| Contributors | Affiliation | Role |
|---|---|---|
| Dick, Gregory J. | University of Michigan | Principal Investigator |
| Kharbush, Jenan | Harvard University | Co-Principal Investigator |
| Rauch, Shannon | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
Methodology:
Detailed sampling and analytical procedures can be found in the published paper (Kharbush et al. 2019). Briefly, nitrogen isotopes were measured in bulk organic matter and chlorophyll collected on 142mm GF/F filters (0.7 µm pore size), over the course of the summer harmful algal bloom in Lake Erie. δ15N values were corrected for a N blank originating from the HPLC solvent and from the oxidizing reagent, according to Higgins et al. (2009). Phytoplankton community composition was determined using a submersible FluoroProbe (bbe Moldaenke GmbH, Germany), which monitors in situ chlorophyll fluorescence. Isotope values were then compared with phytoplankton community composition.
Instrumentation details:
A submersible FluoroProbe, manufactured by bbe Moldaenke GmbH, Germany, was used to monitor in situ chlorophyll fluorescence and to estimate algal community composition. Used with factory calibration settings.
Chlorophyll was purified using an Agilent 1200 series HPLC equipped with multi-wavelength UV/Vis detector and two Zorbax C18 columns (dimensions 4.6 × 250 mm, 5 μm).
δ15N of chlorophyll was measured using the denitrifier method (Sigman et al., 2001), on a Delta V Advantage isotope ratio mass spectrometer with a custom built purge and trap system. Isotopic measurements were standardized to the N2 reference scale using standard reference materials IAEA N3 and USGS 34.
δ15N of biomass collected on GF/Fs was analyzed on a Thermo Scientific Flash IRMS Elemental Analyzer with EA Isolink, coupled to a Delta V Advantage IRMS through a Conflo IV universal interface. Sample δ15N values were calculated using in-house laboratory standards as well as standard reference materials USGS40 and USGS41a.
Problems reported: For samples 6/17/2017, 6/27/2017, and 7/6/2017 no Fluoroprobe community data are available because of an issue with calibration.
Data were analyzed in Microsoft Office Excel and in R Studio.
BCO-DMO Processing:
- formatted date to yyyy-mm-dd;
- renamed column headers to conform with BCO-DMO naming conventions.
| File |
|---|
chl_d15N.csv (Comma Separated Values (.csv), 1.53 KB) MD5:fbf5ee73e9c8df38af76954ac7eaf2ed Primary data file for dataset ID 793501 |
| Parameter | Description | Units |
| Sample_date_collected | Date sample was collected; format: yyyy-mm-dd | unitless |
| Station | GLERL Lake Erie Master Station name | unitless |
| Lat | Latitude | Decimal degrees |
| Long | Longitude; west is negative | Decimal degrees |
| Bulk_biomass_d15N | Average d15N value of bulk biomass collected on GF/F filters, 3 replicates | permil (‰) |
| Bulk_uncertainty | Uncertainty in bulk d15N measurement, 3 replicates | 1 standard devation (‰) |
| Corr_Chl_d15N | Chlorophyll isotope values obtained after correcting for blank and Rayleigh distillation effects | permil (‰) |
| Corr_Chl_uncert | Uncertainty in chlorophyll values, after error propagation | 1 standard devation (‰) |
| Epor | Isotopic offset between bulk and chlorophyll d15N (d15Nbulk biomass - d15Nchloropigment) | permil (‰) |
| Epor_uncert | Uncertainty in Epor after error propagation | 1 standard devation (‰) |
| pcnt_Cyanos | Depth-integrated percentage of algal community composed of cyanobacteria | Percent (%) |
| pcnt_Greens | Depth-integrated percentage of algal community composed of green algae | Percent (%) |
| pcnt_Diatoms | Depth-integrated percentage of algal community composed of diatoms | Percent (%) |
| pcnt_Crypto | Depth-integrated percentage of algal community composed of cryptophytes | Percent (%) |
| Dataset-specific Instrument Name | FluoroProbe |
| Generic Instrument Name | Fluorometer |
| Dataset-specific Description | A submersible FluoroProbe, manufactured by bbe Moldaenke GmbH, Germany, was used to monitor in situ chlorophyll fluorescence and to estimate algal community composition. Used with factory calibration settings. |
| Generic Instrument Description | A fluorometer or fluorimeter is a device used to measure parameters of fluorescence: its intensity and wavelength distribution of emission spectrum after excitation by a certain spectrum of light. The instrument is designed to measure the amount of stimulated electromagnetic radiation produced by pulses of electromagnetic radiation emitted into a water sample or in situ. |
| Dataset-specific Instrument Name | Agilent 1200 |
| Generic Instrument Name | High-Performance Liquid Chromatograph |
| Dataset-specific Description | Chlorophyll was purified using an Agilent 1200 series HPLC equipped with multi-wavelength UV/Vis detector and two Zorbax C18 columns (dimensions 4.6 × 250 mm, 5 μm). |
| Generic Instrument Description | A High-performance liquid chromatograph (HPLC) is a type of liquid chromatography used to separate compounds that are dissolved in solution. HPLC instruments consist of a reservoir of the mobile phase, a pump, an injector, a separation column, and a detector. Compounds are separated by high pressure pumping of the sample mixture onto a column packed with microspheres coated with the stationary phase. The different components in the mixture pass through the column at different rates due to differences in their partitioning behavior between the mobile liquid phase and the stationary phase. |
| Dataset-specific Instrument Name | Delta V Advantage |
