Hydrocarbon-Degrading Bacteria Found Tightly Associated with the 50–70 μm Cell-Size Population of Eukaryotic Phytoplankton in Surface Waters of a Northeast Atlantic Region

The surface of marine eukaryotic phytoplankton can harbour communities of hydrocarbon-degrading bacteria; however, this algal–bacterial association has, hitherto, been only examined with non-axenic laboratory cultures of micro-algae. In this study, we isolated an operationally-defined community of phytoplankton, of cell size 50–70 μm, from a natural community in sea surface waters of a subarctic region in the northeast Atlantic. Using MiSeq 16S rRNA sequencing, we identified several recognized (Alcanivorax, Marinobacter, Oleispira, Porticoccus, Thalassospira) and putative hydrocarbon degraders (Colwelliaceae, Vibrionaceae) tightly associated with the phytoplankton population. We combined fluorescence in situ hybridisation with flow-cytometry (FISH-Flow) to examine the association of Marinobacter with this natural eukaryotic phytoplankton population. About 1.5% of the phytoplankton population contained tightly associated Marinobacter. The remaining Marinobacter population were loosely associated with either eukaryotic phytoplankton cells or non-chlorophyll particulate material. This work is the first to show the presence of obligate, generalist and putative hydrocarbonoclastic bacteria associated with natural populations of eukaryotic phytoplankton directly from sea surface water samples. It also highlights the suitability of FISH-Flow for future studies to examine the spatial and temporal structure and dynamics of these and other algal–bacterial associations in natural seawater samples.

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Nitrogen isotopic response of prokaryotic and eukaryotic phytoplankton to nitrate availability in Sargasso Sea surface waters

Limnology and Oceanography ◽

10.4319/lo.2014.59.3.0972 ◽

2014 ◽

Vol 59 (3) ◽

pp. 972-985 ◽

Cited By ~ 18

Author(s):

Lija A. Treibergs ◽

Sarah E. Fawcett ◽

Michael W. Lomas ◽

Daniel M. Sigman

Keyword(s):

Surface Waters ◽

Sea Surface ◽

Sargasso Sea ◽

Nitrate Availability ◽

Eukaryotic Phytoplankton

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Effects of Dispersants and Biosurfactants on Crude-Oil Biodegradation and Bacterial Community Succession

Microorganisms ◽

10.3390/microorganisms9061200 ◽

2021 ◽

Vol 9 (6) ◽

pp. 1200

Author(s):

Gareth E. Thomas ◽

Jan L. Brant ◽

Pablo Campo ◽

Dave R. Clark ◽

Frederic Coulon ◽

...

Keyword(s):

Crude Oil ◽

Early Stage ◽

Niche Partitioning ◽

Hydrocarbon Biodegradation ◽

Hydrocarbonoclastic Bacteria ◽

Bacterial Response ◽

Oil Biodegradation ◽

Interfacial Surface ◽

Degrading Bacteria ◽

Oil Spill Response

This study evaluated the effects of three commercial dispersants (Finasol OSR 52, Slickgone NS, Superdispersant 25) and three biosurfactants (rhamnolipid, trehalolipid, sophorolipid) in crude-oil seawater microcosms. We analysed the crucial early bacterial response (1 and 3 days). In contrast, most analyses miss this key period and instead focus on later time points after oil and dispersant addition. By focusing on the early stage, we show that dispersants and biosurfactants, which reduce the interfacial surface tension of oil and water, significantly increase the abundance of hydrocarbon-degrading bacteria, and the rate of hydrocarbon biodegradation, within 24 h. A succession of obligate hydrocarbonoclastic bacteria (OHCB), driven by metabolite niche partitioning, is demonstrated. Importantly, this succession has revealed how the OHCB Oleispira, hitherto considered to be a psychrophile, can dominate in the early stages of oil-spill response (1 and 3 days), outcompeting all other OHCB, at the relatively high temperature of 16 °C. Additionally, we demonstrate how some dispersants or biosurfactants can select for specific bacterial genera, especially the biosurfactant rhamnolipid, which appears to provide an advantageous compatibility with Pseudomonas, a genus in which some species synthesize rhamnolipid in the presence of hydrocarbons.

