This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
. Air-sea fluxes of dimethyl sulphide (DMS) and methanethiol (MeSH) from surface seawater in the ... more . Air-sea fluxes of dimethyl sulphide (DMS) and methanethiol (MeSH) from surface seawater in the remote Southern Pacific Ocean were measured in three Air-Sea Interface Tank (ASIT) experiments during the Sea2Cloud voyage in March 2020. The measured fluxes of 0.78 ± 0.44 ng m-2 s-1 and 0.05 ± 0.03 ng m-2 s-1 for DMS and MeSH, respectively, varied between experiments reflecting the different water mass types investigated, with lowest fluxes with subtropical water and highest with biologically-active water with sub-Tropical water and highest from the sub-Tropical Front. Measured DMS fluxes were consistent with calculated fluxes from a two-layer model using DMS concentration in the ASIT seawater. The experiments also determined the influence of elevated ozone, with one ASIT headspace amended with 10 ppbv ozone while the other provided an unamended control. Elevated ozone resulted in a decrease in DMS flux, corresponding to decreased conversion of dimethylsulfoniopropionate (DMSP) to DMS in the seawater. The MeSH:DMS flux range was 11–18 % across experiments, in line with previous observations, indicating that MeSH represents a significant contribution to the atmospheric sulfur budget. Using the ASIT results in combination with ambient seawater concentrations during Sea2Cloud, significant linear correlations were identified for both DMS and MeSH fluxes with nanophytoplankton cell abundance (rDMS= 0.73 and rMeSH= 0.86), indicating an important role for this phytoplankton size class, and also its potential as a proxy for estimating DMS and MeSH emissions in chemistry-climate models.
We analyzed the seawater biogeochemistry for Dissolved Organic Carbon (DOC) composition, includin... more We analyzed the seawater biogeochemistry for Dissolved Organic Carbon (DOC) composition, including Amino Acids, Fatty acids, Chromophoric and Fluorescent DOM, and phytoplankton speciation using Flow Cytometry, optical microscopy and Flowcam. Further details of these seawater measurements are provided in Sellegri et al.
The goal of the Sea2Cloud project is to study the interplay between surface ocean biogeochemical ... more The goal of the Sea2Cloud project is to study the interplay between surface ocean biogeochemical and physical properties, fluxes to the atmosphere, and ultimately their impact on cloud formation under minimal direct anthropogenic influence. Here we present an interdisciplinary approach, combining atmospheric physics and chemistry with marine biogeochemistry, during a voyage between 41° and 47°S in March 2020. In parallel to ambient measurements of atmospheric composition and seawater biogeochemical properties, we describe semicontrolled experiments to characterize nascent sea spray properties and nucleation from gas-phase biogenic emissions. The experimental framework for studying the impact of the predicted evolution of ozone concentration in the Southern Hemisphere is also detailed. After describing the experimental strategy, we present the oceanic and meteorological context including provisional results on atmospheric thermodynamics, composition, and flux measurements. In situ me...
Future change in sea surface temperature may influence climate via various air-sea feedbacks and ... more Future change in sea surface temperature may influence climate via various air-sea feedbacks and pathways. In this study, we investigate the influence of surface seawater biogeochemical composition on the temperature dependence of sea spray number emission fluxes. Dependence of sea spray fluxes was investigated in different water masses (i.e. subantarctic, subtropical and frontal bloom) with contrasting biogeochemical properties across a temperature range from ambient (13-18°C) to 2°C, using seawater circulating in a plunging jet sea spray generator. We observed sea spray total concentration to increase significantly at temperatures below 8 °C, with an average 4-fold increase at 2°C relative to initial concentration at ambient temperatures. This temperature dependence was more pronounced for smaller size sea spray particles (i.e. nucleation and Aitken modes). Moreover, temperature dependence varied with water mass type and so biogeochemical properties. While the sea spray flux at moderate temperatures (8-11°C) was highest in frontal bloom waters, the effect of low temperature on the sea spray flux was highest with subtropical seawaters. The temperature dependence of sea spray flux was also inversely proportional to the seawater cell abundance of the cyanobacterium Synechococcus, which facilitated parameterization of temperature dependence of sea spray emission fluxes as a function of Synechococcus for future implementation in modelling exercises.
