* Bioassays. Test organisms are exposed to an environment and their response is measured. Typical organisms used in bioassays are certain species of plants, bacteria, fish, water fleas (Daphnia), and frogs.
* Community assessments. Also called biosurveys. An entire community of organisms is sampled to see what types of taxa remain. In aquatic ecosystems, these assessments often focus on invertebrates, algae, macrophytes (aquatic plants), fish, or amphibians. Rarely, other large vertebrates (reptiles, birds, and mammals) may be considered.
* Online biomonitoring devices. One example uses chemoreceptor cells of molluscs and similar animals to monitor their coastal and fresh water habitats. Different types of animals are used for this purpose either in the lab or in the field. The study of the opening and closing activity of clams valves is an example of one possible way to monitor in-situ' the quality of fresh and coastal waters.