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Current and Past Projects

The Tale of Three Systems: Fate of Primary Production in the Chukchi Sea (ToTS)
Single-celled photosynthetic primary producers generate most of the fixed carbon that supports Arctic Ocean food webs and drives numerous biogeochemical cycles. Three main sources of net primary production (NPP) have been identified in the Arctic Ocean that differ primarily in their timing and location within the water column. These include (1) single-celled microalgae growing within the sea ice, (2) phytoplankton that bloom in water under the sea ice (UIB), and (3) phytoplankton that bloom in open water, including in the marginal ice zone (MIZ) and at the depth of the subsurface chlorophyll maximum (SCM). Increasing our knowledge of the relative rates of NPP and particle export efficiency from these three systems is critical if we are to understand how continued sea ice loss, and the associated shifts in ice algal and phytoplankton bloom dynamics, will differentially impact benthic and pelagic food webs in shallow seas throughout the Arctic Ocean, including many organisms on which Indigenous human populations rely. Website: ocean.stanford.edu/tots.

Quantifying N2 fixation rates of noncyanobacterial diazotrophs and environmental controls on their activity
Nitrogen (N) is an important element in the ocean that limits the growth of the microscopic marine plants, phytoplankton. Estimates suggest N inputs and losses may not be balanced in the modern ocean, and thus an underestimation of N inputs may explain this imbalance. The conversion of gaseous N2 to biologically available N (N2 fixation) is the largest source of new N to the ocean. It is possible that the “missing” N can be explained by identifying new sources of N2 fixation. N2 fixation relies on a group of microorganisms, termed “diazotrophs,” that utilize N2 for growth, unlike other marine microorganisms. Diazotrophs fall into two groups, cyanobacterial diazotrophs, which are able to derive energy through photosynthesis, and non-cyanobacterial diazotrophs (NCDs), which require a non-light-based energy source. Next to nothing is known about the ecology and biology of NCDs, except that they are ubiquitous in the ocean and contain the nitrogen fixing gene, but no direct measurements of their N2 fixation activity exist. Recent molecular advances for studying organisms at the single cell level now makes the measurement of N2 fixation by NCDs possible. This study is focused on determining whether marine NCDs are actually fixing N2 in the environment and understanding how their N2 fixation is modulated. Determining if NCD activity is an important missing N source in the global oceans has the potential to fill a critical gap in our understanding of the marine N cycle. Data website: ocean.stanford.edu/ncd.

Elucidating Environmental Controls of Productivity in Polynyas and the Western Antarctic Peninsula
Coastal waters surrounding Antarctica represent some of the most biologically rich and most untouched ecosystems on Earth. In large part, this biological richness is concentrated within the numerous openings that riddle the expansive sea ice (these openings are known as polynyas) near the Antarctic continent. These polynyas represent regions of enhanced production known as hot-spots and support the highest animal densities in the Southern Ocean. Many of them are also located adjacent to floating extensions of the vast Antarctic Ice Sheet and receive a substantial amount of meltwater runoff each year during the summer. However, little is known about the specific processes that make these ecosystems so biologically productive. Of the 46 Antarctic coastal polynyas that are presently known, only a handful have been investigated in detail.
This project will develop ecosystem models for the Ross Sea polynya, Amundsen polynya, and Pine Island polynya; three of the most productive Antarctic coastal polynyas. The primary goal is to use these models to better understand the fundamental physical, chemical, and biological interacting processes and differences in these processes that make these systems so biologically productive yet different in some respects (e.g. size and productivity) during the present day settings. Modeling efforts will also be extended to potentially assess how these ecosystems may have functioned in the past and how they might change in the future under different physical and chemical and climatic settings.

Harnessing the Data Revolution to Secure the Future of the Oceans (Stanford Catalyst for Collaborative Solutions)
Climate change is causing profound upheaval in the oceans. That upheaval is compounded by many other stresses, including acidification, pollution, overfishing and destruction of coastal habitats. Together, these pressures threaten to cause catastrophic “state shifts”– the collapse of fisheries, for example, and the sudden and irreversible transformation of ocean ecosystems from vibrant productivity and diversity to barren wastelands. To sustain the health of the oceans, and the ocean resources and services upon which we depend, it is urgent that we understand the risks posed by interacting stresses on the oceans, and equip policymakers, managers, and resource users to manage those risks. This project will build a sustained effort to meet this need and to train a new generation of ocean researchers and leaders who have the orientation, insights, and abilities to address the challenges of oceans in flux.

