Isotopic characterisation of nutrient dynamics and UCDW behaviour in the west Antarctic Peninsula sea ice environment
Lead Research Organisation:
University of Edinburgh
Department Name: Sch of Geosciences
Abstract
This research project aims to examine the ways in which ongoing climate change and sea ice decline at the west Antarctic Peninsula (WAP) are impacting upon nutrient budgets and biogeochemical cycling throughout the region.
The WAP is an ecologically important region of high primary productivity, and nutrient cycling is known to be crucial to phytoplankton production and its relationship with CO2 dynamics. Upper circumpolar deep water (UCDW) is understood to constitute the principal source of nutrients to surface waters throughout the WAP region. UCDW incurs at the shelf break and is transported across the continental shelf, so that nutrients can be supplied to the mixed layer by vertical mixing. This source of nutrients fuels high productivity in coastal regions, with implications for the biological uptake of atmospheric CO2.
Available evidence suggests that sea ice variability can drastically impact phytoplankton biomass and nutrient utilisation in surface waters during the summer growing seasons, but the mechanisms underlying this interaction remain to be fully understood. Sea ice melt and meteoric freshwater inputs can promote phytoplankton blooms by stabilising the upper ocean sufficiently to provide a well-lit surface environment conducive to growth. However, such stratified conditions can also inhibit productivity and the magnitude of the bloom by restricting the resupply of nutrients to the mixed layer. Superimposed onto large interannual variability in chlorophyll, macronutrients and the physical environment, there are strong indications of long-term sea ice decline along the WAP and a concomitant decline in productivity.
This research project seeks to understand the changes in nutrient biogeochemistry underlying these changes in productivity in the WAP sea ice zone, and addresses the central hypothesis that a climate-induced reduction in sea ice and stratification will result in drastic declines in primary production and nitrate utilisation in the surface environment. Such conditions would lead to a simultaneous reduction in the capacity of the oceanic CO2 sink during summer and generate an increased pool of unutilised nitrate in surface waters over the shelf, both of which would hold profound implications for global biogeochemical cycles.
This study will comprise three components:
1. A time-series study over three austral summer growing seasons in Ryder Bay, WAP, to examine temporal changes in fixed nitrogen budgets and cycling, in relation to interannual variability in sea ice, water column structure and productivity.
2. A ship-based transect from the shelf break to Marguerite Bay to examine deep water behaviour and its impact on the supply of nutrients to high productivity coastal regions.
3. Ship-based sampling across the wider WAP shelf region to examine spatial variability in nutrient dynamics, productivity, sea ice and physical oceanography, and give a broader context to the time-series study.
A suite of biogeochemical measurements pertinent to nutrient budgets and cycling will be made during each component of the study. Comprehensive ancillary physical and biological data are available from project partners, to examine productivity and environmental variables alongside these nutrient measurements. A fixed nitrogen budget will be constructed for the WAP shelf on an annual basis and its interannual variability examined in the context of ongoing sea ice losses and changes in phytoplankton productivity.
Nutrient biogeochemistry is central to the relationship between productivity and oceanic uptake of atmospheric CO2, so this study has broad and far-reaching implications for the role of the Southern Ocean CO2 system in regulating global climate. This study will also help to predict the future response of the oceans to ongoing climate change at the wider scale by giving insight into the climatic impacts on nutrient cycling and productivity in the fastest-warming marine environment on Earth.
The WAP is an ecologically important region of high primary productivity, and nutrient cycling is known to be crucial to phytoplankton production and its relationship with CO2 dynamics. Upper circumpolar deep water (UCDW) is understood to constitute the principal source of nutrients to surface waters throughout the WAP region. UCDW incurs at the shelf break and is transported across the continental shelf, so that nutrients can be supplied to the mixed layer by vertical mixing. This source of nutrients fuels high productivity in coastal regions, with implications for the biological uptake of atmospheric CO2.
Available evidence suggests that sea ice variability can drastically impact phytoplankton biomass and nutrient utilisation in surface waters during the summer growing seasons, but the mechanisms underlying this interaction remain to be fully understood. Sea ice melt and meteoric freshwater inputs can promote phytoplankton blooms by stabilising the upper ocean sufficiently to provide a well-lit surface environment conducive to growth. However, such stratified conditions can also inhibit productivity and the magnitude of the bloom by restricting the resupply of nutrients to the mixed layer. Superimposed onto large interannual variability in chlorophyll, macronutrients and the physical environment, there are strong indications of long-term sea ice decline along the WAP and a concomitant decline in productivity.
