Notes On Bioindicators With Definition Types And Examples
Bioindicators Definition and most common Examples
The bioindicator is defined as a species or a group of species whose function or the population can reveal the qualitative state or health of the environment. The most common bioindicators types or examples include Mosses, lichens, Microbial biomass, fungi, actinomycetes, as well as the population of some crustaceans, earthworms, nematodes, termites, ants, etc.
Copepods or other small water crustaceans present in many water bodies can be monitored as their biochemical, physiological, or behavioral changes may indicate a problem within their aquatic ecosystem.
Bioindicators some time called as a biological monitor or biomonitor provides quantitative information about the quality of the environment that surrounds it. Therefore, a good biomonitor will indicate the presence of the pollutant and can also be used to attempt to provide additional information on the amount and intensity of the exposure.
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Bioindicators Types With Examples
Different Bioindicators types and examples can be described from different angles.
Depending on the purpose of the bioindication, we can distinguish three main Bioindicators types
1. compliance indicators
2. Diagnostic indicators
3. Early warning indicators.
- Compliance Indicators: For example, attributes of the fish population are measured at the population, community or ecosystem level and focus on issues such as sustainability of the population or the community as a whole.
- Diagnostic and early warning indicators are measured at the individual or sub-organism (biomarker) level, with early warning indicators focusing on rapid and sensitive responses to environmental changes.
According to the different applications of bioindicators, we can distinguish three following Bioindicators types
1. Environmental indicator
These are the species that respond in a predictable way to environmental changes or disturbance (eg, sentinels, detectors, exploiters, accumulators, biological test organisms). An environmental indicator system is a set of indicators aimed at diagnosing the state of the environment in order to development of environmental policy.
2. Ecological indicator
These are species that are known to be sensitive to pollution, habitat fragmentation or other types of stresses. The indicator response is representative of the community.
3. Biodiversity indicator
This is the species richness in an ecosystem. It directly indicates the variety of species in a community. However, the definition has been broadened to “measurable parameters of biodiversity”, including e.g endemism, species richness, genetic parameters, landscape parameters & population-specific parameters.
Bioindicators Types With Examples In Detail
Following are the bioindicators types with Examples on the basis of the kind of organism being studied or observed.
Plant Indicators
Plants that are very common bioindicators examples include several Mosses or other bryophytes species, some conifers (sensitive to sulfur dioxide contamination) and lichens etc. Plants are used as very sensitive tools for the prediction and recognition of environmental stresses. In recent times, due to industrialization and urbanization, the problem of
water contamination and water pollution has intensified.
Marine plants provide valuable information for predicting the state of the ocean environment because they are immobile and quickly obtain balance with their natural environment. The presence or absence of certain plants or other specific plants provides a great deal of information about the health of the environment.
Lichens commonly found on tree trunks and rocks are made up of both algae and fungi. They respond to ecological changes in forests, including changes in forest structure, air quality and climate. Environmental stress can be indicated by the disappearance of lichen in forests, caused by changes such as increased levels of sulfur dioxide (SO2), sulfur pollutants and nitrogen (N2).
Wolffia globose is an important tool to show cadmium sensitivity and also used to indicate cadmium contamination. Changes in the diversity of phytoplankton species, including Euglena clastica, Phacus tortus, and Trachelon anas, indicate pollution of marine ecosystems
Animals As Bioindicators
Frogs and toads
An increase or decrease in an animal population may indicate damage caused to the ecosystem by pollution. For example, if pollution causes depletion of important food sources, animal species dependent on these food sources will also be reduced number. In addition to monitoring the size and number of certain species, other monitoring mechanisms animal indication includes monitoring the concentration of toxins in animal tissues or monitoring the rate at which malformations occur in the animal population.
Amphibians, especially anurans (frogs and toads), are increasingly used as bioindicators of contaminants accumulation in pollution studies. Anurans absorb toxic chemicals through their skin and larval gills membranes and are sensitive to alterations in their environment.
They have a low detoxification capacity pesticides that are absorbed, inhaled or ingested while eating contaminated food. This allows residues, especially organochlorine pesticides, to build up in their systems. They also have permeable skin that can easily absorb toxic chemicals, making it a model organism for assessing environmental effects factors that may cause the decline of the amphibian population.
These factors allow them to be used as bioindicator organisms to monitor changes in their habitats and in human-induced ecotoxicological studies increasing demands on the environment.
Knowledge and control of environmental agents are essential to maintain the health of the ecosystem. The anurans are increasingly used as bioindicator organisms in pollution studies, such as the study of the effects of agricultural pesticides on the environment.
Environmental assessment to study the environment in which they live is carried out by analyzing their abundance in the area as well as by assessing their locomotive capacity and any abnormal morphological changes, which are deformities and developmental abnormalities. Anurans and deformities could also suggest increased exposure to ultraviolet rays and parasites.
Pond-nesting anurans are particularly susceptible to pollution due to their complex life cycles, which could consist of terrestrial and aquatic life. During their embryonic, morphological, and behavioral development alterations are the most frequently cited effects in relation to chemical exposures. Effects of exposure can lead to shorter body length, lower body mass, and deformities of limbs or other organs. Slowdown development, late morphological changes and the small size of metamorphs lead to an increased risk of mortality and exposure to predation.
