Time series for the chlorophyll-a concentration (chlo-a) over seven years (2005–2012) and for the δ15N from one vibrissa.

a) Periods detected (23, 49, 60, 7, 21, and 115) in the time series for the chlo-a around San Esteban Island. For the chlo-a, the two main harmonics were located temporally at 23 and 49 weeks; b) Peaks detected (36, 20, 29, and 16) in the time series for δ15N in the longest vibrissa in our sample. The resulting number of significant periods in the δ15N of each vibrissa is associated with six months of growth.