An indicator species is any biological species that defines a trait or characteristic of the environment. For an 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, and sometimes act as an early warning to monitoring biologists.
Animal species have been used for indicators for decades to collect information about the many regions. Vertebrate are used as population trends and habitat for other species. Species identification is very important for the conservation of biodiversity. Approximately 1.9 million species have been identified, but there are 3 to 100 million species. Some of them haven't been studied. There are new species every year that are unknown and are still being discovered each year. Indicator species serve as measured environmental conditions.
Some indicator species are also known as sentinel species, i.e. species which are ideal for biomonitoring. Organisms such as oysters, clams, and cockles have been extensively used as biomonitors in marine and estuarine environments. For example, the Mussel Watch Programme is a world-wide project using mussels to assess environmental impacts on coastal waters. Their well-documented feeding habits, stationary condition and their role as integral parts of the food chain are some of the main reasons why oysters and mussels are widely used biomonitors. A considerable amount of contaminant concentrations are found in the surficial sediments (i.e. the finer-grained particulate matter, usually muds, silts or clays) of marine and estuarine environments. A major physical process governing the transport of fine particulate material and associated particle-bound contaminants in estuarine environments is resuspension. Strong winds create surface waves, which, in shallow water (<5m), project energy to the water-sediment interface resulting in resuspension of fine sediment from the upper layers of the estuary floor. Once in suspension, fine material may be transported by tidal currents to other parts of the estuary and possibly to the ocean during multiple reworking phases. Mussels and oysters are filter feeders and therefore uptake is by ingestion of particulates in the water column. Sediment resuspension is thus very important in the bioaccumulation process which aids the evaluation of possible adverse biological effects of sedimentary contaminants in marine and estuarine environments.
Video Indicator species
Examples
- Stoneflies: indicate a high oxygen content in water. They spend the majority of their lives as nymphs. Many species require a high concentration of dissolved oxygen and are found in clean, swift streams with gravel or stone bottom.
- Canary: miners used to use the canary bird like an indicator for the concentration of carbon monoxide in the air. As canaries are more sensitive to carbon monoxide than humans, they were used to detect the lethal gas. If a canary lost consciousness, the miners knew that they must immediately evacuate the mine.
- Mosses: some moss species indicate acidic soil
- Greasewood: indicates saline soil. It only grows on dry, sunny flat valley bottoms of ephemeral stream channels. It is one of the dominant plants throughout Great Basin and Mojave Desert. In high saline areas, greasewood grows in nearly pure stands.
- Lichens: some species indicate low air pollution. As a group, they have a worldwide distribution and grow almost on any surface, for example soil, bark, roof tiles or stone. Because lichens get all their nutrients from the air, many species are very sensitive to air pollution.
- Fungi: can indicate old-growth forests where an abundance of coarse woody debris exists. As wood-decay fungi are the basis of saprotrophic species communities in forest ecosystems, and sensitive to intensive forest management. Their diversity correlates well with insect diversity, and indicates continuum of dead wood at the stand or landscape level. Bracket fungi, in particular, are used as indicators of conservation value in forest inventories, particularly in Nordic countries and Taiga - see example of indicator use in Finland.
- Mollusca: numerous bivalve molluscs indicate the water pollution status. Mollusca, usually bivalve molluscs, are used as bioindicators to monitor the health of both saltwater and freshwater environments. Their population status, structure, physiology, behaviour and even their content of certain elements or compounds can reveal the contamination status of any aquatic ecosystem. They are extremely useful as they are sessile (meaning they do not move around) and they are closely representative of the environment from which they are sampled or placed in (caging) due to bioaccumulation occurring quickly. One of the most famous project in that field is the Mussel Watch Programme but today they are used worldwide for that purpose (Ecotoxicology).
- Tubifex worms: indicate non-potable, stagnant, oxygen-poor water. The worms can survive with little oxygen by waving hemoglobin-rich tail ends to exploit all available oxygen, and can exchange carbon dioxide and oxygen through their skin, in a similar manner to frogs.
Maps Indicator species
No longer believed to be an indicator species
- Agave lechuguilla: a species of agave previously believed to be found only in the Chihuahuan Desert, and as such falsely believed to be an indication of the extent of the desert. Although many sources claim so, it is not an indicator species because it can also be found in the Sonoran and Coahuil deserts too.
Definitions
Lindenmayer et al. suggest seven alternative definitions 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 bioindicator 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.
Type 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.
See also
- Animal sentinel
- Bioindicator
- Biological integrity
- Botanical prospecting for uranium
- Ecological indicator
- Environmental indicator
- Indicator plant
- Indicator value
References
External links
- Indicator Plant/Indicator Animal species marietta.edu--"The Tropical Rain Forest"
- Biological Indicators of Watershed Health: Biological Integrity - US Environmental Protection Agency
- Online biomonitoring of water quality by a 24/7 record of various bivalve molluscs' behavior and physiology worldwide (biological rhythms, growth rate, spawning, daily behavior): the MolluSCAN eye project
- Canary Database: Index
- http://www.britannica.com/EBchecked/topic/286117/indicator-species
- "indicator species". Encyclopædia Britannica. Encyclopædia Britannica Online. Retrieved 11 June 2013.
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