bioindikatror

BIOINDICATOR 

Bio-indicators are physiological, chemical, or behavioral changes that occur in organisms as a result of changes in the environment. Bryophytes of the genus Hypnum are particularly sensitive to pollutants, especially sulfur dioxide. As a result, most bryophytes are not found in cities and industrial areas. Mosses and liverworts, especially Hypnum cupressiforme and Homalotecium serieceum, have also been used as bio-indicators—one example was to monitor radioactive fallout from the Chernobyl nuclear reactor accident in 1986.

Bryophytes are green land plants which lack a vascular system and are simple both morphologically and anatomically. The growth potential in bryophytes is not as highly polarized as vascular plants. Bryophytes grow in a variety of habitats especially in moist places on soil, rocks, trunks and branches of trees and fallen log. They obtain nutrients directly from substances dissolved in ambient moisture. Some substances are probably absorbed directly from the substrate by diffusion through the cells of the gametophyte. Bryophytes are used as reliable indicators of air pollution (Le Blanc & Rao, 1975). They are exploited as bryometers instrument for measuring phytotoxic air pollution. They either independently or together with lichens can be valuable organisms in developing an index of atmospheric purity (IAP) which is based on the number, frequency-coverage and resistance factor of species. This index can provide a fair picture of the long-range effects of pollution in a given area (Rao, 1982). There are two categories of bryophytes in response to pollution:

•  which are very sensitive to pollution and show visible symptoms of injury even in the presence of minute quantities of pollutants. This serve as good indicators of the degree of pollution and also of the nature of pollutant.

• which have the capacity to absorb and retain pollutants in quantities much higher than those absorbed by other plant groups growing in the same habitat. These plants trap and prevent recycling of such pollutants in the ecosystem for different periods of time. Analysis of such plants gives a fair idea about the degree of metal pollution.

“They grow slowly, have a large-scale dependence upon the environment for their nutrition, and, differently from vascular plants, they do not shed parts during growth. Furthermore, their lack of cuticle or stoma means that the different contaminants are absorbed over the entire surface of the organism (Hale, 1969, 1983).” (Environmental pollution, 473).

Lichens as Bioindicators:
 
Though all lichens are sensitive to their environment, there is a ranking system for the most sensitive species to the least. The most affected by pollution are the cyanolichens which consist of Sticta, Peltigera, Pseudocyphellaria and Lobaria, these genera are very sensitive to nitrogen pollution, but are also the greatest nitrogen fixer. Next are the acidophytes; such as Usnea, Bryoria, and Hypogymnia genera, they prefer acidic substrates with low pH levels and low nitrogen levels, while the nitrophytes prefer high pH and nitrogen levels. Some examples of nitrophyte genera are Candelaria, Xanthoria, and Physia. There is also a group called the neurtophytes, some genera being Ramalina, Parmelia, and Melanelia; and you’ve guessed it: they’re the neutral group! The neutrophytes prefer a neutral pH environment.

Bryophytes as Bioindicators:
 
       
Species richness is a great way that bryophytes indicate healthy air quality; the more species the less presumed pollution (Govindapyari, et al 2010).
This tells us again that the air quality in our parking lots is good because wefts are the second most sensitive growth form and there were a comparable amount collected to short turfs, the least sensitive growth form. Premature gametophytes called protonemata are especially sensitive to pollution which makes it difficult for the genera Bryum, Leptobryum, and Funaria to survive because they depend on high reproduction rates to live (Govindapyari, et al. 2010). Despite all of this, bryophytes of any kind are great for an ecosystem because when they absorb pollutants they actually store the chemicals preventing them from being recycled back into the environment (Govindapyari, et al. 2010).

REFERENCES

Conti, M.e., and G. Cecchetti. “Biological Monitoring: Lichens as Bioindicators of Air Pollution          Assessment — a Review.” Environmental Pollution 114.3 (2001): 471-92. Web.
Govindapyari, H. “Bryophytes: Indicators and Monitoring Agents of Polluton.”NeBIO (n.d.): n. pag. Web. 20 Nov. 2015.

Charron, Joelle. Bryophytes and Lichens as Bioindicators: The Evergreen State College Bioblitz Project. Blog. Web. 9 mar. 2017.

Rao, D. N. 1982. Responses of bryophytes to air pollution. Pp. 445-471. In Bryophyte Ecology (ed A. J. E. Smith) Chapman and Hall. London and New York.