Probing the in situ activities of marine microbes in marine oxygen minimum zones

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Dissolved oxygen concentration is a critical organizing principle in the ocean. Over the past 50 years oxygen minimum zones (OMZs) have expanded due to climate change and increased waste run-off from our farms and cities. At present 8% of the ocean is considered oxygen-starved. In certain coastal areas extreme oxygen-starvation produces "dead zones" decimating marine fisheries and destroying food web structure. Changes in microbial community metabolism associated with OMZ formation and expansion alter nutrient and energy flow patterns in the ocean, including production and consumption of greenhouse gases such as carbon dioxide, methane and nitrous oxide. Knowing how microorganisms interact with and respond to ocean oxygen starvation teaches us about the organizing principles that shape ocean food webs and define how microorganisms work together and with their environment to drive nutrient and energy cycles in a time of climate change. Here we request infrastructure funding for an in situ sampling instrument called the PPS that will enable collection of microbial biomass from the oxygen-starved water column of Saanich Inlet with minimal perturbation and high temporal and spatial resolution. This form of sampling will provide more accurate depictions of gene expression that can be correlated with process rate measurements for a wide variety of nutrient and energy cycles. Resulting datasets will inform our understanding of microbial community metabolism in OMZs and provide a training and practice standard for sample collection guiding the peer efforts of scientists working in OMZs throughout the global ocean.