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.

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).

Publications

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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

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Henley S (2018) Macronutrient and carbon supply, uptake and cycling across the Antarctic Peninsula shelf during summer in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences

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Henley S (2017) Macronutrient supply, uptake and recycling in the coastal ocean of the west Antarctic Peninsula in Deep Sea Research Part II: Topical Studies in Oceanography

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Stefels J (2018) Impact of sea-ice melt on dimethyl sulfide (sulfoniopropionate) inventories in surface waters of Marguerite Bay, West Antarctic Peninsula in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences

 
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. 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 in the process of being submitted to 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. The findings of Henley et al. 2019 (in press) will be a key publication to guide ongoing develpment of an internationally-coordinated observing system to detect and elucidate change along the Antarctic Peninsula.
Sectors Aerospace, Defence and Marine,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 public lectures, scientific lecture series, school curricula, science education workshops and interactive outreach activities. More of these 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 this material is currently being worked up.
First Year Of Impact 2009
Sector Education,Culture, Heritage, Museums and Collections
Impact Types Societal

 
Description E3 DTP PhD Studentship
Amount £53,200 (GBP)
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 09/2015 
End 02/2019
 
Description Moray Endowment Fund
Amount £1,441 (GBP)
Organisation University of Edinburgh 
Sector Academic/University
Country United Kingdom
Start 12/2016 
End 07/2017
 
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 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 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