Raphael Martin Kudela - US grants

9912361
Kudela

This collaborative project, involving eleven investigators at five institutions is under the auspices of the Coastal Ocean Processes (CoOP) Program, and it focuses on the role of wind-driven transport in shelf productivity. Wind-driven continental shelves represent a paradox in that while they are characterized by high productivity due to upward fluxes of nutrients into the euphotic zone, wind forcing also represents negative physical and biological controls via offshore transport and deep (light-limiting) mixing of primary producers. Specifically, upwelling ecosystems along mid-latitude eastern boundaries of the ocean are well known for wind forcing and high productivity at lower trophic levels, with concomitant transport of near-surface plankton offshore.

The group of researchers will conduct an interdisciplinary study to examine the roles that wind-driven transport plays in productivity over the shelf off northern California. Research will focus on key processes to explain the integrated functioning of highly productive planktonic systems over eastern boundary shelves in response to wind-driven transport, and specifically, to determine the sensitivity of these processes to both wind intensity and the time scales of wind forcing. Work will also identify specific features of the nutrient-phytoplankton-zooplankton (NPZ) food web that lead to greater or lesser secondary productivity in response to changes in wind forcing.

To implement the study, part of the work will examine the 3-dimensional wind-driven circulation of water concurrently with size-structured distributions of phytoplankton and zooplankton species. Other efforts will study the key physical and biological processes that control primary production, zooplankton population responses, and offshore transport of plankton and nutrients over the strongly wind-driven shelf and slope off Bodega Bay. An integrated sampling scheme coupled with appropriate physical-biological models designed to synthesize and guide the fieldwork has been developed. The fieldwork will be comprised of fixed station time-series, ship surveys, drifter releases, and satellite remote sensing. There are two parts to the fieldwork - one focusing on the mooring array off Bodega Bay, and a second involving ship surveys and drifters. The mooring array places emphasis on eulerian measurements of cross-shelf circulation, aiming also to resolve up/downwelling fluxes. The surveys and drifters place emphasis on transformations in the water column, specifically the maturation of upwelled water as it moves away from the mooring site. By combining these data with the synoptic measurements available from satellites and the integrative aspects of the modeling, the project seeks to address all the important processes associated with wind-driven transport. This promises to unravel the paradox of how wind-driven transport supports high levels of productivity over eastern boundary shelf regions.

This particular component of the study will provide remote sensing data using the AVHRR, SeaWiFS, and GOES platforms, and to further develop existing algorithms and bio-optical models to complement other work in this multi-disciplinary study.

The two intertwined goals of this project are to determine the suite of genes expressed by Pseudo-nitzschia under toxin-producing conditions, and to acquire a better understanding of the connections between environmental conditions and physiological responses leading to toxin production. A set of physiological experiments will permit evaluation of molecular probes generated from gene expression studies. In turn, the molecular probes will be used to
interrogate natural populations and help determine the physiological status of Pseudo-nitzschia in the field. The ultimate goal is to find a specific gene transcript or a pattern of gene expression that is correlated with toxin production in the field. The following hypotheses will be tested:
H1: There are genes or a suite of genes whose expression pattern is highly correlated with toxin production in Pseudo-nitzschia.
H2: A primary trigger for toxin production in Monterey Bay is silicate limitation, so that certain oceanographic conditions permit bloom development.
H3: Silicate limitation may sensitize cells to trace-metal (e.g. copper) stress and the toxin (domoic acid) can function as a metal ion buffer.

Batch and continuous cultures will be stressed with silicate, copper, and iron. Growth, substrate utilization, and physiological parameters (variable fluorescence, nutrient quotas, amino acid pools, including domoic acid) will be assessed. Cells will be harvested for development of cDNA subtraction libraries under different stressors. Gene arrays developed from these libraries will provide molecular probes for field testing. Identification of genes related to toxin production, but not general metabolism, will be facilitated by information generated by the physiology experiments. The laboratory work will be combined with a limited field program for assessment of environmental triggers (e.g. copper, silicate, iron stress) and for testing of the molecular probes. Results from the molecular expression and physiological assays will permit an initial description of the cellular pathways mediating environmental triggers (e.g silicate and metals) for production of toxin.

