On 12 July 2017, the Larsen-C Ice Shelf calved one of the largest iceberg originating from the Antarctic Peninsula ever recorded. As iceberg A68 moves north, it leaves behind an area of 5,800 km2 of seabed newly exposed to open marine conditions. Much of this area has very likely remained ice-covered for centuries and may have been covered since the last inter-glacial (<100kyr) period. The calving of A68 offers a unique scientific opportunity for fundamental research to address questions around the mobility and colonisation capacity of seafloor species and past climate variability.
This NERC-funded Urgency project Larsen-C Benthos aimed to test the hypothesis that under-ice-shelf benthic biodiversity resembles nutrient-poor deep-sea communities by examining the life and habitats formerly under the iceberg A68 in the western Weddell Sea. Unfortunately, heavy sea ice conditions thwarted their attempts at reaching the Larsen C Ice Shelf.
Marine biologist and Principal Investigator, Dr Katrin Linse, from British Antarctic Survey who led the team said:
“We knew that getting through the sea ice to reach Larsen C would be difficult. Naturally, we were disappointed not to get there but safety must come first. The captain and crew have been fantastic and pulled out all the stops to get us to the ice shelf, but our progress became too slow, with just 8kms traveled in 24 hours and we still had over 400kms to travel. Mother Nature had not been kind to us on our mission!
“But we had a ‘Plan B’, we headed north to areas which have never been sampled for benthic biodiversity. The Prince Gustav Channel Ice Shelf and neighbouring Larsen A Ice Shelf collapsed in 1995. We sampled deeper than we planned at Larsen C – down to 1000 metres – and found lots of exciting animals living on the seafloor.”
In September 2017 the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) designated the newly-exposed marine area (adjacent to Larsen C Ice Shelf, Subarea 48.5) as a Stage 1 Special Area for Scientific Study. This allows the area to be protected from potential commercial exploration for an initial period of two years, which is likely to be extended to ten years following further consideration by CCAMLR Members. Read more here.
Larsen-C Benthos was a British Antarctic Survey (BAS) led expedition supported by a NERC Urgency Grant (NE/R012296/1) including scientists from three UK universities (Aberdeen, Newcastle, and Southampton) and the Natural History Museum in London. This core team was supported by national and international scientists and overall included participants from 6 different countries and 9 institutes. The expedition took place on board the BAS research ship the RRS James Clark Ross in early 2018.
Our governing hypothesis is:
“Until the calving of the Larsen-C iceberg, A68, the benthic fauna on the seabed beneath ice shelf has likely comprised oligotrophic assemblages resembling deep-sea Weddell Sea assemblages. The calving of A68, and the exposure of the seabed it covered to open-marine and sea-ice conditions will initiate a rapid colonisation by new species that will transform the benthic ecosystem significantly within 3-5 years.”
To test our hypothesis and document the faunal baseline under Larsen-C, we will deploy trawls (epibenthic sledge (EBS), Agassiz trawl (AGT), bongo net (BN)), mega-corer (MUC), towed camera systems (SUCS & DWCS), CTD, and single and multi-beam echosounders at each station. As the seabed under A68 is uncharted, areas around the proposed stations will be surveyed by swath bathymetry to map seafloor topography. With our holistic sampling approach we will collect information on the assemblage structure, biodiversity and abundance of the in-, epi-, and suprabenthic meio-, macro- and megafauna. This will provide a baseline for assessing ecosystem function with samples of potential food sources such as phyto- and zooplankton as well as organic matter in the sediments and comprise a suite of biological, sedimentological and biogeochemical parameters.
Our key objectives and tasks are:
Biological and environmental data will be analysed with multivariate statistics and compared to assemblages and ecosystems reported from the Southern Ocean shelf, slope and deep-sea, especially those from Larsen-A/B and the bathyal and abyssal Weddell Sea.
Adrian Glover – Natural History Museum
Alan Jamieson – Newcastle University
Will Reid – Newcastle University
Ursula Witte – University of Aberdeen
Jon Copley – University of Southampton
Dieter Piepenburg – Alfred Wegener Institute
Angelika Brandt – Senckenberg Institute
Ann Vanreusel – University of Ghent
Anni Makela – University of Aberdeen
Luisa Federwisch – Alfred Wegener Institute
Melanie Mackenzie – Museum Victoria
Simon Dreutter – Alfred Wegener Institute
Thomas Dahlgren – University of Gothenburg and Uni Research
2 March, 2018
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19 September, 2017
An international agreement is now in place to give special protection to the area of ocean left exposed when one of the largest icebergs ever recorded broke free from the …
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After months of ‘hanging by a thread’ a vast iceberg the size of Norfolk has finally broken off Antarctica’s Larsen C Ice Shelf. Around 30 metres of this 190m thick …
The data collected by this expedition will be used to produce official reports and will be made publicly available through the official SCAR biodiversity data portal – biodiversity.aq.