Table of Contents

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

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

Related Dataset:
EN532 - CTD
EN538 - CTD
Chlorophyll-a: EN532 and EN538
FCM: EN532 and EN538
Particulate N and NO3 isotopes: EN532

Seawater for nutrient assays was collected from the Niskin bottles attached to the CTD/Rosette system into acid cleaned (10% HCl), ‘aged’, 60 ml HDPE (Nalgene) sample bottles. In most cases, samples were analysed immediately for nutrients, and always within 2-3 hours of collection. Nanomolar ammonium was analysed using the method by Holmes (1999) following its reaction with a fluorescent reagent. Nitrate, nitrite were detected using a NOx analyzer from Teledyne Instruments, based on the chemiluminescence reaction of nitric oxide and ozone using Vanadium (III) reduction (Braman and Hendrix 1989). Silicate concentrations were measured on 0.8 µm filtered samples according to Strickland and Parsons (1968), by Daniel Qian and Nicolas Van Oostende at Princeton University. The detection limits were estimated to be 20 nM for NH4, 10 nM for NO2, 50 nM for NO3+NO2 and 100 nM for Si(OH)4.

Clean handling techniques were employed to avoid any contamination of the samples, particularly for the ammonium samples. Dura-Touch gloves were used at all times and samples were not decanted or transferred, but were kept tightly closed until just before ammonium analysis in order to avoid any contamination from external sources. No water column nutrient samples were frozen or stored except for silicate. All sampling and handling techniques, whenever possible, followed the international nutrient GO-SHIP manual (Hydes et al. 2010).

Nutrient measurements made by Andrew and Aimée Babbin onboard the ship and only the “low range” data are reported in case of nitrate. 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

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.