Research

Small coastal embayments are ubiquitous features of coastal upwelling systems and play a disproportionately large role in local ecosystem dynamics. In these upwelling bays, persistent nearshore thermal fronts form downstream of coastal topographic features. Due to their small scales, these fronts are dominated by submesoscale dynamics and likely facilitate strong cross-shelf exchange. While these coastal fronts are frequently observed, there have been no targeted observational studies or systematic modeling studies that resolve submesoscale dynamics and turbulence processes that govern exchange across these fronts. Moreover, observational studies of submesoscale features have generally lagged behind numerical modeling efforts due to their small size and transient nature. Small upwelling bays offer a rare opportunity to study the dynamics of submesoscale fronts in the shallow coastal ocean because their formation is often predictably linked to coastal topographic features. This project is targeted in San Luis Obispo Bay in central California, a small embayment whose length scale is on the order of the local Rossby deformation radius, where previous research from our team has revealed the presence of a persistent and narrow front characterized by sharp temperature gradients, convergence downstream of the upwelling jet, and a strong impact on local hypoxia and harmful algal bloom development. This study integrates field observations and numerical modeling experiments to explore the links between submesoscale fronts, turbulent mixing, and bay-ocean exchange. Repeated observations of the persistent front across various dynamical regimes will allow for a broader understanding of the parameters that drive the evolution of the submesoscale front, overcoming traditional observational barriers of these ephemeral features.

Axial Seamount is the most active submarine volcano in the NE Pacific, having erupted in 1998, 2011, and 2015. Because of this, it is an ideal natural laboratory for the long-term study of active processes at a submarine volcano, with periodic perturbations to hydrothermal systems and chemosynthetic biological communities. Long-term monitoring at Axial has built a remarkable time-series of bottom pressure measurements and repeated bathymetric mapping with Autonomous Underwater Vehicles (AUVs) that have documented a cycle of inflation and deflation of ±2-4 meters that has been used to forecast eruptions with increasing accuracy. Since the 2015, Axial has reinflated to >90% of its pre-eruption threshold, but over this same time period the rate of inflation has slowed by an order of magnitude. Consequently, the next eruption is still likely several years away. This project aims to continue this monitoring effort for another 5 years, while improving the techniques, survey designs, and data analysis on several fronts in order to provide improved constraints for modeling the surface deformation to better understand the magma supply and storage system at the volcano. For this project, we request support for field work with ROV Jason and AUV Sentry at Axial Seamount in 2024, 2026, and 2028. Specifically, we propose to: (1) continue the deformation surveys every other year, including both pressure measurements and AUV bathymetric re-surveys over the next 5 years, (2) modify the ROV-based pressure surveys to become more time-efficient by changing reference sites so that we can add more benchmarks in the caldera to better constrain deformation models, (3) add benchmark sites to constrain slip across the caldera faults to increase our understanding of the relationship between deformation and seismicity, and (4) continue OOI Regional Cabled Array (RCA) seafloor-CTD turn-arounds so that salinity sensors will be in place in the caldera during the next eruption to test a hypothesis about co-eruption brine release. These multi-scale monitoring efforts at Axial Seamount will be leveraged by NSF’s infrastructure investment in the OOI-RCA, which provides real-time monitoring data that greatly enhances these efforts. The results from this study will also help to increase our understanding of the shallow magma supply and storage systems at active basaltic volcanoes, the processes that lead to and trigger eruptions, and the pathways that magma takes to the surface during eruptions. This work at Axial Seamount is aimed at helping us better understand eruption processes at volcanoes on land that are more hazardous to people and property.

