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National News
UK
Richard Hobbs
Arc - back-arc systems
Large areas of the submarine parts of the active South Sandwich
Island arc and its back-arc spreading centre have been mapped using
multibeam bathymetry. Maps are being prepared for publication.
Geochemical and petrological work is currently concentrating on
silicic lavas from seamounts in collaboration with Birkbeck College,
London, and on magmatic processes on the extinct West Scotia
Ridge, and the early structure of the East Scotia and Central Scotia
Seas in collaboration with Cardiff University, the Instituto
Geológico y Minero de España and University of Grenada.
Vent Ecology
Investigations of vent biodiversity and ecology in the East Scotia
Sea back-arc spreading centre are continuing, funded by the NERC
ChEsSO grant (NE/DO1249X/1). The first paper reporting the
hydrothermal sites and vent communities has been published
(Rogers et al., 2012). They have discovered new hydrothermal vent
communities that are probably the first to be found in Antarctic
waters. The communities include new species of crab, barnacles,
limpets, snails, sea anemones, and a predatory seven armed starfish.
They claim that this is a new biogeographic province created by the
environmental conditions of the Southern Ocean. Tyler (National
Oceanography Centre) has another cruise to the sites identified by
Rogers et al (2012) at the end of 2012 (JC080). The ROV Isis will be
used to characterise the chemosynthetic fauna and microbes and the
environmental conditions that sustain them at a range of sites of
active seafloor fluid-flow and will include: a complete a thorough
mapping and documentation at each site; sampling of the of the
vent/seep fluids and plume; a microbial and metazoan sampling
programme; and fish traps. The material will be used for subsequent
lab analyses.
Recently completed cruises:
Rogers (JC066) November 2011. The objectives were to survey,
sample and identify the benthic fauna of seamounts on the
southwest Indian Ridge and map the distribution of species in
relation to topography, hydrography and primary production. It also
assessed Benthic Protected Areas (BPAs) recently proposed by the
fishing industry for conserving the regional biodiversity of seamount
communities. The project represents a major collaboration between
U.K. scientists (Institute of Zoology; Natural History Museum;
Scottish Association for Marine Sciences), the Census of Marine
Life programme (CoML), the World Conservation Union (IUCN),
the UN Food and Agricultural Organisation (FAO) and the fishing
industry (Southern Indian Ocean Deepwater Fishers’ Association;
SIODFA).
Copley (JC067) December 2011. ROV made dives at a deep-sea
hydrothermal vent field on the Southwest Indian Ridge (SWIR), to
test key hypotheses relating to the global biogeography and ecology
of chemosynthetic ecosystems.
Henderson (JC068) December 2011/January 2012. The
concentration of seven critical ocean micronutrients (Fe, Zn, Co,
Cd, Ni, Cu, Mn) were mapped at high spatial resolution for the full
water column on a zonal section across the Atlantic at 40°S,
including the mid-ocean ridge. This research included: determination
of the variations in physical and chemical speciation of these
micronutrients; sources and fluxes, influences of advection and
mixing; and phytoplankton ecosystem structure and functioning.
Leat (JR259) February-March 2012. British Antarctic Survey cruise
on RRS James Clark Ross to Scotia and Weddell Seas. Cruise Report:
Leat, P.T., Tate, A.J., Buys, G., 2012. Geology and Bathymetry, Scotia
and Weddell Seas, RRS James Clark Ross JR259 Cruise Report. British
Antarctic Survey Report AD6/3/JR259. Most of the cruise science
time was spent in the Weddell Sea, doing multibeam bathymetry in
collaboration with biological sampling, but some work was carried
out on the West Scotia Ridge, on segment W5, and in the South
West Scotia Sea near the East Scotia ridge back-arc spreading centre.
Multibeam bathymetry and dredge samples were collected.
Forthcoming cruises:
• Tyler (JC080) end 2012 (see above report on Vent Ecology)
• Copley (JC082) early 2013. We propose to test hypotheses relating
to hydrothermal emissions and associated chemosynthetic faunas
on the Mid-Cayman Rise. This is the deepest known seafloor
seafloor spreading centre and is located in a poorly ventilated and
geographically isolated deep ocean basin. It specifically targets a
INTERRIDGE NEWS 48 VOL.21, 2012