ORCID Profile
0000-0002-2395-9471
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Physical Oceanography | Oceanography | Biological Oceanography | Climate Change Processes | Atmospheric Sciences | Chemical Oceanography | Atmospheric Dynamics | Meteorology | Oceanography | Biological Oceanography | Glaciology | Cloud Physics | Chemical Oceanography | Physical Oceanography | Physical oceanography | Turbulent Flows | Biological oceanography | Chemical oceanography |
ANZSRC Socio-Economic Objective (SEO)
Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Climate Change Models | Physical and Chemical Conditions of Water in Marine Environments | Expanding Knowledge in the Earth Sciences | Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts) | Atmospheric Processes and Dynamics | Climate Variability (excl. Social Impacts) | Atmospheric composition | Climate change | Physical and chemical conditions | Expanding Knowledge in the Environmental Sciences | Expanding Knowledge in the Information and Computing Sciences | Ecosystem Assessment and Management of Marine Environments
Related Links
Publications
Quantifying the influence of sub-mesoscale dynamics on the supply of iron to Southern Ocean phytoplankton blooms
Publisher: Elsevier BV
Date: 09-2016
Supplementary material to "Biogeochemical variability in the equatorial Indian Ocean during the monsoon transition"
Publisher: Copernicus GmbH
Date: 29-04-2014
Widespread And Unprecedented Phytoplankton Blooms Triggered By 2019–2020 Australian Wildfires
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-9414
Abstract: & & Droughts and climate-change-driven warming lead to more frequent and intense wildfires, arguably contributing to the severe 2019& #8211 Australian wildfires. The environmental and ecological impacts of the fires include loss of habitats and the emission of substantial amounts of atmospheric aerosols. Aerosol emissions from wildfires can lead to the atmospheric transport of macronutrients and bio-essential trace metals such as nitrogen and iron, respectively. Previous works suggested that the oceanic deposition of wildfire aerosols can relieve nutrient limitations and, consequently, enhance marine productivity, but direct observations are lacking. Here we use satellite and autonomous biogeochemical Argo float data to evaluate the effect of 2019& #8211 Australian wildfire aerosol deposition on phytoplankton productivity. We find widespread and long-lasting phytoplankton blooms in the Southern Ocean downwind of Australia. Aerosol s les originating from the Australian wildfires contained a high iron content, and atmospheric trajectories show that these aerosols were likely to be transported to the bloom regions, suggesting that the blooms resulted from the fertilization of the iron-limited waters of the Southern Ocean.& &
Southern Ocean productivity in relation to spatial and temporal variation in the physical environment
Publisher: American Geophysical Union (AGU)
Date: 18-01-2003
DOI: 10.1029/2001JC001270
Indonesian throughflow nutrient fluxes and their potential impact on Indian Ocean productivity
Publisher: American Geophysical Union (AGU)
Date: 17-07-2014
DOI: 10.1002/2014GL060593
Biogeochemical‐Argo floats show that chlorophyll increases before carbon in the high‐latitude Southern Ocean spring bloom
Publisher: Wiley
Date: 04-05-2023
DOI: 10.1002/LOL2.10322
Abstract: In the Southern Ocean, phytoplankton blooms are an annually recurring prominent feature that play a significant role in ocean CO 2 uptake. Understanding the timing of the phytoplankton bloom is necessary to provide insights into the underlying physiological drivers, for the study of ecosystem dynamics and consequent patterns in downward carbon export. Previous studies have used chlorophyll (chl) and particulate organic carbon, from either satellites or biogeochemical‐Argo (BGC‐Argo) floats, to investigate bloom phenology, but provide inconsistent findings regarding bloom timing. Here, we compare bloom dynamics based on three diagnostics from 7114 BGC‐Argo float profiles, south of 60°S. Bloom onset consistently occurs earlier when calculated using chl than when based on phytoplankton carbon or nitrate uptake, and the decoupling increases with latitude. This suggests that phytoplankton synthesize increased chl to acclimate to low‐light conditions, before increasing their biomass. These results highlight the importance of considering phytoplankton physiology when choosing proxies for phytoplankton growth.