P.I. Hickey, Barbara (UW)

Project Summary
This proposal focuses on the highly productive Eastern Boundary Columbia river plume. This plume is 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 proposed study will integrate results from the nearby wind-driven CoOP study, as well as with those from nearby GLOBEC and ECOHAB projects to provide definitive new information on alteration of rates of biogeochemical processes by the unique stratification, turbidity, mixing environment and nutrients of a river plume. Moreover, because the Columbia River provides no significant terrigneous nitrate to the plume in the growing season, this study allows plume-endemic processes to be isolated and hence process results can be directly applied to other plumes. Results can also be contrasted with more eutrophic, buoyancy-influenced coastal areas.

The proposed study will address three hypotheses:
- 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.
- The plume enhances cross-margin transport of plankton and nutrients.
- Plume-specific nutrients (Fe and SiO4) alter and enhance productivity on nearby shelves.

The proposed strategy is to compare 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). Results from this study address important question as to why a shelf with weaker upwelling winds is more highly productive than a shelf with stronger winds.

0421510
Ravelo
This Major Research Instrumentation award to University of California Santa Cruz provides funds to establish a cutting-edge stable isotope analytical facility for environmental research. It includes support for the acquisition of three new mass spectrometers plus new front-end systems for sample preparation and separation, and adds capabilities for undertaking natural abundance, isotopically-enriched and compound specific analyses of organic material to the existing two systems that will continue to serve requirements for mineral-phase analyses. The broader impacts of the acquisition include a strong commitment to involve students, researchers and visitors at many levels in research undertaken at the facility. In addition, the instrumentation will be managed as a regional shared-use facility, open to researchers from throughout UCSC and outside, and it will be used to study a wide array of projects with compelling societal relevance (e.g. climate change, pollution). UCSC is providing 30% of the project cost from non-federal funds. This proposal is supported by the Division of Ocean Sciences at NSF.
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ABSTRACT

Proposal # OCE-0623622

Particulate and dissolved organic nitrogenous material (PON & DON) represent the major active pools of reduced organic N in the ocean. Sinking PON and advected DON from the surface into the ocean's interior represent the main pathways for export of new production, nitrogen flux and remineralization, as well as long-term organic nitrogen storage as DON in the deep sea. The chemical identity of organic nitrogen is key to understanding its sources, roles in ocean food webs, and the biogeochemical mechanisms that regulate its cycles. However, the large majority of PON in the deep ocean, and DON at all depths, cannot be identified at the molecular level. Accumulating evidence now indicates that this material is composed of largely unaltered biomolecules (amide N functions), and is likely dominated in most reservoirs by amino acids (AA). While hydrolyzable AA composition has long been a powerful tool for investigating diagenetic transformations, traditional AA measurements have intrinsic limitations for differentiating specific sources and transformations of ON in the ocean's water column.

In this research, two PIs from University of California Santa Cruz will develop a new set of molecular-level tools based on the recognition of *15N and *13C AA stable isotopic patterns that potentially record both a metabolic signature of their synthetic origin, as well as diagnostic signatures of subsequent heterotrophic transformations. They hypothesize that, together with enantiomeric (D/L) ratios, *15N and *13C AA signatures can be used to determine both ultimate source and heterotrophic processing of organic N at a level of specificity and detail that has not previously been possible. To test these hypotheses, they will conduct a set of lab experiments using multiple prokaryotic and eukaryotic algae in a linked series of feeding experiments with bacterial, protist, and macrozooplankton transformations. Upon completion of this proposal, ocean scientists will be in an excellent position to extend these methods from the laboratory to field studies with confidence.

Among its broader impacts, this proposal will have far-reaching implications for our basic understanding of how organic nitrogen cycling works in the ocean. This in turn would have direct and indirect impacts on our understanding of carbon cycling, as well as how other researchers parameterize regional and global biogeochemical models. Undergraduate, graduate and post-doctoral education will be furthered through active participation in laboratory and data synthesis activities. Two graduate students will be provided a unique educational background in molecular level isotopic tools and biogeochemistry. Undergraduate research will also be involved throughout the project.