This research project seeks to understand the changes in nutrient biogeochemistry underlying these changes in productivity in the WAP sea ice zone, and addresses the central hypothesis that a climate-induced reduction in sea ice and stratification will result in drastic declines in primary production and nitrate utilisation in the surface environment. Such conditions would lead to a simultaneous reduction in the capacity of the oceanic CO2 sink during summer and generate an increased pool of unutilised nitrate in surface waters over the shelf, both of which would hold profound implications for global biogeochemical cycles.
This study will comprise three components:
1. A time-series study over three austral summer growing seasons in Ryder Bay, WAP, to examine temporal changes in fixed nitrogen budgets and cycling, in relation to interannual variability in sea ice, water column structure and productivity.
2. A ship-based transect from the shelf break to Marguerite Bay to examine deep water behaviour and its impact on the supply of nutrients to high productivity coastal regions.
3. Ship-based sampling across the wider WAP shelf region to examine spatial variability in nutrient dynamics, productivity, sea ice and physical oceanography, and give a broader context to the time-series study.
A suite of biogeochemical measurements pertinent to nutrient budgets and cycling will be made during each component of the study. Comprehensive ancillary physical and biological data are available from project partners, to examine productivity and environmental variables alongside these nutrient measurements. A fixed nitrogen budget will be constructed for the WAP shelf on an annual basis and its interannual variability examined in the context of ongoing sea ice losses and changes in phytoplankton productivity.
Nutrient biogeochemistry is central to the relationship between productivity and oceanic uptake of atmospheric CO2, so this study has broad and far-reaching implications for the role of the Southern Ocean CO2 system in regulating global climate. This study will also help to predict the future response of the oceans to ongoing climate change at the wider scale by giving insight into the climatic impacts on nutrient cycling and productivity in the fastest-warming marine environment on Earth.
Planned Impact
The most important Impact of this research project will be communication of the key findings and the importance of the oceans and polar regions, in general, to the general public. This will contribute to the knowledge base that informs national and international decision-making, and policy for the Southern Ocean. Impact activities proposed herein will also contribute to public knowledge and quality of life through engagement with cutting-edge research and internationally-relevant science.
The key user community will consist of teachers and students at a number of secondary schools across the UK, as well as members of the general public. One such school will be South Wigston High School in Leicestershire, where a series of visits will build on the already strong relationship between the school and the Fellow. Science workshops will develop the Fellow's previous Outreach work at the school, by demonstrating the practical science behind the knowledge exhibited in previous visits. These science education activities are intended to teach relevant practical science skills and raise the profile of science in student communities. Working with teachers and students will allow the content of the workshops to be incorporated into science teaching programmes and to benefit the maximum number of students, both during the visits and into the future. These science workshops will also be of direct benefit to student development within the school by providing a platform for the school-wide "Science Leaders" scheme. A letter of support from Head Teacher, Mr Gary Toward, demonstrates the school's engagement in this proposal. Whilst communication and plans for Impact activities at South Wigston High School are most advanced, a number of other schools will also benefit from science education and public engagement activities to encourage students to study science at University and to inform and inspire the next generation of polar scientists and enthusiasts.
Members of the general public will also be catered for through engagement events at museums and science centres conducted by the Fellow and in collaboration with the UK Polar Network (see pathways to impact).
The key user community will consist of teachers and students at a number of secondary schools across the UK, as well as members of the general public. One such school will be South Wigston High School in Leicestershire, where a series of visits will build on the already strong relationship between the school and the Fellow. Science workshops will develop the Fellow's previous Outreach work at the school, by demonstrating the practical science behind the knowledge exhibited in previous visits. These science education activities are intended to teach relevant practical science skills and raise the profile of science in student communities. Working with teachers and students will allow the content of the workshops to be incorporated into science teaching programmes and to benefit the maximum number of students, both during the visits and into the future. These science workshops will also be of direct benefit to student development within the school by providing a platform for the school-wide "Science Leaders" scheme. A letter of support from Head Teacher, Mr Gary Toward, demonstrates the school's engagement in this proposal. Whilst communication and plans for Impact activities at South Wigston High School are most advanced, a number of other schools will also benefit from science education and public engagement activities to encourage students to study science at University and to inform and inspire the next generation of polar scientists and enthusiasts.