Seasonality of downward carbon export in the Pacific Southern Ocean revealed by multi-year robotic observations
Publisher: Springer Science and Business Media LLC
Date: 08-03-2023
The Sensitivity Analysis on GNSS-R Soil Moisture Retrieval
Publisher: IEEE
Date: 21-11-2021
Subsurface Chlorophyll-a Maxima in the Southern Ocean
Publisher: Frontiers Media SA
Date: 14-08-2020
Climate change alters stability and species potential interactions in a large marine ecosystem
Publisher: Wiley
Date: 06-10-2017
DOI: 10.1111/GCB.13891
Abstract: We have little empirical evidence of how large-scale overlaps between large numbers of marine species may have altered in response to human impacts. Here, we synthesized all available distribution data (>1 million records) since 1992 for 61 species of the East Australian marine ecosystem, a global hot spot of ocean warming and continuing fisheries exploitation. Using a novel approach, we constructed networks of the annual changes in geographical overlaps between species. Using indices of changes in species overlap, we quantified changes in the ecosystem stability, species robustness, species sensitivity and structural keystone species. We then compared the species overlap indices with environmental and fisheries data to identify potential factors leading to the changes in distributional overlaps between species. We found that the structure of the ecosystem has changed with a decrease in asymmetrical geographical overlaps between species. This suggests that the ecosystem has become less stable and potentially more susceptible to environmental perturbations. Most species have shown a decrease in overlaps with other species. The greatest decrease in species overlap robustness and sensitivity to the loss of other species has occurred in the pelagic community. Some demersal species have become more robust and less sensitive. Pelagic structural keystone species, predominately the tunas and billfish, have been replaced by demersal fish species. The changes in species overlap were strongly correlated with regional oceanographic changes, in particular increasing ocean warming and the southward transport of warmer and saltier water with the East Australian Current, but less correlated with fisheries catch. Our study illustrates how large-scale multispecies distribution changes can help identify structural changes in marine ecosystems associated with climate change.
Illegal fishing bycatch overshadows climate as a driver of albatross population decline
Publisher: Inter-Research Science Center
Date: 14-09-2017
DOI: 10.3354/MEPS12248
Environmental associations with broad‐scale Japanese and Taiwanese pelagic longline effort in the southern I ndian and A tlantic O ceans
Publisher: Wiley
Date: 09-2015
DOI: 10.1111/FOG.12123
The Unusual Surface Chlorophyll Signatures of Southern Ocean Eddies
Publisher: American Geophysical Union (AGU)
Date: 09-2018
DOI: 10.1029/2017JC013628
Relationships Between Air‐Sea CO2 Flux and New Production in the Equatorial Pacific
Publisher: American Geophysical Union (AGU)
Date: 30-03-2022
DOI: 10.1029/2021GB007121
Abstract: The equatorial Pacific is the largest oceanic source of carbon dioxide to the atmosphere. This outgassing varies depending on the El Niño‐Southern Oscillation (ENSO) and decadal climate variability. New production, the amount of phytoplankton net primary production driven by upwelled nitrate, plays a significant role in modulating air‐sea CO 2 fluxes as the biological carbon pump removes carbon from the surface ocean. We aim to understand how the physical drivers of sea surface temperature and wind speed influence interannual and decadal variability of the equatorial Pacific carbon cycle. In the equatorial Pacific, there are three biogeochemical regimes: the upwelling cold tongue east of 140°W and south of the equator (3°N–15°S) the eastern Pacific warm pool north of the equator (3°–15°N) and the 28.5°C western Pacific warm pool, west of 140°W. We find that between 2000 and 2020, air‐sea CO 2 flux and Δ p CO 2 increased in the cold tongue (45 mmolC m −2 yr −2 , 1.5 μatm yr −1 , respectively) but decreased elsewhere, while new production decreased everywhere. The western Pacific occasionally became a weak carbon sink, depending on ENSO and this sink was strongest at 165°E during central Pacific “Modoki” El Niño events. We find that changes in wind speed, temperature and ENSO frequency have altered the surface carbon budget. The mean basin‐wide (150°E−90°W and 15°N–15°S) new production for 2000–2020 was 1.2 ± 0.1 PgC yr −1 and air‐sea CO 2 flux was 0.5 ± 0.1 PgC yr −1 . New production decreased at −7.7 ± 1.6 TgC yr −2 , compared to the CO 2 flux trend of −1.7 ± 1.4 TgC yr −2 .