The northern Gulf of Alaska (GOA) is among the ocean's most productive ecosystems and supports a rich coastal fisheries. Although strong cross-shelf gradients in phytoplankton (chlorophyll decreasing offshore) have been identified, yet the specific factors that regulate and control primary production have only been hypothesized. Cross-shelf patterns in primary production/species composition are consistent with a gradient of iron availability (Strom et al., in press), but this has yet to be rigorously tested. In collaboration with the NSF-funded project Mixing of iron-rich coastal waters with nutrient-rich HNLC waters leading to enhanced phytoplankton biomass: a focus on the northwest Gulf ofAlaska (K. Bruland), this project will examine the influence of cross-shelf exchange and physico-chemical gradients on phytoplankton distributions, physiology, and assemblage structure in the northern GOA, making use of complementary high-resolution iron data and building on the results from previous studies. The proposed work directly complements studies accomplished by the US GLOBEC Coastal Gulf of Alaska (CGOA) program, and is essential to link Bruland's study of trace metal dynamics and speciation to key biological processes. Bruland's project seeks to quantify the inputs of iron from the Copper River, AK, and to characterize and assess the interactions among river inputs and shelf/offshore systems. The quasi-synoptic sampling scheme enables characterization at the mesoscale, the dominant scale of variability in the region. The station grid allows quasi-synoptic sampling while remaining flexible to take advantage of interesting mesoscale features. Should a mesoscale eddy be present, the study will focus on the role that eddy circulation plays in facilitating the offshore transport (suggested by Stabeno et al., 2004) of bio-active trace metals.

This project aims to provide a detailed examination of the phytoplankton rates, assemblage structure, and response to cross-shelf transport/ mixing across gradients in iron and light to better parameterize satellite observations and future modeling efforts. Specific questions include: 1) Do cross-shelf gradients in iron correspond to patterns of carbon assimilation, nutrient uptake, new production, and species composition of phytoplankton in the northern GOA? 2) Do iron and light interact to structure species assemblages and patterns of carbon assimilation? 3) How do frontal regions influence phytoplankton distributions and physiology? 4) What bio-optical properties characterize the different water masses (inshore/offshore), and how well do satellite observations describe phytoplankton standing stocks and rates? 5) What chemical characteristics define the deep Fe-source identified by Lam et al. (2006), and what is the bioavailability of this material when mixed with near-surface waters? This study will provide the first concurrent measurements of iron concentration and phytoplankton physiological parameters in the waters of the northern GOA.

Broader Impacts. The proposed work will be extremely valuable in testing hypotheses arising from many years of effort by GLOBEC CGOA. Data from this study will further our understanding of ocean-climate interactions in an economically and ecologically important region. The results could have far-reaching implications for our basic understanding of coupled biogeochemical cycles in shelf ecosystems. This will have both direct and indirect impacts on our understanding of carbon cycling, as well as how other researchers parameterize regional and global biogeochemical models. Undergraduate, graduate and post-doctoral education will be furthered through active participation in lab, field, and data synthesis activities. Two full time graduate students and a post-doc (this proposal and an NSERC Fellowship) will receive a unique educational background in multidisciplinary oceanography, spanning physical, chemical, and biological processes.

In autumn 2012, Orange County Sanitation District (OCSD) will divert ~150 million gallons/day of secondarily-treated effluent to a nearshore (1 mile offshore) outfall pipe over a period of ~4 weeks. No discharges of this magnitude have been conducted in decades. The planned diversion is expected to create a buoyant surface plume that will spread over much of the coastal region. Because OCSD plans to "super-chlorinate" and then dechlorinate the discharge, the effect of the plume should be predominantly a nutrient addition rather than direct addition of intact microbial populations. The PIs propose to address two broad questions through a study of the plume. First, what happens ecologically and physiologically to the phytoplankton assemblage when nutrients are discharged in the surface ocean for extended periods of time? Second, can this dynamic and shifting environment be sampled by deploying multiple technologies to identify the physical/chemical drivers of the biological response at ecologically relevant space and time scales? They will test two hypotheses: H1: Continual discharge of nutrients to the surface ocean results in a dinoflagellate-dominated bloom which leads to dampening or cessation of vertical migration of the dinoflagellates and drives a shift to net heterotrophy. H2: The bloom will initially result in a strong local sink for carbon dioxide which gradually develops into a strong source as heterotrophy develops.

The study is expected to provide a time-evolving picture of interactions within and between autotrophic and heterotrophic communities and will illustrate the short-term biogeochemical and ecological consequences of sustained nutrient discharge to a shallow coastal site. The planned diversion provides an unprecedented opportunity to study the ecophysiological response in a natural setting over a period of weeks, including the interaction of biology, chemistry, and physics, and it will contribute to basic understanding of anthropogenic nutrient loading to the coastal ocean. Undergraduate and graduate education and training will be furthered through active participation in lab, field, and data synthesis activities involving academic, government, and industry partners.