Microzooplankton taxonomic composition from CTD and OCEAN Sampler samples taken during Marine Productivity programme cruises RRS Discovery DI258, DI262 and DI264 cruises in the Northern North Atlantic and Irminger Sea between November 2001 and August 2002

These datasets contain microzooplankton taxonomic data from CTD and OCEAN Sampler samples collected during the DI258, DI262 and DI264 cruises in the northern North Atlantic, between November 2001 - August 2002. Taxonomic notes are provided for some of the species. All species are placed into size categories (less than 20.00 micrometres, 20.00 - 39.99 micrometres, 40.00 - 59.99 micrometres, 60.00 - 79.99 micrometres, 80.00 - 99.99 micrometres and greater than 100.00 micrometres), based on the average length measurement of species fixed in 10 percent Lugol's iodine. All species are also placed into taxonomic groupings (strombidiids, strobilidiids, tintinnids, <em>Myrionecta rubra</em> and all others). Abundance of each ciliate taxa is measured in cells per ml. Biomass of each ciliate taxa is expressed as nanograms of carbon per millilitre for each station. This was calculated by multiplying the ciliate abundance by the individual species biomass. Individual biomass was calculated from the average biovolume (micrometres cubed) for all species based on length and width measurements made on individual cells fixed in 10 percent Lugol's iodine and conversion to volume using geometric shapes that matched the cell shape. Species biovolumes (micrometres cubed) were converted to 2 percent Lugol's iodine. This was necessary as the biovolume/biomass conversion factor used was based on samples fixed in 2 percent Lugol's iodine (based on unpublished data, the biovolume of ciliates fixed in 10 percent Lugol's iodine is 70 percent that of the biovolume of ciliates fixed in 2 percent). Individual species biomass (picograms of carbon per individual cell) was calculated from biovolume using the equation of Putt and Stoecker (1989) who suggest a conversion factor of 190 femtograms of carbon per micrometre cubed. This is based on ciliates fixed in 2 percent Lugol's iodine. These data were collected for the Marine Productivity (MarProd) programme by scientists from the University of Liverpool School of Biological Sciences.