FIGURE 6.

Niche spaces of Kiel Bay and Arkona Basin functional groups based on multivariate δ¹³C_EAA (a) and bivariate bulk isotope (b; δ¹³C_{lipid corrected} and δ¹⁵N) values. To represent the δ¹³C_EAA data in a bivariate space (see Figure 3 for the independent variables), we used the first two linear discriminant scores encompassing 97.8% of the variability. The groups depicted here contain ≥10 specimens. The niche spaces are visualized by 95% confidence interval around the bivariate means, also called the standard ellipse area (SEA; inner ellipses with broken lines) and 95% prediction ellipses (outer ellipses with full lines), respectively. The convex hulls encompassing the group means are denoted TA_c for the total area of each community. The community niche space is generally more separated for δ¹³C_EAA than bulk isotopes; for example, there is only one overlap of the prediction ellipses between functional groups in the δ¹³C_EAA biplot, but four overlaps in the bulk biplot