Current and Recent Research Projects

Gulf of Alaska (GoA)/ Southern California Bight

We propose a study examining the high-chlorophyll regions that develop at the boundaries of high-nitrate, iron-deplete waters and iron-rich, nitrate-poor coastal waters. The region receiving the bulk of our attention will be the productive waters of the northern and northwestern Gulf of Alaska (GoA) where the HNLC waters of the subarctic eastern Alaska Gyre mix with the iron-rich waters of the Alaskan Coastal Current (ACC). Exchange between coastal waters, which are predicted to be rich in iron, and central GoA waters, rich in macro-nutrients (but deplete in iron), is evident in the form of eddies, resulting in filaments of high chlorophyll extending far into the central GoA (Fig. 1). We propose to evaluate this type of system in two very different regions; the northern Gulf of Alaska (GoA) and the region off Point Conception, California.

We will test the hypothesis that the high biomass observed in satellite imagery in the northwestern GoA in mid-summer is the result of the high river runoff during this time of year into the ACC enriching this region with both dissolved and leachable particulate iron, and the resultant mixing of this high iron coastal water with the HNLC waters of the adjacent GoA via mesoscale eddies. Anticyclonic, mesoscale eddies are of critical importance in mixing of these water types in this region. The iron-rich coastal waters mixing with the macronutrient-rich HNLC waters of the GoA leads to the development of high productivity bands within this eddy-rich region during mid-summer months (Fig. 1). The source and the role of both dissolved and leachable particulate iron concentrations resulting in the observed high phytoplankton biomass in these productive waters will be examined.

We expect that there will be an “Fe-limitation mosaic” in the GoA/ACC region, and are proposing an exploratory effort studying dissolved and particulate iron, along with macronutrients and supporting hydrographic data in this region. Alaskan coastal rivers likely introduce a variable range of macro- and micronutrients, while the mesoscale eddies in this region mix the Fe-deplete HNLC waters of the open GoA with these more productive, but often macronutrient-depleted, shelf waters. This study will provide the data and the impetus to justify including the micronutrient iron in future CoOP- or GLOBEC-type studies in this region (or perhaps justify the exclusion of iron), and provide the background data to plan future, more sophisticated, multi-disciplinary studies with physical and biological oceanographers within this productive and economically important region of the GoA. We will be training a new generation of scientists that will be able to help carry out these future studies.

In the course of addressing these questions, we will provide a large data set on both dissolved and leachable particulate iron concentrations, along with macronutrient (nitrate, silicic acid and phosphate) and hydrographic data, for oceanic modelers. Existing oceanic models do not include the source of dissolved or particulate iron from coastal regions as there is little information on iron inputs from rivers and continental margins (Fung et al. 2000; Moore et al. 2002). This study, carried out in a highly productive regime of the northwestern GoA during mid-summer, would provide valuable information on the role of iron in this type of system.

The second region we propose to study is at the interface of the coastal upwelling HNLC waters found off the Big Sur Coast, central California (Bruland et al. 2001), and the nitrate-poor, iron-rich waters delivered from the Southern California Bight and sources near Point Conception. The source and the role of both dissolved and leachable particulate iron concentrations resulting in the high biomass in this region will also be examined.

River Influences on Shelf Ecosystems (RISE/IMUP)

A Multi-Institutional Collaborative Project Sponsored by the National Science Foundation

A Study of the Columbia River Plume

River plumes significantly alter nutrient supply, plankton growth rates and standing stocks as well as enhance material export from productive coastal areas across continental margins. In this project, we focus on a highly productive Eastern Boundary river plume, the Columbia - a plume sufficiently large to be of regional importance, yet small enough to allow determination of dominant processes affecting river plumes, and to facilitate rate comparisons with regions outside the plume. The typical (upwelling-favorable) wind stress and ambient currents act to move the Columbia River plume away from the coast during high production periods, promoting cross margin export. Available data suggest that the Columbia River affects regional productivity from phytoplankton up the food web to juvenile fish (e.g., salmon).

This study is designed to address the following three hypotheses:

1. During upwelling the growth rate of phytoplankton within the plume exceeds that in nearby areas outside the plume being fueled by the same upwelling macronutrients.
2. The plume enhances cross-margin transport of plankton and nutrients.
3. Plume-specific nutrients (Fe and H4SiO4) alter and enhance productivity on nearby shelves.

There will be a comparison of production rates within the plume and outside the plume, on the more productive shelf to the north of the river mouth (Washington) and the less productive shelf to the south (Oregon).

Coastal upwelling regions in the Pacific Northwest have an additional source of macronutrients and Fe, the Columbia River, which enriches both plume waters and sediments north of the mouth. A cross-margin transect off northern Oregon across the southwest flowing plume shows silicate values in excess of 40 µM at the salinity minimum, in marked contrast to nitrate concentrations of less than 4 µM. Upwelling waters in this region have nitrate concentrations close to the silicate concentrations. Exceptionally high Fe concentrations of 20 to 35 nM are observed together with these macronutrients in the Columbia River plume.

