A bioindicator is any species (an "indicator species") or group of species whose function, population, or status can reveal the qualitative status of the environment. For example, copepods and other small water crustaceans that are present in many water bodies can be monitored for changes (biochemical, physiological, or behavioural) that may indicate a problem within their ecosystem. Bioindicators can tell us about the cumulative effects of different pollutants in the ecosystem and about how long a problem may have been present, which physical and chemical testing cannot.
A biological monitor, or biomonitor, can be defined as an organism that provides quantitative information on the quality of the environment around it. Therefore, a good biomonitor will indicate the presence of the pollutant and also attempt to provide additional information about the amount and intensity of the exposure.
A bioindicator is an organism or biological response that reveals the presence of the pollutants by the occurrence of typical symptoms or measurable responses, and is therefore more qualitative. These organisms (or communities of organisms) deliver information on alterations in the environment or the quantity of environmental pollutants by changing in one of the following ways: physiologically, chemically or behaviourally. The information can be deduced through the study of:
- their content of certain elements or compounds
- their morphological or cellular structure
- metabolic biochemical processes
- population structure(s)
The importance and relevance of biomonitors, rather than man-made equipment, is justified by the statement: "There is no better indicator of the status of a species or a system than a species or system itself." Bioindicators have the ability to indicate indirect biotic effects of pollutants when many physical or chemical measurements cannot. Through bioindicators, scientists need to observe only the single indicating species to check on the environment rather than monitor the whole community.
The use of a biomonitor is described as biological monitoring (abbr. biomonitoring) and is the use of the properties of an organism to obtain information on certain aspects of the biosphere. Biomonitoring of air pollutants can be passive or active. Passive methods observe plants growing naturally within the area of interest. Active methods detect the presence of air pollutants by placing test plants of known response and genotype into the study area.
The presence or absence of certain plant or other vegetative life in an ecosystem can provide important clues about the health of the environment: environmental preservation.
Lichens are organisms comprising both fungi and algae. They are found on rocks and tree trunks, and they respond to environmental changes in forests, including changes in forest structure – conservation biology, air quality, and climate. The disappearance of lichens in a forest may indicate environmental stresses, such as high levels of sulfur dioxide, sulfur-based pollutants, and nitrogen oxides. The composition and total biomass of algal species in aquatic systems serves as an important metric for organic water pollution and nutrient loading such as nitrogen and phosphorus. There are genetically engineered organisms that can respond to toxicity levels in the environment; e.g., a type of genetically engineered grass that grows a different colour if there are toxins in the soil.[clarification needed]
Animal indicators and toxins
Changes in animal populations, whether increases or decreases, can indicate pollution. For example, if pollution causes depletion of a plant, animal species that depend on that plant will experience population decline. Conversely, overpopulation may be opportunistic growth of a species in response to loss of other species in an ecosystem.
Pollution can be monitored by measuring any of several variables in animals: the concentration of toxins in animal tissues; the rate at which deformities arise in animal populations; behaviour in the field or in the laboratory.
Frogs and toads as bioindicators
Amphibians, particularly anurans which consist of frogs and toads, are increasingly used as bioindicators of contaminant accumulation in pollution studies. Anurans absorb toxic chemicals through their skin and larval gill membranes and are sensitive to alterations in their environment. They have a poor ability to detoxify pesticides that are absorbed, inhaled, or ingested by eating contaminated food. This allows residues, especially of organochlorine pesticides, to accumulate in their systems. They also have permeable skin that can easily absorb toxic chemicals, making them a model organism for assessing the effects of environmental factors that may cause the declines of amphibian population. These factors allow them to be used as bioindicator organisms to follow changes in their habitats and in ecotoxicological studies due to humans increasing demands on the environment.
