Fig. 4.

Feeding rates of free-living Symbiodinium sp. on Synechococcus sp. and H.akashiwo prey. (A) Ingestion rate of Symbiodinium on Synechococcus as a function of the initial prey concentration (x, cells mL⁻¹). Symbols represent treatment mean ±1 SE. The curves are fitted to the Michaelis–Menten equations using all of the treatments. Ingestion rate: (cells Symbiodinium⁻¹ h⁻¹) = 5.3 [x/(3.9 × 10⁵ + x)], R² = 0.581. (B and C) Ingestion (B) and growth rates (C) of Symbiodinium sp. on H. akashiwo as a function of the mean prey concentration (x, cells mL⁻¹). Ingestion rate: (cells Symbiodinium⁻¹ d⁻¹) = 1.2 [x/(2,280 + x)]; R² = 0.838. Growth rate: (d⁻¹) = 0.467 [(x + 1,720)/(880 + (x + 1,720))]; R² = 0.608. (D and E) Effects of inorganic nutrients on feeding rates of free-living Symbiodinium sp. Ingestion (D) and growth rates (E) of Symbiodinium sp. on H. akashiwo under different nutrient conditions; Red bars indicate no added prey; blue bars, mean prey concentrations = 15,200–19,600 cells mL⁻¹. F, f/2 medium (see Materials and Methods for concentrations); F-N, N-depleted f/2 medium; F-P, P-depleted f/2 medium; F-NP, N- and P- depleted f/2 medium. Symbols represent treatment mean ±1 SE.