The Role of the Bruland Lab:

The Bruland lab will be responsible for measurements of the dissolved trace metals, iron and manganese, along with macronutrients during 4 cruises in the high flow period and one in the low flow period. Discrete samples at depth will be obtained using 30 liter Teflon-coated GO-Flo bottles hung on Kevlar hydroline. Dissolved Fe will be determined onboard ship by a voltammetric method (Rue and Bruland, 1997; Bruland et al., 2001) and by flow-injection analysis using a catalytic spectrophotometric method (Weeks and Bruland, 2002). Particulate Fe analyses will be performed on a large subset of samples (Landing and Bruland, 1987).

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Sampling and Analysis of Fe: SAFe, an international collaboration

Funded by the National Science Foundation

Principal Investigator - Ken Johnson, Monterey Bay Aquarium Research Institute

Co-PI - Ken Bruland, UC Santa Cruz

The goal of this project is to conduct such a collaborative exercise among a large group of experienced analysts to determine dissolved iron concentrations at sea and in the laboratory. This exercise will focus on the entire spectrum of activities involved in making iron measurements, ranging from sampling, filtration, storage and analysis. A series of samples will be archived for analysis in shore based laboratories to ensure that all types of analytical methods for iron are considered and possibly for distribution as an interim iron standard. Where differences are apparent, the work should establish the basis needed to assess the mechanisms that account for the difference. Ultimately, the goal is to enable the ocean science community to compare measurements of dissolved iron made at different places and times in the ocean with a high degree of confidence in the differences or similarities that are detected. This project is a multi-institutional collaboration that is designed to resolve differences that remain in measurements of iron in seawater. It is led by a Steering Committee of experienced iron analysts (Boyle, Bruland, Coale, Johnson, Measures and Moffett). In addition, a broad spectrum of research groups with extensive experience in measuring iron are participating in the collaboration by making measurements at sea (in the US: Landing, Sedwick, Wells, Wu; in Europe: Blain, Croot, de Baar, van den Berg, Worsfold). In addition, a number of Japanese scientists are interested in the collaboration, but may have a conflict with a previously scheduled field program.

The broader impacts of this project extend to a variety of areas. The results will greatly enhance the infrastructure for ocean observations across space and time by allowing iron measurements to be broadly intercompared with the confidence that measurements are compatible. Without such assurance, global surveys and time series observations are nearly impossible. Although education is not a direct component of this work, the results will enable consistent measurements of iron concentrations at the graduate student level - a task that was often prohibitive due to the high level of training that was required.

Center for Integrated Marine Technologies (CIMT)

A Multi-Institutional Collaborative Project Sponsored by NOAA

"From Wind to Whales: Using An Integrated Ocean Observation System To Understand California's Upwelling Ecosystem"

The Center for Integrated Marine Technologies is combining emerging technologies and data integration approaches to determine the processes underlying the dynamics of the coastal upwelling ecosystems along the California coast. CIMT consists of a group of physical, biological, and geochemical oceanographers; ecologists, resources managers, and remote sensing experts, together with instrumentation and networking engineers. The CIMT efforts are focused on the Monterey Bay region of the Monterey Bay National Marine Sanctuary (MBNMS) - from Pt. Año Nuevo to the North to Pt. Lobos to the South out to 122°05' west longitude. This region roughly encompasses the effects of the Davenport/Año Nuevo upwelling region.

The CIMT has initiated a new approach to interdisciplinary coastal research by simultaneously collecting and integrating data collected via remote sensing, coastal observation moorings, shipboard surveys, and apex predator tagging and tracking. By utilizing technology on these different platforms, we can examine temporal changes in the Monterey Bay coastal environment using (mooring-based measurements) within local (ship-based measurements) and regional (satellite-based measurements). Individually, each component measures physical, biological and chemical components of coastal processes at specific temporal and spatial scales. Integrated together, they provide the data to develop predictive models across multiple spatial and temporal scales of how marine resources respond to variability in coastal dynamics. CIMT is integrating the measurement of a range of key parameters for understanding coastal dynamics.

The Role of the Bruland Lab:

The Bruland lab is involved in the ship-based measurements of iron and manganese taken aboard monthly shipboard surveys of Monterey Bay.

A system to collect samples for dissolved and particulate iron and manganese at each of the transect stations has been installed. This research effort entailed the design and fabrication of a new sampling system for the R/V John Martin. This system has been operational starting in the November 2002 cruise. The group is working on optical proxies for particulate and dissolved iron. We are also testing a new bio-optical package (funded by the Institute for Geophysics and Planetary Physics, IGPP, and the Center for the Dynamics and Evolution of Land-Sea Interface, CDELSI), which preliminary results suggest may be used to map bio-available iron. If successful, this would allow us to use the trace-metal measurements as quality control points, with spatial interpolation from the bio-optics.

