12 Habitat 3D Complexity Effects on the Processes Structuring . . .
191
12.4 Broad Classes of Ecological Processes and Spatial Scales
Evolutionary processes have selected functional and behavioral traits that are adapted
to specific environments. The selected pool of functional and behavioral traits is
filtered by environments through ecological processes what governs distribution patterns of species within seascape (Morris 2011). Ecological processes may be studied
according to three broad classes: (i) differential settlement/recruitment, (ii) differential mortality and (iii) active choice of the favored habitat. None of them is necessary
exclusive, difference in composition and abundance of species between habitats
could be the result of their combination (Olabarria et al. 2002; Morris 2003, 2011).
Moreover, these processes may act at distinct spatial scales.
12.4.1 Differential Settlement Affected by Environmental
Conditions at Multiple Spatial Scales
Most of demersal fish species inhabiting temperate coastal waters worldwide experience a complex life cycle. Usually, it is divided into a vagrant planktonic phase
(corresponding to the stages egg and larvae) and a relatively sedentary benthic phase
(from the stage post-settlers to adult) (Di Franco et al. 2011). During the planktonic phase, eggs and larvae disperse depending mainly on oceanographic patterns.
The metamorphosis from larvae to juvenile triggers the transition from planktonic to
benthic environment that is called “settlement”. Due to oceanographic patterns (as
currents, water temperature etc), juveniles that disperse may settle in greater number
to one locality than to others (Di Franco et al. 2011).
In coastal environments, the seascape is usually heterogeneous at a fine spatial
scale, and the different habitats are interspersed forming like a mosaic. Considering that difference in larval arrival occurs at a spatial scale that encompass habitat
heterogeneity, all habitats composing one locality homogenous in term of larval arrival will exhibit the same settlement rate. According to this point, local difference
in post-settlement juveniles between adjacent habitats should be due to differential
mortality or movement across habitats rather than difference in larval supply. This
however stresses the need to consider multiple spatial scales when studying links
between habitat and post-settlement juveniles (Rilov and Schiel 2011).
12.4.2 Differential Mortality and Active Habitat Selection Affected
at Finer Spatial Scales
At a finer spatial scale, assuming that the different habitats have been exposed to
the same settlement rates, difference in post-settlement juveniles’ densities among
habitats may be due to differential mortality and/or active choice of the favored
191
12.4 Broad Classes of Ecological Processes and Spatial Scales
Evolutionary processes have selected functional and behavioral traits that are adapted
to specific environments. The selected pool of functional and behavioral traits is
filtered by environments through ecological processes what governs distribution patterns of species within seascape (Morris 2011). Ecological processes may be studied
according to three broad classes: (i) differential settlement/recruitment, (ii) differential mortality and (iii) active choice of the favored habitat. None of them is necessary
exclusive, difference in composition and abundance of species between habitats
could be the result of their combination (Olabarria et al. 2002; Morris 2003, 2011).
Moreover, these processes may act at distinct spatial scales.
12.4.1 Differential Settlement Affected by Environmental
Conditions at Multiple Spatial Scales
Most of demersal fish species inhabiting temperate coastal waters worldwide experience a complex life cycle. Usually, it is divided into a vagrant planktonic phase
(corresponding to the stages egg and larvae) and a relatively sedentary benthic phase
(from the stage post-settlers to adult) (Di Franco et al. 2011). During the planktonic phase, eggs and larvae disperse depending mainly on oceanographic patterns.
The metamorphosis from larvae to juvenile triggers the transition from planktonic to
benthic environment that is called “settlement”. Due to oceanographic patterns (as
currents, water temperature etc), juveniles that disperse may settle in greater number
to one locality than to others (Di Franco et al. 2011).
In coastal environments, the seascape is usually heterogeneous at a fine spatial
scale, and the different habitats are interspersed forming like a mosaic. Considering that difference in larval arrival occurs at a spatial scale that encompass habitat
heterogeneity, all habitats composing one locality homogenous in term of larval arrival will exhibit the same settlement rate. According to this point, local difference
in post-settlement juveniles between adjacent habitats should be due to differential
mortality or movement across habitats rather than difference in larval supply. This
however stresses the need to consider multiple spatial scales when studying links
between habitat and post-settlement juveniles (Rilov and Schiel 2011).
12.4.2 Differential Mortality and Active Habitat Selection Affected
at Finer Spatial Scales
At a finer spatial scale, assuming that the different habitats have been exposed to
the same settlement rates, difference in post-settlement juveniles’ densities among
habitats may be due to differential mortality and/or active choice of the favored