Figure 3

Comparison of FluorIS to a spectrometer.

Nighttime images taken at 5 m in Bocas Del Toro, Panama. (a) Images show an Orbicella franksi coral head in reflectance and fluorescence and the three color ellipses depict spectrometer measurement locations that were marked on the corals with a colored tack. In the plots, the solid and dashed lines depict the spectrometer and the camera measurements, respectively, with line colors corresponding to the tack color. All values are normalized to 1 at 685 nm, for comparison. Spatial differences in relative fluorescence between the three areas captured by the spectrometer closely match the camera measurements. (b) The wide field-of-view of FluorIS enables visualization and quantification of changes in fluorescence across colonies and reveals that the GFPs were only present in significant concentrations in the lower part of the Montastrea franksi colony shown, even though this difference is barely perceptible in the reflectance image. (c) Scatter plot comparing the ratio between green fluorescence intensity to red fluorescence intensity (GFP/CHL), for both the FluorIS system and the spectrometer, revealing highly correlated measurements (r = 0.898, with p < 0.001, Spearman rank correlation coefficient). Data points include all 105 measurements (3 locations for each of the 35 corals). The red line depicts the result of robust regression on the data, while the green line indicates a slope of 1.0.