Chlorophyll a and nutrient concentrations, Alkaline Phosphatase Activity, phytoplankton abundance, and nitrogen fixation rates from cruise JC150 incubation experiment D, July-August 2017.

This dataset includes chlorophyll a and nutrient concentrations, alkaline phosphatase activity, phytoplankton abundance, and nitrogen fixation rates obtained from a group of nutrient addition experiments (Experiment D) carried out on board the RRS James Cook cruise JC150. These data were obtained after incubating thirty-six 20 L bottles of seawater for 48 hours at in-situ light and temperature conditions. Approximately 800 L of seawater were collected for the experiment from a total from 7 different locations (on 7 different days) in the subtropical North Atlantic Ocean during July and August 2017. The water was collected from a depth of 40 m using either bottles on a titanium CTD rosette or a FISH pump. The incubation bottles contained either seawater with no additional nutrients (control) or varying concentrations of single or combined additional nutrients, specifically zinc, iron, nitrogen (in the form of nitrate/ammonium), esters, and cobalt. Chlorophyll a and alkaline phosphatase activity were measured using a Turner 10Au field fluorometer. Inorganic nutrients were measured at the nanomolar level using flow colorimetric techniques with 2 metre Liquid waveguides. Dissolved organic phosphorus (DOP) was quantified as the difference in Dissolved Inorganic Phosphorus (DIP) concentrations before and after persulfate oxidation measured by a Bran and Leubbe QuAAtro 5-channel autoanalyser. Rates of nitrogen fixation were determined using a bubble-release method. Phytoplankton cell abundance (Synechococcus, Prochlorococus, Picoeukaryotes and low and high DNA content bacteria) were determined using flow cytometry. Data were collected in order to determine the importance of zinc on the phytoplankton community growth, as part of the Natural Environment Research Council (NERC) Discovery Science grant - Zinc, Iron and Phosphorus Co-Limitation in the Ocean (ZIPLOc), grant references NE/N001079/1 and NE/N001125/1.