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Ecological Indicators Lichens as Biological Indicators oLichens are very sensitive to air pollution and water pollution. Areas with healthy lichen populations are lower in air pollution and water pollution. Lichens can thus be used as reliable biological indicators of pollution. Lecanora conizaeoides is the most tolerant of all lichens to SO2, thus occurs in city also. Thus lichens are used as pollution monitors. oAt the same time, a dead lichen thalii are capable of absorbing F, heavy metals including SO2 and Pb. Lichens are also utilized for survey of long life nuclides (a distinct kind of atom or nucleus characterized by a specific number of protons and neutrons) like strontium (90Sr) and caesium (137Cs) released from nuclear explosions. Other organism as Biological Indicators Other flora and fauna are also biological indicators. For example: oBacteria: Bacteria E.Coli can indicate the water pollution. Bacteria like Pseudomonas, Clostridium, and Streptococcus are used in assessment (estimation) and prediction of changes in marine environment induced by human activities. Pseudomonas metabolizes oil and converts into harmless end product as CO2 and H2O. oAlgae: Algae such as Ulva is used in monitoring the water quality of estuaries. Some other algaes are used to monitor the Heavy metal pollution of water. Similarly, algae Chlorella is used to monitor toxic substances in water. Some algae indicate the soil pollution such as soil pesticides. oFungi: Fungi are also used to monitor of oil pollution, Scolecobasidium, Mortierella, Humicola, Verticillum are able to utilize waste oil. Ii) oHigher plants as ecological indicator: Some higher plants are also used a Ecological Indicators. Medicago sativa grow in low SO2. Rumex acetosella grow in acidic soil.