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The Bering Sea, Alaska

Funded by the National Science Foundation

Trace metal micronutrients and phytoplankton dynamics - a focus on the Bering Sea and the role of iron

The purpose of this project is to investigate the role of micronutrient trace metals (with a focus on iron) in influencing phytoplankton communities. We are examining the major high-nutrient, low-chlorophyll regions of the oceanic Bering Sea gyre - a region we predict will be iron limited. We are also studying the Bering Sea Shelf - a productive region that covers almost half of the Bering Sea. This is an extremely wide continental shelf, ranging from 500 to over 800 km in width. There has been mention of an "iron curtain" occurring over the inner shelf of the Bering Sea; however there are no data available to confirm this idea. There is a "Green Belt" of high chlorophyll and primary production that occurs throughout the summer at the shelf break which must receive adequate iron along with macro-nutrients to sustain itself. An emphasis of this project is to examine the distribution of iron (and other micronutrient trace metals) relative to the macronutrient distributions in order to gain insight into the relative supply and demand of micro- and macronutrient elements in the various regions of the Bering Sea.

San Francisco Bay, California

Funded by the Office of Naval Research and the State of California

We have been examining the potential role of copper as a toxic element in the San Francisco Bay. The toxicity of Cu to micro-organisms is proportional to the free Cu2+ concentration, [Cu2+], rather than to the total copper concentration. Kristen Buck has developed and applied a method based upon the added ligand salicylaldoxime (SA) to set up a competing equilibrium with natural Cu-binding ligands (L1) and the use of adsorptive cathodic stripping voltammetry to detect the Cu(SA)2. With this approach she is able to determine the copper speciation and concentrations of [Cu2+]. Matt Hurst has also carried out studies on copper speciation using an approach based upon anodic stripping voltammetry and a thin mercury film, rotating glassy-carbon disc electrode with a novel nafion film to protect it from interferences. This research has been funded by both the Office of Naval Research and the State of California

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Center for Environmental Bioinorganic Chemistry (CEBIC)

Ken Bruland is a Co-PI and Maeve Lohan is a postdoctoral fellow in the Center for Environmental BioInorganic Chemistry (CEBIC) with Professor Francois Morel at Princeton University as the PI. The establishment of CEBIC at the Princeton Environmental Institute brings together the complimentary expertise of bioinorganic chemists, geochemists, environmental microbiologists, and industrial researchers to elucidate the molecular mechanisms of the function, fate, and effect of trace metals in the environment. 23 researchers from Princeton University, Rutgers University, University of California at Santa Cruz, Santa Barbara and San Diego, McGill University, and Exxon Research and Engineering Corporation are participating in CEBIC.

CEBIC's Mission:

In recent years, human activity has affected several of the earth's most important biogeochemical cycles. Deforestation and the burning of fossil fuels have altered the balance between inorganic and organic forms of carbon, increasing the atmospheric concentration of carbon dioxide and contributing to global warming. Widespread planting of legumes and the production of chemical fertilizers have made available more "fixed" nitrogen and, in certain areas, increased the rate of growth of plants and photosynthetic microorganisms. Desertification, the conversion of biologically productive land mass into desert, has increased the concentrations of trace metals in areas of the seas. Volatilization of metal-containing substances in waste incinerators, cars, and fossil-fuel-burning power plants has also increased the trace metal concentration in some marine environments.

Legions of marine microorganisms extract iron, zinc, and other trace metals from sea water, store them, and then use them to catalyze biochemical processes that enable not just the survival and growth of individual organisms but also the global flux of essential elements like carbon and nitrogen. Among other things, trace metals are needed to:

1. make inorganic carbon available for photosynthesis, cell growth, and fuel, reducing the atmospheric concentration of the greenhouse gas CO2 in the process
2. break down hydrocarbons, a class of molecules that nourishes some organisms and poisons others
3. cycle nitrogen from one chemical form into another, making it available, e.g., for producing the world's food supply and nourishing toxic algal blooms-and then making it unavailable again.

Some trace metal ions are essential, others are toxic. Metals like lead, mercury, and cadmium can substitute for essential metals, rendering metal-containing biomolecules nonfunctional or harmful. Even essential metals are toxic when present in excess.

We won't be prepared to effectively manage ecosystems and the global environment until we understand in detail both beneficial and toxic trace-metal activities. To this end, CEBIC's research program addresses many interrelated, molecular-level questions regarding the fate and function of trace metals in aquatic systems, particularly marine systems.

To organize our discussion of the major research topics of CEBIC it is convenient to simply follow a metal from its entry into the environment to its point of biological action in a microorganism.

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Chemical Analysis and Research on the Biological Dynamics of Iron in the Sea (CHARYBDIS)

Funded by the National Science Foundation

"The Peru Cruise"

Research Cruise August 21 - September 28, 2000, San Diego - Galapagos - Chile

The interdependence of the chemistry of Fe and Zn and phytoplankton dynamics in coastal upwelling regimes

The Peru cruise (San Diego, California to Arica, Chile) was completed in September 2000. The Peru upwelling system is in a semi-arid region with seasonal river input and has many similarities to the central California upwelling system. The Peru cruise was during the dry season when the river input was negligible and allowed us to test the hypotheses and ideas that had been developed in the studies of the upwelling regimes off central California. The Peru cruise also included studies of the Costa Rica Upwelling Dome and the "island effect" of the Galapagos Islands being a source of iron in the HNLC equatorial Pacific. This research cruise utilized the R.V. Melville and allowed a suite of collaborative investigators to carry out studies on trace metal/phytoplankton interactions.