Members of the general public will also be catered for through engagement events at museums and science centres conducted by the Fellow and in collaboration with the UK Polar Network (see pathways to impact).
People |
ORCID iD |
Sian Henley (Principal Investigator / Fellow) |
Publications
Annett A
(2017)
Silica cycling and isotopic composition in northern Marguerite Bay on the rapidly-warming western Antarctic Peninsula
in Deep Sea Research Part II: Topical Studies in Oceanography
Belcher A
(2023)
Seasonal cycles of biogeochemical fluxes in the Scotia Sea, Southern Ocean: a stable isotope approach
in Biogeosciences
Cassarino L
(2020)
Sedimentary Nutrient Supply in Productive Hot Spots off the West Antarctic Peninsula Revealed by Silicon Isotopes
in Global Biogeochemical Cycles
Dittrich R
(2022)
Dissolved organic carbon and nitrogen cycling along the west Antarctic Peninsula during summer
in Progress in Oceanography
Gourmelen N
(2017)
Channelized Melting Drives Thinning Under a Rapidly Melting Antarctic Ice Shelf
in Geophysical Research Letters
Hendry K
(2017)
Understanding a Changing West Antarctic Peninsula
in Eos
Hendry K.
(2018)
Understanding a Changing West Antarctic Peninsula
in Eos
Henley S
(2019)
Variability and change in the west Antarctic Peninsula marine system: Research priorities and opportunities
in Progress in Oceanography
Description | Nutrient recycling plays a key role in fuelling Southern Ocean food webs. Nutrient and carbon uptake is controlled by sea ice dynamics and ocean physics on an annual basis. Changes in nutrient uptake and cycling have serious consequences throughout the food web and for air-sea exchange of climate-active gases. Changes underway and anticipated across the Southern Ocean have important consequences for ecosystem functioning and ocean-climate feedbacks at regional and global scales. A comprehensive, year-round and well-integrated observing system is required to understand environmental change around Antarctica over seasonal-to-decadal timescales. |
Exploitation Route | All data are publicly available through NERC data centres for use by the international scientific community. Some data generated by this grant will also be useful as input data for biogeochemical models. Henley et al. 2019, Progress in Oceanography, will be a key publication to guide ongoing development of an internationally-coordinated observing system to detect and elucidate change along the Antarctic Peninsula. The findings of Henley et al. 2020, Frontiers in Marine Science, will have a direct impact on policy-making for the Southern Ocean and potentially in global climate regulation through the IPCC AR6. |
Sectors | Aerospace Defence and Marine Digital/Communication/Information Technologies (including Software) Education Environment Leisure Activities including Sports Recreation and Tourism Culture Heritage Museums and Collections Security and Diplomacy Transport |
Description | My findings have been used as the basis for policy and decision-making, as well as public lectures, scientific lecture series, school curricula, science education workshops and interactive outreach activities. More of these science-policy interactions, public engagement and school ventures are planned. I have an active twitter account (@drsianhenley) that I use for science communication and environmental awareness, and my findings have contributed to various blogs. I have also contributed in filming for film and TV campaigns, and to radio programmes and written media. |
First Year Of Impact | 2009 |
Sector | Aerospace, Defence and Marine,Education,Environment,Government, Democracy and Justice,Culture, Heritage, Museums and Collections |
Impact Types | Cultural Societal Policy & public services |
Description | Contribution to MCCIP Overseas Territories Polar Report Card 2021 |
Geographic Reach | Multiple continents/international |
Policy Influence Type | Participation in a guidance/advisory committee |
Impact | Some of these impacts already materialising; others expected in near future at national and international levels. |
URL | https://www.mccip.org.uk/uk-overseas-territories |
Description | Marine Ecosystem Assessment for the Southern Ocean (MEASO) |
Geographic Reach | Multiple continents/international |
Policy Influence Type | Citation in other policy documents |
Impact | Supporting the evidence base for international decision-making around climate change (IPCC) and environmental protection and human activities in Antarctica (Antarctic Treaty System and Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) |
Description | E3 DTP PhD Studentship |
Amount | £53,200 (GBP) |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 08/2015 |
End | 02/2019 |
Description | How do climate-driven shifts in phytoplankton communities influence carbon and nitrogen uptake and recycling along the west Antarctic Peninsula? |
Amount | £62,000 (GBP) |
Funding ID | 2449105 |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 08/2020 |
End | 02/2024 |
Description | Moray Endowment Fund |
Amount | £1,441 (GBP) |