Knowledge and control of environmental agents is essential for sustaining the health of ecosystems. Anurans are increasingly utilized as bioindicator organisms in pollution studies such as studying the effects of agricultural pesticides on the environment. Environmental assessment to study the environment in which they live in is performed by analyzing their abundance in the area as well as assessing their locomotive ability and any abnormal morphological changes, which are deformities and abnormalities in development. Decline of anurans and malformations could also suggest increased exposure to ultra-violet light and parasites.
Pond breeding anurans are especially sensitive to pollution because of their complex life cycles, which could consist of terrestrial and aquatic living. During the embryonic development of them, morphological and behavioral alterations are the effects most frequently cited in connection with chemical exposures. Effects of exposure may result in shorter body length, lower body mass and malformations of limbs or other organs. The slow development, late morphological change, and small metamorph size result in increased risk of mortality and exposure to predation.
Microorganisms can be used as indicators of aquatic or terrestrial ecosystem health. Found in large quantities, microorganisms are easier to sample than other organisms. Some microorganisms will produce new proteins, called stress proteins, when exposed to contaminants such as cadmium and benzene. These stress proteins can be used as an early warning system to detect changes in levels of pollution.
In oil and gas exploration
Microbial Prospecting for oil and gas (MPOG) is often used to identify prospective areas for oil and gas occurrences. In many cases oil and gas is known to seep toward the surface as a hydrocarbon reservoir will usually leak or have leaked towards the surface through buoyancy forces overcoming sealing pressures. These hydrocarbons can alter the chemical and microbial occurrences found in the near surface soils or can be picked up directly. Techniques used for MPOG include DNA analysis, simple bug counts after culturing a soil sample in a hydrocarbon based medium or by looking at the consumption of hydrocarbon gases in a culture cell.
Microalgae in water quality
Microalgae have gained attention in the recent years due to several reasons because of their greater sensitivity to pollutants than many other organisms. In addition they occur abundantly in nature, they are an essential component in very many food webs, they are easy to culture and to use in assays and there are few if any ethical issues involved in their use.
Euglena gracilis is a motile freshwater photosynthetic flagellate. Although Euglena is rather tolerant to acidity, it responds rapidly and sensitively to environmental stresses such as heavy metals or inorganic and organic compounds. Typical responses are the inhibition of movement and the change of orientation parameters. Moreover, this organism is very easy to handle and grows, making it a very useful tool for eco-toxicological assessments. One very useful particularity of this organism is the gravitactic orientation, which is very sensitive to pollutants. The gravireceptors are impaired by pollutants such as heavy metals and organic or inorganic compounds. Therefore, the presence of such substances is associated with random movement of the cells in the water column. For short term tests, gravitactic orientation of E. gracilis is very sensitive. Other species such as Paramecium biaurelia (see Paramecium aurelia) also use gravitactic orientation.
Automatic bioassay is possible, using the flagellate Euglena gracilis in a device which measures their motility at different dilutions of the possibly polluted water sample, to determine the EC50(the concentration of sample which affects 50 percent of organisms) and the G-value (lowest dilution factor at which no-significant toxic affect can be measured).
Macroinvertebrates are useful and convenient indicators of the ecological health of a water body. They are almost always present, and are easy to sample and identify. The sensitivity of the range of macroinvertebrates found will enable an objective judgement of the ecological condition to be made. Tolerance values are commonly used to assess water pollution.
In Europe, a remote online biomonitoring system was designed in 2006. It is based on bivalve molluscs and the exchange of real time data between a remote intelligent device in the field (able to work for more than 1 year without in-situ human intervention) and a data centre designed to capture, process and distribute on the web information derived from the data. The technique relates bivalve behaviour, specifically shell gaping activity, to water quality changes. This technology has been successfully used for the assessment of coastal water quality in various countries (France, Spain, Norway, Russia, Svalbard (Ny Alesund) and New Caledonia).
In the United States, the Environmental Protection Agency (EPA) published Rapid Bioassessment Protocols, in 1999, based on measuring macroinvertebrates, as well as periphyton and fish for assessment of water quality.