<p>Even though oceans cover over 70% of the Earth’s surfa... more <p>Even though oceans cover over 70% of the Earth’s surface, the ways in which oceans interact with climate are not fully known. Marine micro-organisms such as phytoplankton can play an important role in regulating climate by releasing different chemical species into air. In air these chemical species can react and form new aerosol particles. If grown to large enough sizes, aerosols can influence climate by acting as cloud condensation nuclei which influence the formation and properties of clouds. Even though a connection of marine biology and climate through aerosol formation was first proposed already over 30 years ago, the processes related to this connection are still uncertain.</p><p>To unravel how seawater properties affect aerosol formation and to identify which chemical species are responsible for aerosol formation, we built two Air-Sea-Interaction Tanks (ASIT) that isolate 1000 l of seawater and 1000 l of air directly above the water. The used seawater was collected from different locations during a ship campaign on board the R/V Tangaroa in the South West Pacific Ocean, close to Chatham Rise, east of New Zealand. Seawater from one location was kept in the tanks for 2-3 days and then changed. By using seawater collected from different locations, we could obtain water with different biological populations. To monitor the seawater, we took daily samples to determine its chemical and biological properties.</p><p>The air in the tanks was continuously flushed with particle filtered air. This way the air had on average 40 min to interact with the seawater surface before being sampled. Our air sampling was continuous and consisted of aerosol and air chemistry measurements. The instrumentation included measurements of aerosol number concentration from 1 to 500 nm and  chemical species ranging from ozone and sulphur dioxide to volatile organic compounds and chemical composition of molecular clusters.</p><p>Joining the seawater and atmospheric data together can give us an idea of what chemical species are emitted from the water into the atmosphere and whether these species can form new aerosol particles. Our preliminary results show a small number of particles in the freshly nucleated size range of 1-3 nm in the ASIT headspaces, indicating that new aerosol particles can form in the ASIT headspaces. In this presentation, we will also explore which chemical species could be responsible for aerosol formation and which plankton groups could be related to the emissions of these species. Combining these results with ambient data and modelling work can shed light on how important new particle formation from marine sources is for climate.</p><p>Acknowledgements: Sea2Cloud project is funded by European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 771369).</p>
The effects of elevated concentrations of dissolved inorganic phosphate in seawater on the growth... more The effects of elevated concentrations of dissolved inorganic phosphate in seawater on the growth and survival of juvenile abalone, Haliotis iris
INTRODUCTION 3 1.1 Overview What are rhodoliths? Distribution Structure and ecosystem functions o... more INTRODUCTION 3 1.1 Overview What are rhodoliths? Distribution Structure and ecosystem functions of rhodolith beds Knowledge about rhodoliths in New Zealand Threats and vulnerability 1.2 Objectives 1.2.1 Overall Objectives 1.2.2 Specific Objectives 2. METHODS 8 Species investigated Locations and sites 2.1 Objective 1 2.1.1 Characterisation of the beds: qualitative and quantitative site characteristics 2.1.1.1 Mapping the beds 2.1.1.2 Physical characteristics of the beds: in situ characterisation of the habitat a. Sediment characteristics b. Light, temperature, and water motion 2.1.2 Characterisation of biodiversity of the rhodolith beds 2.1.2.1 Sampling protocols 2.1.2.2 Processing of samples a. Rhodolith species composition and attributes i. Number ii. Size and shape iii. Growth b. Identification of associated diversity i. Invertebrates ii. Macroalgae iii. Fish 2.1.2.3 Data analyses a. Diversity and community comparisons b. Rarity 2.2 Objective 2 2.2.1 Techniques for measurement of rhodolith growth and condition a. Buoyant weight b. Alizarin red c.