Organisation | University of Edinburgh |
Sector | Academic/University |
Country | United Kingdom |
Start | 12/2016 |
End | 07/2017 |
Title | Sediment trap fluxes and stable isotopes of particulate carbon, nitrogen and biogenic silica from the Scotia Sea in 2018 |
Description | Results of sediment trap analysis conducted by British Antarctic Survey, University of Edinburgh and University of Bristol. Particulate fluxes and isotopic compositions of particulate organic carbon, nitrogen and biogenic silica are presented. Data from two sediment traps deployed in the Scotia Sea, Southern Ocean, are presented (shallow=400m, and deep = 2000m), with 14 samples for each spread across the year 2018 to capture the seasonal cycle from January to December. Each sample was split into multiple fractions for these multiple analyses. Data facilitate the understanding of the magnitude and drivers of particulate fluxes in the Scotia Sea, Southern Ocean. Work funded by NC-ALI funding to the British Antarctic Survey Ecosystems programme. Sian Henley supported by: NE/K010034/1. |
Type Of Material | Database/Collection of data |
Year Produced | 2023 |
Provided To Others? | Yes |
URL | https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/01761 |
Description | BAS: Antarctic fieldwork |
Organisation | British Antarctic Survey |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | My research team provides detailed biogeochemical data to BAS core science programs, thus enhancing scientific output and understanding |
Collaborator Contribution | BAS provides scientific facilities and all logistics for Antarctic fieldwork |
Impact | Henley et al., 2012 Bryant et al., 2013 Annett et al., 2013 Annett et al., 2015 Henley et al., in review |
Start Year | 2008 |
Description | CGS: Stable isotopes in coastal Antarctic waters |
Organisation | National Oceanography Centre |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | I took the role of fieldwork team leader for the core Southern Ocean cruise for this collaborative project, and provided one work package |
Collaborator Contribution | National Oceanography Centre provided ship time, berths for the research team, and logistical and scientific support. University of Bristol led the proposal overall, and contributed one work package and fieldwork personnel. |
Impact | Successful cruise and full dataset of nitrogen and silicon isotopes, and ancillary biogeochemical and physical oceanographic data. To be processed and published as soon as possible. |
Start Year | 2014 |
Description | CGS: Stable isotopes in coastal Antarctic waters |
Organisation | University of Bristol |
Department | School of Earth Sciences |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | I took the role of fieldwork team leader for the core Southern Ocean cruise for this collaborative project, and provided one work package |
Collaborator Contribution | National Oceanography Centre provided ship time, berths for the research team, and logistical and scientific support. University of Bristol led the proposal overall, and contributed one work package and fieldwork personnel. |
Impact | Successful cruise and full dataset of nitrogen and silicon isotopes, and ancillary biogeochemical and physical oceanographic data. To be processed and published as soon as possible. |
Start Year | 2014 |
Description | LMG: Collaboration and PhD studentship support |
Organisation | Columbia University |
Department | Earth and Environmental Sciences |
Country | United States |
Sector | Academic/University |
PI Contribution | My research team provides isotopic data to the Pal-LTER project, thus enhancing scientific outputs and understanding. We also provide scientific and logistical support for fieldwork. |
Collaborator Contribution | Columbia University and the Palmer Antarctica Long-Term Ecological Research (Pal-LTER) project contribute ship time, berths for the research team, scientific and logistical support, and PhD supervision. |
Impact | One PhD studentship Three successful cruises and full sets of isotopic data for the Antarctic Peninsula region. To be processed and published as soon as possible. |
Start Year | 2013 |
Description | SUERC: isotope partnership |
Organisation | University of Glasgow |
Department | Scottish Universities Environmental Research Centre |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Established and developed an analytical technique for nitrate isotopes |
Collaborator Contribution | Staff time, consumables, analytical costs and support |
Impact | Henley et al., 2012 Bryant et al., 2013 Henley et al., in review Significant datasets |
Start Year | 2009 |
Description | Antarctica and the Southern Ocean: dabbling in icy-cold waters |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Public lecture hosted by the Edinburgh Global Academy to celebrate the 150th Anniversary of the birth of William Speirs Bruce |
Year(s) Of Engagement Activity | 2017 |
