Chemosynthetically-driven ecosystems south of the Polar Front: biogeography and ecology

We propose an analysis of the chemosynthetic ecosystems in Antarctica south of the Polar Front. We will conduct a detailed investigation and analysis of four contrasting types of chemosynthetically-driven communities, together with their regional tectonic setting. The communities chosen for our investigation comprise: those associated with high-temperature, bare-rock hydrothermal vents (East Scotia Ridge), high-temperature, sediment-hosted hydrothermal activity (Bransfield Strait), mud volcanoes (South Sandwich fore-arc basin) and methane hydrates (north of King George Island). We propose three cruises and subsequent laboratory-based programmes. Cruise 1 will be to the East Scotia Sea where we will examine the tectonic setting and sample the hydrothermal discharge using autonomous underwater vehicles and the hydrothermal sampler BRIDGET. Cruise 2 will be to the same area and will use the UK Remotely Operated Vehicle (ROV) Isis to dive on, sample and characterise the biological and physical environment surrounding vent and seep sites identified during Cruise 1. Cruise 3 will be a combined geophysical, chemical and biological cruise, using the ROV Isis to dive upon and examine hydrothermal and cold seep environments both north and south of King George Island, Antarctic Peninsula. Subsequent analysis will compare the hydrothermal and seep chemistry among these four sites. We will use morphological, molecular, lipid and stable isotope analyses of microbial and metazoan populations to determine the phylogeography of species, and understand the food web processes. Our programme will determine whether colonisation of vents and seeps, in these most isolated of chemosynthetically-driven ecosystems, is driven by oceanographic or tectonic processes or whether any site is, instead, host to completely isolated evolution.