Research

This project will conduct the first physical oceanography survey of a deep ocean trench allowing examination of spatial gradients and potential mechanisms of hadal ventilation. The Kermadec Trench, northeast of New Zealand, is the world's fifth deepest trench. The Kermadec Trench is expected to be have short residence time and detectable spatial gradients as the South Pacific Deep Western Boundary Current transporting Antarctic Bottom Water along its 1200 km length and the generation of strong internal tides on the neighboring Kermadec Ridge. Multiple collocated and overlapping deployments on free-falling 11 km depth rated instruments and the ship's 6km rated CTD will be conducted at 12 sites along the trench axis and additional 15 off-axis sites. The 11 km rated instruments are: 1) The University of Hawaii's Hadal Water Column Profiler (HWCP) records full depth vertical profiles of temperature, conductivity, dissolved oxygen, turbulent microstructure (mixing), horizontal current velocity via a geo-electromagnetic current meter, 200 kHz bioacoustic backscatter, and video. It also has a small 11 bottle water trace metal clean water sampler. 2) The University of Rhode Island's Deep Autonomous profiler (DAP) is a lander, water column profiler, and Niskin-based sampler capable of collecting environmental data (T, S, oxygen, density, camera, and sound), recording video segments, and collecting water samples throughout the water column or while resting at the seafloor. 3) At six multiday stations a small bottom mooring consisting of a single point acoustic current meter, a temperature/pressure logger and two acoustic releases will also be deployed. All three of the above 11 km rated instruments use syntactic foam for flotation. A 150 kHz upward looking and a 300 kHz downward looking Lowered ADCP will be attached to the ship's CTD frame.

We seek a few days of shiptime to recover and redeploy a Wirewalker mooring within the Galapagos archipelago and do some simple water sampling at both locations. The mooring is configured to be deployed in roughly 400 m of water and is presently ~20 km north of Kicker Rock off the NW coast of San Cristobal Island. We wish to recover the mooring and redeploy it in Elizabeth Bay on the west side of Isabela Island. These two deployments are funded components of our NSF project "Collaborative Research: BoCP-Implementation: The influence of different nutrient delivery modes on functional biodiversity of marine plankton in a changing ocean". The Wirewalker was deployed last summer from the RV Langseth and we had intended to use an Ecuadorian vessel for the recovery and redeployment but that has not been possible to arrange. We estimate 3 days of shiptime will be needed, half of which is transit time between the two locations.

Understanding how melt aggregates in the mantle during melting remains a critical open question in mantle geodynamics and volcano science. Although melt transport has been typically modeled as diffuse porous media flow, a variety of geological, geochemical, experimental, and theoretical results suggest the possibility of melt localization at lengthscales of 10s of m - km due to two-phase flow instabilities (e.g., reactive transport, shear banding) and long-distance (100s of km) lateral melt transport. However, it has been challenging to observationally validate theoretical models of two-phase melt transport and assess the importance of melt channelization in the mantle across different tectonic settings. One geodynamic setting that provides an ideal natural laboratory to understand this sub-lithospheric melt transport and extraction is the interaction of the off-axis mantle plumes with nearby mid-ocean ridges (< 1000 km distance), wherein the mantle plume provides a distinct geochemical tracer (compared to MORB) for tracking melt transport processes. The key characteristic of this interaction is the presence of volcanic lineaments such as the Wolf-Darwin Ridge in Galápagos, a ~ 200 km long volcanic feature. In our previous work we find that a variety of geophysical and geochemical observations for the Galápagos lineaments are naturally explained in a model where the Wolf-Darwin lineament overlies a volatile- and melt-rich channel connecting the Galápagos plume to the Galápagos spreading ridge. Such lineaments are found in other plume-ridge interaction settings worldwide (e.g. Reunion, Easter, and Discovery). We propose to use a combination of new geophysical (MT data, geodynamics models for 3D plume flow) and novel geochemical observations of the Galápagos lineaments and the Galápagos spreading ridge. Specifically, we propose to use an array of ~ 60 state-of-the-art broadband marine MT instruments to measure the sub-lithospheric electrical conductivity in sections along and across the lineaments and the plume-affected ridge segments. Synthetic MT modeling demonstrates that the conductivity signals associated with sub lithospheric melt channels that we hypothesize are very likely to be detectable. We will couple the results from the MT survey with first principles geodynamical models for Galápagos plume flow towards the ridge and the associated two-phase flow instabilities in order to test the thermodynamic consistency of our findings and discern among the different possible melt channelization mechanisms. Finally, while the MT instruments are recording data, we propose to collect dredge samples along both the northern Galápagos volcanic lineaments and the lineamentspreading ridge intersections to estimate the melt volatile content and geochemically constrain the contribution of the plume component using a combination of rare earth modeling and novel isotope measurements. This work will lead to significant, if not transformative, advances in our understanding of plume-ridge interaction and mantle melt transport processes in general

