B vitamins (thiamin, B1; biotin B7; cobalamin, B12) are organic molecules necessary for all the biological transformations of the chemical elements that support life on Earth. Because most organisms lack the ability to synthesize several vitamins, their vitamin needs and environmental accessibility could define which, when, and where specific phytoplankton species flourish. Despite the early discovery of their relevance in the 1940s, most current marine vitamin research is still based on laboratory experiments or studies focusing on the biological responses of B vitamin additions on algae and bacteria. However, geographical distributions of B vitamins in the ocean are mostly unknown, as they have only been measured in a few marine basins. This dataset contains B vitamin distribution measurements and ancillary (physical, chemical, and biological) parameters to elucidate the effects of vitamin availability on phytoplankton and bacteria species in surface waters of the world ocean collected during the Malaspina circumnavigation expedition. The different B vitamins were analyzed using a triple quadrupole mass spectrometer coupled to a liquid chromatography system after a solid-phase extraction with a C18 resin. This global map of vitamins is being used to determine the importance of dissolved B vitamins in microbial species biogeography, a still unresolved ecological riddle. Another objective of the study is to establish how ambient vitamin concentrations, combined with bioactive trace elements and macronutrients, promote changes in the relative abundance of different eukaryotic and prokaryotic plankton species on the surface ocean.

Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • BCO-DMO Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

All sampling and analytical procedures are reported in [Estrada M, Delgado M, Blasco D, Latasa M, Cabello AM, Benítez-Barrios V, et al. (2016) Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans. PLoS ONE 11(3): e0151699. doi:10.1371/journal. pone.0151699] and are detailed below.

Hydrography and sampling details
In general, two vertical profiles of Conductivity-Temperature-Depth (CTD) were carried out at a fixed position every day, a first one down to 4000 m depth at 5:00 and a second one, starting around 10:00 local time, down to 200 m depth. The CTD, a SeaBird 9/11-plus, was equipped with dual conductivity and temperature sensors, calibrated at the SeaBird laboratory before the cruise. Water samples were obtained using a rosette of 24 10-liter Niskin bottles. Profiles of underwater photosynthetically active radiation (PAR) were obtained with a 4π Biospherical QCP2300-HP sensor attached to the CTD. The mixed layer depth (MLD) was defined [Monterey G, Levitus S (1997) Seasonal variability of mixed layer depth for the world ocean. Washington D. C.: U. S. Government Printing Office. 96 p] as the first depth (z) where σθ(z)- σθ(10)> 0.125 kg m-3, where σθ(z) and σθ(10) are, respectively, the potential density anomalies at depths z and 10 m. The Ocean Data View software [Schlitzer R (2013) Ocean Data View. http://odv.awi.de] was used to present the distribution of hydrographical variables.

Water samples for nutrient and total Chl a determination were collected from about 10 depths between surface and 200 m, including those selected for phytoplankton sampling. Water for fractionated Chl a analyses and for phytoplankton examination was taken from the Niskin bottles of the second cast of the rosette, at the depth of the 20% light level and at the depth of the subsurface chlorophyll a (Chl a) maximum (SCM). Additional surface seawater samples (3 m depth) were collected with a 30 L Niskin bottle.

Phytoplankton analysis
Approximately 250 cm3 of water were placed in a glass bottle and fixed with hexamine-buffered formaldehyde solution (4% final formalin concentration). A 100 cm3 composite chamber was filled with sample water and its content was allowed to settle for 48 hours. At least two transects of the chamber bottom were observed with an inverted microscope [Utermöhl H (1958) Zur Vervollkommung der quantitativen Phytoplankton-Methodik. Mitt Int Verein Limnol 9: 1–38.] at 312 X magnification to enumerate the most frequent, generally smaller, phytoplankton forms. Additionally, the whole chamber bottom was examined at 125 X magnification to count the larger, less frequent cells. In both cases, all cells encountered were tallied. Classification was done at the genus or species level when possible, but many taxa could not be identified and were pooled in categories such as “small flagellates” or “small dinoflagellates”.

