Aquatic environments have no known true specific indicator species, as do terrestrial habitats. However, aquatic environmental studies show that organisms may colonize a substrate dependent on factors such as size, position, exposure to current, water temperature, current speed, water depth, the presence of algal communities, or detritus. Certain aquatic insects such as the chironomid midges (Deptera, Chironomidae) and caddisflies (Trichoptera) are capable of colonizing immersed bodies; and with the known biology of a specific species of insect for a certain geographic area, time intervals of submersion can be established. (Author abstract)