The power spectrum analysis found that the cyclic pattern in the
feeding activity of crabs and in the Chlorophyll a content could be
explained by sine waves of 16.17 and 15.52 days period, respectively
(Table 1). Likelihood Ratio Tests indicated that the sine wave
component of times series had the same frequency but different
amplitude and phase (Table 1 and 2). The phase difference between
both time series was 5.76 days (95% Bootstrap confidence limit: 4.26,
7.42).