Chlorophyll a, inorganic nutrient determinations and metal determination
To determine total Chl a concentration [Estrada M (2012) Determinación fluorimétrica de la clorofila a. In: Moreno-Ostos E, editor. Expedición de circunnavegación Malaspina 2010: Cambio global y exploración de la biodiversidad del océano Libro blanco de métodos y técnicas de trabajo oceanográfico. Madrid: CSIC. pp. 399–405], a volume of water ranging between 200 and 500 cm3 was filtered through GF/F glass fiber filters that were subsequently frozen at -20°C and, after a minimum of 6 hours, introduced in acetone 90% and left for 24 hours in a refrigerator, in the dark. The fluorescence of the acetonic extracts was determined with a Turner Designs fluorimeter calibrated with a Chl a standard (Sigma-Aldrich); no phaeopigment correction was applied. Chl a concentration for different size fractions was obtained by sequential filtering of
an additional 500 cm3 water sample through Poretics (polycarbonate) membrane filters of pore sizes 20 μm, 2 μm and 0.2 μm. Total Chl a values are those of the GF/F filters; however, as these filters tended systematically to collect more Chl a than 0.2 μm membrane filters, the proportion of Chl a in a particular size fraction was referred to the total obtained by adding up the Chl a collected in the three consecutive membrane filters. Dissolved inorganic nutrients were analyzed with a Skalar AutoAnalyzer, using the procedures of Grasshoff et al. [Grasshoff K, Kremling K, Erhardt M (1999) Methods of Seawater Analysis. Weinheim: Wiley-VCH. 632 p], as described in [Blasco D, De la Fuente Gamero P, Galindo M (2012) Muestreo y análisis de nutrientes inorgánicos disueltos en agua de mar. In: Moreno-Ostos E, editor. Expedición de circunnavegación Malaspina 2010: Cambio global y exploración de la biodiversidad del océano Libro blanco de métodos y técnicas de trabajo oceanográfico Madrid: CSIC. pp. 103–121]. Metal concentrations were analyzed as described in [Pinedo-González, P., et al. (2015), Surface distribution of dissolved trace metals in the oligotrophic ocean and their influence on phytoplankton biomass and productivity, Global Biogeochem. Cycles, 29, 1763–1781, doi:10.1002/ 2015GB005149] using a Thermo Element 2 HR-ICP-MS.

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NSF Award Abstract:
B-vitamins (thiamin, B1; biotin B7; cobalamin, B12) are organic molecules necessary for all the biological transformations of the chemical elements that support life on Earth. Without the activity of those molecules, the chemistry of life on Earth—as we know it—would end. In marine systems, the availability of B-vitamins also affects food web dynamics by controlling both bacterial and phytoplankton growth and species diversity. Because many organisms that can make several B-vitamins lack the ability to synthesize others, their vitamin needs and environmental accessibility could define which, when, and where specific phytoplankton species flourish. As a result, planktonic communities in nature need to constantly share B-vitamins in a complex mosaic of interdependencies. Despite the early discovery of their relevance in the 1940s, most current marine vitamin research is still based on laboratory experiments or studies focusing on the biological responses of B-vitamin additions on algae and bacteria. Yet, vitamin distributions in the world ocean are mostly unknown, as they have only been measured in a few marine basins. Thus, the actual effect of their natural distributions in phytoplankton communities is still a mystery today. The main goal of this project is to elucidate the effects of B-vitamins availability on the spatial distributions of different phytoplankton species in surface waters of the world ocean. These data are needed to start untangling the rules by which members of the microbial plankton are interconnected through vitamin exchange and to determine how these essential interrelations may control surface ocean ecosystem functioning, such as phytoplankton and bacterial growth. Ultimately understanding these controls and their dynamics is critical to predicting future changes in the marine environment. In the future greenhouse world, the ocean is expected to be of paramount importance, providing the required protein to nurture future human populations and to reduce the levels of human-produced atmospheric CO2 through its uptake by photosynthetic organisms with different vitamin requirements.

This study is to establish the first global map of B-vitamin distributions in surface waters of the world ocean collected during the Malaspina circumnavigation expedition. This global map of vitamins is being used to determine their importance on phytoplankton species biogeography, a still unresolved ecological riddle. Another objective of the study is to establish how ambient vitamin concentrations, combined with bioactive trace elements and macronutrients, promote changes in the relative abundance of different eukaryotic and prokaryotic plankton species on the surface ocean. Overall, this is the first global study on the role of B-vitamins on ecosystem functioning and species composition in subtropical and tropical open ocean environments including the ocean gyres. The investigators are carrying out targeted metagenomic analyses to identify B-vitamins synthesizers and consumers within the planktonic community at several globally distributed stations across the Atlantic, Pacific, and Indian oceans. The extensive datasets already generated by the hundreds of participants of the Malaspina expedition is fully available to interpret the vitamin results. This study allows us to expand our understanding of B-vitamin distributions on a global scale and further investigate how surface ocean’s plankton community dynamics are intertwined with ambient B-vitamin pools.

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.