This dataset contains the Chlorophyll a concentration, picophytoplankton abundance, and abundance, cell area, and cell volume of large nano- and micro-phytoplankton from temperature and nutrient incubation experiments. The samples used for the experiments were taken along the Atlantic Meridional Transect (AMT) during RRS Discovery cruise DY110 (AMT29) between the 13th October 2019 and 25th November 2019. Samples were taken from the incubation at the start and end of the incubation period (0 and 96 hours) for analysis of chlorophyll a concentration and abundance and cell volume of large nano- and micro-phytoplankton. Chlorophyll a concentration was determined with a Turner Designs Trilogy fluorometer. Large nano- and microphytoplankton were analysed by automated digital imaging using a Yokogawa Fluid Imaging Technologies FlowCAM 8400. Samples were taken from the incubation at 24-hour intervals to determine the abundance of picoeukaryotes and cyanobacteria Prochlorococcus and Synechococcus by flow cytometry using a Becton Dickinson FACSort equipped with an air-cooled laser providing blue light at 488 nm. These experiments aimed to characterise the interactive effect of simultaneous changes on temperature and nutrient availability in tropical and subtropical phytoplankton assemblages. These data were collected by scientists from the University of Vigo, for the project: TRIATLAS South and Tropical Atlantic climate-based marine ecosystem prediction for sustainable management (H2020). These data are available under the most recent version of the NERC Open Government Licence.

This dataset contains depth profiles of the mean abundance of cyanobacteria and small (<20 um) phytoplankton reported in cells per millilitre. Samples were measured using flow cytometry during the Atlantic Meridional Transect (AMT) cruise AMT25 (JR15001). The samples were collected between September and November 2015 from 200 m to the surface, using a Seabird CTD system with a rosette of 24 Niskin bottles of 20 L volume. Samples were collected from the predawn and noon CTDs and were stored in a refrigerator and analysed within 3 hours of collection. In total 915 discrete samples were analysed and quantified using a Becton Dickinson FACSort flow cytometer which characterised and enumerated Prochlorococcus sp. and Synechococcus sp. (cyanobacteria) and pico- and eukaryotic phytoplankton, based on their light scattering and autofluorescence properties. Data were analysed onboard the ship during the cruise.

This dataset contains depth profiles of the mean abundance of microbial bacteria, cyanobacteria and small (<20 um) phytoplankton reported in cells per millilitre. Samples were measured using flow cytometry during the Atlantic Meridional Transect (AMT) cruise AMT27 (DY084/DY085). The samples were collected between September and November 2017 from 200 m to the surface, using a Seabird CTD system with a rosette of 24 Niskin bottles of 20 L volume. Samples were collected from the predawn and noon CTDs and were stored in a refrigerator and analysed within 3 hours of collection. In total 966 discrete samples were analysed and quantified using a Becton Dickinson FACSort flow cytometer which characterised and enumerated Prochlorococcus sp. and Synechococcus sp. (cyanobacteria), pico- and eukaryotic phytoplankton and microbial bacteria based on their light scattering and autofluorescence properties. Data were analysed onboard the ship during the cruise.

This dataset contains depth profiles of the mean abundance of microbial bacteria, cyanobacteria and small (<20 um) phytoplankton reported in cells per millilitre. Samples were measured using flow cytometry during the Atlantic Meridional Transect (AMT) cruise AMT26 (JR16001). The samples were collected between September and November 2016 from 200 m to the surface, using a Seabird CTD system with a rosette of 24 Niskin bottles of 20 L volume. Samples were collected from the predawn and noon CTDs and were stored in a refrigerator and analysed within 3 hours of collection. In total 943 discrete samples were analysed and quantified using a Becton Dickinson FACSort flow cytometer which characterised and enumerated Prochlorococcus sp. and Synechococcus sp. (cyanobacteria), pico- and eukaryotic phytoplankton and microbial bacteria based on their light scattering and autofluorescence properties. Data were analysed onboard the ship during the cruise.

This dataset contains depth profiles of the mean abundance of microbial bacteria, cyanobacteria and small (<20 um) phytoplankton reported in cells per millilitre. Samples were measured using flow cytometry during the Atlantic Meridional Transect (AMT) cruise AMT29 (DY110). The samples were collected between October and November 2019 from 200 m to the surface, using a Seabird CTD system with a rosette of 24 Niskin bottles of 20 L volume. Samples were collected from the predawn and noon CTDs and were stored in a refrigerator and analysed within 3 hours of collection. In total 820 discrete samples were analysed and quantified using a Becton Dickinson FACSort flow cytometer which characterised and enumerated Prochlorococcus sp. and Synechococcus sp. (cyanobacteria), pico- and eukaryotic phytoplankton and microbial bacteria based on their light scattering and autofluorescence properties. Data were analysed onboard the ship during the cruise.