Macroinvertebrates
Marine invertebrates are the most common among the types and examples of Bioindicators in the aquatic ecosystem. Aquatic invertebrates live in the lower parts of the waters. They are also called benthic macroinvertebrates, or benthos (benthic = low, macro = large, invertebrate = animal without a backbone) and are good indicators of watershed health because they are easy to identify in a laboratory, often live more than a year, have reduced mobility and are integrators of environmental condition.
Macroinvertebrates are useful and practical indicators of the ecological health of water bodies and terrestrial ecosystems. The sensitivity of the range of macroinvertebrates found will allow an objective judgment of the condition to be made. Tolerance values are commonly used to assess water pollution and degradation in the environment, such as human activities (e.g. selective logging and forest fires) in tropical forests.
In Europe, a remote online biomonitoring system was designed in 2006. It is based on bivalve molluscs and real-time data exchange between a remote intelligent device in the field (capable of operating for more than 1 year without in-situ human intervention) and a data center designed to capture, process, and distribute web information derived from the data.
The technique concerns the behavior of bivalves, in particular the opening of the shells activity, changes in water quality. This technology has been used successfully for the assessment of water quality in various countries (France, Spain, Norway, Russia, Svalbard (Ny Alesund) and New Caledonia).
In the United States, the Environmental Protection Agency (EPA) has published rapid bioassessment protocols, in 1999, based on the measurement of macroinvertebrates, as well as periphyton and fish for water assessment 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 South African rivers.
Crustaceans
Crayfish have also been identified as suitable organism among various examples of bioindicators under appropriate conditions.
Microbial Indicators
Chemical pollutants
Microorganisms can be used as indicators of the health of aquatic or terrestrial ecosystems. Found in large quantities, microorganisms are easier to sample than other organisms. Some microorganisms produce new proteins, called stress proteins when exposed to contaminants such as cadmium and benzene. Those stress proteins can be used as an early warning system to detect changes in pollution levels.
In oil and gas exploration
Microbial prospecting (MPOG) is often used to identify potential areas for oil and gas occurrences. In many cases, oil and gas are known to seep to the surface because a reservoir of hydrocarbons usually leaks or has leaked to the surface by buoyancy forces overcoming sealing pressures.
These hydrocarbons can alter chemical and microbial occurrences present in soils near the surface or can be retrieved directly. Techniques used for MPOG include DNA analysis, counting single bugs after cultivation of a sample of soil in a hydrocarbon-based medium or by looking at the consumption of hydrocarbon gas in a cultured cell.
Phytoplankton or Microalgae as Bioindicators
Microalgae have gained attention in recent years for several reasons, including their greater sensitivity to pollutants than many other organisms. In addition, they are present in abundance in nature, they are an essential element composing many food webs, they are easy to grow and use in trials and there is little or none at all ethical issues related to their use.
Euglena gracilis is a mobile, freshwater, photosynthetic flagellate. Although Euglena is quite tolerant of acidity, it responds quickly and sensitively to environmental stresses such as heavy or inorganic metals and organic compounds. Typical responses are inhibition of movement and a change in orientation settings.
In addition, this organism is very easy to handle and cultivate, which makes it a very useful tool for ecotoxicological evaluations. A very useful feature of this organism is the gravitactic orientation, which is very sensitive to pollutants.
Gravoreceptors are altered by pollutants such as heavy metals and organic substances or inorganic compounds. Therefore, the presence of such substances is associated with a random movement of the cells in the water column. For short-term testing, the gravitactic orientation of E. gracilis is very sensitive.
Other species such as Paramecium biaurelia (see Paramecium aurelia) also use gravitactics
orientation.
An automatic bioassay is possible, using the Euglena gracilis flagellates in a device that measures their motility at different dilutions of the possibly polluted water sample, to determine the EC50 (the concentration of sample that affects 50 percent of organisms) and the G-value (lowest dilution factor at which the toxic effect can be measured).
Zooplanktons
Zooplankton are microscopic animals that live near the surface of the body of water. They are poor swimmers, relying instead on tides and currents as transport mechanisms. They feed
phytoplankton, bacterioplankton, or detritus (i.e. sea snow). Zooplankton are a food source for fish.
They also play an important role as bioindicators and help to assess the level of water pollution. In freshwater communities, along with fish, they are the main food complement to many other marine species.
Zooplanktons are believed to be a vital part in the indication of water quality, eutrophication, and production of a body of freshwater. Due to this, these are also on the top list of aquatic bioindicators types and examples. In order to determine the status of a freshwater body, it is necessary to measure seasonal variations and the presence of zooplankton.
Different varieties of species, diversity of biomass, and richness of zooplankton groups can be used to determine the strength of a biological system. The potential of zooplankton as a bioindicator species is bred on the grounds that their development and transport are subject to certain abiotic (e.g. temperature, salinity, stratification, and pollutants) and biotic parameters (e.g. limitation of food, predation, and competition)
Importance of Bioindicators in an Ecosystem
- Bioindicators can tell us about the cumulative effects of different pollutants in the ecosystem and how for a long time, a problem may have been present.
- Changes in animal populations, whether it is increasing or decreasing, can indicate pollution. For example, if pollution causes the depletion of a plant then the animal species that depend on that plant will experience a population decline. Conversely, overpopulation can be the opportunistic growth of one species in response to the loss of others species in an ecosystem.
On the other hand, stress-induced sublethal effects can manifest in animal physiology, morphology, and behavior of individuals long before responses are expressed and observed at the population level.
- The synergistic and antagonistic impacts of various pollutants on a specific population can be monitored and measured..
- Early diagnosis as well as the harmful effects of toxins on plants, as well as on humans, can be monitored.