Magmatic activity along the mid-ocean ridge system accounts for a large portion of the earth’s volcanic output. Associated hydrothermal processes in this system provide a key linkage between the lithosphere and the hydrosphere, transferring significant heat and chemicals to the ocean. At submarine volcanoes in particular, the influx and output of magma appears to vary over time, producing years-to-decades-long cycles of inflation and deflation, which in turn cause pronounced variations in the overlying oceanic crust and the hydrothermal circulation hosted within. Understanding the dynamics of these variations is critical to advancing our knowledge of magma-hydrothermal interaction. Seafloor hydrothermal systems are primarily regulated by their subsurface heat supplies and hydrologic properties such as permeability that regulate crustal fluid flow. The considerable difficulties in establishing concurrent, long-term monitoring of these sub-seafloor properties and surface venting have greatly limited our understanding of hydrothermal variability in relation to submarine magmatic processes. This project will fill this knowledge gap by 1) conducting long-term, high-resolution, time-series measurements of hydrothermal effluent temperature at multiple vent sites across the summit caldera of Axial Seamount, and 2) analyzing the tidal modulation of venting temperature using a one-dimensional, multi-layer poroelastic model to constrain permeability and its temporal variations within the upflow zones beneath the instrumented vent sites. The results from our proposed study, when cross-examined with the observations from the unparalleled geodetic and seismic monitoring established at Axial as part of the OOI-RCA observatory along with existing complementary geophysical observations, will provide a broad context of unprecedented details for us to address the compelling research question: how does hydrothermal discharge vary, in both space and time, in relation to magma movements and associated changes in upflow-zone permeability at Axial?

This cruise is in support of the National Science Foundations Ocean Observatories Initiative Regional Cabled Array (RCA) annual operations and maintenance cruise and will require an ROV (either ROPOS or Jason). It is anticipated that over 100 instruments will be turned (recovered with refurbished instruments reinstalled). Operations will visit all of the RCA sites located west of Newport along the Cascadia Margin (80 m - 2900 m water depth) and ~300 miles off shore at Axial Seamount (~ 2600 m to 1500 m water depth). During the cruise, 6 science pods on the three 2-legged Shallow Profiler moorings at the Slope Base, Axial Base, and the Oregon Offshore sites will be turned. The field program will also turn multiple secondary junction boxes (maximum weight ~ 3200 lbs). The cruise will be hosted on the interactiveoceans website with live streaming of deck and ROV operations and will include the undergraduate students that participate in the UW at-sea experiential learning program VISIONS (VISIONS'25). Similar to past cruises, additional NSF and ONR- funded days will be added onto the RCA field program through PI ship requests. Two legs will be required with 2-3 days in port between legs (Newport, OR).

Photochemical reactions are affected not only by the DOM reactants but also by key inorganic species (such as carbonate, halogen radicals, nitrate, and nitrite). Therefore we propose to investigate DOM photochemistry in two different aquatic systems with differing salinities and nitrate and nitrite levels, but similar concentration ranges of dissolved organic carbon and chromophoric dissolved organic matter, and similar pH ranges. Using these two transects from highly allochthonous to autochthonous DOM, which cover a wide range of DOM quantity and quality, we propose to study the photochemical transformations of DOM carboxyl groups. We will investigate how the phototransformations of these carboxyl groups vary along the two environmental-effect axes of salinity and DOM source.

An interdisciplinary project, consisting of seismic imaging, geochemical analysis of submarine lavas, and geodynamic modeling, is used to investigate the Tonga-Lau-Samoa system. Seismic observations will be obtained from an 18-month deployment of 30 Ocean Bottom Seismographs (OBSs) and 5 land seismometers (including 3 permanent stations) in the northern Tonga-Lau and Samoa regions. Several different seismic imaging techniques will provide 3-D velocity models of the upper mantle, precise earthquake locations will image the slab tear and associated deformation, and the variation of seismic velocity with direction will provide constraints on mantle flow. Lava samples will be dredged at 10 seamount locations east of the Tonga Trench to better understand subduction inputs into the northern Tonga Trench with the goal of understanding the distribution of enriched mantle material in the Lau Basin. The samples will be analyzed for isotopic compositions allowing identification of possible sources of non-Samoan hotspot materials in the Lau Basin, which is critical for geochemical interpretations of mantle flow. A series of geodynamic models will simulate slab-plume interactions with a variety of possible configurations. Using the integrated history of time-dependent mantle flow in the models, the predicted thermal structure and mantle textures can be directly compared with seismic and geochemical observations.