Biogeochemical significance of the abundant, uncultivated symbiotic cyanobacteria UCYN-A
In the marine environment, the contribution of N2 fixation to the fixed nitrogen (N) pool is poorly quantified, in part due to an incomplete understanding on the abundance, activity, and physiology of diazotrophs. The symbiotic unicellular cyanobacteria (UCYN-A) is a poorly characterized, yet globally important, group of marine diazotrophs. UCYN-A is widely distributed in the marine environment, and lives symbiotically with a picoeukaryotic prymnesiophyte alga. We now know that there are multiple ecotypes of UCYN-A, which may be adapted to specific locations in the water-column and different oceanic provinces. Typically N2 fixation was considered unimportant in coastally influenced and non-tropical waters, however recent data shows that multiple subclades of UCYN-A are present. The distribution and rate of N2 fixation by UCYN-A subclades in coastal/nearshore environments is a major unknown in the oceanic N cycle. Its presence in nearshore waters may change the paradigm of the balance between basin N sources (N2 fixation) and sinks (denitrification). Likewise, significant N2 fixation by UCYN-A will need to be considered when determining estimates of new production in coastally influenced waters. This project aims to quantify the significance of different UCYN-A subclades to coastal/nearshore N budgets. It tackles the issue of determining N2 fixation rates by different UCYN-A subclades in coastal waters through rigorous fieldwork off the west coast of North America. Data website: ocean.stanford.edu/ucyna/.

Remote Sensing of Turbidity with Unmanned Aerial Vehicles for Improved Management of Water Quality in San Francisco Bay
Turbidity – a measurement of water clarity – is affected by the amount of particulate matter in water and is a key test of water quality. Measuring turbidity in estuaries like the San Francisco Bay is important because turbidity impacts light availability for the growth of algae, an important indicator of ecosystem health. This project proposes to develop an efficient and cost-effective methodology to measure turbidity using Unmanned Aerial Vehicles that will autonomously measure the spatial distribution of surface turbidity in San Francisco Bay. Researchers will collaborate with the San Francisco Estuary institute as part of the Regional Monitoring Program and Bay Nutrient Management Strategy that provide regulators and policy-makers data for effective Bay water quality management.

SUBICE: Study of Under-ice Blooms In the Chukchi Ecosystem
Over the last several decades, Arctic Ocean ice cover has become substantially thinner and more prone to melting, extending the period of open water. Associated with the loss of sea ice has been an increase in light penetration and a dramatic rise in the productivity of phytoplankton. The PIs' primary objectives are to determine the spatial distribution of large under-ice phytoplankton blooms on the Chukchi Shelf and the physical mechanisms that control them. The project proposed herein will utilize new data obtained from both remote instrumentation (e.g. moorings and satellites) and an interdisciplinary ship-based field program to gain a better understanding of the physical/chemical conditions that favor under-ice bloom development as well as the physiological adaptations that allow phytoplankton to flourish beneath sea ice. Data website: ocean.stanford.edu/subice. Outreach website: arcticspring.org.

From the Ice Sheet to the Sea: An Interdisciplinary Study of the Impact of Extreme Melt on Ocean Stratification and Productivity near West Greenland
The extraordinary 2012 Greenland Ice Sheet (GrIS) melt season was the most extreme among other recent high-melt years (2007 and 2010), with multiple records set for high summer temperatures, melt extent, annual mass loss, and low area-averaged albedo. In addition, drastic changes have also been seen in the coastal waters off western Greenland, with rapid loss of seasonal sea ice cover and declines in primary productivity. The extreme melt of 2012, as well as other high-melt years, provides a unique opportunity to evaluate the sensitivity of ocean stratification to extreme melting and mass loss. We seek to understand the effects of increased GrIS meltwater runoff on coastal ocean physics, biogeochemistry, and ecology, as well as the larger Arctic ecosystem. To follow the melt from the ice sheet to the sea, our interdisciplinary team utilizes multiple remote sensing tools and sophisticated Earth systems models.