An Assessment and Improvement of Satellite Ocean Color Algorithms for the Tropical Pacific Ocean
Publisher: American Geophysical Union (AGU)
Date: 12-2019
DOI: 10.1029/2019JC015498
The subsurface biological structure of Southern Ocean eddies revealed by BGC-Argo floats
Publisher: Elsevier BV
Date: 08-2021
Insights into projected changes in marine heatwaves from a high-resolution ocean circulation model
Publisher: Springer Science and Business Media LLC
Date: 28-08-2020
DOI: 10.1038/S41467-020-18241-X
Abstract: Global climate models project the intensification of marine heatwaves in coming decades due to global warming. However, the spatial resolution of these models is inadequate to resolve mesoscale processes that dominate variability in boundary current regions where societal and economic impacts of marine heatwaves are substantial. Here we compare the historical and projected changes in marine heatwaves in a 0.1° ocean model with 23 coarser-resolution climate models. Western boundary currents are the regions where the models disagree the most with observations and among themselves in simulating marine heatwaves of the past and the future. The lack of eddy-driven variability in the coarse-resolution models results in less intense marine heatwaves over the historical period and greater intensification in the coming decades. Although the projected changes agree well at the global scale, the greater spatial details around western boundary currents provided by the high-resolution model may be valuable for effective adaptation planning.
Calving Event Led to Changes in Phytoplankton Bloom Phenology in the Mertz Polynya, Antarctica
Publisher: American Geophysical Union (AGU)
Date: 11-2020
DOI: 10.1029/2020JC016387
Southern Ocean Iron Enrichment Experiment: Carbon Cycling in High- and Low-Si Waters
Publisher: American Association for the Advancement of Science (AAAS)
Date: 16-04-2004
Abstract: The availability of iron is known to exert a controlling influence on biological productivity in surface waters over large areas of the ocean and may have been an important factor in the variation of the concentration of atmospheric carbon dioxide over glacial cycles. The effect of iron in the Southern Ocean is particularly important because of its large area and abundant nitrate, yet iron-enhanced growth of phytoplankton may be differentially expressed between waters with high silicic acid in the south and low silicic acid in the north, where diatom growth may be limited by both silicic acid and iron. Two mesoscale experiments, designed to investigate the effects of iron enrichment in regions with high and low concentrations of silicic acid, were performed in the Southern Ocean. These experiments demonstrate iron's pivotal role in controlling carbon uptake and regulating atmospheric partial pressure of carbon dioxide.
Japanese and Taiwanese pelagic longline fleet dynamics and the impacts of climate change in the southern Indian Ocean
Publisher: Elsevier BV
Date: 06-2017
Non-linear analysis of chlorophyll a transects as a method of quantifying spatial structure
Publisher: Oxford University Press (OUP)
Date: 1996
Iron links river runoff and shelf width to phytoplankton biomass along the U.S. West Coast
Publisher: American Geophysical Union (AGU)
Date: 02-2007
DOI: 10.1029/2006GL028069
The impact of a Southern Ocean cyclonic eddy on mesopelagic micronekton
Publisher: Wiley
Date: 09-09-2021
Ice Algae Model Intercomparison Project phase 2 (IAMIP2)
Publisher: Copernicus GmbH
Date: 17-11-2020
DOI: 10.5194/GMD-2020-305
Abstract: Abstract. Ice algae play a fundamental role in shaping polar marine ecosystems and biogeochemistry. This role can be investigated by field observations, however the influence of ice algae at the regional and global scales remains unclear due to limited spatial and temporal coverage of observations, and because ice algae are typically not included in current Earth System Models. To address this knowledge gap, we introduce a new model intercomparison project (MIP), referred to here as the Ice Algae Model Intercomparison Project phase 2 (IAMIP2). IAMIP2 is built upon the experience from its previous phase, and expands its scope to global coverage (both Arctic and Antarctic) and centennial timescales (spanning the mid-twentieth century to the end of the twenty-first century). Participating models are three-dimensional regional and global coupled sea ice–ocean models that incorporate sea-ice ecosystem components. These models are driven by the same initial conditions and atmospheric forcing datasets by incorporating and expanding the protocols of the Ocean Model Intercomparison Project, an endorsed MIP of the Coupled Model Intercomparison Project phase 6 (CMIP6). Doing so provides more robust estimates of model bias and uncertainty, and consequently advances the science of polar marine ecosystems and biogeochemistry. A diagnostic protocol is designed to enhance the reusability of the model data products of IAMIP2. Lastly, the limitations and strengths of IAMIP2 are discussed in the context of prospective research outcomes.