Our interdisciplinary team proposes to test the overarching hypothesis that organic matter input to the deep sea drives biological processes that modify geotechnical and geoacoustic properties of the surface layer of sediments. We will explore the spatial and temporal variability and relationships among these properties in the central California slope. This region experiences seasonal and interannual variability in organic matter deposition to the seabed and spatial variability in the infaunal community. We plan to combine seasonal sampling of geological, geotechnical, geoacoustic, biological, and biogeochemical properties along a spatial gradient with high temporal resolution sampling of the bottom boundary layer and seabed surface. Our results will provide insight on the patterns of seabed properties and the mechanisms driving those patterns and will improve our ability to predict and remotely detect changes in deep sea sediments. In this project we aim to use cutting-edge abyssal direct observing and remote sensing techniques including dense thermistor moorings, dye releases, acoustic reflection and scattering measurements, direct turbulence measuring autonomous floats, direct measurements of sediment load, particle size and settling velocity distribution, and bioacoustics in order to synthesize a complete interdisciplinary picture of the deep sea benthic boundary layer.

Field work will include water sampling by CTDs and sediment sampling using piston cores, multicores, and trawls.

Naval Undersea Warfare Center Division, (NAVUNSEAWARCENDIV) Newport Ranges, Engineering, and Analysis Department, Waterfront Operations Branch (Code 7022) supports at-sea testing for advanced unmanned test vehicles, oceanographic systems, and acoustic communications. Branch personnel maintain expertise in safely conducting at-sea exercises and in the deployment and recovery retrieval of various test equipment and devices. Often, supporting tests of this nature requires assets to be used which are not owned by the Government. Examples of such equipment include fixed and rotary wing aircraft, oceangoing vessels, commercial diving support, vessel mobilization support, and use of various pieces of oceanographic equipment. NUWCDIVNPT is planning a test vehicle exercise from 27 - 28 May 2025 at the Jacksonville Shallow Water Tactics and Training Range (JSWTTR), off the coast of Jacksonville, Florida (FL). Up to sixteen (16) test vehicle are planned for evaluation of Operational Software. Services of multiple vessels and one aircraft will be required.

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 into quarterly CalCOFI ocean ecosystem monitoring cruises in the California Current Ecosystem. We will also pair eDNA marine mammal sampling with 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.

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)

Coupled atmosphere-ocean general circulation models have long predicted that rising temperatures will result in enhanced stratification within the upper ocean, suppressing nutrient fluxes into the euphotic zone and negatively impacting primary and export production rates. However, fluxes of nutrients and carbon are controlled by complex linkages between physical mixing and biological processes. Our proposed study using Be-7 as a tracer of upper ocean mixing and transport processes in the Sargasso Sea will result in improved model parameterization of mixing and transport processes, and examine interdecadal variability of nutrient fluxes and oxygen utilization rates. To accomplish these goals, we will take part on eight cruises to the Bermuda Atlantic Times Series (BATS) site and other nearby locations during the period May 2026 to November 2027. Profiles from the upper water column will be obtained using in situ pumps that filter seawater through filters coated with iron hydroxide to absorb Be-7. Dissolved oxygen and nutrient concentrations, which are routinely collected by the times series personnel, will be modeled using diffusive mixing rates determined from Be-7 distributions, resulting in estimates of oxygen utilization and nutrient transport rates. Data collected in a similar study in 2007-08 will be provide for an interdecadal comparison.

