The diving can be challenging due to ocean swell and variable visibility but the reefs have plenty of sea life.
Normal webcams will have daily changes in sunlight and illumination angle and variable visibility due to shifting fume, often making their long-term time-lapse sequences appear distractingly "busy" and therefore less informative.
There's something surreal about the wind-shipped clouds of stinky steam, the alternating hot blasts and cold gusts, the variable visibility, the rich prismatic hues of the water, even the stately procession of global tourists on the boardwalk, whispering and hollering in a dozen languages.
Testing other sampling methods such as the use of 5×50 m or 5×30 m transects, distance sampling or others typically used for sessile organisms did not prove adequate for this region given the highly variable visibility of the region, the strong currents, and the overall patchiness of the reefs (i.e. patches of reef typically separated by patches of sand).
The VCMs and tongue protrusions are typically counted during repeated 2- to 5-min session blocks in an observation cage equipped with a mirror placed in the back to improve visibility, after a variable habituation period to the new environment (up to 1 h), in single freely moving animals without access to food.
Visibility into simultaneous variables (i.e. registers) is also limited and confined to within usually 1024 clock-cycle sample windows at a time.
(F) The contribution of each performance variable to visibility (W t)) based on (2).
A two-way mixed ANOVA with condition as the between subjects variable and visibility as the within participants variable showed a marginally significant main effect of condition, F 2, 40) = 3.10, p =.056, and a significant main effect of visibility, F 1, 40) = 6.47, p =.015.
Categorical variables (light, obstacle visibility, and distress calls) were coded with dummy variables, and continuous variables (date and time) were centered on their means to reduce the risks of collinearity.
Time series data sets of Visibility(t) and other variables were subjected to non linear decomposition using Empirical Mode Decomposition Method (EMD), enabling to obtain total cyclic and acyclic trend components embedded in all data sets.