Meridional Heat and Salt Transport Across the Subantarctic Front by Cold‐Core Eddies
Publisher: American Geophysical Union (AGU)
Date: 02-2019
DOI: 10.1029/2018JC014655
Using non-linear analysis to compare the spatial structure of chlorophyll with passive tracers
Publisher: Oxford University Press (OUP)
Date: 1997
Eddy‐induced carbon transport across the Antarctic Circumpolar Current
Publisher: American Geophysical Union (AGU)
Date: 09-2017
DOI: 10.1002/2017GB005669
Biogeochemical Argo Floats Reveal the Evolution of Subsurface Chlorophyll and Particulate Organic Carbon in Southeast Indian Ocean Eddies
Publisher: American Geophysical Union (AGU)
Date: 30-03-2023
DOI: 10.1029/2022JC018984
Abstract: Eddies modulate open ocean productivity, and this influence depends on both eddy source and evolution. Southeast Indian Ocean eddies are important pathways for the westward transport of biogeochemical anomalies from the Leeuwin current into the central oligotrophic South Indian Ocean (SIO). Eddy processes at the base of the mixed layer may stimulate and sustain phytoplankton, allowing these eddy impacts to persist over thousands of kilometers. We present 4 months of high‐frequency profiles from autonomous floats in one anticyclonic and one cyclonic eddy in the SIO. At the start of observations, from September to October, particulate organic carbon (POC) and especially chlorophyll were higher in the cyclone, and evenly distributed throughout the mixed layers in both eddies. As spring progressed and the eddies were transported westward, chlorophyll and POC concentrated at the base of the mixed layer at depths invisible to satellites, likely reflecting nutrient depletion in overlying waters. In the anticyclone, the increased chlorophyll at depth occurred as POC decreased, suggesting photo‐acclimation and thus both light and nutrient stress. In contrast, in the cyclone chlorophyll to POC ratios remained close to constant as their subsurface maxima formed. In both eddies, the subsurface biomass maxima exhibited no significant change in oxygen saturation state over several months suggesting these communities are sustained by low ongoing productivity in balance with community respiration. Thus, deep biomass layers may represent a mechanism for long‐distance transfer of eddy plankton communities which is not reflected in satellite remote sensing.
Three improved satellite chlorophyll algorithms for the Southern Ocean
Publisher: American Geophysical Union (AGU)
Date: 07-2013
DOI: 10.1002/JGRC.20270
Physical Drivers of Biogeochemical Variability in the Polar Front Meander
Publisher: American Geophysical Union (AGU)
Date: 31-05-2022
DOI: 10.1029/2021JC017863
Abstract: The Southern Ocean plays a vital role in global ocean circulation, and the Polar Front (PF) is one of its most important physical features. The PF meander south of Tasmania, around 153°E, 55°S, is a very dynamic region which spawns mesoscale eddies, and influences local biogeochemistry and sea‐air interaction. By using voyage and ancillary data, we investigated the unusually strong spring bloom in the vicinity of the PF meander in 2018. We infer that the upwelling of deep water at the front and in eddies, brings macronutrients and dissolved iron (dFe) to the surface. Chlorophyll concentration peaked at over 0.6 mg m −3 , which is anomalously high for this area. With reduced iron limitation, the physiological characteristics of phytoplankton in the northern, downstream part of the study area also changed. The photochemical efficiency was improved and released this area from its usual high‐nutrient low‐chlorophyll (HNLC) status. This was mainly indicated by the increase in the dawn Fv/Fm maximum (indictor of photochemical efficiency) from 0.2 to over 0.5. With the biomass increase and healthier community status, we observed consumption of surface dissolved inorganic carbon and increased particulate organic carbon production to about 40 μmol L −1 , forming a weak local carbon sink. Through the investigation of multiple years, a weak positive correlation between mixed layer depth shoaling and phytoplankton growth was found, but there was significant interannual variability in this relationship, likely caused by variable eddy conditions and dFe delivery.
Biogeochemical variability in the central equatorial Indian Ocean during the monsoon transition
Publisher: Copernicus GmbH
Date: 23-04-2015
Abstract: Abstract. In this paper we examine time-series measurements of near-surface chlorophyll concentration from a mooring that was deployed at 80.5°E on the equator in the Indian Ocean in 2010. These data reveal at least six striking spikes in chlorophyll from October through December, at approximately 2-week intervals, that coincide with the development of the fall Wyrtki jets during the transition between the summer and winter monsoons. Concurrent meteorological and in situ physical measurements from the mooring reveal that the chlorophyll pulses are associated with the intensification of eastward winds at the surface and eastward currents in the mixed layer. These observations are inconsistent with upwelling dynamics as they occur in the Atlantic and Pacific oceans, since eastward winds that force Wyrtki jet intensification should drive downwelling. The chlorophyll spikes could be explained by two alternative mechanisms: (1) turbulent entrainment of nutrients and/or chlorophyll from across the base of the mixed layer by wind stirring or Wyrtki jet-induced shear instability or (2) enhanced southward advection of high chlorophyll concentrations into the equatorial zone. The first mechanism is supported by the phasing and litude of the relationship between wind stress and chlorophyll, which suggests that the chlorophyll spikes are the result of turbulent entrainment driven by synoptic zonal wind events. The second mechanism is supported by the observation of eastward flows over the Chagos–Lacca e Ridge, generating high chlorophyll to the north of the equator. Occasional southward advection can then produce the chlorophyll spikes that are observed in the mooring record. Wind-forced biweekly mixed Rossby gravity waves are a ubiquitous feature of the ocean circulation in this region, and we examine the possibility that they may play a role in chlorophyll variability. Statistical analyses and results from the OFAM3 (Ocean Forecasting Australia Model, version 3) eddy-resolving model provide support for both mechanisms. However, the model does not reproduce the observed spikes in chlorophyll. Climatological satellite chlorophyll data show that the elevated chlorophyll concentrations in this region are consistently observed year after year and so are reflective of recurring large-scale wind- and circulation-induced productivity enhancement in the central equatorial Indian Ocean.