The plan for this project is to deploy a set of five bottom-mounted ADCPs across the Gulf Stream for a full year. We plan to directly measure the Gulf Stream volume transport and its variability along the US Southeast Coast. Previous attempts to measure the Gulf Stream have focused on the Florida Straits where the current is confined and thus easier to measure. However the Florida Current joins with the Antilles Current along the Northeast Florida shelf, creating the beginnings of the Gulf Stream proper. It is here where we plan to deploy our moorings. Our hypothesis is that most variability in the Gulf Stream strength is also reflected in tide gauges along the US Southeast coast. There is a long-term record of coastal sea level from Fernandina Beach, which will be directly inshore of our moorings. We also plan to use sea level variability from the Ft. Pulaski tide gauge station. If Gulf Stream variability is correlated to coastal sea level, this offers the possibility to reconstruct Gulf Stream variability going back over 100 years.

Systematic long-term (greater than a few decades in length) time-series observations of aquatic and terrestrial environments have led to a more comprehensive understanding of the natural ecosystem variability and have enabled an assessment of human impacts on ecosystem dynamics. Because of their ability to store and transport large amounts of heat and to absorb carbon dioxide from the atmosphere, the world's oceans play a critical role in modulating environmental conditions for the sustained well-being of both land-based and marine organisms including humans. Despite their recognized scientific and societal importance, long-term records of key ocean processes are rare. In 1988, the Hawaii Ocean Time-series (HOT) program, near Hawaii was established. For over three decades, teams of scientists based at the University of Hawaii have made critical measurements of the 'state of our sea.' These long-term observations have established a baseline against which future states can be compared. The ship-based HOT program complements other diverse ocean observation programs including remote-sensing via satellites, moored buoys, profiling floats, and autonomous underwater vehicles. All HOT program data are publicly available and are frequently used by researchers and policy makers around the world.

Cruises to deploy and recovery meteorological buoys

Service visit for a Fugro Wavescan buoy. Plan will be to bring out a new buoy and mooring line to swap with the deployed mooring. Crane, A frame, and winch needed for operations.

Researchers from NOAA's Atlantic Oceanographic and Meteorological Laboratory (AOML) in Miami, FL, conduct regular bimonthly hydrographic surveys at 27N in the Florida Straits to monitor the transport and water-mass properties of the Florida Current. The Florida Current is part of the Gulf Stream system, which is the upper limb of the western boundary current system in the North Atlantic Ocean. These cruises are a part of the laboratory’s long-running Western Boundary Time Series (WBTS) project and directly measure the Florida Current at nine locations across the Straits of Florida at 27N, between Jupiter, Florida, and the Little Bahama Bank in the Bahamas. WBTS 27N hydrographic sections, conducted bimonthly throughout the year, are critical to improving our understanding of the North Atlantic Subtropical Gyre circulation and the Atlantic Meridional Overturning Circulation (AMOC). Importantly, data collected during these cruises and others are also used to calibrate the 27N submarine cable system which publicly provides daily transport estimates of the Florida Current . The AMOC is a significant factor in climate change, oceanic carbon sequestration, and sustainable fisheries.

The project involves the deployment and precision placement of five large independent frames containing Nuetro sensors on the seafloor using DP and the USBL. The nominal water depth is 200 meters. A single fiber optic cable (5 - 6 KM) will need to be laid on the seafloor back to the shoreside data facility in Twin Harbors, Minnesota. I may use the Blue Herron as the platform for getting the bitter end of the cable ashore in Twin Harbors.

Take field measurements and conduct numerical experiments to determine the relative roles of wind shear inputs, coastally trapped waves, vertical energy fluxes, frictional decay, and nonlinear processes in the spin-up, energy transfer, and decay of near-inertial oscillations near a coastline. A better understanding of the roles of these dynamical terms will inform techniques for assimilation of high-frequency currents and lead to improved coastal predictions.

