ChEss, Biogeography of Chemosynthetic Ecosystems
ChEsSo - Exploration for vents south of the Polar Front

ChEsSo (ChEss in the Southern Ocean) is a UK Consortium Bid, led by Prof Paul A. Tyler (NOCS) for the exploration and investigation of chemosynthetic habitats South of the Polar Front. This multidisciplinnary programme started in April 2008 and ran for 4 years, with cruises in 2009, 2010 and 2011.

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A consortium of marine scientists are to investigate the chemosynthetic environments and associated ecosystems south of the Polar Front. Sites in the East Scotia Sea will be compared with chemosynthetically-driven communities in the Bransfield Strait, and north of King George Island, Antarctica. The primary objective of this work is to evaluate wheter these sites, collectively, represent a Southern Ocean "gateway" to enable gene-flow of chemosynthetic fauna from the Southern Pacific Ocean to the South Atlantic Ocean.

ChEsSo study sites

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Detailed investigation and analysis is being conducted of four contrasting types of chemosynthetically-driven communities, together with their regional tectonic setting, and the specific hydrothermal vent and cold seep environments they inhabit. The communities chosen for the investigation comprise: those associated with high temperature, bare rock hydrothermal vents on the East Scotia Ridge, high temperature, sediment-hosted hydrothermal activity (Bransfield Strait), mud volcanoes (South Sandwich forearc basin) and methane hydrates (north of King George Island). To achieve these aims, three cruises (involving international collabroation) have been planned. Analysis of geological, chemical and biological (both microbial and metazoan) samples will allow comparison of vent and seep communities among the four sites. Morphological, molecular, lipid and stable isotope analyses are being used to determine the phylogeography of species, and understand their food web processes. In concert, this programme will determine whether colonisation of vents and seeps, in these most isolated of chemosynthetically-driven ecosystems, is driven by oceanographic or geologic processes or, instead, whether any site has hosted completely isolated evolution.

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Cruises and initial results

Cruise 1: Jan-Feb. 2009. East Scotia Sea.

A multidisciplinary team on board James Clark Ross used multibeam seafloor mapping, CTD tow-yows and the deep-towed BRIDGET vehicle with video cameras to explore, amongst others, two sites at the East Scotia Ridge. The cruise was highly successful as the first hydrothermal vents south of the Polar Front were located and observed.

Cruise 2: Jan-Feb 2010. East Scotia Sea.

A multidisciplinary team on board James Cook used the ROV Isis further explored, observed and sampled the hydrothermal vents found on E2 and E9.

Cruise 3: 2011. Bransfield Strait

This cruise will be a combined geophysical, chemical and biological cruise, using the ROV ISIS to dive upon and examine vent and seep environments, at least some of which have been closely spatially-constrained already, both north and south of King George Island, Antarctic Peninsula.



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