Seyler North Atlantic water column

CLIVAR (Climate Variability and Predictability) is a core component of the World Climate Research Program (WCRP). CLIVAR's objective, as stated on their website (www.clivar.org) is to describe and understand the ocean-atmosphere processes responsible for climate variability and predictability on seasonal, interannual, decadal, and centennial time-scales, through the collection and analysis of observations and the development and application of models of the coupled climate system, in cooperation with other relevant climate-research and observing activities. In April-May 2012, we participated in a research cruise as part of the US CLIVAR/CO2 Repeat Hydrography program, onboard the UNOLS ships R/V Atlantis. The cruise was a repeat of World Ocean Circulation Experiment (WOCE) line A20 (longitude 52W), previously conducted in 2003. 10-L water samples were collected at a total of 83 stations at varying depth intervals, using a 36-Niskin bottle rosette. We took 0.5-1.0 L samples from the rosette roughly once per day at 16 stations throughout the cruise. At each station, water was taken from at least three distinct zones in the water column, based on data from the CTD: the middle of the mixed layer, the local oxygen minimum, and the middle of the bathypelagic zone. At 7 stations, samples were also drawn from the bottom-most bottle. Biomass was immediately collected on 0.2 um filters under vacuum filtration. SIP microcosms were set up at 13 stations using 13C sodium acetate, 13C urea, 13C sodium bicarbonate, 13C algal lipid/pigment extract, and 15N algal protein extract. The samples submitted to the Earth Microbiome Project represent T=0 time points for the SIP microcosms (before amendment) and extra samples taken for RNA/DNA analysis. Results from SIP are currently being processed.