Productivity and Biogeochemistry of terrestrial ice-bound ecosystems of the maritime Antarctic.

Lead Research Organisation: University of Sheffield
Department Name: Geography

Abstract

The most poorly understood terrestrial habitat in Antarctica is its ice: a significant microbial resource that collectively constitutes the largest single freshwater reservoir of bacteria on the Earth's surface. The total bacterial cell biomass in the Antarctic ice sheet is thought to amount to ~ 2.44 Tg (Priscu and Christner, 2004) and so mass losses from West Antarctic and the Peninsula (~ 180 Gt ice a-1: Ringnot et al, In Press: Nature Letters) mean major biomass and organic carbon fluxes (~ 16 GgC a-1) are taking place whose ecological implications have been completely overlooked. Furthermore, these are viable microorganisms that are so active when melting takes place that they sequester between 50% and 75% of the inorganic snowpack nutrient reservoir (Hodson, 2006) and fix ~ 10 mgC m-2 d-1 from the atmosphere by photosynthesis (Fogg, 1968). Thus snow and ice-bound microorganisms transform enormous quantities of inorganic nutrients and CO2 from the atmosphere into organic biomass while they are in transit to the coast. Here, there is now evidence that glacial and snowmelt runoff can increase marine plankton blooms up to 100 km offshore (Dierssen et al, 2002). A systematic study of the internal biological production and biogeochemistry of snow and ice habitats in the maritime Antarctic is therefore long overdue. Further, since extreme responses to climate change are already being observed here in its soil, lake and coastal ecosystems, we believe that an investigation of the relationship between these changes and those occurring in snow and ice habitats is urgently required. Measurements of the nutrient content of snow and ice prior to melt cannot be used to predict enhanced production in terrestrial, freshwater and marine ecosystems at the ice margin because this neglects the internal nutrient demands imposed by its own biological production. It also offers no insights into the biological CO2 pump in icy habitats, which will dominate the terrestrial ecosystem CO2 budget, yet has never been measured. The net impact of biological production within snow and ice is most likely a significant regional CO2 source, but this flux will become far greater if other parts of coastal Antarctica begin to melt to the same extent as the northern Peninsula and Scotia arc. This project will therefore quantify the microbiology, nutrient economy and productivity of snow and ice surface habitats as they melt in the maritime Antarctic. Our approach will be to establish transects upon Signy Island (South Orkney Islands) that are representative of the broad range of melting and nutrient gradients found along much of the Antarctic Peninsula's west coast and associated archipelagos. These sites will encompass nutrient-rich, high melt rate coastal snowpacks and nutrient impoverished, cold snowpacks at altitudes where melting is sporadic and typically restricted to the surface. We will also follow the retreat of the snowpack up our transects and examine the glacier surface habitats exposed as a consequence. At each site we will establish the microbial community structure and biomass throughout the summer and track the fate of microorganisms as melting removes them from the snow and ice. We will also track nutrients at the same time and measure the melt energy fluxes that drive the whole system. This tight integration of physical, chemical and biological process measurements and also the range of sites being considered are important because they will then enable us to assess other parts of the Antarctic Peninsula not subject to detailed monitoring. For these areas, we will use existing meteorological data and estimates of melt extent to calculate the westward flux of melt, nutrients and microbial biomass that might be expected under current and future melt scenarios. At the same time we will establish the CO2 fluxes as a result of biological activity within Antarctic snow and ice habitats for the first time.

Publications

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Hodson A (2017) Microbes influence the biogeochemical and optical properties of maritime Antarctic snow in Journal of Geophysical Research: Biogeosciences

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Hodson A (2015) Cryospheric ecosystems: a synthesis of snowpack and glacial research in Environmental Research Letters

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Redeker KR (2017) Microbial metabolism directly affects trace gases in (sub) polar snowpacks. in Journal of the Royal Society, Interface

 
Description We have found that:

1) Snowpack microbial communities play a key role in regulating nutrient export by runoff in the maritime Antarctic.

2) Detectable microbial production occurs in Antarctic snow, even under harsh conditions and can influence the trace gases present in the pore spaces between snow grains. This could have implications for the gases that are used in ice core research..

3) Dust and marine fauna can greatly modifiy the nutrient economy and thus productivity of the snow by fertilising it. The result means there are great differences between coastal and inland snowpacks in terms of the microrganisms present and the rate of biological production.

