How do you work out total species cover?

Question

If you have a boulder covered in algae, what is the most accurate way of determining percentage cover for each species on it? Algae can be removed if necessary.

Answer 1

Grid it off with string, then estimate (with a rough count) each grid. The smaller the grid the more accurate, the more work.
Then you have different areas as well as a summed total.

Answer 2

There is really no complete accurate method, depending on the euipment you have. You would firstly work out the area for the whole boulder and then using a grid, made from the simplest of things, such as string. You can calculate how many squares contain what and therefore use your judgement to work out the percentage cover ;)