elevated atmospheric Co 2 concentrations are contributing to ocean acidification (reduced seawate... more elevated atmospheric Co 2 concentrations are contributing to ocean acidification (reduced seawater pH and carbonate concentrations), with potentially major ramifications for marine ecosystems and their functioning. Using a novel in situ experiment we examined impacts of reduced seawater pH on Antarctic sea ice-associated microalgal communities, key primary producers and contributors to food webs. pH levels projected for the following decades-to-end of century (7.86, 7.75, 7.61), and ambient levels (7.99), were maintained for 15 d in under-ice incubation chambers. Light, temperature and dissolved oxygen within the chambers were logged to track diurnal variation, with pH, o 2 , salinity and nutrients assessed daily. Uptake of Co 2 occurred in all treatments, with pH levels significantly elevated in the two extreme treatments. At the lowest pH, despite the utilisation of Co 2 by the productive microalgae, pH did not return to ambient levels and carbonate saturation states remained low; a potential concern for organisms utilising this under-ice habitat. However, microalgal community biomass and composition were not significantly affected and only modest productivity increases were noted, suggesting subtle or slightly positive effects on under-ice algae. This in situ information enables assessment of the influence of future ocean acidification on under-ice community characteristics in a key coastal Antarctic habitat. Physical and biogeochemical changes in the world's oceans associated with anthropogenic greenhouse gas emissions have potential to impact marine organisms and ecosystems 1,2. Ocean acidification, the decline in seawater pH (and concomitant decline in carbonate saturation state) as the oceans absorb more CO 2 , is anticipated to affect organism function 3 and alter marine food web dynamics (e.g. 4). Oceanic pH is predicted to decline by −0.33 pH units by 2090-2099 (relative to 1990-1999 levels) under the current trajectory of the "business as usual" Representative Concentration Pathway emissions scenario (RCP8.5) 5. This represents a considerably faster rate of change, and lower pH, than at any time in the last 25 million years 6 , raising questions of how organisms, populations and communities will respond to this potential challenge that, in some cases, may transcend adaptation capacity time scales. The threat of ocean acidification is particularly great in cold water environments, where CO 2 is absorbed more readily and calcium carbonate minerals are more soluble 7,8. Absorption of CO 2 is occurring more quickly in the Southern Ocean than in subtropical oceans, and its water chemistry is changing at a higher rate than previously predicted 9. That such high latitude regions will experience early ocean acidification, altering benthic and pelagic ecosystems, is a high confidence statement in the most recent Intergovernmental Panel on Climate Change report 10. Seasonally undersaturated carbonate conditions, predicted for the Southern Ocean in the coming decades (i.e. by 2030 in winter months in the Ross Sea 11 ; and by austral summer of 2026-2030 in the Ross Sea, Amundsen Sea and coastal Amundsen Sea 12), will also spread rapidly in aerial extent and temporal durationparticularly from 2040 onwards when atmospheric CO 2 is around 450-500 μatm 9. Antarctic sea ice supports a diverse community of primary producers and consumers, and represents an important multi-trophic module within the broader marine ecosystem 13. Sea ice-associated microalgal communities contribute significantly to seasonal production 13 , with estimates of 10-50% of the annual production of polar seas 14 and as much as 55-65% in ice covered coastal ecosystems 15. Under-ice algal assemblages are an important food resource, not only to organisms utilising the underside of the ice, but also to the benthos below, as ice algae and detritus sink down to the seafloor, seeding microphytobenthic communities and providing a
Developing a New Zealand wide coastal bio-indicator of nitrogen loading using patterns of tissue-... more Developing a New Zealand wide coastal bio-indicator of nitrogen loading using patterns of tissue-δ15N and tissue-N in Ulva macro algae
... Thanks to Nick, Hernando, Paul, Darren, Megan, Charlie, Jake, James and Caroline, Caroline, T... more ... Thanks to Nick, Hernando, Paul, Darren, Megan, Charlie, Jake, James and Caroline, Caroline, Timo and Carolyn, Natalie, Claire, Tim, and all the other friends and students I might have forgotten to mention at the lab during my time for your camaraderie and the good times. ...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
