benthos (version 1.3-8)

iti: Infaunal Trophic Index (ITI)

Description

Computes the Infaunal Trophic Index (ITI) according to Gittenberger & van Loon (2013).

Usage

iti(.data = NULL, taxon, count, group = NULL)
iti_(.data = NULL, taxon, count, group = NULL)
has_iti(.data = NULL, taxon, group = NULL)
has_iti_(.data = NULL, taxon, group = NULL)

Value

numeric vector of length 1 containing the ITI

Arguments

.data

data in a data.frame, tibble, data.table, database etc.

taxon

species names

count

counts of individuals (numeric)

group

sensitivity groups I, II, III, or IV

Functions

• iti_(): version suitable for calling from a function (see package lazyeval).

• has_iti(): tests if an ITI sensitivity group is available for taxon (returns TRUE (available) or FALSE (unavailable))

• has_iti_(): version suitable for calling from a function (see package lazyeval).

Details

The Infaunal Trophic Index (ITI) is given by $$\mathrm{ITI} = 100 \sum_{i=1}^3 \frac{(4-i)}{3} p_i$$ where \(p_i\) is the proportion of species in class \(i\), where

• group I are suspension feeders (highest quality);

• group II are interface feeders

• group III are surface deposit feeders and

• group IV are subsurface deposit feeders (lowest quality).

References

Gittenberger A. and W. van Loon, 2013. Sensitivities of marine macrozoobenthos to environmental pressures in the Netherlands. Nederlandse Faunistische Mededelingen 41: 79-112.

Examples

     iti(taxon = c("Euspira pulchella", "Nephtys cirrosa"), count = c(4, 6))
     
 
   data(oosterschelde)
   has_iti(oosterschelde, TAXON)