Tag: option c: ecology and conservation

Lichens are used as the indicators of air pollution. These structures grow on tree bark and rocks. Air pollutants which are in the gaseous forms get dissolved in the rainwater, especially SO$ _2$ (sulphur dioxide) can damage lichens, and check them from growing. In places where lichens are not growing, it indicates that the air is heavily polluted with sulphur dioxide and other pollutants. 

Lichens are the symbiotic association of the algae and fungi. These absorb their mineral nutrients from the atmosphere rather than the soil. So, the contamination of the atmospheric air will result in their death. Lichens show specific sensitivity to sulphur dioxide and vanish from the area wherever it is present. So, these are called the indicators of the sulphur dioxide pollution.

Coliform bacteria are found in human faeces. Presence of such bacteria (E. coli is a member of the faecal coliform group) in surface water is a common indicator of faecal contamination. Sanitation program test detects the water for clearing contamination of faeces. Cholera vibrio, Salmonella typhi, Entamoeba histolytica are the pathogens found in the stagnant water or when the medical waste contaminates the water body. 

Lichens represent the symbiotic association between the algae and the fungi. These absorb their mineral nutrition from the moisture-laden air rather than the soil. So, the contamination of the air severely impairs their growth and they disappear from the areas that have a heavy concentration of sulphur pollutants in the air. Due to this sensitivity, these are considered to be the bioindicators of air pollution.

Lichen represents the symbiotic association between the algae and fungi. These absorb their mineral nutrients from the atmospheric moisture rather than the soil. So, when the air is contaminated with the sulphur oxides, they show extreme sensitivity to the toxic gas. Their existence is threatened by the oxides of sulphur in the air. The disappearance of the lichen, when exposed to the sulphur oxide, is used as bioindicator of the sulphur pollution in the air. 

Lichens are sensitive to the levels of SO$ _2$ in the atmosphere.

Lichens represent the symbiotic association between the algae and the fungi. These absorb their mineral nutrition from the moisture-laden air rather than the soil. So, the contamination of the air severely impairs their growth and they disappear from the areas that have a heavy concentration of sulphur pollutants in the air. Due to this sensitivity, these are considered to be the bioindicators of air pollution.

An indicator species is the one that either shows sensitivity or sustenance in the pollution. The lichens are the indicator species of air pollution because they cannot survive in the air polluted with the oxides of sulphur, released by industrial emissions. This is so because lichens absorb mineral nutrients from the moisture in the air and any contaminant in the air makes it difficult for them to perform the vital activities of life. Biston betularia is a peppered moth. Their population was dominated by white coloured varieties before the industrialization in England because the predators fed on black moths easily visible on the white coloured bark of the trees. Due to the industrialization, the pollution through emission released soot that was deposited on the white bark of the trees, due to which the white population shifted to black population as the white moths were now eaten by the predators.