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In ecology, rarefaction is a technique to assess species richness from the results of sampling. Rarefaction allows the calculation of species richness for a given number of individual samples, based on the construction of so-called rarefaction curves. This curve is a plot of the number of species as a function of the number of samples.
Freshwater species are beginning to decline at twice the rate of species that live on land or in the ocean. This rapid loss has already placed 27% of 29,500 species dependent on fresh water on the IUCN Red List. [100] Global populations of freshwater fish are collapsing due to water pollution and overfishing. Migratory fish populations have ...
The Red List Index (sampled approach) (SRLI) has been developed in order to determine the threat status and also trends of lesser-known and less charismatic species groups. It is a collaboration between IUCN members and is coordinated through the Institute of Zoology (IoZ), the research division of the Zoological Society of London (ZSL).
Example Bjerrum plot: Change in carbonate system of seawater from ocean acidification.. A Bjerrum plot (named after Niels Bjerrum), sometimes also known as a Sillén diagram (after Lars Gunnar Sillén), or a Hägg diagram (after Gunnar Hägg) [1] is a graph of the concentrations of the different species of a polyprotic acid in a solution, as a function of pH, [2] when the solution is at ...
These papers utilized the compendium to track origination rates (the rate that new species appear or speciate) parallel to extinction rates in the context of geological stages or substages. [60] A review and re-analysis of Sepkoski's data by Bambach (2006) identified 18 distinct mass extinction intervals, including 4 large extinctions in the ...
A biotic index is a scale for showing the quality of an environment by indicating the types and abundances of organisms present in a representative sample of the environment. It is often used to assess the quality of water in marine and freshwater ecosystems.
A more complex model came up with different results, and in practicing conservation biology this can add more confusion to efforts to save a species from the extinction threshold. Transient dynamics, which are effects on the extinction threshold because of instability in either the metapopulation or environmental conditions, is also a large ...
As at July 2018, the OBIS website states that the system provides access to over 45 million observations of nearly 120,000 marine species (the reduced number of names cited being as a result of synonym resolution, i.e. reduction of taxa recorded under multiple names to a single accepted name), based on contributions from 500 institutions from ...