The Biogeochemical Structure of Southern Ocean Mesoscale Eddies
Publisher: American Geophysical Union (AGU)
Date: 08-2020
DOI: 10.1029/2020JC016115
Ice Algae Model Intercomparison Project phase 2 (IAMIP2)
Publisher: Copernicus GmbH
Date: 11-11-2021
Abstract: Abstract. Ice algae play a fundamental role in shaping sea-ice-associated ecosystems and biogeochemistry. This role can be investigated by field observations however the influence of ice algae at the regional and global scales remains unclear due to limited spatial and temporal coverage of observations and because ice algae are typically not included in current Earth system models. To address this knowledge gap, we introduce a new model intercomparison project (MIP), referred to here as the Ice Algae Model Intercomparison Project phase 2 (IAMIP2). IAMIP2 is built upon the experience from its previous phase and expands its scope to global coverage (both Arctic and Antarctic) and centennial timescales (spanning the mid-20th century to the end of the 21st century). Participating models are three-dimensional regional and global coupled sea-ice–ocean models that incorporate sea-ice ecosystem components. These models are driven by the same initial conditions and atmospheric forcing datasets by incorporating and expanding the protocols of the Ocean Model Intercomparison Project, an endorsed MIP of the Coupled Model Intercomparison Project phase 6 (CMIP6). Doing so provides more robust estimates of model bias and uncertainty and consequently advances the science of polar marine ecosystems and biogeochemistry. A diagnostic protocol is designed to enhance the reusability of the model data products of IAMIP2. Lastly, the limitations and strengths of IAMIP2 are discussed in the context of prospective research outcomes.
Observations of Ice Nucleating Particles Over Southern Ocean Waters
Publisher: American Geophysical Union (AGU)
Date: 05-11-2018
DOI: 10.1029/2018GL079981
Evaluating Southern Ocean Carbon Eddy-Pump From Biogeochemical-Argo Floats
Publisher: American Geophysical Union (AGU)
Date: 02-2018
DOI: 10.1002/2017JC012861
New Estimates of Southern Ocean Annual Net Community Production Revealed by BGC‐Argo Floats
Publisher: American Geophysical Union (AGU)
Date: 05-08-2022
DOI: 10.1029/2021GL097372
Abstract: Using an expanding Southern Ocean fleet of biogeochemical Argo (BGC‐Argo) floats, we developed a novel approach to estimate annual net community production (ANCP) by integrating subsurface oxygen drawdown from all available BGC‐Argo oxygen profiles. Our results suggest that, on average, 14% of remineralization occurs between 500 and 1,000 m and 15% occurs between the euphotic depth and 100 m. Using the improved methodology, we estimated total basin‐integrated ANCP in the Southern Ocean to be 3.89 GT C year −1 suggesting a more important role for the Southern Ocean in regulating oceanic carbon storage, atmospheric CO 2 exchange and climate than previously assumed.
Interannual variability in primary productivity driven by sea-ice phenology in the Amundsen Sea polynyas, not ice shelves melting.