Unraveling the Great Ammonium Debate in the San Francisco Bay-Delta
One of the reasons for the dramatic decline of native fish species in the San Francisco Bay-Delta may be massive outputs of ammonium from regional wastewater treatment plants. There is a pressing need to understand the distribution of ammonium and its impact on phytoplankton, the organisms that form the base of the marine food chain. This project will link satellite remote sensing of phytoplankton with a real-time marine sampling system on a research vessel to determine how physical and chemical factors properties interact to control the fate and distribution of phytoplankton in the Bay-Delta. Eventually, this project could result in frequent high-resolution monitoring of the Bay-Delta’s environmental conditions, providing invaluable information for those who use the system as well as those who are charged with managing it.

Phantastic: Phaeocystis antarctica adaptive responses in the Antarctic ecosystem
Global climate change is having significant effects on areas of the Southern Ocean, and a better understanding of this ecosystem will permit predictions about the large-scale implications of these shifts. The haptophyte Phaeocystis antarctica is an important component of the phytoplankton communities in this region, but little is known about the factors controlling its distribution. Preliminary data suggest that P. antarctica posses unique adaptations that allow it to thrive in regions with dynamic light regimes. This research will extend these results to identify the physiological and genetic mechanisms that affect the growth and distribution of P. antarctica. This work will use field and laboratory-based studies and a suite of modern molecular techniques to better understand the biogeography and physiology of this key organism. Data website: ocean.stanford.edu/phantastic

Oligotrophic phytoplankton community response to changes in N substrates and the resulting impact on genetic, taxonomic and functional diversity (Dimensions of Biodiversity)
This project seeks to determine how taxonomic, genetic and functional dimensions of phytoplankton diversity are linked with community-level responses to the availability of different N substrates (NH4+, NO3-, and urea) in one of Earth's largest aquatic habitats, the North Pacific Subtropical Gyre. The project will characterize phytoplankton community composition change and gene expression, photosynthetic performance, carbon fixation, and single-cell level N and C uptake in different taxa within the phytoplankton assemblage in response to different N compounds. The research project is unique in investigating community-to-single-cell level function and species (strain)-specific gene expression patterns using state-of-the-art methods including fast repetition rate fluorometry, nanoscale secondary ion mass spectrometry and a comprehensive marine microbial community microarray. The results will provide predictive understanding of how changes in the availability of key nitrogen pools (N) may impact phytoplankton dynamics and function in the ocean. Data website: ocean.stanford.edu/dimensions

ASPIRE: The Amundsen Sea Polynya International Research Expedition
The Amundsen Sea is a place on Earth about as far as you can get from human civilization. Satellites reveal it to be the most productive region of coastal Antarctica. Nearby glaciers and ice sheets are melting rapidly. Between November 2010 and January 2011, the U.S. Research Icebreaker Nathaniel B. Palmer was joined by the Swedish Icebreaker Oden for the Amundsen Sea Polynya International Research Expedition (ASPIRE). Scientists on the NBP focused on understanding the climate-sensitive dynamics of the open water region, known as a “polynya,” while the Oden investigated the disappearing sea-ice ecosystem nearby. Outreach website: antarcticaspire.org

ICESCAPE: Impacts of Climate change on the Eco-Systems and Chemistry of the Arctic Pacific Environment
ICESCAPE is a multi-year NASA shipborne project. The bulk of the research will take place in the Beaufort and Chukchi Seas in summer of 2010 and fall of 2011. The central science question of this program is, "What is the impact of climate change (natural and anthropogenic) on the biogeochemistry and ecology of the Chukchi and Beaufort seas?" While both of these regions are experiencing significant changes in the ice cover, their biogeochemical response will likely be quite different due to their distinct physical, chemical, and biological differences. Data website at: ocean.stanford.edu/icescape

