1. To quantify benthic community parameters for all size classes of fauna across the Oxygen Minimum Zone (OMZ) 2. To make a detailed assessment across the OMZ of a) sediment accumulation, mixing and irrigation rates and depths and b) environmental factors acting as controls on faunal activity 3. To characterise solid phase and porewater geochemistry of sediments across the OMZ 4. To assess a) faunal digestive Organic Matter (OM) alteration, b) the relative importance of chemo- and photosynthetic food sources, and c) benthic food web structure, across the OMZ 5. To determine porewater profiles and benthic solute fluxes in situ, and to assess faunal OM assimilation and trophic relationships by monitoring tracers during shipboard and in situ incubations 6. To obtain high resolution porewater profiles of oxygen and other key analytes, free of pressure and other effects potentially introduced by core recovery 7. To determine in situ oxygen consumption rates and benthic fluxes 8. To use labelled tracers to assess mixing and irrigation rates, faunal OM assimilation, and size-selective ingestion and mixing 9.To determine sediment denitrification and sulfate reduction rates and their contributions to OM remineralisation