Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information
• Funding

Chlorophyll-a concentrations from CTD casts made during the August-September 2013 EN532 and April-May 2014 EN358 cruises aboard R/V Endeavor. Study sites are located in the subarctic Atlantic Ocean along the 20°W meridian between 50°N and 60°N. Two transects from the US East coast to the subarctic study sites were performed as well.

Discrete chlorophyll a (Chla) samples were measured fluorometrically (Holm-Hansen & Riemann 1978) by Nicolas Van Oostende and Jessica Lueders Dumont at 6 depths spanning the surface, the bottom of the euphotic zone, the mixed layer, and Chla maximum depths. Up to 4 liters of seawater, retrieved directly from the Niskin bottles or the surface seawater inflow, were sequentially filtered through a 20 µm pore-size polycarbonate filter, a 2 µm pore-size polycarbonate filter, and a 0.3 µm pore-size glass fiber filter (GF-75; Sterlitech; 47 mm diameter). Filtrations were performed in the dark under low vacuum (<200 mbar). The Chla filters were packaged into aluminium foil (GF filter), or a 5 ml cryovial, and immediately frozen at -80°C until analysis.

Chlorophyll was extracted in 90% acetone at 4°C overnight and measured using a Turner Trilogy fluorometer, calibrated against a pure Chla standard (Anacystis nidulans Chla, Sigma-Aldrich, Saint-Louis, USA). Measurements were corrected for the fluorescence of phaeopigments after acidification with HCl (24 mM final concentration). Limit of quantification was 1 µg per liter in extract, or approximately 1 ng per liter in the sample. The Chlorophyll a concentration of casts 15 to 41 was measured by James L. Pinckney using the HPLC method derived from the Van Heukelem et al. (1992, 1994) and Pinckney et al. (1996) protocols.

When measurements were below the limit of the quantification, the limit of quantification for that particular measurement is given and accompanied with a quality flag ("6"). 'nd' indicates no measurements were made with a quality flag (“9”).

BCO-DMO Processing:

- added conventional header with dataset name, PI name, version date
- renamed parameters to BCO-DMO standard
- replaced blank cells with nd
- added depth_w to EN538 datasets so they'd match EN532

- replaced original 2016-07-13 EN532 data with new version submitted 2017-07-14. Cast numbers were rearranged.

This project will investigate the taxonomic, genetic and functional diversity of eukaryotic phytoplankton at two North Atlantic sites (subarctic and subtropical) in two seasons.  The PIs will use diagnostic microarrays for community analysis based on functional genes (both DNA and RNA) and next generation sequencing (i.e., transcriptomics using 454 technology) to identify the players, both in terms of community composition and activity, and to explore the functional diversity of the natural assemblage. In order to identify which groups are active in C and N assimilation and which N source is being utilized by the different size and functional groups, both filter-separated and flow cytometry-sorted samples will be used to 1) measure 13C primary production and 15N assimilation by incubations with isotope tracers, 2) measure the natural stable N isotope signatures of different taxonomic groups and 3) link the molecular diversity to the functional diversity in C and N transformations. Using flow cytometry linked to mass spectrometry, these investigators have found an unexpectedly strong differentiation in the form of N assimilated by prokaryotes and eukaryotes, with eukaryotes being more dynamic.

This project will investigate the taxonomic, genetic and functional diversity of eukaryotic phytoplankton and to link this diversity and assemblage composition to the carbon and nitrogen biogeochemistry of the surface ocean. Taxonomic diversity will be investigated by identifying the components of the phytoplankton assemblages using molecular, chemical and microscope methods. Genetic diversity will be explored at several levels, including direct sequencing of clone libraries of key functional genes and metatranscriptomic sequencing and microarray analysis of size fractionated/sorted phytoplankton assemblages. Using natural abundance and tracer stable isotope methods, genetic and taxonomic diversity will be linked to functional diversity in C and N assimilation in size- fractionated and taxon-sorted populations.

(adapted from the NSF Synopsis of Program)
Dimensions of Biodiversity is a program solicitation from the NSF Directorate for Biological Sciences. FY 2010 was year one of the program.  [MORE from NSF]

The NSF Dimensions of Biodiversity program seeks to characterize biodiversity on Earth by using integrative, innovative approaches to fill rapidly the most substantial gaps in our understanding. The program will take a broad view of biodiversity, and in its initial phase will focus on the integration of genetic, taxonomic, and functional dimensions of biodiversity. Project investigators are encouraged to integrate these three dimensions to understand the interactions and feedbacks among them. While this focus complements several core NSF programs, it differs by requiring that multiple dimensions of biodiversity be addressed simultaneously, to understand the roles of biodiversity in critical ecological and evolutionary processes.