12 Habitat 3D Complexity Effects on the Processes Structuring . . .
193
12.5.2 Predation Mortality
In several regions worldwide, post-settlement juveniles are known to be prey item for
various predators. Predation mortality may therefore drive differences in abundance
patterns of juveniles between habitats (Hindell et al. 2000; Beck et al. 2001; Heck
et al. 2003). Analyzing and quantifying interactions between predators, preys and
environmental factors is a quite complex task. For this purpose, the act of predation
may be broken into a series of sequential stages which can be treated separately:
prey detection and location by the predator, pursuit and attack, and capture (O’Brien
1979).
The predation act may be accomplished following three different broad classes
of tactics. The chase (or pursuit) predator actively searches a prey item and uses
its superiority in swimming speed for catching. In opposition, the sit-and-wait (or
ambush) predator counts rather on the surprise. It waits motionless camouflaged in
the environment until one prey enters its attack range, which is small. An intermediate
tactic is used by the stalk-attack predator that actively searches for prey item. Once
a prey is detected, stalk-attack predator approaches furtively until the prey is within
the attack range, which is medium, and makes a speed burst to capture it (Matsuda
et al. 1993; Horinouchi et al. 2009; Schultz and Kruschel 2010).
Habitat structural complexity interacts with the different stages of the predation
act, what affects predation success accordingly to the tactic. In highly complex habitats, habitat-elements may interfere with prey detection/location for active searchers
(chase and stalk-attack tactics), while for ambush predators, encounter rate depends
only on prey density and mobility. Moreover, mobility of predators (that are most
of the time larger than their prey) may be relatively more constrained by habitatelements than prey mobility. This decreases the predation success rate sharply for
chase predator (long distance pursuit) and slightly for stalk-attack predator (medium
distance pursuit). As ambush tactic involves almost no predator mobility, habitat
structural complexity should not facilitate prey escape. In some way, it may also
be considered that habitat-elements enhance furtive wait of ambush predator and
furtive approach of stalk-attack predator, for both tactics the use of camouflage has
a paramount role (see Box 4) (Lima and Dill 1990; Lima 1992, 1998).
193
12.5.2 Predation Mortality
In several regions worldwide, post-settlement juveniles are known to be prey item for
various predators. Predation mortality may therefore drive differences in abundance
patterns of juveniles between habitats (Hindell et al. 2000; Beck et al. 2001; Heck
et al. 2003). Analyzing and quantifying interactions between predators, preys and
environmental factors is a quite complex task. For this purpose, the act of predation
may be broken into a series of sequential stages which can be treated separately:
prey detection and location by the predator, pursuit and attack, and capture (O’Brien
1979).
The predation act may be accomplished following three different broad classes
of tactics. The chase (or pursuit) predator actively searches a prey item and uses
its superiority in swimming speed for catching. In opposition, the sit-and-wait (or
ambush) predator counts rather on the surprise. It waits motionless camouflaged in
the environment until one prey enters its attack range, which is small. An intermediate
tactic is used by the stalk-attack predator that actively searches for prey item. Once
a prey is detected, stalk-attack predator approaches furtively until the prey is within
the attack range, which is medium, and makes a speed burst to capture it (Matsuda
et al. 1993; Horinouchi et al. 2009; Schultz and Kruschel 2010).
Habitat structural complexity interacts with the different stages of the predation
act, what affects predation success accordingly to the tactic. In highly complex habitats, habitat-elements may interfere with prey detection/location for active searchers
(chase and stalk-attack tactics), while for ambush predators, encounter rate depends
only on prey density and mobility. Moreover, mobility of predators (that are most
of the time larger than their prey) may be relatively more constrained by habitatelements than prey mobility. This decreases the predation success rate sharply for
chase predator (long distance pursuit) and slightly for stalk-attack predator (medium
distance pursuit). As ambush tactic involves almost no predator mobility, habitat
structural complexity should not facilitate prey escape. In some way, it may also
be considered that habitat-elements enhance furtive wait of ambush predator and
furtive approach of stalk-attack predator, for both tactics the use of camouflage has
a paramount role (see Box 4) (Lima and Dill 1990; Lima 1992, 1998).