Trophic structure of the pelagic food web in the East China Sea

Zoological Studies

Table 1 Comparison of linear models and piecewise models

Response	Predictor	AIC linear model	AIC piecewise model	Cut point
Larval fish	SST^a	452.1	440.5	25.3
	SSS	460.6	462.1	32.2
	Zooplankton biomass	446.6	447.0	−1.9
Zooplankton	SST	358.4	360.2	25.2
	SSS	363.9	362.9	32.8
	Phytoplankton biomass	354.2	358.0	8.9
Phytoplankton	SST^a	216.0	192.6	24.8
	SSS^a	216.6	204.7	32.0
	DIN^a	211.4	198.9	10.4
	PO₄	219.4	223.4	0.2
	SiO₃	219.6	213.1	16.3
Zooplankton/phytoplankton ratio	SST	363.0	364.8	24.5
Zooplankton/phytoplankton ratio	SSS	362.4	365.4	28.3
	DIN	353.2	355.5	9.0
	PO₄	342.9	348.2	0.5
	SiO₃	353.8	356.8	4.7
	Larval fish density	356.2	360.2	−1.3

The relationships between the abundance/biomass of each trophic level and each predictor variable were analyzed using generalized linear mixed-effects models and mixed-effects piecewise regression models, and the AIC values of the two approaches were compared.
^aThe piecewise model had a much better fit compared to the linear model (ΔAIC ≥ 10), indicating a change of relationship at the cut point.