Table 1.
Size and carbon and nitrogen contents of P. grani nauplii and the experimental algae.
Table 2.
Prey concentrations in the feeding experiments.
Fig 1.
Paracartia grani nauplii clearance and ingestion rates as a function of the average prey concentration in the unialgal experiments.
Holling type III equations were fitted to data on Isochrysis galbana, Rhodomonas salina, Heterocapsa sp. and Gymnodinium litoralis. Holling type II equations were fitted to data on Thalassiosira weissflogii.
Table 3.
Parameters (±SE) of the Holling type II and type III functional response models fitted.
Fig 2.
Maximum clearance rates of Paracartia grani nauplii in the unialgal experiments as a function of the prey:predator size ratio.
Nan: Nannochloropsis oculata; Iso: Isochrysis galbana; Rho: Rhodomonas salina; Het: Heterocapsa sp.; Tw: Thalassiosira weissflogii; Gym: Gymnodinium litoralis; Aka: Akashiwo sanguinea
Fig 3.
Carbon feeding rates of Paracartia grani nauplii on unialgal suspension of the three algae used in the mixture experiments.
Clearance (A) and ingestion (B) rates as a function of the average prey concentration. Fits like in Fig 1.
Fig 4.
Effects of the presence of alternative prey on the functional response of Paracartia grani nauplii on Isochrysis galbana.
(A) Clearance rate as a function of Isochrysis galbana concentration in unialgal suspension and in mixture with Heterocapsa sp. (B) Clearance rate as a function of Isochrysis galbana concentration in unialgal suspension and in mixture with Gymnodinium litoralis. (C) Ingestion rate as a function of Isochrysis galbana concentration in unialgal suspension and in mixture with Heterocapsa sp. (D) Ingestion rate as a function of Isochrysis galbana concentration in unialgal suspension and in mixture with Gymnodinium litoralis. Unialgal data were fit to non-linear equations like in Fig 1. For the bialgal experiments, correction for Isochrysis-sized particles generated when feeding on the larger prey are also shown (see text). Mixed suspension data were fit with linear equations (only shown for the uncorrected values).
Table 4.
Feeding rates on the alternative prey in the bialgal experiments.
Fig 5.
Observed and expected relative contribution of the primary and secondary prey in the diet of nauplii as a function of their relative carbon contribution in the bialgal suspension.
(A) Isochrysis galbana in the bialgal suspension composed of Isochrysis galbana and Heterocapsa sp.; (B) Isochrysis galbana in the bialgal suspension composed of Isochrysis galbana and Gymnodinium litoralis. Corrections for Isochrysis-sized particles generated when feeding on the larger prey are also shown (see text). Line is spline fit to the data.
Fig 6.
Total (both prey) ingestion rate of Paracartia grani nauplii as a function of total prey concentration in the bialgal experiments.