What are Bioindicators? Uses and Types of Bioindicators The Science – How do Bioindicators Work? Traditional Bioassays Biotechnology-Based Bioassays Biotechnology and Bioindicators Current Research Areas in Bioindicators Sustainable Development and Bioindicators Bibliography

What are Bioindicators?

Bioindicators are organisms, such as lichens, birds, and bacteria, that are used to monitor the health of the environment. The organisms are monitored for changes that may indicate a problem within their ecosystem. The changes can be chemical, physiological, or behavioural.

Uses and Types of Bioindicators

Each organism within an ecosystem has the ability to report on the health of its environment. Bioindicators are used to:

• detect changes in the natural environment;
• monitor for the presence of pollution and its effect on the ecosystem in which the organism lives;
• monitor the progress of environmental cleanup; and,
• test substances, like drinking water, for the presence of contaminants.

Types of bioindicators and their uses include the following:

• Plant Indicators -- The presence or absence of certain plant or other vegetative life in an ecosystem can provide important clues about the health of the environment.
  
  Lichens, often found on rocks and tree trunks, are organisms consisting of both fungi and algae. They respond to environmental changes in forests, including changes in forest structure, 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.
  
  
• Animal Indicators -- An increase or decrease in an animal population may indicate damage to the ecosystem caused by pollution. For example, if pollution causes the depletion of important food sources, animal species dependent upon these food sources will also be reduced in number. In addition to monitoring the size and number of certain species, other mechanisms of animal indication include monitoring the concentration of toxins in animal tissues, or monitoring the rate at which deformities arise in animal populations.
  
  
• Microbial Indicators -- 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 like cadmium and benzene. These stress proteins can be used as an early warning system to detect low levels of pollution.

The Science – How do Bioindicators Work?

Specific physiological and behavioural changes in bioindicators are used to detect changes in environmental health. The specific changes differ from organism to organism. The use of organisms as bioindicators encompasses many areas of science. Wildlife conservation genetics is an example of how traditional approaches can be combined with emerging biotechnologies to improve accuracy, and to collect information not available through conventional methods. Wildlife conservation genetics combines traditional monitoring of wildlife populations, like racoons, with the scientific discipline of genetics, to gain information about the health of ecosystems.

Behavioural and population changes in a species can be observed by scientists, but physiological changes must be detected using special tests. Bioassays require samples from organisms to detect changes in the environment. These tests may be used to ensure drinking water safety or to measure river health. In the future, as research identifies new ways to use microbes, these uses will expand to include testing of soil and air.

Bioassays can be carried out in traditional ways and with new biotechnology-derived methods. These methods are outlined in more detail below.

Case Study: Testing Water
Bioluminescent bacteria are being used to test water for environmental toxins. If there are toxins present in the water, the cellular metabolism of the bacteria is inhibited or disrupted. This affects the quality or amount of light emitted by the bacteria. Unlike traditional tests, this one is very quick – taking from five to 30 minutes to complete. However, it only indicates the presence of a toxin and cannot identify the specific toxin causing the change in the organism.

Traditional Bioassays

In traditional bioassays, a bioindicator organism is introduced to environmental samples, such as soil or water, and researchers observe any changes that occur as a result of exposure. These methods are based primarily on observation to detect changes. Examples of traditional bioassay methods include the following:

• measurement of plant root growth in suspected polluted environments and comparison of the measured growth rate against normal root growth rates.
  
  
• exposure of microorganisms to an environment and observation of any changes in the organism related to toxin exposure, such as the presence of stress proteins produced when cells are exposed to harmful environmental conditions.

Biotechnology-Based Bioassays

• DNA Microarray Technology -- Using DNA microarray technology, environmental samples, such as water, are tested for the actual genetic material of an organism. This form of testing is used to detect dangerous microorganisms in the environment, such as E. Coli bacteria in water.
  