Publisher: Copernicus GmbH
Date: 03-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-3687
Abstract: & & Ice shelves have been melting, thinning and retreating along the coast of West Antarctica for the past four decades, most notably in the Amundsen Sea sector. This area hosts two highly productive coastal polynyas, the Pine Island polynya and the Amundsen Sea polynya, whose opening triggers two of the largest phytoplankton blooms in the Southern Ocean. Previous work in the area suggests that ice shelf melting and thinning increases the iron content of coastal seawater, which could potentially boost ocean primary productivity locally. In this work, we use historical (1992-2017) remote sensing observations of net primary productivity, sea-ice concentration and rate of ice shelves melting to investigate the strength of this connection for these two large polynyas. We used the Abbot, Cosgrove, Pine Island, Thwaites, Dotson and Getz ice shelves for our analyses. Our initial results suggest no significant trends in net primary productivity though time but a large interannual variability for both polynyas. The basal melt rate and ice thinning seem to not be the main drivers of this interannual variability in these polynyas, but sea-ice coverage variability does seem to play a strong role, potentially allowing increased light availability and stratification. Further investigations of circumpolar deep water inputs and climate modes related to ice shelves melting such as El Ni& #241 o or the southern annular mode are needed to clarify our findings. Our preliminary study points the complexity of ice-ocean systems, where several co-occurring processes influence coastal primary productivity, with consequences for carbon cycling and the climate system.& &
Identifying important species that amplify or mitigate the interactive effects of human impacts on marine food webs
Publisher: Wiley
Date: 25-10-2018
DOI: 10.1111/COBI.13202
Abstract: Some species may have a larger role than others in the transfer of complex effects of multiple human stressors, such as changes in biomass, through marine food webs. We devised a novel approach to identify such species. We constructed annual interaction-effect networks (IENs) of the simulated changes in biomass between species of the southeastern Australian marine system. Each annual IEN was composed of the species linked by either an additive (sum of the in idual stressor response), synergistic (lower biomass compared with additive effects), or antagonistic (greater biomass compared with additive effects) response to the interaction effect of ocean warming, ocean acidification, and fisheries. Structurally, over the simulation period, the number of species and links in the synergistic IENs increased and the network structure became more stable. The stability of the antagonistic IENs decreased and became more vulnerable to the loss of species. In contrast, there was no change in the structural attributes of species linked by an additive response. Using indices common in food-web and network theory, we identified the species in each IEN for which a change in biomass from stressor effects would disproportionately affect the biomass of other species via direct and indirect local, intermediate, and global predator-prey feeding interactions. Knowing the species that transfer the most synergistic or antagonistic responses in a food-web may inform conservation under increasing multiple-stressor impacts.
Vertical transport in the ocean due to sub-mesoscale structures: Impacts in the Kerguelen region
Publisher: Elsevier BV
Date: 08-2014
Distinct iron cycling in a Southern Ocean eddy
Publisher: Springer Science and Business Media LLC
Date: 11-02-2020
DOI: 10.1038/S41467-020-14464-0
Abstract: Mesoscale eddies are ubiquitous in the iron-limited Southern Ocean, controlling ocean-atmosphere exchange processes, however their influence on phytoplankton productivity remains unknown. Here we probed the biogeochemical cycling of iron (Fe) in a cold-core eddy. In-eddy surface dissolved Fe (dFe) concentrations and phytoplankton productivity were exceedingly low relative to external waters. In-eddy phytoplankton Fe-to-carbon uptake ratios were elevated 2–6 fold, indicating upregulated intracellular Fe acquisition resulting in a dFe residence time of ~1 day. Heavy dFe isotope values were measured for in-eddy surface waters highlighting extensive trafficking of dFe by cells. Below the euphotic zone, dFe isotope values were lighter and coincident with peaks in recycled nutrients and cell abundance, indicating enhanced microbially-mediated Fe recycling. Our measurements show that the isolated nature of Southern Ocean eddies can produce distinctly different Fe biogeochemistry compared to surrounding waters with cells upregulating iron uptake and using recycling processes to sustain themselves.
