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8.7.3.23. Diel Vertical Migration

(contributed by Darcy Taniguchi)

To enable diel vertical migration compile with DARWIN_ALLOW_DVM defined in DARWIN_OPTIONS.h. Runtime parameters are given at the bottom of this page.

During the day (when light is available), predators swim towards their preferred light level, PARpref. At night they swim toward the level with maximum food availability (total prey for each predator type).

Higher trophic levels of predators beyond those in the model are represented by an additional mortality term:

\[M^{\text{DVM}}_j = m^{\text{DVM-max}}_j \frac{c_j}{k^{\text{DVM}}_j+c_j} \left( 1 - f^{\text{mort}}_{\text{PAR}\,j} + f^{\text{mort}}_{\text{PAR}\,j} \frac{I} {\frac{k^{\text{DVM}}_j}{k^{\text{DVM}}_j+c_j} k^{\text{PAR-DVM}}_j + I} \right) c_j\]

where \(I\) is total PAR.

A fraction ExportFracDVM(j) of \(M^{\text{DVM}}_j\) goes to particulate organic matter, the rest to dissolved. Non-carbon elements are treated as for regular mortality.

Traits and parameters for diel vertical migration are shown in Table 8.67.

Table 8.67 Traits for diel vertical migration

trait	param	default	units	description
bioswimDVM	a_bioswimDVM	0.03	m/s	swimming speed for diel vertically migrating plankton (pos. upwards) [BSGS13]
	b_bioswimDVM	0
PARpref	a_PARpref	0.0046	μEin/m²/s	preferred PAR isolume for determining DVM; converted from W/m2 [BSGS13]
	b_PARpref	0
mortmaxDVM	a_mortmaxDVM	8.389E-5	1/s	maximum mortality rate related to PAR for DVM (ImaxHP [BSGS13] from [HBH97])
	b_mortmaxDVM	–0.16
ksatDVM	a_ksatDVM	1/a_R_NC	mmol C/m³	half saturation for DVM mortality (K_Z [BSGS13] from [SD10])
	b_ksatDVM	0
ksatPARDVM	a_ksatPARDVM	0.46	μEin/m²/s	half sat for light limitation for DVM (K_irr in [BSGS13])
	b_ksatPARDVM	0
fracPARmort	a_fracPARmort	0.9		fraction of mortality from light-dependent mortality [BSGS13]
	b_fracPARmort	0
ExportFracDVM	a_ExportFracDVM	0.5		fraction of light-dependent mortality from DVM to POM