Additional file 1.
Temporal frequency of light flicker is wavelength dependent across various water depths. (A-D) The frequency distribution of the flicker in downward irradiance at a depth of 2 m (A), 4 m (B), 6 m (C), and 10 m (D) differed across the light spectrum. For clear graphical presentation, the power spectrum of light flicker, normalized to the dominant frequency (1.54 Hz for 2 m, 0.83 Hz for 4 m, 0.80 Hz for 6 m, 0.67 Hz for 10 m) is presented for different wavelengths at 50 nm intervals. (E-G) Cumulative power of wave-induced flicker across wavelengths and water depths. As indices of the distribution of flicker power across temporal frequencies, we calculated the fP50, fP90, and fP99 that stand for the temporal frequencies that correspond to 50, 90, and 99 percent of the cumulative power of wave-induced flicker. fP50, fP90, and fP99 increased toward longer light wavelengths, further supporting the wavelength dependence of the temporal frequency structure of flicker. Note that deeper in the water column, the irradiance at both ends of the spectrum was too low to be considered reliable (see Methods for criteria for excluding data points); therefore, the spectral range presented narrows with depth.
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Sabbah and Hawryshyn BMC Biology 2013 11:77 doi:10.1186/1741-7007-11-77