Background nutrient concentration determines phytoplankton bloom response to marine heatwaves
Publisher: Wiley
Date: 15-07-2020
DOI: 10.1111/GCB.15255
Biogeochemical variability in the equatorial Indian Ocean during the monsoon transition
Publisher: Copernicus GmbH
Date: 29-04-2014
Abstract: Abstract. In this paper we examine time-series measurements of near-surface chlorophyll concentration from a mooring that was deployed at 80.5° E on the equator in the Indian Ocean in 2010. These data reveal at least six striking spikes in chlorophyll in October through December, with approximately 2 week periodicity, that coincide with the development of the fall Wyrtki jets during the transition between the summer and winter monsoons. Concurrent meteorological and in situ physical measurements from the mooring reveal that the chlorophyll pulses are associated with intensification of eastward winds at the surface and eastward currents in the mixed layer. These observations are inconsistent with upwelling dynamics as occurs in the Atlantic and Pacific Oceans, since eastward winds that force Wyrtki jet intensification should drive downwelling. The chlorophyll spikes could be explained by two alternative mechanisms: (1) turbulent entrainment of nutrients and/or chlorophyll from across the base of the mixed layer by wind stirring or Wyrtki jet-induced shear instability or (2) enhanced horizontal advection of high chlorophyll concentrations into the convergent equatorial zone. The first mechanism is supported by the phasing and litude of the relationship between wind stress and chlorophyll, which suggests that the chlorophyll spikes are the result of turbulent entrainment driven by synoptic zonal wind events. The second mechanism is supported by satellite chlorophyll observations that reveal a clear connection between the increased chlorophyll concentrations at the mooring location and larger-scale topographic wake effects from the Chagos–Laca e Ridge upstream. The biweekly periodicity of the chlorophyll spikes appears to be related to the presence of mixed Rossby-gravity waves, also known as Yanai waves, which can be seen throughout the time-series as a biweekly periodicity in the meridional velocities with upward phase propagation. Consistent with hypothesis 2, eastward flows over the Chagos–Laca e Ridge generate high chlorophyll concentrations to the north of the equator and periodic southward advection in the meridional flows associated with Yanai waves produces the chlorophyll spikes that are observed in the mooring record. Yanai waves may also contribute to vertical shear across the base of the mixed layer that could help support entrainment. The OFAM3 eddy-resolving model suggests that both of our proposed mechanisms may be important. Climatological satellite chlorophyll data show that the elevated chlorophyll concentrations in this region are consistently observed year after year and so are reflective of recurring large-scale wind and circulation-induced productivity enhancement in the central equatorial Indian Ocean.
The impact of equatorial Pacific tropical instability waves on hydrography and nutrients: 2004-2005
Publisher: Elsevier BV
Date: 02-2011
Antarctic slush-ice algal accumulation not quantified through conventional satellite imagery: beware the ice of March
Publisher: Copernicus GmbH
Date: 11-11-2015
Abstract: Abstract. Our current knowledge of broad-scale patterns of primary production in the Southern Ocean is derived from satellite ocean-colour estimates of chlorophyll a (Chl a) in the open ocean, typically in spring-summer. Here, we provide evidence that large-scale intra-ice phytoplankton surface aggregation occur off the coast of Antarctica during austral autumn, and that these "blooms" are largely undetected in satellite ocean-colour time series (which mask the ice-covered ocean). We present an analysis of (i) true-colour (visible) satellite imagery in combination with (ii) conventional ocean-colour data, and (iii) direct s ling from a research vessel, to identify and characterise a large-scale intra-ice algal occurrence off the coast of East Antarctica in early autumn (March) 2012. We also present evidence of these autumn "blooms" in other regions (for ex le, Princess Astrid Coast in 2012) and other years (for ex le, Terra Nova Bay in 2015) implying regular and widespread occurrence of these phenomena. The occurrence of such undetected algal accumulations implies that the magnitude of primary production in the Southern Ocean is currently underestimated.
Southern Ocean Phytoplankton Stimulated by Wildfire Emissions and Sustained by Iron Recycling
Publisher: American Geophysical Union (AGU)
Date: 03-06-2202
DOI: 10.1029/2021GL097538
Abstract: Large ash plumes emitted by the 2019–2020 Australian wildfires were associated with a widespread phytoplankton bloom in the iron‐limited Pacific sector of the Southern Ocean. In this study, we used satellite observations and aerosol reanalysis products to study the regional phytoplankton community response to wildfire emissions. The bloom was stimulated by pyrogenic iron fertilization and coincided with elevated cellular pigment concentrations, increased photochemical efficiency, and apparent community structural shifts. Physiological anomalies were consistent with previously observed phytoplankton responses to iron stress relief and persisted for up to 9 months. Supported by a regional iron budget, we conclude that the bloom was sustained by iron recycling and episodic inputs of pyrogenic and dust‐borne mineral iron. The continuous regeneration of iron was likely facilitated by the bloom's large size, mitigating edge dilution effects, as well as enhanced bioavailability of pyrogenic and mineral iron due to atmospheric and chemical processing during long‐range transport.
