Astrid Schnetzer

This project aims to synthesize a number of studies funded by the North Pacific Research Board during field seasons in 2017 and 2019. The lab analyzed and contributed to these efforts to characterize lower trophic level processes in the Arctic, specifically the role that microzooplankton play in carbon and energy flow. The main goal of this synthesis project is to combined the expansive amount of information collected over recent years to describe and predict the consequences of environmental change in Arctic Waters on carbon flow and benthic-pelagic coupling. For this, the lab will be involved in efforts to specifically: 1) provide model input variables on microbial plankton dynamics across space and time, 2) collaborate with investigators that lead model modules on physicochemical and higher trophic level components. The latter will be with an emphasis on phytoplankton-zooplankton connections.

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.

During GOMECC-3, the first biologically-relevant sampling and rate measurements with relationship to OA were conducted. Samples to characterize standing stocks and community structure from picoplankton to mesozooplankton and ichthyoplankton were obtained, and on-deck incubation experiments were conducted to simultaneously measure phytoplankton growth, microplankton grazing rates and copepod consumption. Samples were also collected to quantify phytoplankton biomass (< 20 and > 20 ????????m size fraction) and those data are available in the NOAA repository (https://doi.org/10.25921/yy5k-dw60). Since the biological component of GOMECC-3 was an opportunistic, unfunded effort, not all samples have been analyzed. Preliminary data, however, indicate strong interconnectedness between OA, hypoxia and eutrophication as drivers of productivity, biodiversity and food web dynamics across the GOM regions. We propose to build upon the efforts initiated for GOMECC-3 with our work on GOMECC-4 through two main activities: 1- Conducting plankton net tows at select stations throughout the cruise to collect zooplankton and ichthyoplankton (fish eggs and larvae) for a variety of analyses including fish distribution and abundance, pteropod abundance, larval fish age, growth, condition, diet, and evidence of microplastic ingestion (all factors which affect survival and recruitment to adult populations). 2- Sampling from Niskin bottles at select stations for phyto- and zooplankton studies using traditional and targeted ???????????????omics approaches, with a focus on HAB taxa. This dataset will build on 2017 data to further quantify HAB taxa occurrences, shifts in zooplankton consumers and changes in carbon transfer from primary producers to higher trophic levels in relation to OA gradients and other stressors (microzooplankton and copepod feeding experiments). A priority will be to determine if we can discern indicator species or assemblages and identify sentinel regions that should be used now and in the future to determine susceptibility of biota to OA.

Cyanobacterial Harmful Algal Blooms (HABs) are a major concern within coastal waters of North Carolina including the largest lagoonal estuary in the United States, the Pamlico-Albemarle Sound System (~7,800 km2). Since 2020, a significant number of blooms and fish kills have been reported across Albemarle Sound and its major tributaries, and these reports go hand in hand with the detection of cyanotoxins further raising concerns about toxin transfer to higher trophic levels. Previous research on animal cyanotoxin loads, mainly microcystin concentrations, indicated that toxification occurs in several important recreationally and commonly harvested fish species in their juvenile stages. Overall, our preliminary results yielded body loads repeatedly exceeding Tolerable Daily Intake burdens recommended through the World Health Organization. Here we propose to conudct a Albemarle Sound-wide investigation of microcystin toxification for juvenile bottom, mid-water and bait fish species over a two year period. Already secured samples from 2022 (~100) will be analyzed together with newly collected samples through the Division of Marine Fisheries standard surveys and by engaging local recreational fishermen to document the extent and temporal toxin contamination dynamics. The information will be the first to allow insight into which species or functional groups may be most affected, what times during the year exposure risks may be most acute and whether zones within the Albemarle Sound or its tributaries are hotspots for microcystin contamination. The findings of the project will be shared with other scientists, stakeholders and the community during a mini-symposium in the later stages of the project.

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.

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.

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-????????-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.

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.

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.

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.