: 06-2023

DOI: 10.1029/2022RG000770

Abstract: Antarctic landfast sea ice (fast ice) is stationary sea ice that is attached to the coast, grounded icebergs, ice shelves, or other protrusions on the continental shelf. Fast ice forms in narrow (generally up to 200 km wide) bands, and ranges in thickness from centimeters to tens of meters. In most regions, it forms in autumn, persists through the winter and melts in spring/summer, but can remain throughout the summer in particular locations, becoming multi‐year ice. Despite its relatively limited extent (comprising between about 4% and 13% of overall sea ice), its presence, variability and seasonality are drivers of a wide range of physical, biological and biogeochemical processes, with both local and far‐ranging ramifications for the Earth system. Antarctic fast ice has, until quite recently, been overlooked in studies, likely due to insufficient knowledge of its distribution, leading to its reputation as a “missing piece of the Antarctic puzzle.” This review presents a synthesis of current knowledge of the physical, biogeochemical and biological aspects of fast ice, based on the sub‐domains of: fast ice growth, properties and seasonality remote‐sensing and distribution interactions with the atmosphere and the ocean biogeochemical interactions its role in primary production and fast ice as a habitat for grazers. Finally, we consider the potential state of Antarctic fast ice at the end of the 21st Century, underpinned by Coupled Model Intercomparison Project model projections. This review also gives recommendations for targeted future work to increase our understanding of this critically‐important element of the global cryosphere.

Macquarie University

Location: Australia

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University Of Tasmania

Location: Australia

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Macquarie University

Location: No location found

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University Of Tasmania

Location: No location found

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Discovery Projects - Grant ID: DP0344067

Start Date: 01-2003

End Date: 12-2006

Amount: $305,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP170102261

Start Date: 05-2017

End Date: 05-2023

Amount: $439,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE130100220

Start Date: 2013

End Date: 12-2015

Amount: $150,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0880212

Start Date: 06-2008

End Date: 11-2011

Amount: $255,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0773558

Start Date: 03-2007

End Date: 12-2010

Amount: $263,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100107

Start Date: 2010

End Date: 12-2010

Amount: $400,000.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR200100008

Start Date: 08-2021

End Date: 12-2027

Amount: $20,000,000.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR0354787

Start Date: 01-2004

End Date: 12-2004

Amount: $10,000.00

Funder: Australian Research Council