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Astrid Schnetzer

Assoc Professor


Varsity Research Building 1603



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Date: 09/01/19 - 8/31/22
Amount: $177,356.00
Funding Agencies: National Science Foundation (NSF)

Fluorescence activated cell sorting (FACS) is a technique that involves sorting away select cells (or objects) from complex mixtures based on their intrinsic or acquired fluorescence. FACS is a transformative technology that allows the study of the unculturable microbes (which are numerically dominant in nature) and accomplish tasks that are highly laborious or impossible complete in other ways; the technology has led to significant discoveries in many microbial research fields (e.g. ecology, genetics, physiology, symbiosis/interactions, bioengineering, and bio-prospecting), and nearly single-handedly forged new fields of research, e.g. single cell genomics and transcriptomics, which involves the study of DNA and mRNA from individual cells. More than 25 North Carolina State University (NCSU) faculty, belonging to 4 colleges, have needs for FACS in their research or teaching programs; however, NCSU lacks a FACS instrument optimized for the analysis of non-mammalian microbial cells (e.g. bacteria, archaea and fungi), and to our knowledge, no ‘microbe optimized’ instrument is available at research universities within the Research Triangle of North Carolina (e.g. UNC-CH, Duke University). Here, funds are requested to acquire a Becton Dickinson FACSMelody flow cytometer, a versatile (3 excitation laser, 9-color detection) and ‘turn key’ system, which fundamentally enables microbiological research that is highly laborious or impossible to accomplish without it. The FACSMelody is powerful yet simple to use and generates easy to grasp visual (flow cytometric) data – making it a good potential training and educational tool for undergraduate/graduate courses and workshops. A FACSMelody system is ideal for getting FACS technology rapidly and easily into the hands of faculty in need. Overall, a FACS system for non-mammalian microbial research is needed for NCSU to be innovative, internationally competitive at attracting new faculty and highly talented students, and foster creative future proposals.

Date: 08/01/17 - 7/31/22
Amount: $4,500,000.00
Funding Agencies: US Dept. of Interior (DOI)

The guiding strategy of the Southeast Climate Science Center (SE CSC) is to provide staffing and institutional support for core SE CSC mission areas. The SE CSC's mission involves supporting researchers and managers to co-produce science connected to management decisions (actionable science), coordinating logistics and communications to bring partners and the community together (within NCSU, with USGS researchers, and across the broader community) to discuss global change impacts to the DOI mission, and training the next generation (graduate students) and current managers on how to use and develop global change science.

Date: 03/15/21 - 3/15/22
Amount: $38,000.00
Funding Agencies: NCSU Center for Human Health and the Environment

Cyanobacterial Harmful Algal Blooms (CHABs) adversely affect estuaries and marine sounds as excess biomass leads to discoloration, odor issues, decreased oxygen levels, and subsequent fish kills. Concerns about exposure risks from cyanobacterial toxins through drinking water and food web transfer via shellfish have risen dramatically throughout the world. These concerns have also become a focal point in North Carolina, where efforts to restore natural oyster reefs and the emerging oyster farming industry could be heavily impacted, the latter of which is expected to grow to $100 million by 2030. The extent to which shellfish serve as biotoxin vectors to humans is unknown despite CHABs being a recurrent phenomenon and toxin presence reported throughout North Carolina waters as well as across marine and estuarine food webs. Phycotoxins harm humans in varying ways and the lack of data on toxin loads in shellfish impedes assessing human exposure risks, inhibiting mitigation strategies and the development of forecasting tools. This pilot project will address these knowledge gaps by leveraging CHHE core resources to build existing and new collaborations between scientists and oyster industry partners across North Carolina. We aim to identify dominant toxin-producing cyanobacteria species in North Carolina’s shellfish growing areas and quantify toxin loads in farm-raised oysters. Developing this collaborative information-gathering framework will be crucial to develop follow-up studies addressing links between environmental variability and public health in coastal food production systems.

Date: 08/01/20 - 7/31/21
Amount: $8,861.00
Funding Agencies: NCSU Sea Grant Program

Cyanobacterial Harmful Algal Blooms (CHABs) adversely impact drinking water, fisheries, tourism, real estate and food web resilience. CHABs are on the rise globally and have been linked to a warming climate combined with anthropogenically-enhanced nutrient loading in freshwater systems; so has an increase in the toxicity of CHABs. Cyanotoxins, produced by specific taxa, ingested through water or via the consumption of contaminated shellfish and fish can cause neural, liver, and gastrointestinal disease, death in wildlife, pets, and humans. Impacts on human health due to the aerosolization and subsequent inhalation of waterborne cyanotoxins are less understood but of additional concern. Recently, several toxins, including microcystin (MCY), cylindrospermopsin and anatoxin, were confirmed in NC freshwater systems, with MCY being the most common.Overall, substantial progress has been made characterizing how eutrophication drives cyanobacterial growth but significant challenges remain as we try to link algal biomass (chlorophyll a), cyanobacterial density or species composition to toxin exposure risk. Acquiring highly resolved information on bloom dynamics (species-specific abundance vis-à-vis toxin distribution data) is essential to develop and assess the effectiveness of mitigation strategies and models that aid the protection of lake use, wildlife and humans. This project will i) examine cyanobacterial species composition in relation to MCY concentration and speciation, ii) determine toxin distribution (dissolved and cell-bound fractions) throughout differing bloom phases and iii) assess persistence of MCY in the wake of a bloom (during algal senescence and biomass decay for three aquatic systems.

