resource_length_defaults: Default weight-length parameters for the resource

In mizer: Dynamic Multi-Species Size Spectrum Modelling

Default weight-length parameters for the resource

Description

The resource is a composite of everything from bacteria to macrozooplankton, so it has no taxonomic length-weight relationship. The default is the geometric one that plankton ecology uses instead: the equivalent spherical diameter of an organism with the density of water,

w = \frac{\pi}{6} l^3,

with w in grams and l in centimetres. On a mizer size grid this puts the smallest resource sizes at a fraction of a micrometre and a milligram organism at about a millimetre, which is the right order for bacteria and copepods respectively.

Usage

resource_length_defaults

Format

A list with entries a and b.

Details

Note that this is a different convention from the one the species use: a fish of a given weight is longer than a sphere of the same weight, by a factor (a_{fish}/a_{resource})^{-1/3}, about 3.7 for the mizer default a = 0.01. That difference is real rather than an artefact — a 1 mg copepod really is shorter than a 1 mg fish larva — but it does mean the resource and the species sit on the plot at their own conventions.

See Also

resource_params()

mizer documentation built on Aug. 31, 2026, 5:08 p.m.