The R/V Atlantis will be making a transit cruise in early November from Golfito to Manzanillo. We request that two technicians from Scripps join the transit cruise to launch a Wave Glider on the transit route. We expect it will lengthen the duration of the cruise by an hour and a half.

Marine microbial communities often harbor many closely related, yet distinct lineages or clades. What drives this microdiversity and, importantly, what is the level of functional redundancy among the clades and the value of this diversity for ecosystem functioning and resilience remain poorly understood questions that are highly relevant for better understanding and modeling the diversity and ecological contributions of marine microbes. Oxygen minimum zones (OMZs) are ideal sites to study functional diversification and redundancy as they represent highly productive, high biomass regions of the ocean. These zones are characterized by phylogenetically and functionally diverse microbial assemblages with key roles in global nutrient cycles, notably the anaerobic conversion of bioavailable nitrogen to nitrogen-containing gas. Further, OMZs are predicted to expand as an effect of climate change, making the ocean less hospitable for fish and other marine organisms and likely exacerbating climate change by releasing potent greenhouse gases, including nitrous oxide (N2O) produced from microbial denitrification. Despite the importance of OMZs for the ocean ecosystem and the intense research focus on OMZs during the past two decades, good model organisms that represent key players in OMZs and can be studied to advance current understanding of organic matter and greenhouse gas turnover in OMZs, as well as processes of microbial diversification, are lacking. Our team has recently made an important discovery describing unanticipated patterns of microbial diversity and functions in OMZs (Tsementzi et al. 2016, Nature). Using a combination of single-cell genomics, biochemical rate measurements, and enzyme assays, we showed that OMZ SAR11 bacteria, the most abundant group of heterotrophic bacteria in the oceans, span several diverse clades distinct from those of oxygen-rich waters. Notably, OMZ SAR11 have acquired the ability to respire nitrate in place of oxygen, resulting in the production of nitrite, a critical intermediate for downstream processes of nitrous oxide or dinitrogen gas production via either denitrification or anaerobic ammonia oxidation (anammox). These results implicate SAR11 as a major but previously unrecognized contributor to pathways of ocean nitrogen loss. However, the environmental conditions driving the diversification and niche specialization of low oxygen-adapted SAR11 remain essentially uncharacterized, as does the quantitative understanding of the contribution of SAR11 to OMZ biogeochemical cycles, notably dissolved organic matter (DOM) degradation and nutrient cycling. With a good model organism in hand (OMZ SAR11), several metagenomes, single amplified genome sequences and archived samples from various OMZs available, and an experienced research team, this proposal is poised to provide new insights into marine microbial diversity and function. We propose two specific objectives: 1. Elucidate the underlying mechanisms that maintain clade diversity in OMZ SAR11. We hypothesize that each clade has unique gene content tuned to specific conditions of oxygen, nutrient, and DOM availability. We will employ single cell genomics and long-read metagenomics to characterize hundreds of SAR11 representatives from the world’s largest OMZ to test this hypothesis. 2. Quantify the relative contribution of distinct OMZ SAR11 subclades to community composition and metabolism across OMZ chemical gradients. We hypothesize that adaptation by distinct SAR11 subclades to the OMZ involves differential gene content as well as differential expression of shared gene content (including the two copies of nitrate reductases) depending on oxygen, nitrate, and DOC availability. To test this, we will use metatranscriptomes and chemical and rate measurements sampled at high spatial resolution over depth in the OMZ and in incubations amended with varying oxygen and nitrate levels. Intellectual merit: Despite intensive research over the last few decades, quantitative understanding of the biogeochemistry of OMZs remains incomplete, in part due to a lack of appropriate model organisms for study. We will optimize current and develop new genomic approaches to efficiently study key uncultivated organisms in OMZs and provide new insights into their activity and their role in the cycling of nitrogen and carbon. Therefore, this project will fulfill a critical gap in our understanding of biological diversity in the oceans and provide lessons and techniques that will be useful for studying other marine microbial processes.