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C. Hily and M. Bernard
typology. Consequently, if we can have a landscape reading in the intertidal zone
and an analysis based on its habitat composition and distribution—and eventually
others dimensions as cultural, aesthetic or socio-economical -, it is not possible to
situate this analysis in a reference grid. Such reference classification would integrate
all the components but also the interactions between these components. Moreover
the concepts developed in terrestrial landscape ecology are today discussed in order
to know whether they could apply to sea or if new approaches must be developed for
the seascape ecology (Pittman et al. 2011). We consider that if the terminology and
concepts developed for the terrestrial applications are equally applicable to the study
of intertidal environments and allow to describe their heterogeneity, some processes
remain however specific of marine environment such as the connectivity between
patches and the role of corridors (Turner 2005), the phase of immersion facilitating
the exchanges and connectivity between patches and at higher scales.
13.3 Structure of the Rocky Intertidalscapes
On rocky shores, intertidalscape depends mainly of (1) wave exposure that structures habitats in a horizontal dimension, along a gradient of exposure decreasing
from the tips of rocky headlands to coves and sheltered bays, and (2) emersion, that
structures habitats on a vertical dimension according the tidal excursion gradient.
As a consequence of this second gradient, zonation is the pattern of distribution of
the dominant macroalgal and macrofaunal organisms, both in term of abundances
and cover rates of the substratum matrix, observable as successive bands from the
high to the lower shore (numerous papers have been published on the rockyshore
organization from Lewis 1964 to Menge and Branch 2000). Crossing exposure and
emersion gradients give the main structuring components of the intertidalscape. For
the observer who looks for a landscape reading at a site scale (i.e. a cove, a beach,
a little bay), an intertidal zone looks like a mosaic of various colors, structured
in a horizontal zonation alterning dark bands dominated by macroalgae (fucoids)
and grey bands dominated by macrofauna or bare rock. In the western European
coasts, from the high shore to the lower shore, the first level, corresponding to the
supralittoral zone under the wave splash and spray influence, is generally characterized by two lichen bands: firstly a yellow-orange-grey band mixing various erected
and species (Caloplaca marina, Xantoria parietina, Ramalina spp.) and lower on
the shore, a black band mainly composed of the encrusting lichen Verrucaria mora
species. Under these bands of lichens, different bands of macroalgae (fucoids such as
Pelvetia canaliculata, Ascophyllum nodosum, Fucus vesiculosus, Fucus serratus, red
seaweeds such as Chondrus crispus, Palmaria palmate, Osmundea pinnatifidan or
Laminaria such as Laminaria digitata, Laminaria hyperborea. . . ) and macrofauna
(barnacles, limpets, mussels) are easily identified at the intertidalscape level from
exposed to sheltered situations, as three main zones described by authors as: littoral
fringe (= high mediolittoral zone), eulittoral zone (= medium and low mediolittoral
C. Hily and M. Bernard
typology. Consequently, if we can have a landscape reading in the intertidal zone
and an analysis based on its habitat composition and distribution—and eventually
others dimensions as cultural, aesthetic or socio-economical -, it is not possible to
situate this analysis in a reference grid. Such reference classification would integrate
all the components but also the interactions between these components. Moreover
the concepts developed in terrestrial landscape ecology are today discussed in order
to know whether they could apply to sea or if new approaches must be developed for
the seascape ecology (Pittman et al. 2011). We consider that if the terminology and
concepts developed for the terrestrial applications are equally applicable to the study
of intertidal environments and allow to describe their heterogeneity, some processes
remain however specific of marine environment such as the connectivity between
patches and the role of corridors (Turner 2005), the phase of immersion facilitating
the exchanges and connectivity between patches and at higher scales.
13.3 Structure of the Rocky Intertidalscapes
On rocky shores, intertidalscape depends mainly of (1) wave exposure that structures habitats in a horizontal dimension, along a gradient of exposure decreasing
from the tips of rocky headlands to coves and sheltered bays, and (2) emersion, that
structures habitats on a vertical dimension according the tidal excursion gradient.
As a consequence of this second gradient, zonation is the pattern of distribution of
the dominant macroalgal and macrofaunal organisms, both in term of abundances
and cover rates of the substratum matrix, observable as successive bands from the
high to the lower shore (numerous papers have been published on the rockyshore
organization from Lewis 1964 to Menge and Branch 2000). Crossing exposure and
emersion gradients give the main structuring components of the intertidalscape. For
the observer who looks for a landscape reading at a site scale (i.e. a cove, a beach,
a little bay), an intertidal zone looks like a mosaic of various colors, structured
in a horizontal zonation alterning dark bands dominated by macroalgae (fucoids)
and grey bands dominated by macrofauna or bare rock. In the western European
coasts, from the high shore to the lower shore, the first level, corresponding to the
supralittoral zone under the wave splash and spray influence, is generally characterized by two lichen bands: firstly a yellow-orange-grey band mixing various erected
and species (Caloplaca marina, Xantoria parietina, Ramalina spp.) and lower on
the shore, a black band mainly composed of the encrusting lichen Verrucaria mora
species. Under these bands of lichens, different bands of macroalgae (fucoids such as
Pelvetia canaliculata, Ascophyllum nodosum, Fucus vesiculosus, Fucus serratus, red
seaweeds such as Chondrus crispus, Palmaria palmate, Osmundea pinnatifidan or
Laminaria such as Laminaria digitata, Laminaria hyperborea. . . ) and macrofauna
(barnacles, limpets, mussels) are easily identified at the intertidalscape level from
exposed to sheltered situations, as three main zones described by authors as: littoral
fringe (= high mediolittoral zone), eulittoral zone (= medium and low mediolittoral