In South Africa, the Southern African Scoring System (SASS) method is based on benthic macroinvertebrates, and is used for the assessment of water quality in Southern African rivers. The SASS aquatic biomonitoring tool has been refined over the past 30 years and is now on the fifth version (SASS5) in accordance with the ISO/IEC 17025 protocol. The SASS5 method is used by the South African Department of Water Affairs as a standard method for River Health Assessment, which feeds the national River Health Programme and the national Rivers Database.
The imposex phenomenon in the dog conch species of sea snail leads to the abnormal development of a penis in females, but does not cause sterility. Because of this, the species has been suggested as a good indicator of pollution with organic man-made tin compounds in Malaysian ports.
- Barbour, M.T.; Gerritsen, J.; Stribling, J.B. (1999). Rapid Bioassessment Protocols for Use in Streams and Wadeable Rivers: Periphyton, Benthic Macroinvertebrates and Fish, Second Edition (Report). Washington, D.C.: U.S. Environmental Protection Agency (EPA). EPA 841-B-99-002.
- Karr, James R. (1981). "Assessment of biotic integrity using fish communities". Fisheries. 6 (6): 21–27. ISSN 1548-8446. doi:10.1577/1548-8446(1981)006<0021:AOBIUF>2.0.CO;2.
- NCSU Water Quality Group. "Biomonitoring". WATERSHEDSS: A Decision Support System for Nonpoint Source Pollution Control. Raleigh, NC: North Carolina State University. Retrieved 2016-07-31.
- Tingey, David T. (1989). "Bio indicators in Air Pollution Research – Applications and Constraints". Biologic Markers of Air-Pollution Stress and Damage in Forests. Washington, DC: National Academies Press: 73–80. ISBN 978-0-309-07833-7.
- "Bioindicators". Science Learning Hub. The University of Waikato, New Zealand. 2015-02-10.
- Government of Canada. "Biobasics: bio-indicatorrs". Archived from the original on October 3, 2011.
- Chessman, Bruce (2003). SIGNAL 2 – A Scoring System for Macro-invertebrate ('Water Bugs') in Australian Rivers (PDF). Monitoring River Heath Initiative Technical Report no. 31. Canberra: Commonwealth of Australia, Department of the Environment and Heritage. ISBN 0642548978.
- Halper, Mark (2006-12-03). "Saving Lives And Limbs With a Weed". Time. Retrieved 2016-06-22.
- Grabarkiewicz, Jeffrey D.; Davis, Wayne S. (November 2008). An Introduction to Freshwater Fishes As Biological Indicators (Report). EPA. p. 1. EPA-260-R-08-016.
- Université Bordeaux et al. MolluSCAN eye project
- Simon, E., Braun, M. & Tóthmérész, B. Water Air Soil Pollut (2010) 209: 467. doi:10.1007/s11270-009-0214-6
- Lambert, M. R. K. (1997-01-01). "Environmental Effects of Heavy Spillage from a Destroyed Pesticide Store near Hargeisa (Somaliland) Assessed During the Dry Season, Using Reptiles and Amphibians as Bioindicators". Archives of Environmental Contamination and Toxicology. 32 (1): 80–93. ISSN 0090-4341. doi:10.1007/s002449900158.
- Center for Global Environmental Education. What are the frogs trying to tell us? OR Malformed Amphibians. Retrieved from http://cgee.hamline.edu/frogs/archives/corner3.html
- Silvia, Carmem; Rosa, Larissa; Souza, Raphael Bastao de; Giuliano, Danielli; Thiago, Guilherme (2011). Bioindicators and Biomarkers in the Assessment of Soil Toxicity. InTech. doi:10.5772/25042.
- Venturino, A., Rosenbaum, E., De Castro, A. C., Anguiano, O. L., Gauna, L., De Schroeder, T. F., & De D'Angelo, A. P. (2003). Biomarkers of effect in toads and frogs. Biomarkers, 8(3/4), 167.
