11 Management of Infralittoral Habitats: Towards a Seascape Scale Approach
163
in landscape ecology: what are the capacities of organisms to disperse through the
landscape?
Historically, landscape ecology has been mainly focused on terrestrial ecosystems,
with the aim of understanding how biocenosis can be structured in the context of
human activities, in particular those related to agriculture and urban development.
The transfer of the discipline to marine ecosystems is much more recent, since the
term ‘seascape’ only appeared in the 1980s (Pittman et al. 2011). The main difficulty
lies in the characterisation of seascapes limited technically by a restricted field of
vision and by the means of observation available.
When we consider a stretch of coastline, the infralittoral sea bottom has the
appearance of a mosaic of geomorphological and biological units characterised by
their biotic and abiotic components (Chapman 1995): depending on the scale and
on the components under consideration, these units are referred to as ecosystems,
biocenosis, habitats or micro-habitats. This mosaic of units makes up a seascape, the
scale of which may range from a dozen or so metres to a dozen or more kilometres.
In the ecologists’ sense, a submarine landscape is thus a sum of habitats of which
the emergent properties are different from the simple addition of the properties of
each habitat. One of the most significant emergent properties in seascape ecology
is the connectivity between these units that depends very strongly, as in terrestrial
environment, on the level of fragmentation of the seascape and on the capacity for
exchange of individuals between habitats (Basterretxea et al. 2012; Gillanders et al.
2003; Mumby 2006; Cowen et al. 2007; Di Franco et al. 2012).
This pluridisciplinary notion of underwater landscapes has recently reappeared
with the current upsurge of public authority management of the marine environment
(Musard O. comm. pers.). The necessity for this kind of management is due to the
multiplicity of stakeholders, users, pressures and threats that result (over-exploitation
of resources, destruction of habitats by over-frequentation or embankments, pollution, etc.). In the littoral zone, the real interface between the marine environment and
the continental zone, this range of threats that are facing the seascapes (Coll et al.
2010) represent challenges for the scientific community, management organisations
and public authority decision makers.
In order to plan the management of a given coastal marine area, the managing
organisation responsible begins by surveying the initial state of that environment,
that is describing the natural components of the landscape, the human uses made
of it, the pressures and possible threats facing these components, while taking into
account the continuity with the terrestrial domain. This provides a basis for identifying the management priorities and for proposing management aims and a plan of
action designed, by means of specific measures, to achieve these aims. In the current
climate of participative democracy, the issues, aims and actions are defined in consultation with the various stakeholders in the coastal environment (e.g. the Natura 2000
approach). This type of consensus-seeking process is in contrast with the ‘private
preserve’ approach to policy-making prevalent in the 1970–1980s (Francour et al.
2001).
In order to define the priority issues, one of the approaches used consists in identifying within the landscape mosaic the units where the interactions between natural
components and anthropic pressures engender impacts (threats) that are particularly
163
in landscape ecology: what are the capacities of organisms to disperse through the
landscape?
Historically, landscape ecology has been mainly focused on terrestrial ecosystems,
with the aim of understanding how biocenosis can be structured in the context of
human activities, in particular those related to agriculture and urban development.
The transfer of the discipline to marine ecosystems is much more recent, since the
term ‘seascape’ only appeared in the 1980s (Pittman et al. 2011). The main difficulty
lies in the characterisation of seascapes limited technically by a restricted field of
vision and by the means of observation available.
When we consider a stretch of coastline, the infralittoral sea bottom has the
appearance of a mosaic of geomorphological and biological units characterised by
their biotic and abiotic components (Chapman 1995): depending on the scale and
on the components under consideration, these units are referred to as ecosystems,
biocenosis, habitats or micro-habitats. This mosaic of units makes up a seascape, the
scale of which may range from a dozen or so metres to a dozen or more kilometres.
In the ecologists’ sense, a submarine landscape is thus a sum of habitats of which
the emergent properties are different from the simple addition of the properties of
each habitat. One of the most significant emergent properties in seascape ecology
is the connectivity between these units that depends very strongly, as in terrestrial
environment, on the level of fragmentation of the seascape and on the capacity for
exchange of individuals between habitats (Basterretxea et al. 2012; Gillanders et al.
2003; Mumby 2006; Cowen et al. 2007; Di Franco et al. 2012).
This pluridisciplinary notion of underwater landscapes has recently reappeared
with the current upsurge of public authority management of the marine environment
(Musard O. comm. pers.). The necessity for this kind of management is due to the
multiplicity of stakeholders, users, pressures and threats that result (over-exploitation
of resources, destruction of habitats by over-frequentation or embankments, pollution, etc.). In the littoral zone, the real interface between the marine environment and
the continental zone, this range of threats that are facing the seascapes (Coll et al.
2010) represent challenges for the scientific community, management organisations
and public authority decision makers.
In order to plan the management of a given coastal marine area, the managing
organisation responsible begins by surveying the initial state of that environment,
that is describing the natural components of the landscape, the human uses made
of it, the pressures and possible threats facing these components, while taking into
account the continuity with the terrestrial domain. This provides a basis for identifying the management priorities and for proposing management aims and a plan of
action designed, by means of specific measures, to achieve these aims. In the current
climate of participative democracy, the issues, aims and actions are defined in consultation with the various stakeholders in the coastal environment (e.g. the Natura 2000
approach). This type of consensus-seeking process is in contrast with the ‘private
preserve’ approach to policy-making prevalent in the 1970–1980s (Francour et al.
2001).
In order to define the priority issues, one of the approaches used consists in identifying within the landscape mosaic the units where the interactions between natural
components and anthropic pressures engender impacts (threats) that are particularly