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Pollution-induced community tolerance
Pollution-Induced Community Tolerance (PICT) is an approach to measuring the response of pollution induced selective pressures on a community. It is an eco-toxicological tool that approaches community tolerance to pollution from a holistic stand point. Community Tolerance can increase in one of three ways: physical adaptations or phenotypic plasticity, selection of favorable genotypes, and the replacement of sensitive species by tolerant species in a community.
PICT differs from the Population Tolerance Approach to Community Tolerance in that it can be easily applied to any ecosystem and it is not critical to use a representative test organism, as with the Population Tolerance Approach.
==Community Tolerance==
Community tolerance can be used as indicator for determining if a toxicant has a disturbance on an exposed community for multiple types of organisms.〔Rotter, Stefanie, Frederic Sans-Piche, Georg Streck, Rolf Altenburger, and Mechthild Schmitt-Jansen. 17 January 2011. "Active Bio-monitoring of Contamination in Aquatic Systems—An in Situ Translocation Experiment Applying the PICT Concept." Elsevier. Aquatic Toxicology 101 (1): 228-236. http://www.sciencedirect.com/science/article/pii/S0166445X10004066.〕 Tolerance of a toxicant can increase by three ways; physiological adaptation also known as the phenotypic plasticity of an individual, tolerant genotypes selected within a population over time, and the replacement of species with more tolerant ones within a community.〔Blanck, Hans, S. A. Wangberg, and S. Molander. 1988. "Pollution-Induced Community Tolerance - A New Ecotoxicological Tool." Functional Testing of Aquatic Biota for Estimating Hazards of Chemicals. American Society for Testing and Materials. STP 988: 219-230. http://www.astm.org/DIGITAL_LIBRARY/STP/PAGES/STP26265S.htm.〕 Physiological adaptation, or phenotypic plasticity, is the ability of an individual organism to change its phenotype in response to changes in the environment.〔Miner, Benjamin G., Sonia E. Sultan, Steven G. Morgan, Dianna K. Padilla, and Rick A. Relyea. 12 December 2005. "Ecological Consequences of Phenotypic Plasticity." Elsevier. Trends in Ecology and Evolution. 20 (12): 685-692). http://bama.ua.edu/~rlearley/Miner_2005.pdf.〕 This can occur with huge variance between the type of organism and the type of the disturbance they experience. Natural selection that occurs over several generations causes an entire population to exhibit specific selection of genotypes.〔Darwin, Charles. 1859. "Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life." London: John Murray. 1st Edition. http://graphics8.nytimes.com/packages/images/nytint/docs/charles-darwin-on-the-origin-of-species/original.pdf〕 Overtime, tolerant genotypes can be selected over non tolerant ones and can cause a shift in a population’s genome.〔Blanck, Hans. 22 September 2010. “A Critical Review of Procedures and Approaches Used for Assessing Pollution-Induced Community Tolerance (PICT) in Biotic Communities, Human and Ecological Risk Assessment.” Human and Ecological Risk Assessment: An International Journal. 8 (5): 1003-1034. http://www.tandfonline.com/doi/pdf/10.1080/1080-700291905792.〕 Natural selection can also cause a replacement of less tolerant species with more tolerant species.〔 All of these aspects can alter a communities’ structure drastically and if a toxicant can be identified as the culprit, action can take place to prevent that toxicant from further accumulating .〔 PICT can be used for linkage between cause and effect of the toxicants due to the structure of a community that has survived the event also known as toxicant-induced succession (TIS).〔 Toxicant-Induced succession would be the development of more tolerant generations once a chemical was introduced into the environment.
There are two types of tolerances that can occur; multiple and co-tolerance. Multiple tolerances can elevate an individual’s ability to tolerate several toxicants present at once.〔 This means that depending on the type of chemicals present in the environment, the concentration, and the organisms that are affected could alter the environment in multiple different ways. Co tolerance is the ability of an organism to develop a tolerance to a certain toxicant in short term tests, and obtain that tolerance for other toxicants similar to the first.〔 Toxicant can cause co-tolerance for species if they’re closely related chemistry or have similar modes of action.〔 It can be difficult to determine with type of tolerance is occurring if there are multiple types of toxicants in a community because they could be acting simultaneously. Basically it is difficult to understand what exactly may be going on in a community without testing it with multiple ecotoxicological tools with long and short term toxicity tests.
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