168
A. Cheminée et al.
11.3 Case Study: The Nurseries of Diplodus spp. and the Zoning
of the Calanques National Park
11.3.1 The Main Issues
The species of the Sparidae belonging to the genus Diplodus are the prey of professional and amateur fishers, in particular for underwater fishing (Coll et al. 2004;
Guidetti et al. 2008). They are of major economic interest throughout the Mediterranean coastal areas. These fishes, that prey on sea urchins, perform ