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S. Thorin et al.
17.2 Methods
17.2.1 The Proposed Seascape Integrity Index: Basic Concepts
The methodology proposed to score marine sites addresses three factors: biological,
geomorphologic (i.e. 3D complexity) and anthropogenic. As most of the littoral
habitats within a landscape are now affected by human activities (e.g. tourism, urban
development, industries), we considered that the development of such a landscape
integrity index should take into account the anthropogenic pressure.
A landscape is a heterogeneous environment wherein spatial and temporal limits
are determined by the observer’s sight. The explored environment is then dependent
on the perception and the position of the observer, and is variable due to the environmental conditions. To address the underwater visibility problem and the seascape
spatial scale, the only possible option is to consider the submarine observer as mobile. The landscape scale is thus assimilated into what a diver can perceive during
a 40-minute course which corresponds approximately to the average duration of a
classical dive. Even with restricted underwater visibility, the observer can visit several different environments or habitats, similar to the progressive landscape reading
described by Musard et al. (2007).
17.2.2 Major Landscape Criteria
The architecture of submarine bottoms is of prime importance to highlight the habitat
mosaic which forms them: relief variations, structural diversity and the nature of the
architectural elements are directly linked with habitat diversity. This criterion then
needs to be fully exploited, with an evaluation of the sea bottom quality which specifies the value of various relief types that can be encountered when diving. The landscape quality could also be evaluated through the population richness that colonizes
and sometimes constitutes sea bottoms: “the landscape appearance of this submarine
space is largely conditioned by the existence of fauna which, occasionally, becomes
a structuring element of the landscape” (Musard et al. 2007). We then specifically
focused on species noteworthy for their size, colour or abundance, which are constitutive landscape elements. These species are considered as contributing to the aesthetic
and/or landscape value of the marine natural heritage (Francour and Bellan-Santini
2007). The biological quality of a landscape can also be linked to the presence of
structuring species in the community, i.e. species that create by themselves new
habitats such as coralligenous bottoms or Posidonia oceanica meadows.
The Relief factor corresponds to physical descriptors structuring the sea bottoms’
relief. For every descriptor, the quotations are defined from zero (lack of relief) to a
maximal value which varies, depending on its landscape potential (Table 17.1).
The Biological factor focuses on species that can be observed during diving (large
enough and easily recognizable underwater) and that can influence the landscape
(large size species, forming abundant populations or with outstanding shape or colour
S. Thorin et al.
17.2 Methods
17.2.1 The Proposed Seascape Integrity Index: Basic Concepts
The methodology proposed to score marine sites addresses three factors: biological,
geomorphologic (i.e. 3D complexity) and anthropogenic. As most of the littoral
habitats within a landscape are now affected by human activities (e.g. tourism, urban
development, industries), we considered that the development of such a landscape
integrity index should take into account the anthropogenic pressure.
A landscape is a heterogeneous environment wherein spatial and temporal limits
are determined by the observer’s sight. The explored environment is then dependent
on the perception and the position of the observer, and is variable due to the environmental conditions. To address the underwater visibility problem and the seascape
spatial scale, the only possible option is to consider the submarine observer as mobile. The landscape scale is thus assimilated into what a diver can perceive during
a 40-minute course which corresponds approximately to the average duration of a
classical dive. Even with restricted underwater visibility, the observer can visit several different environments or habitats, similar to the progressive landscape reading
described by Musard et al. (2007).
17.2.2 Major Landscape Criteria
The architecture of submarine bottoms is of prime importance to highlight the habitat
mosaic which forms them: relief variations, structural diversity and the nature of the
architectural elements are directly linked with habitat diversity. This criterion then
needs to be fully exploited, with an evaluation of the sea bottom quality which specifies the value of various relief types that can be encountered when diving. The landscape quality could also be evaluated through the population richness that colonizes
and sometimes constitutes sea bottoms: “the landscape appearance of this submarine
space is largely conditioned by the existence of fauna which, occasionally, becomes
a structuring element of the landscape” (Musard et al. 2007). We then specifically
focused on species noteworthy for their size, colour or abundance, which are constitutive landscape elements. These species are considered as contributing to the aesthetic
and/or landscape value of the marine natural heritage (Francour and Bellan-Santini
2007). The biological quality of a landscape can also be linked to the presence of
structuring species in the community, i.e. species that create by themselves new
habitats such as coralligenous bottoms or Posidonia oceanica meadows.
The Relief factor corresponds to physical descriptors structuring the sea bottoms’
relief. For every descriptor, the quotations are defined from zero (lack of relief) to a
maximal value which varies, depending on its landscape potential (Table 17.1).
The Biological factor focuses on species that can be observed during diving (large
enough and easily recognizable underwater) and that can influence the landscape
(large size species, forming abundant populations or with outstanding shape or colour