Isotopic fraction between lipids and bulk biomass of phytoplankton, terrestrial matter and bacteria.

The biomarker fatty acids (FA) used for δ13C analysis were characteristic of each strain. Carbon, lipid and phospholipid (PL) content of selected groups of phytoplankton, bacteria and terrestrial organic matter, are averages of selected strains (see Table 1). Isotopic difference (Δ) were calculation by subtracting the δ13C value of lipid, phospholipid (PL) or biomarker fatty acid (biomarker FA) from the δ13C value of bulk biomass (biom).