A5037808245- Arctic and Antarctic ice dynamics
- Marine and coastal ecosystems
- Methane Hydrates and Related Phenomena
- Oceanographic and Atmospheric Processes
- Marine Biology and Ecology Research
- Cryospheric studies and observations
- Ocean Acidification Effects and Responses
- Microbial Community Ecology and Physiology
- Polar Research and Ecology
- Marine and coastal plant biology
- Marine and environmental studies
- Diverse Educational Innovations Studies
- Geology and Paleoclimatology Research
- Outdoor and Experiential Education
- Conservation, Ecology, Wildlife Education
- Innovative Teaching and Learning Methods
- Isotope Analysis in Ecology
- Climate change and permafrost
- Plant Water Relations and Carbon Dynamics
- Marine Bivalve and Aquaculture Studies
- Educational Strategies and Epistemologies
- Marine Toxins and Detection Methods
- Science Education and Pedagogy
- Food Industry and Aquatic Biology
- Building materials and conservation
Woods Hole Oceanographic Institution
2017-2022
Stanford University
2009-2022
Digital Research Alliance of Canada
2022
Palo Alto University
2015
In midsummer, diatoms have taken advantage of thinning ice cover to feed in nutrient-rich waters.
In search of an explanation for some the greenest waters ever seen in coastal Antarctica and their possible link to fastest melting glaciers declining summer sea ice, Amundse ...
Abstract To evaluate what drives phytoplankton photosynthesis rates in the Amundsen Sea Polynya (ASP), Antarctica, during spring bloom, we studied biomass, rates, and water column productivity a bloom of Phaeocystis antarctica (Haptophyceae) tested effects iron (Fe) light availability on these parameters bioassay experiments deck incubators. Phytoplankton biomass were highest (20 µg chlorophyll L−1 6.5 g C m−2 d−1) central ASP where sea ice melt surface warming enhanced stratification,...
Abstract As the physical environment of Arctic Ocean shifts seasonally from ice‐covered to open water, limiting resource for phytoplankton growth light nutrients. To understand photophysiological responses these environmental changes, we evaluated photoacclimation strategies during low‐light, high‐nutrient, spring and high‐light, low‐nutrient, ice‐free summer. Field results show that effectively acclimated reduced irradiance beneath sea ice by maximizing absorption photosynthetic capacity....
Abstract Recent attention has focused on accelerated glacial losses along the Amundsen Sea coast that result from changes in atmosphere and ocean circulation, with sea ice playing a mediating but not well-understood role. Here, we investigated how changed over period of 1979 to 2014, focusing spatio-temporal edge advance/retreat percent cover relation winds. In contrast widespread decreases east increases west Sea, were confined three areas: (i) offshore shelf break, (ii) southern Pine...
Abstract We report results from a yearlong, moored sediment trap in the Amundsen Sea Polynya (ASP), first such time series this remote and productive ecosystem. Results are compared to long-term (1992–2013) western Antarctic Peninsula (WAP). The ASP was deployed December 2010 2011 at 350 m depth. observed two brief, but high flux events, peaking 8 5 mmol C m−2 d−1 January 2011, respectively, with total annual capture of 315 m−2. Both peak fluxes exceeded comparable WAP observations. Like...
Major changes to Arctic marine ecosystems have resulted in longer growing seasons with increased phytoplankton production over larger areas. In the Chukchi Sea, high productivity fuels intense benthic denitrification creating a nitrogen (N) deficit that is transported through Atlantic Ocean, where it likely fixation. Given rapid pace of environmental change and potentially globally significant N deficit, we conducted experiments aimed at understanding microbial utilization Sea. Ship-board...
Abstract The Palmer Long‐Term Ecological Research program has sampled waters of the western Antarctic Peninsula (wAP) annually each summer since 1990. However, information about wAP prior to peak phytoplankton bloom in January is sparse. Here we present results from a spring process cruise that early stages development 2014. Sea ice concentrations were high on shelf relative nonshelf waters, especially toward south. Macronutrients and nonlimiting growth both while dissolved iron only shelf....
