Bioindicator in the context of Behavioural

Trebouxia is a unicellular green alga. It is a photosynthetic organism that can exist in almost all habitats found in polar, tropical, and temperate regions. It can either exist in a symbiotic relationship with fungi in the form of lichen or it can survive independently as a free-living organism alone or in colonies. Trebouxia is the most common photobiont in extant lichens. It is a primary producer of marine, freshwater and terrestrial ecosystems. It uses carotenoids and chlorophyll a and b to harvest energy from the sun and provide nutrients to various animals and insects.

An ancestor of Trebouxia may have introduced photosynthesis into terrestrial habitats approximately 450 million years ago. It is also a bioindicator of habitat disturbances, freshwater quality, air pollution, carbon dioxide concentration, and climate change. Furthermore, its life cycle is complex and much research needs to be done to characterize it more completely. For decades, the presence of sexual reproduction was unknown. However, recent (2000s) molecular evidence of recombination and the observation of sexual fusions of gametes to form zygotes suggest that sexual reproduction occurs.

A biotic index is a scale for showing the quality of an environment by indicating the types and abundances of organisms present in a representative sample of the environment. It is often used to assess the quality of water in marine and freshwater ecosystems. Numerous biotic indices have been created to account for the indicator species found in each region of study. The concept of the biotic index was developed by Cherie Stephens in an effort to provide a simple measurement of stream pollution and its effects on the biology of the stream.

The grooved carpet shell, or Palourde clam, Ruditapes decussatus, or Venerupis decussatus, is a clam (bivalve mollusc) in the family Veneridae. It is distributed worldwide and is highly prized due to its ecological and economic interest. It has been proposed as a bioindicator.

This species is one of the most popular and profitable mollusks of lagoonal and coastal sites in the Mediterranean and adjoining Atlantic coast where it has been collected for generations for culinary use. It is consumed fresh and canned. Several dishes like Spaghetti alle vongole and the Portuguese Amêijoas à Bulhão Pato, make use of it.

Mysida is an order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch or "marsupium" in females. The fact that the larvae are reared in this pouch and are not free-swimming characterises the order. The mysid's head bears a pair of stalked eyes and two pairs of antennae. The thorax consists of eight segments each bearing branching limbs, the whole concealed beneath a protective carapace and the abdomen has six segments and usually further small limbs.

Mysids are found throughout the world in both shallow and deep marine waters where they can be benthic or pelagic, but they are also important in some fresh water and brackish ecosystems. Many benthic species make daily vertical migrations into higher parts of the water column. Mysids are filter feeders, omnivores that feed on algae, detritus and zooplankton. Some mysids are cultured in laboratories for experimental purposes and are used as a food source for other cultured marine organisms. They are sensitive to water pollution, so are sometimes used as bioindicators to monitor water quality.

Humans have made multiple uses of molluscs, including as food, and they feature in art and in literature.

Useful interactions with molluscs range from their use as food, where species as diverse as snails and squid are eaten in many countries, to the employment of molluscs as shell money and to make dyestuffs and musical instruments, for personal adornment with seashells, pearls, or mother-of-pearl, as items to be collected, as fictionalised sea monsters, and as raw materials for craft items such as Sailor's Valentines. Some bivalves are used as bioindicators to monitor the health of marine and freshwater environments.