Date: 04/01/19 - 3/31/20
Amount: $24,980.00
Funding Agencies: NCSU Sea Grant Program

Cyanobacterial Harmful Algal Blooms (CyanoHABs) in NC estuarine and freshwater systems are a growing concern for local communities, governmental agencies and public utilities. Cyano-HABs are on the rise and adversely impact drinking water, tourism, real estate, fisheries and food safety. Cyanotoxins, produced by specific taxa and ingested through water, can cause neural, liver, and gastrointestinal disease, and death in wildlife, pets, and humans. In North Carolina, recent severe algal blooms in the Chowan River have been drawing attention from the public as well as the Department of Environmental Quality (NCDEQ). Prior to 2013, algal blooms of similar magnitude had not been observed since the 70’s. The continued presence of potential toxin producers, such as Dolichospermum planctonicum, and the confirmation of microcystin (MCY) in August 2013 and again in 2015 had NC Health and Human Services (NCDHHS) release several public advisories to avoid any contact with water, to keep any pets out of the water and to not eat fish from affected areas. The goal of this project is to examine potential food web exposure to cyanotoxins during recurrent CyanoHABs in the Chowan River/Albemarle Sound region. We propose to i) Conduct monthly testing of cyanotoxin loads (mainly MCY and CYL) in commonly caught fish species and blue crab; ii) Analyze spatiotemporal toxin dynamics in relation to animal loads and pertinent physicochemical information. We build on previous work where we characterized toxin dynamics in the Chowan River region and will continue to leverage our proposed efforts on previously established partnerships with local groups, citizens and monitoring agencies bestowed with water quality issues.

Date: 12/01/17 - 11/30/19
Amount: $55,187.00
Funding Agencies: National Science Foundation (NSF)

The continental shelf waters of the northwestern Gulf of Mexico (GOM) are currently experiencing a massive pulse of freshwater input as a result of record-breaking rainfall from Hurricane Harvey. The timing, magnitude, and constituent loads of Harvey flood waters are driving shifts in plankton community composition and distribution patterns on the Louisiana-Texas shelf. The timing of this disturbance coincides with the summer-fall spawning seasons for economically important fisheries (e.g. red drum, sea trouts, snappers) raising additional questions of longer term effects of food web disruptions on recruitment. We propose to compare phyto- and zooplankton assemblages and grazing interactions pre- and post flood by building on field data collected during a July 2017 Gulf of Mexico Ecosystems and Carbon Cycle (GOMECC) cruise along the Louisiana-Texas shelf. Replicate data sets, proposed here, will allow for the evaluation of immediate effects from the hurricane over monthly to seasonal time scales. Additional access to archived ichthyo- and mesozooplankton samples and data from NOAA’s Southeast Area Monitoring and Assessment Program’s (SEAMAP) long-term plankton surveys will allow interpretation of plankton regime shifts in a multiyear and decadal context.

Date: 10/01/16 - 9/30/19
Amount: $131,512.00
Funding Agencies: National Oceanic & Atmospheric Administration (NOAA)

This project aims to research lower trophic level processes in the Arctic, specifically the role that microzooplantkon play in carbon and energy flow. The project is embedded in a larger program that entails field work in 2017 and 2019 during summer/fall in the Chukchi and Beaufort Seas. Physical measurements and investigations on phytoplankton species composition and productivity, meso/macrozooplankton abundance and community composition will be combined with fish population data from trawling to characterize food web dynamics. Microzooplankton abundance and species composition shifts will be analyzed in relation to community structure changes of primary producers and changes within upper trophic organisms to provide insight into food web efficiency and ecosystem function in Arctic waters. To date, microzooplantkon, that include unicellular protists to early developmental stages of invertebrates, are one of the least characterized important ecological components within marine food webs.