The MERCI cruises are multi-mission expeditions co-sponsored by both the Coral Propagation Techniques (CPT) as well as Habitat Assessment and Evaluation (HAE) projects to support coral propagation activities as well as documenting and mesophotic and deep benthic communities and habitats under the Mesophotic and Deep Benthic Communities portfolio (MDBC). MERCI (Mesophotic Expeditions for the Restoration of Coral and other Invertebrates) missions began in 2022 to support coral husbandry and propagation as well as habitat and community assessment in reference areas not affected by the Deepwater Horizon Oil spill. Thus far, the expeditions have been conducted in and around the Flower Gardens National Marine Sanctuary (FGBNMS) West of the Mississippi River. The MERCI-4 expedition will follow upon MERCI-1,2 and 3, working in the mesophotic depth zone (50 - 400 m) of the northwestern Gulf of Mexico with an observation-class ROV. The vehicle will conduct exploratory transects, building on knowledge in and around the FGBNMS expansion area. The ROV will collect coral samples for live aquaria, coral husbandry, reproduction, genetic, and microbiome studies.

We propose a combined field and laboratory program with a modeling effort to evaluate if different physical modes of nutrient delivery, in close proximity to each other, exert sufficient controls on nutrient availability and influence phytoplankton functional biodiversity and that of their zooplankton grazers. Distinct mechanisms have been identified that enhance nutrient concentrations to the upper ocean, but which are expected to support different rates and time histories of nutrient delivery. We hypothesize that varying physiological traits of phytoplankton nutrient acquisition and storage will conform to these inputs. The proposed study site is the Galápagos Archipelago in the eastern equatorial Pacific Ocean. Measurements collected there by members of our team since 2014 suggest three modes of nutrient delivery are operative (topographic upwelling, island wakes and internal tides), and that phytoplankton communities differentially respond to these modes. For this proposal, intensive shipboard sampling will be augmented by 12-month deployments of a vertical profiler mooring to observe i) an isolated island wake and ii) interaction of the archipelago with the Equatorial Undercurrent (EUC) and upwelling on the western side of the archipelago. Internal tides are believed to have a significant influence on the system and also will be observed. The longer-term observational efforts will generate time series of currents, hydrographic properties including nitrate and chlorophyll a fluorescence and include biweekly water sampling of the region for molecular characterization of the phyto- and zoo-plankton communities. Intensive shipboard surveys will additionally measure a suite of hydrographic and plankton properties, including community composition, primary productivity, nutrient uptake rates and changes in gene expression driven either directly or indirectly by the physical forcing. Laboratory culture studies using phytoplankton isolates obtained from the region will be used to characterize nutrient uptake and storage characteristics to complement the field studies. The result will also inform parameterization of a simple plankton model forced by time series of nutrient delivery representative of the three physical modes at play, used to test if bottom-up control can explain observed distributions and temporal variability. A suite of phytoplankton parameterizations will be investigated, informed by observed species-specific characteristics, to determine which phytoplankton functional traits are favored by which physical mode. The overarching goal of the project is to examine how these specific physical mechanisms influence the functional biodiversity of plankton communities through increasing nutrient inputs into the mixed layer, leading to strong, yet perhaps predictable biological variability in a changing ocean environment.

These cruises utilize funding provided by the University of Minnesota. Chief Scientists will be completing seed research cruises or using their ship time to take graduate and undergraduate students on the research vessel Blue Heron.

