SGER: Oxygen Minimum Zone Control of Benthic Processes on the Peru-Chile Margin: El Nino Influence

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9803861 Levin Extreme concentrations of resources (low oxygen, high food) for benthic organisms occur in oxygen minimum zones (OMZs), technically defined as regions where oxygen concentrations fall below 0.5 ml/1. Midwater oxygen minima are strongly developed in the eastern Pacific Ocean and intercept much of the continental margin along the Americas. This is also a region of the world ocean where hydrography and the intensity of the OMZ are heavily affected by interdecadal climate change such as ENSO. We propose a multidisciplinary investigation of sediment geochemistry, bioturbation, bacteria, foraminifera, metazoans, and fish scales in sediments within and beneath the OMZ. These components are strongly affected by oxygenation level, which varies significantly during, E1 Ni o and La Ni a conditions. This proposal requests seed funds for a program to test hypotheses about oxygen minimum zone influence on benthic shelf and slope communities off Peru and Chile, and the extent to which E1 Ni o-related events modify benthic community processes. Results will be compared to ongoing studies of benthic processes in other low oxygen settings (OMZs and methane seeps) off Mexico, California and Oregon. This effort will advance understanding of relationships among abiotic factors and benthic processes that are critical to accurate evaluations of modern and ancient (paleo-) environments, natural population cycles and management of coastal marine resources. The program will involve participation of US (Scripps), Chilean (University de Concepcion), and Peruvian (IMARPE) scientists.