. Air-sea fluxes of dimethyl sulphide (DMS) and methanethiol (MeSH) from surface seawater in the ... more . Air-sea fluxes of dimethyl sulphide (DMS) and methanethiol (MeSH) from surface seawater in the remote Southern Pacific Ocean were measured in three Air-Sea Interface Tank (ASIT) experiments during the Sea2Cloud voyage in March 2020. The measured fluxes of 0.78 ± 0.44 ng m-2 s-1 and 0.05 ± 0.03 ng m-2 s-1 for DMS and MeSH, respectively, varied between experiments reflecting the different water mass types investigated, with lowest fluxes with subtropical water and highest with biologically-active water with sub-Tropical water and highest from the sub-Tropical Front. Measured DMS fluxes were consistent with calculated fluxes from a two-layer model using DMS concentration in the ASIT seawater. The experiments also determined the influence of elevated ozone, with one ASIT headspace amended with 10 ppbv ozone while the other provided an unamended control. Elevated ozone resulted in a decrease in DMS flux, corresponding to decreased conversion of dimethylsulfoniopropionate (DMSP) to DMS in the seawater. The MeSH:DMS flux range was 11–18 % across experiments, in line with previous observations, indicating that MeSH represents a significant contribution to the atmospheric sulfur budget. Using the ASIT results in combination with ambient seawater concentrations during Sea2Cloud, significant linear correlations were identified for both DMS and MeSH fluxes with nanophytoplankton cell abundance (rDMS= 0.73 and rMeSH= 0.86), indicating an important role for this phytoplankton size class, and also its potential as a proxy for estimating DMS and MeSH emissions in chemistry-climate models.
We analyzed the seawater biogeochemistry for Dissolved Organic Carbon (DOC) composition, includin... more We analyzed the seawater biogeochemistry for Dissolved Organic Carbon (DOC) composition, including Amino Acids, Fatty acids, Chromophoric and Fluorescent DOM, and phytoplankton speciation using Flow Cytometry, optical microscopy and Flowcam. Further details of these seawater measurements are provided in Sellegri et al.
The goal of the Sea2Cloud project is to study the interplay between surface ocean biogeochemical ... more The goal of the Sea2Cloud project is to study the interplay between surface ocean biogeochemical and physical properties, fluxes to the atmosphere, and ultimately their impact on cloud formation under minimal direct anthropogenic influence. Here we present an interdisciplinary approach, combining atmospheric physics and chemistry with marine biogeochemistry, during a voyage between 41° and 47°S in March 2020. In parallel to ambient measurements of atmospheric composition and seawater biogeochemical properties, we describe semicontrolled experiments to characterize nascent sea spray properties and nucleation from gas-phase biogenic emissions. The experimental framework for studying the impact of the predicted evolution of ozone concentration in the Southern Hemisphere is also detailed. After describing the experimental strategy, we present the oceanic and meteorological context including provisional results on atmospheric thermodynamics, composition, and flux measurements. In situ me...
Future change in sea surface temperature may influence climate via various air-sea feedbacks and ... more Future change in sea surface temperature may influence climate via various air-sea feedbacks and pathways. In this study, we investigate the influence of surface seawater biogeochemical composition on the temperature dependence of sea spray number emission fluxes. Dependence of sea spray fluxes was investigated in different water masses (i.e. subantarctic, subtropical and frontal bloom) with contrasting biogeochemical properties across a temperature range from ambient (13-18°C) to 2°C, using seawater circulating in a plunging jet sea spray generator. We observed sea spray total concentration to increase significantly at temperatures below 8 °C, with an average 4-fold increase at 2°C relative to initial concentration at ambient temperatures. This temperature dependence was more pronounced for smaller size sea spray particles (i.e. nucleation and Aitken modes). Moreover, temperature dependence varied with water mass type and so biogeochemical properties. While the sea spray flux at moderate temperatures (8-11°C) was highest in frontal bloom waters, the effect of low temperature on the sea spray flux was highest with subtropical seawaters. The temperature dependence of sea spray flux was also inversely proportional to the seawater cell abundance of the cyanobacterium Synechococcus, which facilitated parameterization of temperature dependence of sea spray emission fluxes as a function of Synechococcus for future implementation in modelling exercises.
