Everything about Indicator Species totally explained
An
indicator species is any
biological species that defines a trait or
characteristic of the environment. For example, a species may delineate an
ecoregion or indicate an
environmental condition such as a
disease outbreak,
pollution, species competition or
climate change. Indicator species can be among the most sensitive species in a region, acting as an early warning to monitoring biologists.
Indicators of range
As an indicator species of a range, an environmental
ecoregion is typically defined. The
Chitymomma is an
Agave that regionally helps define the
Chihuahuan Desert of Northern
Mexico and the
SW United States. In
Central America, the
Guatemalan magnolia elevationally defines the limits of the
cloud forests of mountains.
For
paleoclimates, an extant species may be an indicator of a former climate condition. The
Discus macclintocki snail defines a former
Ice sheet region of the northern
Midwestern United States.
In some cases entire groups of fauna and flora may be an indicator of range.
Invasive species that enter an ecoregion advance at rates dependent on environmental conditions such as temperature, food supply and physical barriers. An example is the spread of the
Africanized bee as it enters southern
North America.
Specialized uses
Prospecting has been a minor use of indicator species.
Folklore may lead to recent attempts to use some species as an
indicator to search for specific
natural resources, such as
water. For finding
uranium,
botanical prospecting uses various plants, including
Astragalus,
Oenothera, and
Desert trumpet.
Indicators of environmental condition
Recent examples of
North American species affected by environmental changes are the
American Dipper and the
Gray Jay. The American Dipper is a bird that requires a habitat of clear, mountainous streams, and can be displaced by
siltation from land development, land-wasting runoff and forest fire runoff. The Gray Jay has become less common in southerly (warmer) parts of its range, apparently because its food supply has been affected by rising temperatures due to
global warming.
Many indicator species of the
ocean systems are
fish,
invertebrates,
periphyton,
macrophytes and specific species of ocean birds (like the
Atlantic Puffin).
Amphibians are also common indicator species, as they may have become repositories of
bioindicator chemicals, or of ecological conditions relating to
global warming,
air pollution chemicals, newly extant diseases (
fungus), or environmental pressure on the ecosystem, which affect the population numbers, and the quality of the individuals.
Lichens are indicators of air quality. They are particularly sensitive to
sulfur dioxide, a
gas emitted from exhaust and industrial fumes, and so are rarely found in large cities and towns or by roads. Filamentose, fruticose and foliose varieties are particularly sensitive. Their presence indicates air very low in sulfur dioxide.
Crustose, leprose and squamulose varieties are more tolerant of poor air.
Definitions
Lindenmayer
et al (2000) suggest 7 alternative defintions of indicator species:
- a species whose presence indicates the presence of a set of other species and whose absence indicates the lack of that entire set of species;
- a keystone species, which is a species whose addition to or loss from an ecosystem leads to major changes in abundance or occurrence of at least one other species
- a species whose presence indicates human-created abiotic conditions such as air or water pollution (often called a pollution indicator species
- a dominant species that provides much of the biomass or number of individuals in an area
- a species that indicates particular environmental conditions such as certain soil or rock types
- a species thought to be sensitive to and therefore to serve as an early warning indicator of environmental changes such as global warming or modified fire regimes (sometimes called a bio-indicator species
- a management indicator species, which is a species that reflects the effects of a disturbance regime or the efficacy of efforts to mitigate disturbance effects.
Types 1, 2, and 4 have been proposed as indicators of
biological diversity and types 3, 5, 6, and 7 as indicators of abiotic conditions and/or changes in ecological processes.
Further Information
Get more info on 'Indicator Species'.
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