Crossroads is a Lagrangian field program combined with numerical modeling aimed at describing the processes that break or maintain connectivity of the lower limb of the Atlantic Meridional Overturning Circulation (AMOC). Crossroads will be embedded in highly complementary field projects by Canadian and European researchers with the same fundamental question regarding connectivity. Specific objective is to determine the processes governing the deep circulation along the western boundary between the subpolar and subtropical North Atlantic—the so-called "transition zone" (TZ), thought to be critical to the latitudinal coherence of the AMOC. We will directly observe the interaction between the deepest layers of the Deep Western Boundary Current (DWBC) with the North Atlantic Current through the TZ by releasing acoustically tracked RAFOS floats in the DWBC east of the Grand Banks at 2500-3800-m depth and track them for two years as they drift through the TZ. The field program is embedded in a complementary hydrographic, Eulerian and modeling investigation also focused on the connectivity of the DWBC through the TZ funded by the EU "Explaining and Predicting Overturning Circulation" (EPOC) and French "Crossroads" programs, which will be leveraged scientifically and logistically.

We propose to carry out a research cruise aboard the R/V Sikuliaq in 2025 that will integrate the foundational pillars of the research project into a single activity. The 15-18-day cruise will run from Seward to Nome making stops for research operations and community workshops along the way. Port calls include Chignik Bay with community visits via small boat ops in Atka, St. Paul, and Gambell. Participants will include Indigenous representatives from partner communities (8), project scientists, students, and educators (7), filmmakers and publicists (3), a project evaluator (1), Sikuliaq research technicians (3) and NSF NNA representatives (1). This ship-time request will be leveraged to apply for additional funding through the State of Alaska Sikuliaq Program.

The goal of the project is to understand nitrous oxide (N2O) consumption in surface waters, by measuring rates of N2O consumption, determining what factors control the rates, and characterizing the microbes involved in the process. Nitrous oxide consumption in surface waters has the potential to reduce net emissions of N2O to the atmosphere, but because biological N2O consumption is considered to be an obligately anaerobic process, it is generally not considered in evaluating N2O flux from the surface ocean. We have detected the presence of microbes capable of N2O consumption, and have measured potential rates of N2O consumption, in fully oxygenated surface waters. In order to assess its potential importance on a global scale, we need to measure N2O consumption in regions where N2O production is low on an aerial basis, but large overall because those regions comprise 97% of the surface ocean. Ship time is requested for one expedition to the North Atlantic, a region where N2O is close to equilibrium with the atmosphere, and can be a weak net source or sink. The region in the North Atlantic is not directly connected to any strong oceanic N2O sources and thus represents the vast oxygenated surface ocean where the only known source of N2O is nitrification. The proposal describes a multi prong attack on the problem, including field work (see below) and molecular biological analysis of microbes and pathways associated with N2O consumption.

This cruise in the northern Gulf of America (nGOA), provides an opportunity to sample sediments underlying a hypoxic water mass. Using multi-isotope and microbial ecology approaches we will use these samples to investigate sedimentary nitrous oxide production and consumption in the nGOA. Concentration, stable isotopic and isotopomer data, 15N-labeled rate measurements as well as molecular ecology data will be generated and synthesized to determine 1) the net sediment-water column flux of N2O, 2) N2O production and consumption rates for different processes, 3) controls by environmental conditions (e.g., oxygen (O2), hydrogen sulfide (H2S), and nutrient concentrations, O2 penetration depth, as well as organic matter elemental composition), and 4) the link between measured rates and the active processes that lead to N2O production by bacteria, archaea, and microbial eukaryotes, as well as bacterial and archaeal N2O consumption.

These research cruises are the baseline measures for the size of the low-oxygen zone (hypoxic zone) for the Mississippi River Nutrient/Hypoxia Task Force, a federal/state interagency working group. The goal of the Task Force is to reduce nutrients within the Mississippi River watershed so that the problems of hypoxia are diminished.