<p>Even though oceans cover over 70% of the Earth’s surfa... more <p>Even though oceans cover over 70% of the Earth’s surface, the ways in which oceans interact with climate are not fully known. Marine micro-organisms such as phytoplankton can play an important role in regulating climate by releasing different chemical species into air. In air these chemical species can react and form new aerosol particles. If grown to large enough sizes, aerosols can influence climate by acting as cloud condensation nuclei which influence the formation and properties of clouds. Even though a connection of marine biology and climate through aerosol formation was first proposed already over 30 years ago, the processes related to this connection are still uncertain.</p><p>To unravel how seawater properties affect aerosol formation and to identify which chemical species are responsible for aerosol formation, we built two Air-Sea-Interaction Tanks (ASIT) that isolate 1000 l of seawater and 1000 l of air directly above the water. The used seawater was collected from different locations during a ship campaign on board the R/V Tangaroa in the South West Pacific Ocean, close to Chatham Rise, east of New Zealand. Seawater from one location was kept in the tanks for 2-3 days and then changed. By using seawater collected from different locations, we could obtain water with different biological populations. To monitor the seawater, we took daily samples to determine its chemical and biological properties.</p><p>The air in the tanks was continuously flushed with particle filtered air. This way the air had on average 40 min to interact with the seawater surface before being sampled. Our air sampling was continuous and consisted of aerosol and air chemistry measurements. The instrumentation included measurements of aerosol number concentration from 1 to 500 nm and  chemical species ranging from ozone and sulphur dioxide to volatile organic compounds and chemical composition of molecular clusters.</p><p>Joining the seawater and atmospheric data together can give us an idea of what chemical species are emitted from the water into the atmosphere and whether these species can form new aerosol particles. Our preliminary results show a small number of particles in the freshly nucleated size range of 1-3 nm in the ASIT headspaces, indicating that new aerosol particles can form in the ASIT headspaces. In this presentation, we will also explore which chemical species could be responsible for aerosol formation and which plankton groups could be related to the emissions of these species. Combining these results with ambient data and modelling work can shed light on how important new particle formation from marine sources is for climate.</p><p>Acknowledgements: Sea2Cloud project is funded by European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 771369).</p>
The effects of elevated concentrations of dissolved inorganic phosphate in seawater on the growth... more The effects of elevated concentrations of dissolved inorganic phosphate in seawater on the growth and survival of juvenile abalone, Haliotis iris
INTRODUCTION 3 1.1 Overview What are rhodoliths? Distribution Structure and ecosystem functions o... more INTRODUCTION 3 1.1 Overview What are rhodoliths? Distribution Structure and ecosystem functions of rhodolith beds Knowledge about rhodoliths in New Zealand Threats and vulnerability 1.2 Objectives 1.2.1 Overall Objectives 1.2.2 Specific Objectives 2. METHODS 8 Species investigated Locations and sites 2.1 Objective 1 2.1.1 Characterisation of the beds: qualitative and quantitative site characteristics 2.1.1.1 Mapping the beds 2.1.1.2 Physical characteristics of the beds: in situ characterisation of the habitat a. Sediment characteristics b. Light, temperature, and water motion 2.1.2 Characterisation of biodiversity of the rhodolith beds 2.1.2.1 Sampling protocols 2.1.2.2 Processing of samples a. Rhodolith species composition and attributes i. Number ii. Size and shape iii. Growth b. Identification of associated diversity i. Invertebrates ii. Macroalgae iii. Fish 2.1.2.3 Data analyses a. Diversity and community comparisons b. Rarity 2.2 Objective 2 2.2.1 Techniques for measurement of rhodolith growth and condition a. Buoyant weight b. Alizarin red c.