Widespread phytoplankton blooms triggered by 2019–2020 Australian wildfires
Publisher: Springer Science and Business Media LLC
Date: 15-09-2021
DOI: 10.1038/S41586-021-03805-8
Abstract: Droughts and climate-change-driven warming are leading to more frequent and intense wildfires
The Impact of a Southern Ocean Cyclonic Eddy on Mesopelagic Micronekton
Publisher: American Geophysical Union (AGU)
Date: 11-2022
DOI: 10.1029/2022JC018893
Abstract: Mesoscale eddies shape the foraging ecology of predators such as marine mammals and seabirds. A growing number of animal tracking studies show that predators alter their swimming, ing, and foraging behavior within mesoscale eddies. However, little is known about how Southern Ocean eddies influence the distribution of mesopelagic micronekton (fish, squid, and crustaceans), which are major prey items of megafauna. Studies in other oceanic regions have found that eddies can influence the abundance and community composition of micronekton. Here, we analyze acoustic observations from a 14‐day survey of a cyclonic mesoscale eddy, its surrounding waters, and the Polar Frontal Zone (PFZ) waters where the eddy formed. We report and interpret spatial patterns of acoustic backscatter at 18 and 75 kHz, proxies indicating combined changes in species, size, and abundance of micronekton. We find that the vertical distribution of acoustic backscatter matched the underwater light conditions characteristic of the eddy core, periphery, and surrounding waters, at scales smaller than 10 km. The median water‐column integrated acoustic backscatter values in the eddy core were only half of those measured in the Sub‐Antarctic Zone waters surrounding the eddy, but similar to those measured in the PFZ, where the eddy originated 27 days prior. These results suggest that, as for physical and chemical tracers, the eddy maintained its biological characteristics from its source waters creating a unique habitat compared to its surroundings.
Phytoplankton patchiness: quantifying the biological contribution using Fast Repetition Rate Fluorometry
Publisher: Oxford University Press (OUP)
Date: 1997
Supplementary material to "Antarctic slush-ice algal accumulation not quantified through conventional satellite imagery: Beware the ice of March"
Publisher: Copernicus GmbH
Date: 11-11-2015
A Sustained Ocean Observing System in the Indian Ocean for Climate Related Scientific Knowledge and Societal Needs
Publisher: Frontiers Media SA
Date: 28-06-2019
Sea Ice Meltwater and Circumpolar Deep Water Drive Contrasting Productivity in Three Antarctic Polynyas
Publisher: American Geophysical Union (AGU)
Date: 05-2019
DOI: 10.1029/2019JC015071
Remote assessment of the fate of phytoplankton in the Southern Ocean sea-ice zone
Publisher: Springer Science and Business Media LLC
Date: 19-06-2020
DOI: 10.1038/S41467-020-16931-0
Abstract: In the Southern Ocean, large-scale phytoplankton blooms occur in open water and the sea-ice zone (SIZ). These blooms have a range of fates including physical advection, downward carbon export, or grazing. Here, we determine the magnitude, timing and spatial trends of the biogeochemical (export) and ecological (foodwebs) fates of phytoplankton, based on seven BGC-Argo floats spanning three years across the SIZ. We calculate loss terms using the production of chlorophyll—based on nitrate depletion—compared with measured chlorophyll. Export losses are estimated using conspicuous chlorophyll pulses at depth. By subtracting export losses, we calculate grazing-mediated losses. Herbivory accounts for ~90% of the annually-averaged losses (169 mg C m −2 d −1 ), and phytodetritus POC export comprises ~10%. Furthermore, export and grazing losses each exhibit distinctive seasonality captured by all floats spanning 60°S to 69°S. These similar trends reveal widespread patterns in phytoplankton fate throughout the Southern Ocean SIZ.
A Road Map to IndOOS-2: Better Observations of the Rapidly Warming Indian Ocean
Publisher: American Meteorological Society
Date: 11-2020
Abstract: The Indian Ocean Observing System (IndOOS), established in 2006, is a multinational network of sustained oceanic measurements that underpin understanding and forecasting of weather and climate for the Indian Ocean region and beyond. Almost one-third of humanity lives around the Indian Ocean, many in countries dependent on fisheries and rain-fed agriculture that are vulnerable to climate variability and extremes. The Indian Ocean alone has absorbed a quarter of the global oceanic heat uptake over the last two decades and the fate of this heat and its impact on future change is unknown. Climate models project accelerating sea level rise, more frequent extremes in monsoon rainfall, and decreasing oceanic productivity. In view of these new scientific challenges, a 3-yr international review of the IndOOS by more than 60 scientific experts now highlights the need for an enhanced observing network that can better meet societal challenges, and provide more reliable forecasts. Here we present core findings from this review, including the need for 1) chemical, biological, and ecosystem measurements alongside physical parameters 2) expansion into the western tropics to improve understanding of the monsoon circulation 3) better-resolved upper ocean processes to improve understanding of air–sea coupling and yield better subseasonal to seasonal predictions and 4) expansion into key coastal regions and the deep ocean to better constrain the basinwide energy budget. These goals will require new agreements and partnerships with and among Indian Ocean rim countries, creating opportunities for them to enhance their monitoring and forecasting capacity as part of IndOOS-2.
Tropical Pacific Observing System
Publisher: Frontiers Media SA
Date: 18-02-2019
Related Organisations
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