Default weight-length parameters for the resource
Source:R/setResource.R
resource_length_defaults.RdThe 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.
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.