13 Can We use a Landscape Approach to Assess Natural and Anthropogenic . . .
205
zone) and sublittoral zone (= emerged fringe of the infralittoral zone). Then, a landscape reading can be based on identification and spatialization of color and rugosity
of patches distributed as a mosaic in a rocky matrix. It can give broadly but rapidly
the main structure and functioning patterns, and can be the basis of a diachronic
analyses to survey the evolution of the relative surfaces of the patches.
If these patterns are recognized since many years, the large possibilities offered
by such global landscape analysis remained largely unexploited. However at a larger
scale, remote sensing and aerial photographs analysis provided very helpful results
to characterize the dynamics of decreasing of the fucoids and kelp beds in Brittany.
Nevertheless, if some studies provided good bases for a coastal seascape ecology
(Lima and Zollner 1996) future research efforts are needed to link spatial patterning
of intertidal habitats and ecosystem functioning. Finally the possibilities given by
the landscape ecology to characterize human disturbances on the shore, remained
largely unexplored.
In a rocky intertidal seascape, matrix is the rock substratum. This latter can show
a heterogeneity at a smaller scale like the occurrence of boulders, crevices or tide
pools. Patches are mainly biogenic patches of macroalgal and dense macrofaunal
populations of gregarious sedentary species, mostly fixed on the substratum. At the
landscape scale, some anthropogenic structures can be present: mainly oyster farms
structures. Thus, the intertidalscape is a complex spatial mosaic of heterogeneous
habitats, depending both on the heterogeneity of the rocky matrix and of environmental factors including anthropogenic ones. Within this landscape, some mobile
macrofaunal species are predators, mainly large crustaceans and fishes at the high tide
period and birds at the low tide period. They can induce indirect interactions between
the intertidalscape components. Man is also an element of these species which can
control some components by a professional and recreational fishing activity or algal
harvesting (fucoids and red seaweeds), either from boats or scuba diving at the high
tide period or through a hand-fishing activity at the low tide period. These activities
do not only concern interactions between species (predator/prey interactions) and
connectivity between patches, but can also deeply modify the spatial organization
of habitat patches. As an example, the hand-fishing for shellfish (crabs, abalones,
clams. . . ) on the lower eulittoral boulder fields, can induce strong modifications of
the habitat structure that can be rapidly identified at the intertidalscape scale.
13.4 Temporal Scales and Evolution in Intertidalscapes
Intertidalscapes are different from terrestrial landscapes and subtidal seascapes
because of the strong visual modifications induced by the daily succession of emersion/submersion periods and its variability in terms of tidal range according the tidal
cycles. The periodic changes of intertidalscape are not only visuals but also functional, with drastic modifications of energy and fluxes of matter, metabolism, and
moving of the mobile large carnivorous species. On the other hand, intertidalscapes
show fewer seasonal changes than temperate terrestrial landscapes.
Moreover, strong changes in the intertidalscape can also be due to stochastic
natural or anthropogenic catastrophic events. Storms associated with big waves are
205
zone) and sublittoral zone (= emerged fringe of the infralittoral zone). Then, a landscape reading can be based on identification and spatialization of color and rugosity
of patches distributed as a mosaic in a rocky matrix. It can give broadly but rapidly
the main structure and functioning patterns, and can be the basis of a diachronic
analyses to survey the evolution of the relative surfaces of the patches.
If these patterns are recognized since many years, the large possibilities offered
by such global landscape analysis remained largely unexploited. However at a larger
scale, remote sensing and aerial photographs analysis provided very helpful results
to characterize the dynamics of decreasing of the fucoids and kelp beds in Brittany.
Nevertheless, if some studies provided good bases for a coastal seascape ecology
(Lima and Zollner 1996) future research efforts are needed to link spatial patterning
of intertidal habitats and ecosystem functioning. Finally the possibilities given by
the landscape ecology to characterize human disturbances on the shore, remained
largely unexplored.
In a rocky intertidal seascape, matrix is the rock substratum. This latter can show
a heterogeneity at a smaller scale like the occurrence of boulders, crevices or tide
pools. Patches are mainly biogenic patches of macroalgal and dense macrofaunal
populations of gregarious sedentary species, mostly fixed on the substratum. At the
landscape scale, some anthropogenic structures can be present: mainly oyster farms
structures. Thus, the intertidalscape is a complex spatial mosaic of heterogeneous
habitats, depending both on the heterogeneity of the rocky matrix and of environmental factors including anthropogenic ones. Within this landscape, some mobile
macrofaunal species are predators, mainly large crustaceans and fishes at the high tide
period and birds at the low tide period. They can induce indirect interactions between
the intertidalscape components. Man is also an element of these species which can
control some components by a professional and recreational fishing activity or algal
harvesting (fucoids and red seaweeds), either from boats or scuba diving at the high
tide period or through a hand-fishing activity at the low tide period. These activities
do not only concern interactions between species (predator/prey interactions) and
connectivity between patches, but can also deeply modify the spatial organization
of habitat patches. As an example, the hand-fishing for shellfish (crabs, abalones,
clams. . . ) on the lower eulittoral boulder fields, can induce strong modifications of
the habitat structure that can be rapidly identified at the intertidalscape scale.
13.4 Temporal Scales and Evolution in Intertidalscapes
Intertidalscapes are different from terrestrial landscapes and subtidal seascapes
because of the strong visual modifications induced by the daily succession of emersion/submersion periods and its variability in terms of tidal range according the tidal
cycles. The periodic changes of intertidalscape are not only visuals but also functional, with drastic modifications of energy and fluxes of matter, metabolism, and
moving of the mobile large carnivorous species. On the other hand, intertidalscapes
show fewer seasonal changes than temperate terrestrial landscapes.
Moreover, strong changes in the intertidalscape can also be due to stochastic
natural or anthropogenic catastrophic events. Storms associated with big waves are