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Sea-surface CO<sub>2</sub> fugacity in the subpolar North Atlantic

Biogeosciences ◽

10.5194/bg-5-535-2008 ◽

2008 ◽

Vol 5 (2) ◽

pp. 535-547 ◽

Cited By ~ 42

Author(s):

A. Olsen ◽

K. R. Brown ◽

M. Chierici ◽

T. Johannessen ◽

C. Neill

Keyword(s):

North Atlantic ◽

Surface Waters ◽

Mixed Layer Depth ◽

Sea Surface ◽

First Year ◽

Layer Depth ◽

High Resolution Data ◽

Chl A ◽

Wide Range ◽

Summer Warming

Abstract. We present the first year-long subpolar trans-Atlantic set of surface seawater CO2 fugacity (fCO2sw) data. The data were obtained aboard the MV Nuka Arctica in 2005 and provide a quasi-continuous picture of the fCO2sw variability between Denmark and Greenland. Complementary real-time high-resolution data of surface chlorophyll-a (chl-a) concentrations and mixed layer depth (MLD) estimates have been collocated with the fCO2sw data. Off-shelf fCO2sw data exhibit a pronounced seasonal cycle. In winter, surface waters are saturated to slightly supersaturated over a wide range of temperatures. Through spring and summer, fCO2sw decreases by approximately 60 μatm, due to biological carbon consumption, which is not fully counteracted by the fCO2sw increase due to summer warming. The changes are synchronous with changes in chl-a concentrations and MLD, both of which are exponentially correlated with fCO2sw in off-shelf regions.

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Climate Response to External Sources of Freshwater: North Atlantic versus the Southern Ocean

Journal of Climate ◽

10.1175/jcli4015.1 ◽

2007 ◽

Vol 20 (3) ◽

pp. 436-448 ◽

Cited By ~ 102

Author(s):

Ronald J. Stouffer ◽

Dan Seidov ◽

Bernd J. Haupt

Keyword(s):

Southern Ocean ◽

Southern Hemisphere ◽

North Atlantic ◽

Surface Waters ◽

Real World ◽

The Other ◽

Sea Surface ◽

The North ◽

The North Atlantic ◽

The Antarctic

Abstract The response of an atmosphere–ocean general circulation model (AOGCM) to perturbations of freshwater fluxes across the sea surface in the North Atlantic and Southern Ocean is investigated. The purpose of this study is to investigate aspects of the so-called bipolar seesaw where one hemisphere warms and the other cools and vice versa due to changes in the ocean meridional overturning. The experimental design is idealized where 1 Sv (1 Sv ≡ 106 m3 s−1) of freshwater is added to the ocean surface for 100 model years and then removed. In one case, the freshwater perturbation is located in the Atlantic Ocean from 50° to 70°N. In the second case, it is located south of 60°S in the Southern Ocean. In the case where the North Atlantic surface waters are freshened, the Atlantic thermohaline circulation (THC) and associated northward oceanic heat transport weaken. In the Antarctic surface freshening case, the Atlantic THC is mainly unchanged with a slight weakening toward the end of the integration. This weakening is associated with the spreading of the fresh sea surface anomaly from the Southern Ocean into the rest of the World Ocean. There are two mechanisms that may be responsible for such weakening of the Atlantic THC. First is that the sea surface salinity (SSS) contrast between the North Atlantic and North Pacific is reduced. And, second, when freshwater from the Southern Ocean reaches the high latitudes of the North Atlantic Ocean, it hinders the sinking of the surface waters, leading to the weakening of the THC. The spreading of the fresh SSS anomaly from the Southern Ocean into the surface waters worldwide was not seen in earlier experiments. Given the geography and climatology of the Southern Hemisphere where the climatological surface winds push the surface waters northward away from the Antarctic continent, it seems likely that the spreading of the fresh surface water anomaly could occur in the real world. A remarkable symmetry between the two freshwater perturbation experiments in the surface air temperature (SAT) response can be seen. In both cases, the hemisphere with the freshwater perturbation cools, while the opposite hemisphere warms slightly. In the zonally averaged SAT figures, both the magnitude and the pattern of the anomalies look similar between the two cases. The oceanic response, on the other hand, is very different for the two freshwater cases, as noted above for the spreading of the SSS anomaly and the associated THC response. If the differences between the atmospheric and oceanic responses apply to the real world, then the interpretation of paleodata may need to be revisited. To arrive at a correct interpretation, it matters whether or not the evidence is mainly of atmospheric or oceanic origin. Also, given the sensitivity of the results to the exact details of the freshwater perturbation locations, especially in the Southern Hemisphere, a more realistic scenario must be constructed to explore these questions.