We would like to introduce the students to oceanographic techniques: plankton net tows, mid-water and bottom trawling, soft sediment multi-corer, and Van Veen grab as well as whale and seabird observations and basic ship operations. We expect to depart MARFAC 7am and return to port in the evening ~9-pm

To carry out the recovery and redeployment of the NSF Ocean Observatories Initiative (OOI) Irminger Sea Array, servicing four moorings and up to five gliders in an area southeast of Greenland (38-41W, 58-61N). The platforms will carry multidisciplinary instrumentation and provide the capability for real time communication of data and control of sampling. A surface mooring will instrument the sea surface and upper ocean, capturing the surface forcing and upper ocean variability. A profiling mooring will measure through the water column. Two additional taut subsurface moorings and the gliders will complete the capabilities to obtain vertical profiles and sample the mesoscale (10s to 100 km) variability at the site. Shipboard data will be obtained to assess the performance of the instrumentation.

Conduct CalCOFI surveys off Southern California quarterly, two of these on UNOLS ships.

Conduct CalCOFI surveys off Southern California quarterly, two of these on UNOLS ships.

We aim to understand the transport, persistence and distribution of environmental DNA (eDNA) in marine environments from marine mammal targets. With support from the ONR Multidisciplinary University Research Initiatives (MURI) program, we will use ongoing and existing large-scale projects across the West Coast to understand eDNA on multiple spatial, vertical, and temporal scales, with a minimum of additional sampling effort. Our major objectives are: (1) to understand the fate and transport of eDNA and thereby interpret eDNA detections from marine mammals in a spatially and temporally explicit context; (2) to evaluate eDNA as a complement to -- or plausibly, as an alternative to -- traditional visual observations and acoustics detections for cetaceans; and, (3)To apply the lessons learned to map marine mammals along the US west coast using eDNA. As part of this effort we will integrate marine mammal eDNA sampling and detection protocols into quarterly CalCOFI (California Cooperative Oceanic Fisheries Investigations) ocean ecosystem monitoring cruises in the California Current Ecosystem. We will also pair eDNA marine mammal sampling with ongoing acoustic and visual surveys of marine mammals as part of the CalCOFI cruise plan. Collectively, these efforts will provide an unparalleled testbed for the validation and calibration of emerging eDNA sampling methods for cetacean detection and location prediction.

The California Current Ecosystem (CCE) Long-Term Ecological Research (LTER) site is a coastal upwelling biome and the site of a 73-year (ongoing) spatially-resolved ocean timeseries (CalCOFI) that has demonstrated physical forcing on multiple spatiotemporal scales with concomitant impacts on ocean biota. The CCE is part of the larger LTER Network, founded in 1980 by the National Science Foundation. CCE-LTER studies are making excellent progress towards diagnosing mechanisms of ecosystem change in a major upwelling ecosystem and developing a quantitative framework for forecasting future changes. Our field site is in the CA Current upwelling regime, centered around Point Conception, within the CalCOFI time series station plan. The CCE LTER field program includes several different elements: experimental process cruises, time series cruises (ship time augmented on existing CalCOFI cruises) and mooring servicing cruises to maintain the deep water CCE1 and CCE2 moorings. The science carried out on these field expeditions is highly interdisciplinary, involving elements of biological, chemical, and physical oceanography.

Placement of a neutrino detector in Western Lake Superior

Bacteria and their viruses (phages) comprise a massive reservoir of genetic information that is exchanged and rearranged though a broad range of host-virus interactions. For example, marine phages can kill their host, modify their host’s genome, or use virally encoded auxiliary metabolic genes (AMGs) to regulate host metabolic processes during an infection. This suggests that phages can contribute directly to the cycling of key nutrients such as carbon and nitrogen. Nitrogen cycling is particularly important in Oxygen Minimum Zones (OMZs) where up to 25% of the fixed nitrogen in the ocean is lost as microbially produced gas through denitrification and other processes. The chemoautotrophic and denitrifying bacteria SUP05 is one of the most abundant clades in OMZs, with up to a third of these cells being reported as infected with phages. This suggests that cells infected with viruses (virocells) impact nitrogen cycling and particularly nitrogen loss through denitrification. Much of what is currently known about SUP05 and their phages is from ‘omics’ analyses, which largely result in highly fragmented and non-clonal genomes. These sequence data suggest that some SUP05 have the potential to carry out all the sequential steps in denitrification, producing N 2 gas. However, other cells appear to have incomplete denitrification pathways, leading to the production of key N-cycling intermediates such as nitrite (NO 2 - ) and nitrous oxide (N 2 O), a potent greenhouse gas. Yet, whether missing steps in denitrification are due to encoding of incomplete pathways or are an artifact of fragmented and incomplete genomes is not clear. Further, the conditions for N-cycling (link) versus N-loss (sink) processes by SUP05 are unknown. Evidence of interactions and cultured host-virus systems are needed to determine the denitrification activities of cells and virocells under different conditions. This project represents an interdisciplinary study that will use a combination of field observations, mesocosm experiments, and laboratory studies to identify the roles of genetically distinct cells and virocells in N-link and N-sink processes.

