Changes between Version 2 and Version 3 of EwEugPredictingConsumption
- Timestamp:
- 2010-11-21 23:32:03 (13 years ago)
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EwEugPredictingConsumption
v2 v3 1 1 == 3.5 Predicting consumption == 2 2 3 Ecosim bases the crucial assumption for prediction of consumption rates on a simple Lotka-Volterra or ‘mass action’ assumption, modified to consider ‘foraging arena’ properties. Following this, prey can be states that are or are not vulnerable to predation, for instance by hiding, (e.g., in crevices of coral reefs or inside a school) when not feeding, and only being subject to predation when having left their shelter to feed, (see Figure 3.3 in [[Vulnerabilities in Ecosim.htm|Vulnerabilities in Ecosim]]). In the original Ecosim formulations (Walters et al 1997, 2000) the consumption rate for a given predator ''i'' feeding on a prey ''j'' was thus predicted from,3 Ecosim bases the crucial assumption for prediction of consumption rates on a simple Lotka-Volterra or 'mass action' assumption, modified to consider 'foraging arena' properties. Following this, prey can be states that are or are not vulnerable to predation, for instance by hiding, (e.g., in crevices of coral reefs or inside a school) when not feeding, and only being subject to predation when having left their shelter to feed, (see Figure 3.3 in [EwEugVulnerabilitiesInEcosim Vulnerabilities in Ecosim]). In the original Ecosim formulations (Walters et al 1997, 2000) the consumption rate for a given predator ''i'' feeding on a prey ''j'' was thus predicted from, 4 4 5 5 [[Image(wiki:EwEugImages:08000026.png)]] ''' Eq. 51''' … … 7 7 where, ''a'',,''ij'',, is the effective search rate for predator ''i'' feeding on a prey ''j'', ''v'',,''ij'',, base vulnerability expressing the rate with which prey move between being vulnerable and not vulnerable, ''B,,i,,'' prey biomass, ''P,,j,,'' predator abundance (''N,,j,,'' for split pool groups discussed later, and ''B,,j,,'' for other groups). 8 8 9 The model as implemented argues that ‘top-down vs. bottom-up’ control is in fact a continuum, where low ''v''’s implies bottom-up and high v’s top-down control.9 The model as implemented argues that 'top-down vs. bottom-up' control is in fact a continuum, where low ''v'''s implies bottom-up and high v's top-down control. 10 10 11 11 Early experience with Ecosim has led to a more elaborate expression to describe the consumption: … … 17 17 [[Image(wiki:EwEugImages:08000028.png)]] '''Eq. 53''' 18 18 19 where ''h,,j,,'' is the predator handling time. The feeding time factors are discussed further in '' Foraging time and predation risk'' (see [[Foraging time and predation.htm|Eq. 65]]). A vulnerability setting of 1 will result in consumption being estimated using bottom-up conditions only through19 where ''h,,j,,'' is the predator handling time. The feeding time factors are discussed further in ''[EwEugForagingTimeAndPredationRisk Foraging time and predation risk]''. A vulnerability setting of 1 will result in consumption being estimated using bottom-up conditions only through 20 20 21 21 [[Image(wiki:EwEugImages:08000029.png)]]
