Aquatic Ecosystems, HIPM Processes


Death is the permanent cessation of all biological functions that sustain a particular living organism. Phenomena which commonly bring about death include biological aging (senescence), predation, malnutrition, disease, suicide, murder and accidents or trauma resulting in terminal injury. Bodies of living organisms begin to decompose shortly after death.

-- Death (WP)

Models of aquatic ecologies do not typically model all deadly phenomena. However, some (eg, disease, malnutrition, predation, senescence) are clearly of interest.


  • Both Phytoplankton and Zooplankton can die because of Grazing by other organisms.

Data Structures

The death_exp process models first-order exponential death.

:type    "death"

:relates {
  :D { :generic_entities     [ de    ] }  ;; Detritus

  :E { :generic_entities     [ ee    ] }  ;; Environment

  :S { :generic_entities     [ pe ze ] }  ;; Species

:id      "death_exp"

:differential_eqs {
  :D.conc      "(1.0 - E.beta) * S.death_rate * S.conc"

  :S.conc      "-1 * 1 /         S.death_rate * S.conc"

The death_exp2 process models second-order exponential death (see Steee and Henderson 1992, Edwards 2001). This is often used to model both natural mortality as well as loss to grazers of a higher trophic level not explicitly modeled. This could, of course, be generalized. This is sometimes called a "closure term".

:id      "death_exp2"

:differential_eqs {
  ;; carbon concentration of Detritus and Species
  :D.conc      "-1             * S.death_rate * (S.conc * S.conc)"
  :S.conc      "(1.0 - E.beta) * S.death_rate * (S.conc * S.conc)"

See Data Structures for details.

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Topic revision: r8 - 21 Jul 2013, RichMorin
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