Abstract Synoptic and historical shipboard data, spanning the period 1981–2017, are used to investigate seasonal evolution of water masses on northeastern Chukchi shelf quantify circulation patterns their impact nutrient distributions. We find that Alaskan coastal extends Barrow Canyon along pathway, with peak presence in September, while Pacific Winter Water (WW) continually drains off through summer. The depth‐averaged under light winds is characterized by a strong Coastal Current (ACC)...
During the 2010–2011 ‘Impacts of Climate Change on EcoSystems and Chemistry Arctic Pacific Environment’ project, we measured photosynthetic parameters in natural phytoplankton assemblages from Chukchi Beaufort seas. Water‐column samples were taken near surface (3.1 ± 0.9 m) subsurface (28 10.3 at ∼ 85 stations each year representing a wide range ecological conditions, including under sea ice (UI) open water (OW). The physiological response to light was used assess photo‐acclimation,...
Abstract Measurements of late springtime nutrient concentrations in Arctic waters are relatively rare due to the extensive sea ice cover that makes sampling difficult. During SUBICE (Study Under‐ice Blooms In Chukchi Ecosystem) cruise May–June 2014, an survey hydrography and prebloom inorganic macronutrients, oxygen, particulate organic carbon nitrogen, chlorophyll a was conducted northeastern Sea. Cold (<−1.5°C) winter water prevalent throughout study area, column weakly stratified....
Abstract Light and dissolved iron (dFe) availability control net primary production (NPP) in much of the Southern Ocean, but controller during spring western Antarctic Peninsula has never been assessed. Underwater light dFe are sensitive to climate‐induced changes upper ocean circulation, stratification, sea ice cover, which can affect NPP phytoplankton community composition, both alter carbon drawdown food web structure. We estimated situ NPP, production, heterotrophic respiration...
Abstract Spring phytoplankton growth in polar marine ecosystems is limited by light availability beneath ice‐covered waters, particularly early the season prior to snowmelt and melt pond formation. Leads of open water increase transmission ocean are sites air‐sea exchange. We explore role leads controlling bloom dynamics within sea ice zone Arctic Ocean. Data presented from spring measurements Chukchi Sea during Study Under‐ice Blooms In Ecosystem (SUBICE) program May June 2014. observed...
Abstract Partial pressure of CO2 (pCO2) and dissolved oxygen (DO) in the surface waters Amundsen Sea Polynya (ASP) were measured during austral summer 2010–2011 on International Research Expedition (ASPIRE). Surface pCO2 central polynya was as low 130 µatm, mainly due to strong net primary production. Comparing saturation states DO distinguished dominant factors (biological activity, temperature, upwelling, ice melt) controlling across regions. Air-sea flux, estimated using average shipboard...
Abstract To understand the controls on distributions of ice algal communities in spring and role algae under‐ice bloom development through possible seeding, we sampled water column Chukchi Beaufort Seas over summer. Field observations showed that high springtime concentrations bottom were released from into by Furthermore, during our sampling, highly variable. Declines biomass physiological state correlated with melt, rather than light or nutrient availability. Nonparametric multivariate...
Abstract Light and iron availability are intertwined in controlling Southern Ocean primary production because several photosynthetic proteins require iron. Changes light can also affect phytoplankton species composition, which impacts nutrient cycling, carbon drawdown, food web structure. To investigate the interactive effects of on growth, photosynthesis, photoacclimation strategy, micronutrient stress‐induced protein expression, we conducted five bioassay experiments during spring waters...
The apparently obligate symbiosis between the diazotroph Candidatus Atelocyanobacterium thalassa (UCYN-A) and its haptophyte host, Braarudosphaera bigelowii , has recently been found to fix dinitrogen (N 2 ) in polar waters at rates (per cell) comparable those observed tropical/subtropical oligotrophic ocean basins. This study presents novel observation that this increased abundance during a wind-driven upwelling event along Alaskan Beaufort shelfbreak. As relaxed, relative of B. among...