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SupplementalMaterials
Rarefaction Curves
We plotted rarefaction curves for each fish predator in 2010 and 2011, adding stomachs in random order and using 1000 permutations to determine 95% confidence intervals for the curve.
Comparisons of Individual Predator Diets Using Different Metrics
Number of Prey Consumed vs. Biomass
Overall patterns in diet composition were similar for rockfish and halibut regardless of whether we used number consumed or biomass as a metric (Figs. S2 and S3). Salmon diet composition was different depending on the metric used, with fish prey de-emphasized when using number consumed (Fig.S4).
Number of Prey Consumed vs. Frequency of Occurrence
Rockfish diets (55 taxa) differed in number of prey consumed between 2010 and 2011 (MRPP, Count: A = 0.0465, p = 0.006; Occurrence: A = 0.1675, p < 0.0001). The strength of the difference between years was greater for the frequency of occurrence metric, suggesting that the difference may be driven by prey categories consumed frequently but in relatively small numbers. Several prey categories appeared to be driving the differences between years. Fish constituted a greater percentage of the black rockfish diets in the 2010, although the 2011 diets had a more diverse invertebrate component (Table 1).
Common murre diets differed in number of prey consumed between 2010 and 2011, but not in frequency of occurrence (MRPP, Count: A = 0.175, p = 0.0007, Occurrence: A = 0.025, p = 0.244). The lack of difference in frequency of occurrence between years is likely caused by relatively few prey categories used in the analysis (n= 10), and relatively large number of samples collected during each sampling week (n = 11-277), resulting in a diet matrix where most prey categories were present in each week of sampling.
Comparisons of Predator length, prey length and nMDS axes
We plotted scatterplots of predator length and prey length against both nMDS axes for each year of the study.
Supplementary Figure Captions
Figure S1. Rarefaction curves of black rockfish, Chinook salmon and Pacific halibut diets in 2010 and 2011. The dark blue line represents the rarefaction curve for the number of prey species identified, and the lighter blue shaded area shows 95% confidence intervals.
Figure S2. Black rockfish diets, shown as percent of total biomass (S2a) and number consumed (S2b).
Figure S3. Pacific halibut diets, shown as proportion of total biomass (S3a) and number consumed (S3b).
Figures S4. Chinook salmon diets, shown as proportion of total biomass (S4a) and number consumed (S4b). As in Table 1, one outlier sample was excluded from 2011 in these unstandardized data, but was retained in the statistical analyses.
Figure S5. Scatterplots of mean predator length for each sample unit of the fish predator ordinations and their corresponding nMDS scores for Axis 1 and 2.
Figure S6. Scatterplots of mean prey length for each sample unit of the fish predator ordinations and their corresponding nMDS scores for Axis 1 and 2.
Figure S7. Scatterplots of mean predator length for each sample unit of the all predator ordinations and their corresponding nMDS scores for Axis 1 and 2.
Figure S8. Scatterplots of mean prey length for each sample unit of the all predator ordinations and their corresponding nMDS scores for Axis 1 and 2.