Fig. 5: Linear relationship between C:N ratios (mol:mol) and the ratio of carbohydrates (carbon-rich organic compounds) to amino acids (nitrogen-rich organic compounds), or carbo:AA ratio, on a molar carbon basis.

Data are from size-fractionated particles within the euphotic zone at the BATS site in August and November 2021. Orthogonal regression was fit using the MATLAB function linortfit2. One outlier was omitted, with a carbo:AA ratio of ~3.6 and a C:N ratio of ~14. The same figure, including the outlier, can be seen in Supplementary Fig. 6. Horizontal error bars represent standard deviations of replicates, while vertical error bars represent the standard deviation and include uncertainty from blank corrections and filter splitting by weight.