I have already created the id and water mask rasters for my area of interest. 

But I do not understand very well what is stated on the web site:

"ArcGIS Spatial Analyst Block Statistics tool to compute how many high resolution cells occupy the lower resolution cells and obtain a proportion ranging from 0 to 1. This will work both for high resolution presence/absence data (classified as 0 or 1) or high resolution percent cover data (ranging from 0 to 100). In the latter case, if values range from 0 to 100, you may have to divide by 100 to rescale them to 0 to 1."

My questions are:

The input raster must be the high resolution reef data raster for the Block statistics tool?

Is the statistic that I must compute the sum of how many cells of reef data are within the neighborhood of the cell size of the low resolution raster?

Best regards and thank you in advantage, 

Diana Carrillo