Fig. 1
δ13C–δ15N scatter-plot of all species included in the present study (standard deviations are reported; for details on acronyms see Table 1). Two significantly different groups of species (G1 and G2) are highlighted in the figure (Student’s t test P < 0.05). Other species like M-m, M-v, Amm, S-m, Krill, POM and SOM were significantly different from all (Student’s t test P < 0.05) [Stable isotope ratios measure the ratio of the heavy (13C and 15N) and light (12C and 14N) in a sample. Thus, samples that contain more of the heavy isotope are referred to as “enriched” and are “heavier” than other samples (i.e. values tending to be more positive); those that contain less of the heavy isotope are “depleted” and are “lighter” than other samples (i.e. values tending to be more negative]