Figure 1.
Timing and position of sensor deployments.
(A) Position of sites in the reef-flat to reef-slope transect on distance to shore-depth axes. Sites are numbered consecutively (S1–S21) from left to right. Horizontal dotted line marks the depth at which the long-term time series was located. (B) Time series plots of daily averaged temperature, salinity, dissolved oxygen concentration and pH from the long-term station. Vertical dotted lines mark the starts of the two-weeks deployments along the transect. Crosses on top of the pH time series correspond to in situ water measurements of pH. The names of the sites used in the deployments are shown on top.
Figure 2.
Example of 3 simultaneous time-series of pH.
Simultaneous time-series of pH, taken from October 20th to November 9th 2011. The sites shown are: S4 (in blue), located 8.2 m offshore at a depth of 0.4 m, S18 (in green), located 31.6 m offshore at a depth of 3.7 m, and the long-term station (in red), located at 1.7 m depth over a bottom 3 meters deep. (A) Time series plot. (B) Histograms of frequencies of pH values during this period. (C) Power spectral densities. Darker straight lines in (C) depict the best fit power-law models between frequencies 1/8 h−1 and 3 h−1 obtained using linear least squares method. The vertical dashed and dotted lines in the spectra mark the diurnal and semi-diurnal frequencies respectively.
Figure 3.
Time series of decomposed variances.
Variance decomposition of temperature, dissolved O2 concentration and pH in the long-term time series station, obtained using a running window of two weeks. Left axes scale absolute variances (black lines), and right axes the relative contribution (in %) of each frequency range to total variance. To perform the spectral analyses the time-series need to be uninterrupted; thus short gaps in the signals resulted in the long gaps observed in the figure.
Figure 4.
Relative decomposed covariances vs. variances.
Relative decomposed covariances derived from cross-spectral analyses between transect sites and long-term station vs. relative decomposed variances derived from auto-spectral analyses of transect sites. (A) Temperature, (B) Dissolved oxygen concentration, (C) pH.
Table 1.
Variance components analyses (VCA).
Figure 5.
Variance decomposition along the transect.
Variance decomposition of temperature, dissolved O2 concentration and pH for each one of the deployments along the inshore/offshore transect. Left axes scale absolute variances (black lines), and right axes the relative contribution (in %) of each frequency range to total variance. Sites are ordered from shallowest and closest to shore (S1) to deepest and most offshore (S21). The asterisk marks the average values from the long-term water column station, positioned within the transect according to its depth.
Figure 6.
Amplitudes of oscillations by frequency ranges.
Amplitudes A are calculated from decomposed variances, assuming that all parameters have a normal distribution, as A = 4·√σ2. Vertical dash lines mark the position of the long-term time series station.
Figure 7.
Spectral slopes vs. distance from shore and depth.
Spectral slopes of temperature (A & B), dissolved O2 (C & D) and pH (E & F) vs. distance from shore (left column) and depth (right column) of each station along the transect. Dots with error bars represent the fitted slopes with 95% confidence intervals. Empty squares with error bars show the mean ± standard deviation of all the spectral slopes in the long-term station estimated for each period of deployment. Dashed horizontal lines mark the −5/3 typical of 3D isotropic turbulence spectra.
Table 2.
Amplitude of fluctuations at different frequency ranges.