4) These gradients in biomass and biological production are not readily observed on the surface using satellite and airborne observations because the penetration of sunlight into snow allows algal blooms to develop at depth. Therefore the best means of modelling regional biological production in the maritime Antarctic is to establish the extent of melting, since biological production increases markedly when meltwater is available.

5) Snowmelt interaction with glacial rock flour, inorganic and organic matter in soils can fertilise coastal ecosystems following iron acquisition.
Exploitation Route To demonstrate marine ecosystem change during climate warming in the Antarctic Peninsula region.

To show that iron fertilisation of the Scotia Sea and others like it can be caused by meltwater runoff, as well as the better known dust, iceberg and coastal sediment sources.
Sectors Education,Environment,Other

URL http://www.ecoantarctica.group.shef.ac.uk/
 
Description South Georgia and the South Sandwich Islands Small Grant
Amount £23,000 (GBP)
Organisation Government of South Georgia and the South Sandwich Islands 
Sector Public
Country South Georgia and the South Sandwich Islands
Start 01/2013 
End 12/2013
 
Description South Georgia and the South Sandwich Islands Small Grant
Amount £23,000 (GBP)
Organisation Government of South Georgia and the South Sandwich Islands 
Sector Public
Country South Georgia and the South Sandwich Islands
Start 01/2013 
End 12/2013
 
Title Albedo changes on Gourlay Snowfield and Tuva Glacier on Signy Island, Antarctica 
Description Snapshot survey of snow albedo on SIgny Island submitted to NERC Polar Data Centre 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact N/A 
 
Title Bacterial diversity of Gourlay Snowfield and Tuva Glacier on Signy Island, Antarctica 
Description Submission of data describing molecular microbiology of snow bacteria to NERC Polar Data Centre 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
Impact N/A 
 
Title Ecosystem production in snow and ice on Gourlay Snowfield and Tuva Glacier on Signy Island, Antarctica 
Description Submission of snow biological production data to the NERC Polar Data Centre 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact N/A 
 
Title Snow and ice properties of Gourlay Snowfield and Tuva Glacier on Signy Island, Antarctica 
Description Submission of snow physical and chemical data to the NERC Polar Data Centre 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact N/A 
 
Description Biogeochemistry of snow and meltwater in Hurd Peninsula area, Livingston Island, South Shetland Is. 
Organisation University of Lisbon
Country Portugal 
Sector Academic/University 
PI Contribution Support during fieldwork for Portuguese team
Collaborator Contribution Logistical support to collect water and sediment samples from a further glaciated island of the Scotia Sea area
Impact In Progress
Start Year 2014
 
Description Microbial biogeography of South Georgia soils: implications for nutrient enrichment of coastal waters 
Organisation National Museum of Natural History
Country United States 
Sector Academic/University 
PI Contribution Collection of soil and stream samples from South Georgia
Collaborator Contribution Payment for collection of stream, sediment and soil samples for expansion of NERC AFI award to other parts of the Scotia Sea area
Impact In Progress
Start Year 2013
 
Description Invited Seminar: Biogeochemistry of Arctic and Antarctic glacial meltwaters (CEH Edinburgh) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Research collaboration was discussed.

None
Year(s) Of Engagement Activity 2012
 
Description Invited Seminar: Glacier ecology and meltwater biogeochemistry (University of Leeds) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact New research collaborations were initiated afterwards

A NERC grant was submitted that is now under consideration
Year(s) Of Engagement Activity 2013
 
Description Junior school Visit, March 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact A presentation, movie and Q+A session with year 6 school children about working in Antarctica
Year(s) Of Engagement Activity 2015
 
Description Presentation to Governor and residents of South Georgia 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact The scientific nature of our work and its consequences were discussed informally afterwards. It was reported as a news item "Rich Life Even in Glaciers" - see URL below.

None were observed
Year(s) Of Engagement Activity 2013
URL http://www.sgisland.gs/index.php/%28h%29South_Georgia_Newsletter%2C_January_2013
 
Description Workshop, University of Northumbria, May 27th and 28th 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Workshop was directed toward next generation of research into biogeochemical and ecological impacts of increased melting in the ANtarctic Peninsula region. Particular emphasis was given toward early career stage researchers.
Year(s) Of Engagement Activity 2015