Figure 6.

Species roles variability in the planktonic food web from the Gulf of Naples (Italy) at transitions between oligotrophic or blue and eutrophic or green states. (a, b) Relationships between weighted overlap (WO) and weighted centrality (WI) for web nodes at blue and green states, respectively; numbers are nodes id (see Table 1) and their position indicate nodes position in the x‐y plot; colors are as in Figures 3 and 4; and white arrows indicate “C” and “S” nodes, that is, “couplers” and “shifters” animals, respectively, with the first not modifying their network position and the second modifying their (niche) overlap (WO) at blue‐green shifts. (c) Coupling behavior in a consumer node such as Appendicularia (#50 in a, b; herein, this node is coded as “C”). When the system shifts between green and blue states, a coupler, that is, a highly generalist consumer, undergoes strong rewiring, from resources nodes “r_1‐5” to resources nodes “r_6‐10,” and it remains at the center of fluxes—as a consequence, its positional importance does not change, as well as its niche overlap. (d) Shifting behavior in a consumer node such as calanoid copepods (#44‐49 in A‐B; herein, this node is coded as “S”). When the system shifts between green and blue states, a shifter, that is, a highly selective consumer, shifts between distinct trophic pathways—as a consequence, its positional importance largely changes, as well as its niche overlap, which is higher at green than blue states. Notice that nodes without codes are other consumers competing with the shifter node, while r_1‐3 nodes are resources nodes