Chlorophyll a concentrations measured along the cruise track of AE1812 which transected from the Sargasso Sea to Coastal Rhode Island during May 2018.

Data Type: Cruise Results
Version: 1
Version Date: 2020-08-14

» Collaborative Research: Defining the biogeochemical drivers of diatom physiological ecology in the North Atlantic (North Atlantic Diatoms)
Rynearson, Tatiana A.University of Rhode Island (URI-GSO)Lead Principal Investigator
Jenkins, Bethany D.University of Rhode Island (URI-GSO)Co-Principal Investigator
Haskins, ChristinaWoods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager

Chlorophyll a concentrations measured along the cruise track of AE1812 which transected from the Sargasso Sea to Coastal Rhode Island during May 2018.


Spatial Extent: N:41.193917 E:-63.2384 S:31.684933 W:-70.96835
Temporal Extent: 2018-05-02 - 2018-05-15

Acquisition Description

In situ Chlorophyll a was measured at each station along the AE1812 cruise track. A CTD was deployed to collect water from the euphotic zone. Samples were filtered in triplicate onto GF/F and 5µm and 20µm polycarbonate filters.

Chl a was extracted from filters in 100% denatured ethanol for 12 hours, measured on a 10-AU Fluorometer, and chlorophyll a and phaeophytin concentrations were calculated based on a predetermined calibration curve. Concentrations on each filter were used to determine total chl a within each size fraction.

Processing Description

Data was processed in R 3.6.2 (R-Core-Team 2019)

BCO-DMO Data Manager Processing Notes:
* added a conventional header with dataset name, PI name, version date
* modified parameter names to conform with BCO-DMO naming conventions
* blank values in this dataset are displayed as "nd" for "no data."  nd is the default missing data identifier in the BCO-DMO system.
* converted datetime into ISO_DateTime_UTC format
* converted latitude and longitude from degrees decimal minutes to decimal degrees 
* set types for each data column

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ISO_DateTime_UTCDate and time of sample collection YYYY-MM-DDTHH:MM:SS[.xx]Z
lat_convertedLatitude of sample collection degrees
lon_convertedLongitude of sample collection degrees
stationStation of CTD cast unitless
castCTD cast number unitless
niskin_bottle_IDBottle ID of niskin used to collect sample unitless
depthdepth of sample collection m
size_fractionsize fraction analyzed based on pore size of filter m
tube_IDID of the tube unitless
vol_filteredVolume of seawater filtered for chl a analysis ml
vol_extractedVolume of ethanol used to extract chl a ml
FbFluorescence before acidification RFU
FaFluorescence after acidification RFU
blank_subt_FbBlank corrected fluorescence before acidification RFU
blank_subt_FaBlank corrected fluorescence after acidification RFU
chlaChlorophyll a concentration g/L
phaeoPhaeophytin concentration g/L

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Dataset-specific Instrument Name
10AU Fluorometer (Turner Designs, San Jose, CA)
Generic Instrument Name
Turner Designs Fluorometer 10-AU
Generic Instrument Description
The Turner Designs 10-AU Field Fluorometer is used to measure Chlorophyll fluorescence. The 10AU Fluorometer can be set up for continuous-flow monitoring or discrete sample analyses. A variety of compounds can be measured using application-specific optical filters available from the manufacturer. (read more from Turner Designs,, Sunnyvale, CA, USA)

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R/V Atlantic Explorer
Start Date
End Date

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Project Information

Collaborative Research: Defining the biogeochemical drivers of diatom physiological ecology in the North Atlantic (North Atlantic Diatoms)

Coverage: North Atlantic

NSF abstract:

About half of photosynthesis on earth is generated by marine phytoplankton, single celled organisms that drift with tides and currents. Within the phytoplankton, the diatoms conduct nearly half of this photosynthesis, exerting profound control over global carbon cycling. Despite their importance, there are surprisingly fundamental gaps in understanding how diatoms function in their natural environment, in part because methods to assess in situ physiology are lacking. This project focuses on the application of a powerful new approach, called Quantitative Metabolic Fingerprinting (QMF), to address this knowledge gap and examine species-specific physiology in the field. The project will provide transformative insights into how ocean geochemistry controls the distribution of diatoms, the metabolic responses of individual diatom species, and how metabolic potential is partitioned between diatom species, thus providing new insights into the structure and function of marine systems. The overarching goal is to examine how diatom species respond to changes in biogeochemistry across marine provinces, from the coast to the open ocean, by following shifts in diatom physiology using QMF. This research is critical to understand future changes in oceanic phytoplankton in response to climate and environmental change. Furthermore, activities on this project will include supporting a graduate student and postdoctoral fellow and delivering the Artistic Oceanographer Program (AOP) to diverse middle school age children and teachers in the NYC metropolitan area and to middle-school girls in the Girl Scouts of RI, reaching an anticipated 60 children and 30 teachers annually. The programs will foster multidisciplinary hands-on learning and will directly impact STEM education at a critical point in the pipeline by targeting diverse middle-school aged groups in both NY and RI.

In laboratory studies with cultured isolates, there are profound differences among diatom species' responses to nutrient limitation. Thus, it is likely that different species contribute differently to nutrient uptake, carbon flux and burial. However, marine ecosystem models often rely on physiological attributes drawn from just one species and apply those attributes globally (e.g. coastal species used to model open ocean dynamics) or choose a single average value to represent all species across the world's oceans. In part, this is due to a relatively poor understanding of diatom physiological ecology and a limited tool set for assessing in situ diatom physiological ecology. This research project will address this specific challenge by explicitly tracking metabolic pathways, measuring their regulation and determining their taxonomic distribution in a suite of environmentally significant diatoms using a state of the art, species-specific approach. A research expedition is set in the North Atlantic, a system that plays a major role in carbon cycling. Starting with a New England coastal shelf site, samples will be collected from the coast where diatoms thrive, to the open ocean and a site of a long term ocean time series station (the Bermuda Atlantic Time Series) where diatom growth is muted by nutrient limitation. This research takes advantage of new ocean observatories initiative (OOI) and time series information. Through the research expedition and downstream laboratory experiments, the molecular pathways of nutrient metabolism and related gene expression in a suite of environmentally significant diatoms will be identified. Data will be combined to predict major limiting factors and potentially important substrates for diatoms across marine provinces. Importantly, this integrated approach takes advantage of new advances in molecular and bioinformatics tools to examine in situ physiological ecology at the species-specific level, a key knowledge gap in the field.

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Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)

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