DynaLiFe: Shedding dynamic light on iron limitation: The interplay of iron limitation and dynamic irradiance conditions in governing the phytoplankton distribution in the Southern Ocean.
The Southern Ocean plays an important role in the global carbon cycle, due to its large size and unique physiochemical characteristics. Approximately 25% of total anthropogenic CO2 uptake by the oceans takes place in the Southern Ocean, mainly via primary production by phytoplankton. However, changes in the Antarctic climate may impact phytoplankton primary productivity and hence the carbon export by the Southern Ocean. Previous experiments in our laboratory have identified taxon-specific differences in photoacclimation to different light conditions that contribute to explaining observed spatial distributions. However, photoacclimation does not seem to be the only factor that controls the phytoplankton distribution, iron demand might play a role as well. Experiments will be conducted on research cruises in the Southern Ocean to test our hypotheses. Data website at: ocean.stanford.edu/dynalife

Iron fertilization of the Southern Ocean: Regional simulation and analysis of C-sequestration in the Ross Sea
A modified version of the dynamic 3-dimensional mesoscale Coupled Ice, Atmosphere, and Ocean model (CIAO) of the Ross Sea ecosystem is being used to simulate the impact of environmental perturbations upon primary production and biogenic CO2 uptake. Three major hypotheses are being tested during the course this study. Hypothesis 1 deals with the degree of iron-cycle complexity required to simulate the dynamics of added iron in surface waters; Hypothesis 2 addresses the most effective iron fertilization strategy given differences in particle flux and export for blooms dominated by different phytoplankton taxa (e.g. diatoms and P. antarctica); Hypothesis 3 is concerned with assessing the degree of feedback between CO2 sequestration and N2O liberation as a result of iron additions.

Photosynthetic characteristics, carbon metabolism, and nutrient requirements of Phaeocystis antarctica and diatoms from the Ross, Sea, Antarctica
Within the Ross Sea, the most productive area of the Southern Ocean, only about two-thirds of the available macronutrients are consumed by phytoplankton prior to the exhaustion of the available iron (Fe). Were more Fe made available, annual production in these waters could be increased by about 50%, depending upon what phytoplankton taxa dominates. One objective of this study is to quantify characteristics of the photophysiology, carbon metabolism, and nutrient acquisition that determines the conditions under which either diatoms or P. antarctica will dominate the phytoplankton population. The second is to determine the potential of each population to act as a sink for atmospheric CO2.

Probing acclimation in Prochlorococcus ecotypes through analyses of global gene expression
Despite its discovery only a little over a decade ago, the prochlorophyte Prochlorococcus marinus has been shown to be very abundant in oligotrophic tropical and subtropical open oceans and among the most productive phytoplankton in the oceanic gyres (accounting for up to 80% of primary production). As such, it is an important component of the marine food web for a significant fraction of the world's oceans. Or primary goal is to determinee the molecular and physiological constraints that set limits on the ability of the different Prochlorococcus

Primary Production and Air-Sea CO2 Exchange in the Northern Polar Seas
Climate in the Arctic is changing faster than anywhere else on the globe. A key question that needs to be addressed is what role the Arctic plays in modulating changing climate and how it will likely respond in the fact of anticipated future changes. The primary objective of this study is to quantify the contribution of Arctic waters to global primary production, and more importantly, to air-sea CO2 exchange. To do so, we will use multi-platform satellite data along with numerical models of primary production to characterize seasonal to interannual changes in rates of primary production and air-sea CO2 exchange within the Arctic Ocean and adjacent northern polar seas. Computed changes in these quantities will be related to dynamics of sea ice cover and the major climate modes (e.g. ENSO, PDO, AO) to gain a better understanding of how C-cycling in Arctic seas are likely to respond to human-induced alterations in global climate.

Global climate change and infectious disease
Our proposed work examines the link between the environment (sea surface temperature), microbial pollution, and the associated risks and rates of illness in coastal waters. Specifically, we will examine physical and biological attributes of coastal systems that result in an observable, understandable, and predictable relationship between sea surface temperature, microbial pollution (i.e. pathogenic and non-pathogenic enteric organisms) along shorelines of urban beaches, and rates of illness. (with Ali Boehm, CEE)

ITR: Computational induction of scientific process models
Despite the relative simplicity of the marine ecosystem in the Ross Sea and the high quality data available for model parameterization and validation, there are still a number of processes that are poorly understood and poorly constrained in the current model. Processes such as zooplankton feeding on phytoplankton can take many functional forms, and it is not clear which is the most suitable for this ecosystem. Not surprisingly, the numeric parameters that these processes would require are also poorly known. The same is true for processes such as sinking of particulate material and conversion of this organic material back into organic forms by bacteria. The space of candidate models is far too great for humans to enumerate systematically. Thus, computational methods for constructing and parameterizing such models are being used to provide valuable insights into which biological processes and coefficients are most compatible with the field data. (with Pat Langley, ISLE)

