Short-term experiment (7 days) with nine Chaetoceros affinis genotypes at seven nitrate levels

Measurements of cell size and cell density in a short-term experiment (7 days) of nine Chaetoceros affinis genotypes (http://roscoff-culture-collection.org/; B63: RCC6347, B67: RCC6348, B68: RCC6349, B74: RCC6350) separately at seven nitrate levels 2.5, 5, 7.5, 12.5, 20, 30, and 40 μmol L−1 N) and 2 μmoL-1 phosphate. Silicate concentrations were aligned to reflect a 1:1.5 N:Si ratio. Prior to the experiment each genotype was acclimated over two weeks at initial nutrient concentrations of 1.8 µmol L-1 P, 30 µmol L-1 N, and 40 µmol L-1 Si.