Table 2.

Regression models of gill P_i uptake kinetics

Model	Km	Vmax	HC	Adj R2	SSR	Sig.
Linear				0.673	543,721
2-Parameter	0.56 ± 0.4	1,347 ± 544		0.8665	54,433
3-Parameter	0.23 ± 0.01	801 ± 24	3.5 ± 0.6	0.9955	1,232	P < 0.01

P_i, inorganic phosphate; K_m, apparent affinity constant (mmol/l); V_max, estimated maximal transport velocity (nmol · g⁻¹ · h⁻¹); HC, Hill coefficient; Adj R², adjusted coefficient of determination; SSR, sum of squared residuals; Sig., significance of additional parameter above the simpler model.

The 3-parameter model provides a significantly better fit of the data (P < 0.01) by the extra sum of squares F-test. Parameters shown are best estimate ± SE.