- Rasheed, M. A.; et al. (2015). "Application of geo-microbial prospecting method for finding oil and gas reservoirs". Frontiers of Earth Science. 9 (1): 40–50. doi:10.1007/s11707-014-0448-5.
- Azizullah, Azizullah; Murad, Waheed; Muhammad, Adnan; Waheed, Ullah; Häder, Donat-Peter (2013). "Gravitactic orientation of Euglena gracilis - a sensitive endpoint for ecotoxicological assessment of water pollutants". Frontiers in Environmental Science. 1 (4): 1–4. doi:10.3389/fenvs.2013.00004.
- Tahedl, Harald; Donat-Peter, Haeder (2001). "Automated Biomonitoring Using Real Time Movement Analysis of Euglena gracilis". Ecotoxicology and Environmental Safety. 48 (2): 161–169. PMID 11161690. doi:10.1006/eesa.2000.2004.
- Hemmersbach, Ruth; Simon, Anja; Waßer, Kai; Hauslage, Jens; Christianen, Peter C.M.; Albers, Peter W.; Lebert, Michael; Richter, Peter; Alt, Wolfgang; Anken, Ralf (2014). "Impact of a High Magnetic Field on the Orientation of Gravitactic Unicellular Organisms—A Critical Consideration about the Application of Magnetic Fields to Mimic Functional Weightlessness". Astrobiology. 14 (3): 205–215. PMC . PMID 24621307. doi:10.1089/ast.2013.1085.
- Tahedl, Harald; Hader, Donat-Peter (1999). "Fast examination of water quality using the automatic biotest ECOTOX based on the movement behavior of a freshwater flagellate". Water Research. 33 (2): 426–432. doi:10.1016/s0043-1354(98)00224-3.
- Ahmed, Hoda; Häder, Donat-Peter (2011). "Monitoring of Waste Water Samples Using the ECOTOX Biosystem and the Flagellate Alga Euglena gracilis". Water, Air, & Soil Pollution. 216: 547–560. doi:10.1007/s11270-010-0552-4.
- Gooderham, John; Tsyrlin, Edward (2002). The Waterbug Book: A Guide to the Freshwater Macroinvertebrates of Temperate Australia. Collingswood, Victoria: CSIRO Publishing. ISBN 0 643 06668 3.
- Chang, F.C. & J.E. Lawrence (2014). "Tolerance Values of Benthic Macroinvertebrates for Stream Biomonitoring: Assessment of Assumptions Underlying Scoring Systems Worldwide". Environmental Monitoring and Assessment. 186 (4): 2135–2149. PMID 24214297. doi:10.1007/s10661-013-3523-6.
- "Biological Stream Monitoring". Izaak Walton League of America. Archived from the original on 2015-04-21. Retrieved 2010-08-14.
- Volunteer Stream Monitoring: A Methods Manual (PDF) (Report). EPA. November 1997. EPA 841-B-97-003.
- Dickens, CWS; Graham, PM (2002). "The Southern Africa Scoring System (SASS) version 5 rapid bioassessment for rivers" (PDF). African Journal of Aquatic Science. 27: 1–10. doi:10.2989/16085914.2002.9626569.
- Cob, Z. C.; Arshad, A.; Bujang, J. S.; Ghaffar, M. A. (2011). "Description and evaluation of imposex in Strombus canarium Linnaeus, 1758 (Gastropoda, Strombidae): a potential bio-indicator of tributyltin pollution". Environmental Monitoring and Assessment. 178 (1–4): 393–400. PMID 20824325. doi:10.1007/s10661-010-1698-7.
- Environmental Biomarkers Initiative at Pacific Northwest National Laboratory - U.S. Department of Energy, Richland, WA
- Volunteer Monitoring Program - U.S. EPA
- The National River Health Programme - South Africa
- Pyxine cocoes Nyl. - A Foliose Lichen as a Potential Bio-indicator/Bio-monitor of Air Pollution in Philippines: An Update by Isidro A. T. Savillo