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Large Enrichment of Anthropogenic Organic Matter Degrading Bacteria in the Sea-Surface Microlayer at Coastal Livingston Island (Antarctica)

Frontiers in Microbiology ◽

10.3389/fmicb.2020.571983 ◽

2020 ◽

Vol 11 ◽

Author(s):

Alícia Martinez-Varela ◽

Gemma Casas ◽

Benjamin Piña ◽

Jordi Dachs ◽

Maria Vila-Costa

Keyword(s):

Organic Matter ◽

Sea Surface ◽

Surface Microlayer ◽

Livingston Island ◽

Sea Surface Microlayer ◽

Degrading Bacteria

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Palynological evidence of sea-surface conditions in the Barents Sea off northeast Svalbard during the postglacial period

Quaternary Research ◽

10.1017/qua.2020.2 ◽

2020 ◽

pp. 1-15

Author(s):

Camille Brice ◽

Anne de Vernal ◽

Elena Ivanova ◽

Simon van Bellen ◽

Nicolas Van Nieuwenhove

Keyword(s):

Sea Ice ◽

Surface Waters ◽

Barents Sea ◽

Ice Cover ◽

Atlantic Water ◽

Transitional Period ◽

Sea Surface ◽

Sea Surface Salinity ◽

Surface Conditions ◽

The Barents Sea

Abstract Postglacial changes in sea-surface conditions, including sea-ice cover, summer temperature, salinity, and productivity were reconstructed from the analyses of dinocyst assemblages in core S2528 collected in the northwestern Barents Sea. The results show glaciomarine-type conditions until about 11,300 ± 300 cal yr BP and limited influence of Atlantic water at the surface into the Barents Sea possibly due to the proximity of the Svalbard-Barents Sea ice sheet. This was followed by a transitional period generally characterized by cold conditions with dense sea-ice cover and low-salinity pulses likely related to episodic freshwater or meltwater discharge, which lasted until 8700 ± 700 cal yr BP. The onset of “interglacial” conditions in surface waters was marked by a major change in dinocyst assemblages, from dominant heterotrophic to dominant phototrophic taxa. Until 4100 ± 150 cal yr BP, however, sea-surface conditions remained cold, while sea-surface salinity and sea-ice cover recorded large amplitude variations. By ~4000 cal yr BP optimum sea-surface temperature of up to 4°C in summer and maximum salinity of ~34 psu suggest enhanced influence of Atlantic water, and productivity reached up to 150 gC/m2/yr. After 2200 ± 1300 cal yr BP, a distinct cooling trend accompanied by sea-ice spreading characterized surface waters. Hence, during the Holocene, with exception of an interval spanning about 4000 to 2000 cal yr BP, the northern Barents Sea experienced harsh environments, relatively low productivity, and unstable conditions probably unsuitable for human settlements.

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Isotopic fractionation of carbon during uptake by phytoplankton across the South Atlantic subtropical convergence

Biogeosciences ◽

10.5194/bg-16-3621-2019 ◽

2019 ◽

Vol 16 (18) ◽

pp. 3621-3635 ◽

Cited By ~ 2

Author(s):

Robyn E. Tuerena ◽

Raja S. Ganeshram ◽

Matthew P. Humphreys ◽

Thomas J. Browning ◽

Heather Bouman ◽

...

Keyword(s):

Food Web ◽

Cell Size ◽

Surface Waters ◽

Isotopic Fractionation ◽

Water Masses ◽

Global Ocean ◽

Carbon Uptake ◽

The South ◽

Marine Food Web ◽

Marine Food

Abstract. The stable isotopic composition of particulate organic carbon (δ13CPOC) in the surface waters of the global ocean can vary with the aqueous CO2 concentration ([CO2(aq)]) and affects the trophic transfer of carbon isotopes in the marine food web. Other factors such as cell size, growth rate and carbon concentrating mechanisms decouple this observed correlation. Here, the variability in δ13CPOC is investigated in surface waters across the south subtropical convergence (SSTC) in the Atlantic Ocean, to determine carbon isotope fractionation (εp) by phytoplankton and the contrasting mechanisms of carbon uptake in the subantarctic and subtropical water masses. Our results indicate that cell size is the primary determinant of δ13CPOC across the Atlantic SSTC in summer. Combining cell size estimates with CO2 concentrations, we can accurately estimate εp within the varying surface water masses in this region. We further utilize these results to investigate future changes in εp with increased anthropogenic carbon availability. Our results suggest that smaller cells, which are prevalent in the subtropical ocean, will respond less to increased [CO2(aq)] than the larger cells found south of the SSTC and in the wider Southern Ocean. In the subantarctic water masses, isotopic fractionation during carbon uptake will likely increase, both with increasing CO2 availability to the cell, but also if increased stratification leads to decreases in average community cell size. Coupled with decreasing δ13C of [CO2(aq)] due to anthropogenic CO2 emissions, this change in isotopic fractionation and lowering of δ13CPOC may propagate through the marine food web, with implications for the use of δ13CPOC as a tracer of dietary sources in the marine environment.

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