Contributors | Affiliation | Role |
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Ward, Bess B. | Princeton University | Principal Investigator |
Lee, Jenna | Princeton University | Scientist |
Mickle, Audrey | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
The mesocosm experiment was performed in August 2021 on the R/V Hugh Sharp, cruise HRS2110, at a station near the mouth of Chesapeake Bay. Surface water (2–5 m) was collected from the study site (37.27o N, 76.09o W), located near the mouth of the bay. Incubation medium was prepared by pumping surface water (~5 m) directly from the sample site through a series of nylon mesh and glass fiber filters, ending with a 0.3 μm filter, using a double diaphragm pump into three 24-L translucent polycarbonate (PC) carboys. Surface water inoculum was collected using a rosette system with 12–L Niskin bottles and a CTD profiler from 2–4 m depth and pre–filtered through 210 μm nylon mesh before being added to the mesocosms to produce a 10 % inoculation. Carboys were incubated for eight days in an on–deck water bath, using a seawater flow–through system drawn from surface water and a plastic screen shade covering to keep incubation temperature and light similar to in situ conditions.
Samples for nutrient concentrations were collected from each carboy three times per day, at approximately 06:00, 12:00, and 18:00 local time. Samples were filtered through a 0.22 μm syringe filter into 50–mL plastic conical tubes and stored at –20o C until analysis. Reactive nitrite (NO2-) and silicate (silicic acid, H4SiO4) concentrations were measured on a ThermoScience Genesys150 UV–Vis spectrophotometer using colorimetric methods (sulfanilamide + N–(1–naphthyl)–ethylenediamine and metol sulfite, respectively) modified from Strickland and Parsons (1972). NO2- + NO3- concentration was measured via chemiluminescent detection using a Teledyne NOx analyzer (NOxBox) according to Braman & Hendrix (1989). NO3- concentrations were calculated by subtracting the colorimetrically derived NO2- concentrations from their paired NO2- + NO3- NOxBox concentrations.
- Imported "Mesocosm_CB2021_Nutrients.xlsx" into the BCO-DMO dataset
- Created additional datetime field in UTC
- Export file as "959925_v1_mesocosm_cb_nutrients.csv"
File |
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959925_v1_mesocosm_cb_nutrients.csv (Comma Separated Values (.csv), 6.60 KB) MD5:afd8282ab4096fce1f58604ff31f0b68 Primary data file for dataset ID 959925, version 1 |
Parameter | Description | Units |
Samp_No | Sample number | unitless |
Carboy | Sample source; carboy A, B, or C | unitless |
Rep | Replicate number | unitless |
Date_Local | Date of sampling event (UTC-4) | unitless |
Time_Local | Time of sampling event (UTC-4, 24-hr time) | unitless |
ISO_DateTime_UTC | Datetime of sampling event in UTC | unitless |
Nitrite | Nitrite (NO2) concentration; detection limit = 0.25 | micromolar (µM) |
Nitrate | Nitrate (NO3) concentration; detection limit = 0.00015 | micromolar (µM) |
Phosphate | Phosphate (PO4) concentration; detection limit = 0.1 | micromolar (µM) |
Silicate | Silicate (SiO4) concentration; detection limit = 0.5 | micromolar (µM) |
Notes | Notes | unitless |
Dataset-specific Instrument Name | ThermoScience Genesys150 UV–Vis spectrophotometer |
Generic Instrument Name | Spectrometer |
Dataset-specific Description | Reactive nitrite (NO2-) and silicate (silicic acid, H4SiO4) concentrations were measured on a ThermoScience Genesys150 UV–Vis spectrophotometer using colorimetric methods (sulfanilamide + N–(1–naphthyl)–ethylenediamine and metol sulfite, respectively) modified from Strickland and Parsons (1972). |
Generic Instrument Description | A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum. |
Website | |
Platform | R/V Hugh R. Sharp |
Start Date | 2021-08-03 |
End Date | 2021-08-21 |
Description | See more information about this cruise in Rolling Deck to Repository (R2R): https://www.rvdata.us/search/cruise/HRS2110 |
NSF Award Abstract:
A recent global survey of surface ocean waters revealed that microbial parasites comprise half of the eukaryotic plankton diversity and suggested that biological interactions, including parasites, play an important role in the ecology of many types of microscopic algae, which are the base of the ocean food web, but not diatoms. Diatoms are among the most abundant microalgae, particularly in upwelling areas where nutrient-rich deep currents feed the ocean's surface and support the world's greatest fisheries. Yet this survey did not investigate high-productivity regions, leaving a significant knowledge gap. Diatoms may be successful in upwelling regions because they evade predators and parasites, but it seems more reasonable that they, like all other microalgae, also have biological enemies. In this study, the researchers use a large set of available samples from upwelling regions to investigate the effect of parasites on the proliferation of diatom communities and resulting primary production. The project supports a graduate student and provides hands-on research experiences for high school and undergraduate college students. The study data are also integrated into courses taught by the principal investigator.
The discovery that half of the eukaryotic diversity in the Tara Oceans sequence database belongs to putatively parasitic microbes implies a revolution in our understanding of biological control of primary production. Ecosystem models are only beginning to incorporate the effect of viruses on production and community composition, but eukaryotic parasites add yet another dimension with potentially vast biogeochemical implications. While viral predation is generally thought to divert material flux away from grazers and into the dissolved organic carbon pool, increasing community diversity and microbial biomass, phytoplankton biomass diverted into parasite biomass becomes available to grazers. Experimental determination of parasite activity is difficult in natural systems, so most of the evidence for diversity, abundance, and host interactions of eukaryotic parasites is based on DNA sequence data. The Tara Oceans database suggests that diatoms have very few biotic interactions, leading to a stronger dependence on bottom-up factors (e.g., nutrients). However, this database did not represent high productivity upwelling regions. This project addresses two hypotheses: 1) diatoms in highly productive episodic upwelling systems are involved in host-parasite interactions that can be identified in co-occurrence networks during blooms; and 2) the community composition and abundance of host-parasite pairs vary over the course of the bloom in a manner consistent with density dependence on the host. In this project, abundance, diversity, and dynamics of parasites in upwelling systems are investigated by tag sequencing, metagenomics, and targeted qPCR of diatom-parasite pairs identified from archived samples from diatom-dominated upwelling systems (California Current, Eastern Tropical Pacific), the North Atlantic Spring bloom, and from two mesocosm experiments of diatom blooms induced by inoculation of surface seawater into nitrate-rich Monterey Bay seawater. Biogeochemical parameters (nutrients, primary production, nitrate assimilation, etc.) for those samples are available. In addition, the research team is using the outputs of the bioinformatics analysis in network and time series analysis to discover links among hosts and parasites.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
Funding Source | Award |
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NSF Division of Ocean Sciences (NSF OCE) |