Consumer‐food systems: why type I functional responses are exclusive to filter feeders

Abstract

The functional response of a consumer is the relationship between its consumption rate and the abundance of its food. A functional response is said to be of type I if consumption rate increases linearly with food abundance up to a threshold level at which it remains constant. According to conventional wisdom, such type I responses are more frequent among filter feeders than among other consumers. However, the validity of this claim has never been tested. We review 814 functional responses from 235 studies, thereby showing that type I responses are not only exceptionally frequent among filter feeders but that they have only been reported from these consumers. These findings can be understood by considering the conditions that a consumer must fulfil in order to show a type I response. First, the handling condition: the consumer must have a negligibly small handling time (i.e. the time needed for capturing and eating a food item), or it must be able to search for and to capture food while handling other food. Second, the satiation condition: unless its gut is completely filled and gut passage time is minimal, the consumer must search for food at a maximal rate with maximal effort. It thus has to spend much time on foraging (i.e. searching for food and handling it). Our functional response review suggests that only filter feeders sometimes meet both of these conditions. This suggestion is reasonable because filter feeders typically fulfil the handling condition and can meet the satiation condition without losing time, for they are, by contrast to non-filter feeders, able simultaneously to perform foraging and non-foraging activities, such as migration or reproduction.

Intake rates and the functional response in shorebirds (Charadriiformes) eating macro-invertebrates

“…Despite its importance for so many ecological studies, remarkably few functional responses have been described for foragers in the wild ( Jeschke, Kopp & Tollrian, 2004), even in such well-studied animals as birds. The present study was undertaken to try to construct a method by which the parameters of the functional response could be estimated so that they could be used in individual-based models (IBMs) -that are also behaviour-based -of shorebird (Charadriiformes) populations (Goss-Custard & Stillman, in press).…”

Emergence of Holling type III zooplankton functional response: Bringing together field evidence and mathematical modelling

“…Holling types I and II) for most herbivorous zooplankton species (e.g. DeMott, 1982;Hansen et al, 1990, Hirst andBunker, 2003;Jeschke et al, 2004). As a result, a rather strong opinion in the literature is that implementation of Holling III type in plankton models is biologically meaningless (DeMott 1982;Scheffer and De Boer 1996;Murdoch et al 1998).…”

“…This is especially true for modelling of eutrophic aquatic ecosystems where the choice of type of zooplankton functional response becomes crucial for predicting the outcome of grazing control of algae (Truscott and Brindley, 1994;Hernández-GarcÕa and López, 2004;Fussmann and Blasius, 2005). Implementation of an appropriate type of functional response for herbivorous zooplankton and, in particular, the correctness of the use of Holling type III (a sigmoid-shaped) response has provoked a vivid discussion in the literature (Rothhaupt and Lampert, 1992;Scheffer and De Boer, 1996;Murdoch et al, 1998;Jeschke et al, 2004;Sarnelle and Wilson, 2008). In this paper, I will consider the current problem from a different angle.…”

Effects of acute and chronic temperature changes on the functional responses of the dogfish Scyliorhinus canicula (Linnaeus, 1758) towards amphipod prey Echinogammarus marinus (Leach, 1815)

“…It is clear that species with a higher functional response (e.g., higher attack rates, lower handling times, higher asymptote) have a higher impact potential (Bollache et al 2008;Haddaway et al 2012;Dick et al 2013). Functional responses are categorised into: the Type I rectilinear response, usually only found in filter feeders where resource consumption is not limited by handling time (Jeschke et al 2004); the Type II inversely density dependent response with high prey consumption at low densities; and Type III sigmoidal, positively density dependent response whereupon prey have a low-density refuge (Oaten and Murdoch 1975). Within these response types, it is also possible to quantify the associated parameters of attack rate, handling time and maximum feeding rates (Juliano 2001;Dick et al 2013).…”