Description | Antarctica; land of extremes, endeavour, adventure and excellent science |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | Public outreach talk about living and working in Antarctica. Audience response and feedback was outstanding and I have been invited back as one of the best talks of the last 25 years. |
Year(s) Of Engagement Activity | 2014 |
Description | Climate change and the role of the oceans - a view from the south |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Public lecture to communicate importance of oceans and climate change, which sparked much discussion, debate and follow-up activities. |
Year(s) Of Engagement Activity | 2016 |
Description | Contribution to UNFCCC COP26 |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Policymakers/politicians |
Results and Impact | I represented the international Southern Ocean community at the UNFCCC COP26 through my roles with SOOS, SCAR, MEASO and the Southern Ocean Task Force for the UN Ocean Decade. I co-organised a focus day in the UNFCCC Blue Zone Cryosphere Pavilion, led an expert session, gave two talks and engaged with policy-makers, NGOs and the private sector throughout the Conference. I also co-hosted a session with the Scottish Government focusing on Arctic change and communities in the Blue Zone Nordic Pavilion. |
Year(s) Of Engagement Activity | 2021 |
URL | https://www.youtube.com/channel/UCr_TPYUAyh13kVbQjzVKh0g/videos |
Description | Contribution to UNFCCC COP27 |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Policymakers/politicians |
Results and Impact | Leadership of a Southern Ocean session at the ICCI Cryosphere Pavilion in UNFCCC Blue Zone at COP27 Contribution to Polar Oceans session at the ICCI Cryosphere Pavilion in UNFCCC Blue Zone at COP27 |
Year(s) Of Engagement Activity | 2022 |
URL | https://www.youtube.com/watch?v=NWfPphIFvg4&list=PL7jYwbz8AZmj0-W3k4hfHB1eoEiMc0GSy&index=5 |
Description | Finding and applying for fellowship funding - PhD and beyond |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Postgraduate students |
Results and Impact | Expert panel on career development at the UKPN polar marine sciences workshop, University of East Anglia |
Year(s) Of Engagement Activity | 2014 |
Description | Frontiers in Geoscience lecture |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Postgraduate students |
Results and Impact | Lecture and group discussion with PhD students |
Year(s) Of Engagement Activity | 2015 |
Description | GSL Careers Day: Post-doctoral research |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Postgraduate students |
Results and Impact | Talk on careers in academic research at the Geological Society of London's Careers Day 2015. Excellent feedback and much interest in pursuing an academic career. |
Year(s) Of Engagement Activity | 2015 |
Description | Guest blog for British Antarctic Survey: Ready for Antarctic trip number five! |
Form Of Engagement Activity | Engagement focused website, blog or social media channel |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Guest blog about Antarctic fieldwork and marine research |
Year(s) Of Engagement Activity | 2015 |
Description | Ocean science busking |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Public engagement activities in Central London as part of NERC's 50th Anniversary Celebrations with RRS Discovery |
Year(s) Of Engagement Activity | 2015 |
Description | Polar science engagement event - EISF2017 |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Public engagement event showcasing UK and international polar research, as a launch event for the Edinburgh International Science Festival (EISF). Our Dynamic Earth, Edinburgh, 1-2 April 2017. |
Year(s) Of Engagement Activity | 2017 |
Description | Policy brief for European Commission: the Southern Ocean on Europe's shores |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Policymakers/politicians |
Results and Impact | Policy brief for members of European Commission about why the Southern Ocean is important for Europe, in support of more effective policy-making and investment in research funding. |
Year(s) Of Engagement Activity | 2022 |
Description | Sailing the Fellow-ship |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Postgraduate students |
Results and Impact | Invited talk on applying for a personal Fellowship for postdocs and PhD students |
Year(s) Of Engagement Activity | 2015 |
Description | Shaping environmental science: inspiring the next generation of women in science |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Postgraduate students |
Results and Impact | Workshop to discuss current opportunities and challenges for women in science, to inspire junior female scientists, and to pave the way for a new NERC equality initiative |
Year(s) Of Engagement Activity | 2015 |
Description | UKPN: Going the extra mile |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Postgraduate students |
Results and Impact | Keynote lecture on the importance of additional skills and extra-curricular activities beyond pure research, at UKPN Science and Society workshop. |
Year(s) Of Engagement Activity | 2014 |