Modeling UV-B effects on primary production throughout the Southern Ocean using multi-sensor satellite data
We are studying the impact of an Antarctic ozone "hole" event on primary productivity throughout most of the Southern Ocean. This study combines state-of-the-art physiological and bio-optical models of Antarctic primary production with unique Antarctic satellite Data. These satellite data include visible CZCS and SeaWiFS imagery for estimating algal distributions, AVHRR imagery for mapping cloud cover, TOMS data for estimating UVR fluxes, and Special Sensor Microwave Imager (SSM/I) measurements of surface brightness temperature for mapping sea ice concentration. Some of the satellite data is used as input to a radiative transfer model that will calculate UV-A, UV-B, and photosynthetically active radiation (PAR, 400-700 nm) at the Antarctic ocean surface. These radiation fluxes are used to force the bio-optical models, which also take into account the geographic distribution of Antarctic phytoplankton as estimated from the past three decades of oceanographic studies in the Antarctic.

A coupled ice-ocean model of mesoscale physical/biological interactions in the Ross Sea
The primary objective of this research is to understand the principal processes that control the flux of carbon (and related biologically active chemical substances) from surface waters to the deep ocean in the southwestern Ross Sea, the site of the Southern Ocean Joint Global Ocean Flux Study (SOJGOFS). For this a dynamic 3-dimensional model of the coupled sea ice/ice edge/open water ecosystem in the southwestern Ross Sea is being developed to investigate the complex interactions between environmental forcing and the production (primary and secondary) and fate of biogenic carbon which will synthesize observational data collected both in the field (during SOJGOFS and ROAVERRS) and remotely via satellite.

Research on Ocean-Atmosphere Variability and Ecosystem Response in the Ross Sea (ROAVERRS)
ROAVERRS is an interdisciplinary study of meteorologic forcing phenomena, sea ice dynamics, ocean hydrography, primary productivity, and benthic-pelagic coupling in the southwestern Ross Sea, Antarctica. The primary goal is to examine how changes in aspects of the polar climate system, in this case wind and temperature, influence marine productivity on a large Antarctic continental shelf. In the Ross Sea, katabatic winds and mesocyclones influence the spatial and temporal distribution of ice cover as well as upper ocean mixed-layer depth and thus control net primary production in sea ice and open water systems. The standing stock and structure of bottom-dwelling biological communities are also linked to meteorologic processes, owing to intra-seasonal and interannual variation in the horizontal and vertical flux of organic carbon produced in the upper ocean.

The relationship between sea ice and phytoplankton blooms in the western Ross Sea
Satellite data can be an important source of large scale phytoplankton distributions and primary productivity estimates at high latitudes. However, spatial distributions of phytoplankton were relatively unknown until the launch of the Coastal Zone Color Scanner (CZCS) aboard the Nimbus-7 satellite. Since then, substantial phytoplankton blooms in several areas of the Southern Ocean have been reported, often in association with retreating sea ice edges or in coastal polynyas. Unfortunately, the presence of sea ice can present a problem for the interpretation of CZCS imagery at high latitudes. It is crucial, therefore, to determine the extent to which small ice floes are present in highly pigmented Southern Ocean waters. The primary objective of this study is to use RADARSAT SAR data to investigate the relationship between sea ice and phytoplankton distributions in the western Ross Sea.

Remote sensing of phytoplankton production in the Southern Ocean
This project involves high spatial and temporal resolution mapping of sea ice (SSM/I), sea surface temperature (AVHRR), and phytoplankton pigment (SeaWiFS, OCTS/ADEOS, MOS) distributions in the Southern Ocean. The primary objective is to investigate the relationship between mesoscale features (e.g. frontal zones, eddies, marginal ice zone, etc.) which can be observed from space, and rates of primary productivity. To date, few large scale, high resolution studies of the Southern Ocean have been attempted using remote sensing technology, which is unfortunate because in situ sampling in this hostile environment is very difficult and expensive.

Last updated: May 31, 2023