| Generic Instrument Name | Isotope-ratio Mass Spectrometer |
| Dataset-specific Description | δ15N of chlorophyll was measured using the denitrifier method (Sigman et al., 2001), on a Delta V Advantage isotope ratio mass spectrometer with a custom built purge and trap system. Isotopic measurements were standardized to the N2 reference scale using standard reference materials IAEA N3 and USGS 34. |
| Generic Instrument Description | The Isotope-ratio Mass Spectrometer is a particular type of mass spectrometer used to measure the relative abundance of isotopes in a given sample (e.g. VG Prism II Isotope Ratio Mass-Spectrometer). |
| Dataset-specific Instrument Name | Thermo Scientific Flash IRMS Elemental Analyzer with EA Isolink |
| Generic Instrument Name | Isotope-ratio Mass Spectrometer |
| Dataset-specific Description | δ15N of biomass collected on GF/Fs was analyzed on a Thermo Scientific Flash IRMS Elemental Analyzer with EA Isolink, coupled to a Delta V Advantage IRMS through a Conflo IV universal interface. Sample δ15N values were calculated using in-house laboratory standards as well as standard reference materials USGS40 and USGS41a. |
| Generic Instrument Description | The Isotope-ratio Mass Spectrometer is a particular type of mass spectrometer used to measure the relative abundance of isotopes in a given sample (e.g. VG Prism II Isotope Ratio Mass-Spectrometer). |
| Website | |
| Platform | NOAA R4108 |
| Start Date | 2017-06-17 |
| End Date | 2017-10-17 |
| Description | 2017 NOAA GLERL weekly monitoring of Western Lake Erie. Day cruises; no cruise IDs.
Dates: 6/17/17, 6/27/17, 7/6/17, 7/12/17, 7/18/17, 7/25/17, 8/1/17, 8/8/17, 8/15/17, 8/22/17, 8/29/17, 9/5/17, 9/12/17, 9/19/17, 9/26/17, 10/3/17, 10/11/17, 10/17/17 |
NSF Award Abstract:
Toxic cyanobacterial harmful algal blooms (CHABs) are now a worldwide problem that poses dangers for humans and aquatic organisms including life-threatening sickness, beach closures, health alerts, and drinking water treatment plant closures. This project focuses on the basic science needed to understand interactions between the microorganisms present in CHABs and the chemistry of the lakes they inhabit. In particular, it will study the sources, fate, and effects of hydrogen peroxide, which is a potentially important control on the toxicity and species present within these blooms. This research will be conducted in Lake Erie, a source of drinking water for 11 million people that is threatened by CHABs annually. Results will be directly integrated into two water quality models that are widely used by water managers and other stakeholders. This project will support the training of two PhD students, including a first-generation college attendee, and undergraduate students from backgrounds that are underrepresented in the earth sciences. Research will also be integrated into outreach aimed at increasing diversity in the earth sciences by involving women and underrepresented minorities in K-12 as well as college and adult educational settings.
The overall goal of this project is to determine the influence of hydrogen peroxide (H2O2) on cyanobacterial community composition and function in nearshore ecosystems. Preliminary results from Lake Erie show that dominant primary producers rely on heterotrophic bacteria to draw down H2O2 from transiently high environmental levels that are likely inhibitory to members of the cyanobacterial community. This suggests that H2O2 plays important and still poorly understood roles in aquatic microbial ecology. A combination of field sampling, experiments, and state-of-the art "-omics" will be used to test the overall hypothesis that H2O2 decomposition by heterotrophic "helpers" is an important determinant of microbial interactions and community structure and function. Lake Erie will be studied because (i) it is a model system for shallow coastal areas receiving high terrestrial nutrient runoff, (ii) it offers strong inshore-offshore gradients of light and nutrients for comparative studies, and (iii) existing sampling infrastructure, archived samples, and preliminary data can be leveraged. Field and laboratory experiments and measurements will be integrated to answer the following questions: Q1: What drives the temporal dynamics of H2O2 concentrations? Q2: Which enzymes and organisms are responsible for protecting the community via biological H2O2 decay? Q3: How does protection from H2O2 by helpers influence the composition and function of the community? The study will perform controlled lab experiments on cultures and on natural waters during different points of the bloom. Measures of H2O2 concentrations and rates of production and decay, along with supporting chemical and biological measurements, will be used to assess the major sources and sinks of H2O2. Molecular tools will be used to determine the pathways underpinning H2O2 decay and the effect of H2O2 on cyanobacterial community composition function. In parallel, impacts of varying H2O2 concentrations on growth rates of major cyanobacteria will be assessed experimentally. These experimental results will be placed into context through comparisons with the structure and function of microbial communities from field samples across spatial, temporal, and chemical gradients in this coastal ecosystem. The approach of integrating studies of H2O2 with "-omics" in natural systems is novel, and will advance our fundamental knowledge and understanding of the relationship between microbial community composition and function.
| Funding Source | Award |
|---|---|
| NSF Division of Ocean Sciences (NSF OCE) |