This dataset contains depth profiles of the mean abundance of microbial bacteria, cyanobacteria and small (<20 um) phytoplankton reported in cells per millilitre. Samples were measured using flow cytometry during the Atlantic Meridional Transect (AMT) cruise AMT28 (JR18001). The samples were collected between September and October 2018 from 200 m to the surface, using a Seabird CTD system with a rosette of 24 Niskin bottles of 20 L volume. Samples were collected from the predawn and noon CTDs and were stored in a refrigerator and analysed within 3 hours of collection. In total 755 discrete samples were analysed and quantified using a Becton Dickinson FACSort flow cytometer which characterised and enumerated Prochlorococcus sp. and Synechococcus sp. (cyanobacteria), pico- and eukaryotic phytoplankton and microbial bacteria based on their light scattering and autofluorescence properties. Data were analysed onboard the ship during the cruise.

This dataset contains depth profiles of the mean abundance of microbial bacteria, cyanobacteria and small (<20 um) phytoplankton reported in cells per millilitre. Samples were measured using flow cytometry during the Atlantic Meridional Transect (AMT) cruise AMT13 (JR20030910/JR91). The samples were collected between September and October 2003 from 200 m to the surface, using a Seabird CTD system with a rosette of 24 Niskin bottles of 20 L volume. Samples were collected from the predawn and noon CTDs and were stored in a refrigerator and analysed within 3 hours of collection. In total 835 discrete samples were analysed and quantified using a Becton Dickinson FACSort flow cytometer which characterised and enumerated Prochlorococcus sp. and Synechococcus sp. (cyanobacteria), pico- and eukaryotic phytoplankton and microbial bacteria based on their light scattering and autofluorescence properties. Data were analysed onboard the ship during the cruise.

This dataset contains depth profiles of the mean abundance of microbial bacteria, cyanobacteria and small (<20 um) phytoplankton reported in cells per millilitre. Samples were measured using flow cytometry during the Atlantic Meridional Transect (AMT) cruise AMT16 (D294). The samples were collected between May and June 2005 from 200 m to the surface, using a Seabird CTD system with a rosette of 24 Niskin bottles of 20 L volume. Samples were collected from the predawn and noon CTDs and were stored in a refrigerator and analysed within 3 hours of collection. In total 835 discrete samples were analysed and quantified using a Becton Dickinson FACSort flow cytometer which characterised and enumerated Prochlorococcus sp. and Synechococcus sp. (cyanobacteria), pico- and eukaryotic phytoplankton and microbial bacteria based on their light scattering and autofluorescence properties. Data were analysed onboard the ship during the cruise.

This dataset contains depth profiles of the mean abundance of cyanobacteria and small (<20 um) phytoplankton reported in cells per millilitre. Samples were measured using flow cytometry during the Atlantic Meridional Transect (AMT) cruise AMT18 (JR20081003/JR218). The samples were collected between October and November 2008 from 200 m to the surface, using a Seabird CTD system with a rosette of 24 Niskin bottles of 20 L volume. Samples were collected from the predawn and noon CTDs and were stored in a refrigerator and analysed within 3 hours of collection. In total 684 discrete samples were analysed and quantified using a Becton Dickinson FACSort flow cytometer which characterised and enumerated Prochlorococcus sp. and Synechococcus sp. (cyanobacteria) and pico- and eukaryotic phytoplankton, based on their light scattering and autofluorescence properties. Data were analysed onboard the ship during the cruise.

This dataset contains depth profiles of the mean abundance of cyanobacteria and small (<20 um) phytoplankton reported in cells per millilitre. Samples were measured using flow cytometry during the Atlantic Meridional Transect (AMT) cruise AMT19 (JC039). The samples were collected between October and December 2009 from 200 m to the surface, using a Seabird CTD system with a rosette of 24 Niskin bottles of 20 L volume. Samples were collected from the predawn and noon CTDs and were stored in a refrigerator and analysed within 3 hours of collection. In total 792 discrete samples were analysed and quantified using a Becton Dickinson FACSort flow cytometer which characterised and enumerated Prochlorococcus sp. and Synechococcus sp. (cyanobacteria) and pico- and eukaryotic phytoplankton, based on their light scattering and autofluorescence properties. Data were analysed onboard the ship during the cruise.