One of the longest open-ocean hydrographic stations in the world is maintained at the Hydrostation S site (formerly known as the Panulirus site) located ~25 km southeast of Bermuda in the North Atlantic Ocean. This program of repeat biweekly hydrographic observations began in 1954 (by Hank Stommel) and now, in its seventh decade, has proved to be the catalyst for numerous studies of ocean physics, biological processes and biogeochemistry. Hydrostation S continues to be recognized as one of the most important sustained ocean time–series. The renewal of the Hydrostation S program is proposed herein, extending this invaluable time–series of ocean hydrography to almost 70 years. The upper ocean warming trend has strengthened (about +1.4° C since the 1970's; ~+0.8°C in last decade) with significant salinification (+0.16). Deeper waters such as the Labrador Sea Water has cooled by a few tenths of a degree and freshened with a marked decadal oscillation. The signature of deoxygenation has been observed at Hydrostation S in the upper ocean (about 4 µmoles kg -1 decade -1 decrease in dissolved oxygen) as well as the oxygen minimum zone (~2.5 µmoles kg -1 decade -1 ). Hydrostation S also supports the longest global ocean CO 2 and acidification time-series (from 1983 to present) The major objective of the proposal is to continue Hydrostation S into the eighth decade with numerous questions related to warming and cooling, salinification and freshening, deoxygenation and insights on biogeochemical changes over time. This program constitutes frequent water column sampling of temperature, salinity, and dissolved oxygen (and indirectly, sampling of important ocean carbon time–series) of the North Atlantic subtropical gyre at the Hydrostation S site. Such work is complementary to other sustained observations such as the Bermuda Atlantic Time–series Study (BATS) and Ocean Flux Program (OFP). We propose to carry out a similar sampling format that has been followed for the past 68 years. As for the past ten years, we would continue to conduct two CTD profiles to better capture the deep–water variability while maintaining all the previous discrete depths. The first CTD cast will profile to full ocean depth (3,300–3,500 m) while the second CTD cast will profile to 500 m (to allow for instrumentation not rated for full ocean depth such as a PAR sensor). One indirect objective will be to continue to collaboratively evaluate a BIOS-based glider program with Hydrostation S data as critically important ground truthing data. The existing glider program has challenging issue, and the aim of this effort is to use robust and highly accurate Hydrostation S data to test the capability of emerging technologies over the next five to ten years.

