The substance, base, or nutrient on which, or the medium in which, a fixed organism is attached. Substrate types include soil, rocks, water, and leaf tissues.
(The degree in which the rocks and cobble are stuck in the stream. If you can pick up the rocks
and a cloud of material floats away embeddedness is normal.)
Greater than 75% of site area
50 to 75% of the site area.
25 to 50% of the site area.
Less than 25% of the site area.