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Abstract The timing of biological events, known as phenology, plays a key role in shaping ecosystem dynamics, and climate change can significantly alter these timings. The Gulf of Maine on the Northeast U.S. Shelf is vulnerable to warming temperatures and other climate impacts, which could affect the distribution and production of plankton species sensitive to phenological shifts. In this study, we apply a novel data‐driven modeling approach to long‐term datasets to understand the population variability ofCalanus finmarchicus, a lipid‐rich copepod that is fundamental to the Gulf of Maine food web. Our results reveal how phenology impacts the complex intermingling of top‐down and bottom‐up controls. We find that early initiation of the annual phytoplankton bloom prompts an early start to the reproductive season for populations ofC. finmarchicusin the inner Gulf of Maine, resulting in high spring abundance. This spring condition appears to be conducive to enhanced predation pressure later in the season, consequently resulting in overall lowC. finmarchicusabundance in the fall. These biologically controlled dynamics are less pronounced in the outer Gulf of Maine, where water exchanges near the boundary have a greater influence. Our analysis augments existing hypotheses in fisheries oceanography and classical ecological theory by considering unique plankton life‐history characteristics and shelf sea dynamics, offering new insights into the biological factors drivingC. finmarchicusvariability. 

Abstract. Carbonyl sulfide (COS) is the most abundant sulfur gas in the atmosphere with links to terrestrial and oceanic productivity. We measured COS in ice core air from an intermediate-depth ice core from the South Pole using both dry and wet extraction methods, recovering a 52 500-year record. We find evidence for COS production in the firn, altering the atmospheric signal preserved in the ice core. Mean sea salt aerosol concentrations from the same depth are a good proxy for the COS production, which disproportionately impacts the measurements from glacial period ice with high sea salt aerosol concentrations. The COS measurements are corrected using sea salt sodium (ssNa) as a proxy for the excess COS resulting from the production. The ssNa-corrected COS record displays substantially less COS in the glacial period atmosphere than the Holocene and a 2 to 4-fold COS rise during the deglaciation synchronous with the associated climate signal. The deglacial COS rise was primarily source driven. Oceanic emissions in the form of COS, carbon disulfide (CS2), and dimethylsulfide (DMS) are collectively the largest natural source of atmospheric COS. A large increase in ocean COS emissions during the deglaciation suggests enhancements in emissions of ocean sulfur gases via processes that involve ocean productivity, although we cannot quantify individual contributions from each gas. 

Abstract Are the oceans turning into deserts? Rising temperature, increasing surface stratification, and decreasing vertical inputs of nutrients are expected to cause an expansion of warm, nutrient deplete ecosystems. Such an expansion is predicted to negatively affect a trio of key ocean biogeochemical features: phytoplankton biomass, primary productivity, and carbon export. However, phytoplankton communities are complex adaptive systems with immense diversity that could render them at least partially resilient to global changes. This can be illustrated by the biology of theProchlorococcus“collective.” Adaptations to counter stress, use of alternative nutrient sources, and frugal resource allocation can allowProchlorococcusto buffer climate‐driven changes in nutrient availability. In contrast, cell physiology is more sensitive to temperature changes. Here, we argue that biogeochemical models need to consider the adaptive potential of diverse phytoplankton communities. However, a full understanding of phytoplankton resilience to future ocean changes is hampered by a lack of global biogeographic observations to test theories. We propose that the resilience may in fact be greater in oligotrophic waters than currently considered with implications for future predictions of phytoplankton biomass, primary productivity, and carbon export.