Long-term observations over several decades are a powerful tool for investigating ocean physics, biology, and chemistry, and the response of the oceans to environmental change. The Bermuda Atlantic Time-Series Study, known as BATS, has been running continuously since 1988. The research goals of the BATS program are: (1) to improve our understanding of the time-varying components of the ocean carbon cycle and the cycles of related nutrient elements such as nitrogen, phosphorus, and silicon; and, (2) to identify the relevant physical, chemical and ecosystem properties responsible for this variability. In addition, the BATS program has strong and diverse broader impacts, contributing to the field of ocean sciences by providing high quality ocean observations and data for seagoing scientists and modelers, and a framework through which researchers can conceive and test hypotheses. This award will support the operations of the BATS program for five more years. The primary BATS research themes are as follows: (1) Quantify the role of ocean-atmosphere coupling and climate variability on air-sea exchange of CO2, and carbon export to the ocean interior; (2) Document trends and the controls on the interannual to decadal scale variability in carbon and nutrient cycles to their coupling in the surface and deep ocean via the Redfield Ratio paradigm; (3) Quantify the response of planktonic community structure and function, and impact on biogeochemical cycles to variability in surface fluxes and dynamical processes; (4) Facilitate development, calibration and validation of next generation oceanographic sensors, tools and technologies; and, (5) Generate a dataset that can be utilized by empiricists, modelers and students. This research integrates ocean physics, chemistry and biology into a framework for understanding oceanic processes and ocean change in the North Atlantic subtropical gyre. The existing 29 years of BATS data provide robust constraints on seasonal and interannual variability, the response of the Sargasso Sea ecosystem to natural climate variability, and signal detection of potential ocean changes. This project would extend the BATS program through years 31-35 to address a series of ten interlinked questions through integrated research approaches and a multitude of collaborative efforts. In addition to the themes above, and embedded into the ten questions and approaches, the BATS team will focus on, for example, coupling of particle production and biogeochemistry; revisiting the complexities of the biological carbon pump; oxygen decline; and changes in the hydrography, physics, ocean carbon cycle and biogeochemistry of the Sargasso Sea. The highest quality data observation and collection will be maintained and used to address these questions. Importantly, a wide range of collaborations at the BATS site, spanning the physical and biogeochemical disciplines, will aid these broad goals. Strong links to community stakeholders, and close collaboration (including methods intercomparisons and personnel exchanges) with the Hawaii Ocean Time-series are proposed. This work will extend the research findings of the project into educational and training opportunities within and beyond the oceanographic community, including training and mentorship of both undergraduate and graduate students.

This is intended as an educational experience for the MPL internship program in 2025. Sea-going activities will include CTD with water sampling, plankton net tows, collecting data from shipboard flow-through, ADCP, and MET systems. Science party may bring aboard optical systems and microscopes.

C-Streams addresses a key knowledge gap regarding how carbon uptake over the North Atlantic is controlled by ocean circulation. We are all aware that the Gulf Stream is important for heat supply to northern latitudes, but here we investigate how this current is crucial for setting carbon dioxide uptake from the atmosphere. Working with US partners, we will measure the strength and variability of Gulf Stream property transports in Florida Straits. We will measure the downstream evolution of Gulf Stream nutrient and carbon concentrations over 2000 miles using targeted observations by autonomous instruments, novel analyses and model simulations. We will determine how the Gulf Stream provides a far field control of North Atlantic carbon uptake, providing an alternative paradigm to the prevailing view of control by stratification. We will then assess whether climate models provide the right response of the North Atlantic carbon sink to climate change and for the right reasons. We will deploy 3 moorings with biogeochemical instrumentation at 27 N in the Florida Straits - the same latitude as the NOAA WBTS repeat stations and the new NSF FOCUS array - to continuously measure property transports of the Gulf Stream over a two-year period. In particular, these moorings will resolve the nitrate and low-carbon transports of the relatively fresh deep waters in the Straits that originate in the southern hemisphere. It is hypothesized that northward advection of these waters fuels uptake of anthropogenic carbon in the North Atlantic. We will deploy gliders and Argo floats to quantify mixing and entrainment of these waters along their northward path in the Gulf Stream

We request the use of a research vessel and ROV to collect sediment cores from a cold seep site. The site is located at Mississippi Canyon lease block 118 in the Gulf of Mexico. Cores will be retrieved and characterized through geochemistry, microbiology, and rate analysis. Coring operations will target seep related features, i.e. carbonates, oil stained sediment, tube worms, and methane bubbles. The cruise will encompass approximately 10 science days. Additionally, we request the use of a rad van for the use of 35S. The purpose of the research is to define the link between viral activity and sulfate reducing microorganisms.