Fig. 7.

Mean net Ca²⁺ (a) and titratable alkalinity (b) fluxes (μmol g⁻¹ h⁻¹ ± SEM) as a function of ambient [Ca²⁺] for egg masses of the pond snail L. stagnalis. Values are for day 7 egg masses that were fluxed for 24 h. Regression line is a Michaelis–Menten curve (Net Ca²⁺: k _m = 91 ± 41.5 μmol l⁻¹ Ca²⁺, V _max = 0.4 ± 0.06 μmol g⁻¹ h⁻¹, R ² = 0.84, P < 0.002). There was no significant relationship between [Ca²⁺] and TA net flux (P > 0.05); however the curve is the best fit trace assuming Michaelis–Menten saturation kinetics. Sample size is indicated for respective [Ca²⁺] above each data point