Project description:In the surface ocean, carbon is fixed by phytoplankton and respired by the entire marine community at an astonishingly high rate. At any point in time, the difference between these two processes yields a carbon pool in surface particles that is a combination of both freshly fixed and partially degraded material. On a molecular level, we have a limited knowledge of the small molecules, or metabolites, within this pool. Specific metabolites have been shown to be responsible for fueling respiration, maintaining organismal interactions, and transferring energy throughout the microbial community. Metabolomics, or the direct observation and quantification of the small molecules that are the result of cellular activity, provides an important lens through which we can begin to assess the standing stocks of small compounds that likely fuel a great deal of heterotrophic activity in the surface ocean. Here we describe community metabolomes of particulate material into the North Pacific Ocean and compare the metabolomes to a variety of phytoplankton grown in the lab. Using both targeted and untargeted metabolomics, we identify metabolites in the particulate carbon pool and explore their latitudinal and phylogenetic distributions. This analysis reveals several compounds that have not been previously recognized as abundant components of the marine organic carbon pool. We found that the community metabolome showed distinct differences between the regimes that likely reflects the phytoplankton community present. The community metabolome in surface waters of the subtropical domain was remarkably consistent even when sampled weeks apart, while the northern regions showed a patichier and less reproducible community metabolome. Some individual compounds showed distinct patterns between oceanographic regimes, including homarine, an abundant molecule that can contribute up to 4\% of the total particulate carbon pool in marine surface waters. Glutamic acid and glutamine showed opposite patterns in the oceanographic regimes, suggesting differences in community-level nitrogen assimilation in these different regimes. Overall, this study offers a new perspective into particulate carbon composition in oceanographic research, reveals important carbon pools that may fuel the microbial loop, and suggests an altered community-level nitrogen assimilation capacity over the North Pacific transition zone.

Project description:In the surface ocean, carbon is fixed by phytoplankton and respired by the entire marine community at an astonishingly high rate. At any point in time, the difference between these two processes yields a carbon pool in surface particles that is a combination of both freshly fixed and partially degraded material. On a molecular level, we have a limited knowledge of the small molecules, or metabolites, within this pool. Specific metabolites have been shown to be responsible for fueling respiration, maintaining organismal interactions, and transferring energy throughout the microbial community. Metabolomics, or the direct observation and quantification of the small molecules that are the result of cellular activity, provides an important lens through which we can begin to assess the standing stocks of small compounds that likely fuel a great deal of heterotrophic activity in the surface ocean. Here we describe community metabolomes of particulate material into the North Pacific Ocean and compare the metabolomes to a variety of phytoplankton grown in the lab. Using both targeted and untargeted metabolomics, we identify metabolites in the particulate carbon pool and explore their latitudinal and phylogenetic distributions. This analysis reveals several compounds that have not been previously recognized as abundant components of the marine organic carbon pool. We found that the community metabolome showed distinct differences between the regimes that likely reflects the phytoplankton community present. The community metabolome in surface waters of the subtropical domain was remarkably consistent even when sampled weeks apart, while the northern regions showed a patchier and less reproducible community metabolome. Some individual compounds showed distinct patterns between oceanographic regimes, including homarine, an abundant molecule that can contribute up to 4% of the total particulate carbon pool in marine surface waters. Glutamic acid and glutamine showed opposite patterns in the oceanographic regimes, suggesting differences in community-level nitrogen assimilation in these different regimes. Overall, this study offers a new perspective into particulate carbon composition in oceanographic research, reveals important carbon pools that may fuel the microbial loop, and suggests an altered community-level nitrogen assimilation capacity over the North Pacific transition zone.

Dataset Information

Insights into the controls on metabolite distributions along a latitudinal transect of the western Atlantic Ocean

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