  DNA microarrays are stamp-sized glass or silicon microchips that are embedded with thousands of single-stranded DNA or RNA. In this case, the DNA is that of the microorganisms being tested for. The microarrays are manufactured using samples of microorganisms. If the same type of microorganisms are present in the water sample, the DNA or RNA on the array will react with the complementary DNA or RNA of the microorganism in the sample. This identifies its presence in the sample. When these tests are fully developed, it will take as little as four hours to test for microbial presence in environmental samples, such as drinking water and soil. Traditional chemical-based tests take an average of 48 hours.
  
  Learn More About DNA Microarrays
  
  
• Fluorescence In-Situ Hybridisation (FISH) -- This is a method for detecting the presence of particular genes in a sample. As a bioindicator, FISH can determine whether or not specific microorganisms are polluting certain areas. It does this by testing environmental samples for the presence of microbial genes. A fluorescent marker is attached to the DNA of the type of microorganism being testing. This marked DNA is now called a 'probe.' Environmental samples are fixed onto a slide, and the slide is exposed to the flourescent DNA probe. If the polluting microorganism is present on the slide, its DNA will bind to the fluorescent probe, causing the slide to glow with ultraviolet light. Detection of this ultraviolet light by a special fluorescent microscope demonstrates the presence of polluting microorganisms in the sample.

Biotechnology and Bioindicators

Currently, biotechnology-based tests are being used to identify changes in indicator species to gauge the presence of pollutants in the environment. Many of the tests being developed are designed to detect pollutants in rivers and drinking water sources. These tests will be faster and more accurate than conventional tests in detecting metabolic changes within microorganisms. Microbial bioindicators are also being researched to detect pollution in other substances, such as soil.

Current Research Areas in Bioindicators

Bioindicator research is currently focussed on developing more rapid and reliable tests for the presence of microorganisms in water and soil. Tests for drinking water are a special area of concern for both developed and developing countries. Although biotechnology-based tests currently exist for drinking water, there are still many pollutants that are not detectable. Scientists are busy trying to replace time consuming, traditional methods with newer, faster, and more reliable tests based on biotechnology.

Sustainable Development and Bioindicators

Bioindicators are a method of monitoring or detecting the negative impacts that industrial activity has on the environment. This information helps develop strategies that will prevent or lower such effects and make industry more sustainable. The role of bioindicators in sustainable development will help ensure that industry leaves the smallest footprint possible on the environment.

Bibliography

Environment Canada. "Testing the World's Drinking Water." Science and Technology Bulletin.www.ec.gc.ca/science/sandemar99/article6_e.html December 2001.

European Centre for Nature Conservation. "ELISA: Environmental Indicators for Sustainable Agriculture Final Report." European Centre for Nature Conservation. www.ecnc.nl/doc/projects/elisa.html December 2001.

European Initiative for Biotechnology Education (EIBE). "Biotechnology and the Environment." EIBE. www.rdg.ac.uk/EIBE/ENGLISH/U16.HTM December 2001.

Faculty of Medicine, University of Ottawa. "Centre For Research on Environmental Biotechnology (CREM) Brochure." University of Ottawa. www.uottawa.ca/academic/med/microbio/bmi/bmicrem.html. December 2001.

Jacobson, K. Bruce. "Biosensors and Other Medical and Environmental Probes." Oak Ridge National Laboratory. www.ornl.gov/ORNLReview/rev29_3/text/biosens.htm December 2001.

Simonson, Sara. "Lichens and Lichen-Feeding Moths as Bioindicators of Air Pollution in the Rocky Mountain Front Range." Colorado State University. www.colostate.edu/Depts/Ent...es/en570/papers_1996/simonson.html December 2001.

Stevens, Dr. Melita, Dr. Nicholas Ashbolt, and DR. David Cunliffe. "Microbial Indicators of Water Quality – An NHMRC Discussion Paper." National Health and Medical Research Council.

Veal, Duncan ed. "Microbial Indicators of River Health – 1997 Workshop." Australian Land and Water Resources Research and Development Corporation. January 1998.