Calculates the rate at which a predator of a particular species and size consumes biomass of each prey species and resource. The diet has units of grams/year.

getDiet(
  params,
  n = initialN(params),
  n_pp = initialNResource(params),
  n_other = initialNOther(params),
  proportion = TRUE
)

Arguments

params

A MizerParams object

n

A matrix of species abundances (species x size).

n_pp

A vector of the resource abundance by size

n_other

A list of abundances for other dynamical components of the ecosystem

proportion

If TRUE (default) the function returns the diet as a proportion of the total consumption rate. If FALSE it returns the consumption rate in grams per year.

Value

An array (predator species x predator size x (prey species + resource + other components) )

Details

Returns the rates \(D_{ij}(w)\) at which a predator of species \(i\) and size \(w\) consumes biomass from prey species \(j\). This is calculated from the predation kernel \(\phi_i(w, w_p)\), the search volume \(\gamma_i(w)\), the feeding level \(f_i(w)\), the species interaction matrix \(\theta_{ij}\) and the prey abundance density \(N_j(w_p)\): $$ D_{ij}(w, w_p) = (1-f_i(w)) \gamma_i(w) \theta_{ij} \int N_j(w_p) \phi_i(w, w_p) w_p dw_p. $$ The prey index \(j\) runs over all species and the resource. It also runs over any extra ecosystem components in your model for which you have defined an encounter rate function. This encounter rate is multiplied by \(1-f_i(w)\) to give the rate of consumption of biomass from these extra components.

This function performs the same integration as getEncounter() but does not aggregate over prey species, and multiplies by \(1-f_i(w)\) to get the consumed biomass rather than the available biomass. Outside the range of sizes for a predator species the returned rate is zero.

See also

plotDiet()

Other summary functions: getBiomass(), getGrowthCurves(), getN(), getSSB(), getYieldGear(), getYield()

Examples

diet <- getDiet(NS_params)
str(diet)
#>  num [1:12, 1:100, 1:13] 8.94e-18 6.86e-19 3.46e-18 1.75e-09 1.12e-17 ...
#>  - attr(*, "dimnames")=List of 3
#>   ..$ predator: chr [1:12] "Sprat" "Sandeel" "N.pout" "Herring" ...
#>   ..$ w       : chr [1:100] "0.001" "0.00119" "0.00142" "0.0017" ...
#>   ..$ prey    : chr [1:13] "Sprat" "Sandeel" "N.pout" "Herring" ...