elevated atmospheric Co 2 concentrations are contributing to ocean acidification (reduced seawate... more elevated atmospheric Co 2 concentrations are contributing to ocean acidification (reduced seawater pH and carbonate concentrations), with potentially major ramifications for marine ecosystems and their functioning. Using a novel in situ experiment we examined impacts of reduced seawater pH on Antarctic sea ice-associated microalgal communities, key primary producers and contributors to food webs. pH levels projected for the following decades-to-end of century (7.86, 7.75, 7.61), and ambient levels (7.99), were maintained for 15 d in under-ice incubation chambers. Light, temperature and dissolved oxygen within the chambers were logged to track diurnal variation, with pH, o 2 , salinity and nutrients assessed daily. Uptake of Co 2 occurred in all treatments, with pH levels significantly elevated in the two extreme treatments. At the lowest pH, despite the utilisation of Co 2 by the productive microalgae, pH did not return to ambient levels and carbonate saturation states remained low; a potential concern for organisms utilising this under-ice habitat. However, microalgal community biomass and composition were not significantly affected and only modest productivity increases were noted, suggesting subtle or slightly positive effects on under-ice algae. This in situ information enables assessment of the influence of future ocean acidification on under-ice community characteristics in a key coastal Antarctic habitat. Physical and biogeochemical changes in the world's oceans associated with anthropogenic greenhouse gas emissions have potential to impact marine organisms and ecosystems 1,2. Ocean acidification, the decline in seawater pH (and concomitant decline in carbonate saturation state) as the oceans absorb more CO 2 , is anticipated to affect organism function 3 and alter marine food web dynamics (e.g. 4). Oceanic pH is predicted to decline by −0.33 pH units by 2090-2099 (relative to 1990-1999 levels) under the current trajectory of the "business as usual" Representative Concentration Pathway emissions scenario (RCP8.5) 5. This represents a considerably faster rate of change, and lower pH, than at any time in the last 25 million years 6 , raising questions of how organisms, populations and communities will respond to this potential challenge that, in some cases, may transcend adaptation capacity time scales. The threat of ocean acidification is particularly great in cold water environments, where CO 2 is absorbed more readily and calcium carbonate minerals are more soluble 7,8. Absorption of CO 2 is occurring more quickly in the Southern Ocean than in subtropical oceans, and its water chemistry is changing at a higher rate than previously predicted 9. That such high latitude regions will experience early ocean acidification, altering benthic and pelagic ecosystems, is a high confidence statement in the most recent Intergovernmental Panel on Climate Change report 10. Seasonally undersaturated carbonate conditions, predicted for the Southern Ocean in the coming decades (i.e. by 2030 in winter months in the Ross Sea 11 ; and by austral summer of 2026-2030 in the Ross Sea, Amundsen Sea and coastal Amundsen Sea 12), will also spread rapidly in aerial extent and temporal durationparticularly from 2040 onwards when atmospheric CO 2 is around 450-500 μatm 9. Antarctic sea ice supports a diverse community of primary producers and consumers, and represents an important multi-trophic module within the broader marine ecosystem 13. Sea ice-associated microalgal communities contribute significantly to seasonal production 13 , with estimates of 10-50% of the annual production of polar seas 14 and as much as 55-65% in ice covered coastal ecosystems 15. Under-ice algal assemblages are an important food resource, not only to organisms utilising the underside of the ice, but also to the benthos below, as ice algae and detritus sink down to the seafloor, seeding microphytobenthic communities and providing a
Developing a New Zealand wide coastal bio-indicator of nitrogen loading using patterns of tissue-... more Developing a New Zealand wide coastal bio-indicator of nitrogen loading using patterns of tissue-δ15N and tissue-N in Ulva macro algae
... Thanks to Nick, Hernando, Paul, Darren, Megan, Charlie, Jake, James and Caroline, Caroline, T... more ... Thanks to Nick, Hernando, Paul, Darren, Megan, Charlie, Jake, James and Caroline, Caroline, Timo and Carolyn, Natalie, Claire, Tim, and all the other friends and students I might have forgotten to mention at the lab during my time for your camaraderie and the good times. ...
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