# Sсhorygin similarity coefficient for a series of samples

This online calculator allows you to use a table of species distrubution in samples to calculate the Schorygin coefficient (or commonality coefficient of specific abundance) in pairs for each pair in a series of samples.

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#### Timur

Created: 2023-11-14 16:07:26, Last updated: 2023-11-15 08:39:06

The calculator calculates the normalized values, i.e. the table can be filled in with the original species abundance data. You can read about the Schorygin index and how to estimate species abundance below the calculator.

#### Sсhorygin similarity coefficient for a series of samples

The row and column from which the matrix begins, with rows corresponding to species and columns to samples. The contents of the cells to the left and above are interpreted as the titles of the corresponding rows and columns. By default, the cell in the second column of the second row is considered to be the start of the data.

#### First data cell

The cell from which the matrix begins, with rows corresponding to species and columns to samples. The contents of cells to the left and above are interpreted as row and column headings of the corresponding rows and columns
The table should be copied from an Excel or csv file. Rows should correspond to species, columns to samples.
Digits after the decimal point: 2
The file is very large. Browser slowdown may occur during loading and creation.

### Sсhorygin Index

When studying different biocenoses (communities), the task of assessing their similarity often arises. There are a large number of indices based on the assessment of similarity of species composition that do not take into account the contribution of species. The Schorygin index is used as a measure of proximity when comparing objects with each other, and specific quantitative values of species are used for analysis, i.e. the ratio of the value of a species to the total value of all species. The index was proposed by the A.A. Schorygin for the ichthyological ecological problem of comparing the fish feeding spectrum as a coefficient of commonality of specific abundance1. Subsequently, this index was applied by B.A. Weistein to assess the community similarity2. To date, the index is known to be used to assess similarity in communities of different organisms: columbines, plant communities, and microbiota.

The Schorygin index value is calculated according to the formula.
$SHR=\sum min(p_i_1, p_i_2)$
where min(pi1,pi2) is the lower of the two relative abundances of the i-th species in the compared samples,
$p_i_j=n_i/N_j$
if nij is the abundance of the i-th species in the j-th sample, and
$N_j=\sum n_i_j$

Species participation can be assessed on the basis of projective cover, biomass, participation scores and others. Projective cover is mainly used for assessing ground cover plants, determining the area occupied by a species when it is projected onto the soil. Biomass, i.e. the mass of animals or plants that are present in a community, is more commonly used. For many species, their biomass in the volume of habitat is determined - this is common for aquatic species. There are various methods of biomass calculation designed specifically to account for above- and belowground plant biomass, microbial biomass, phyto- and zooplankton biomass. Often it is the biomass indicators that are determined in point equivalent.

1. The Schorygin A.A.: Nutrition, selectivity and food relationships of some Gobiidae of the Caspian Sea. // Zoological Journal. Vol. 18, Vyp. 1, p. 27-51.

2. Shitikov V.K., Rosenberg G.S., Zinchenko T.D. Quantitative hydroecology: methods of system identification. - Togliatti: IEWB RAS, 2003. - 463 p.

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