Date: 05/01/15 - 4/30/19
Amount: $574,652.00
Funding Agencies: National Science Foundation (NSF)

Overview: Chromophoric dissolved organic matter (CDOM) is an important fraction of the marine carbon cycle that controls most light absorption and many photochemical and biological processes in the ocean. Despite its importance, the chemical basis for the formation of oceanic CDOM remains unclear. Laboratory studies support the paradigm that bacterial transformation of phytoplankton particulate organic matter (POM) and DOM produces the humic-like CDOM signals observed in the deep ocean. However, prior studies of oceanic CDOM using absorbance and fluorescence fit an electronic interaction (EI) model of intramolecular charge transfer (CT) reactions between donor and acceptor molecules common to partially-oxidized terrestrial molecules (e.g., lignin) found in humic substances. This proposal will test the hypothesis that phytoplankton and bacteria provide a source of donors (e.g., aromatic amino acids) and acceptors (quinones) which are microbially-transformed and linked, enabling CT contacts between them and creating oceanic CDOM. Hotspots for the formation of planktonic CDOM may be marine aggregates of phytoplankton detritus (marine snow). We will systematically study phytoplankton growth including marine snow formation, using roller bottles as a laboratory set-up that favors the formation of marine snow. A new technique of measuring base-extracted POM (BEPOM) absorbance and fluorescence will assist in testing fit of planktonic CDOM to the EI model, supplemented with measurement of its probable chemical precursors, thus explaining the production of CDOM in the ocean by linking the optics and chemistry of planktonic CDOM formation. Determining the time course and extent of phytoplankton POM and DOM transformation by heterotrophic bacterial (enzymatic hydrolysis) during the same phytoplankton growth experiments will provide an in-depth understanding as to how bacterial transformation of marine snow-associated planktonic organic matter drives CDOM production throughout the ocean. Intellectual Merit: This work represents a mechanistic study that will improve our understanding of the role of phytoplankton as the major source of CDOM in the open ocean. The key merit of this proposal is testing the fit of the EI model to planktonic CDOM via examination of: 1) its fluorescent quantum yields, 2) wavelength dependence of its fluorescence emission, and 3) alteration of its absorbance and fluorescence after borohydride reduction. These results will determine if intramolecular charge transfer occurs between reduced aromatics derived from amino acids and microbially-sourced quinones. A second merit is quantifying the importance of aggregate formation for oceanic CDOM formation. One implication of these results is that biomolecules in phytoplankton as on land must undergo a microbially-mediated transformation prior to developing chemical structures that give rise to CDOM?s optical properties. Broader Impacts: The importance of planktonic CDOM is not restricted to oceanography and the knowledge gained in this project will transfer to limnology and aquatic biogeochemistry as a whole. This study will provide unequivocal evidence for the remote sensing community that the CDOM spectra in the open ocean (and some lakes) are derived from phytoplankton. Each PI will utilize data gained from their respective research in classroom instruction and student mentoring. Beyond the classroom, we will work the NCSU Science House and the Nature Research Center at the North Carolina Science Museum of Natural Sciences to connect this important research topic with the general public. Using results from the work proposed, we will develop an interactive multimedia module for public display entitled, ?Light and Life in the Ocean,? at the NC Museum of Natural Sciences. Visitors to the display will be able to modify light via computer interface and learn effects of light on the ocean ecosystem. This module will be complemented with demonstrations and presentations at the UNC-CH Science Expo, a yearly event that introduces over 8000 members of the general public to scientific research taking place at UNC. As is possible, the PIs will conduct live feeds of shipboard and laboratory activities via Skype to classes at elementary schools in the Raleigh area so students can ?Ask an Oceanographer? questions regarding the experience and importance of conducting oceanographic research at sea and in the laboratory.

Date: 07/01/17 - 11/01/18
Amount: $75,000.00
Funding Agencies: Chancellor's Innovation Fund (CIF)

Innovative Reagents and Measurements to Detect the Neurotoxin BMAA in Food, Water, and in Humans and Determine its Role in ALS

Date: 02/01/16 - 7/31/18
Amount: $75,000.00
Funding Agencies: National Oceanic & Atmospheric Administration (NOAA)

Blooms of the toxigenic cyanobacteria, Microcystis spp., are an increasingly pressing problem in coastal rivers of North Carolina and around the world. Toxic Microcystis blooms shade beneficial primary producers, alter food webs, fuel hypoxia, and threaten the safety and sustainability of seafood and drinking water resources. Over the past decade, recurrent summer Microcystis blooms in the middle reach of the Cape Fear River (CFR), NC have threatened the ecological health of the River and estuary, and its value as the water supply for a rapidly growing coastal region with ~0.5 million residents. Uncertainties about the origin and drivers of Microcystis blooms in the CFR have impeded progress toward developing effective management for the CFR. The primary project objective is to provide information on the environmental drivers of toxic Microcystis blooms in the CFR including the importance of in situ production within the CFR channel vs. lateral tributary inputs as bloom origins, and the importance of river flows, temperature, light, and nutrients conditions for in situ bloom development. We will accomplish this objective by using novel drifter-incubation experiments and solid phase adsorption toxin tracking (SPATT) toxin measurements combined with traditional fixed-station sampling. By assessing in-situ growth in tandem with transport through the CFR using drifters, we will determine the time-scale necessary for blooms to develop and assess the drivers of in situ production. Measurement of the growth time-scale under ambient light and nutrient regimes is the key piece of information missing from previous studies in NC rivers and will provide information critical for predicting and managing blooms.

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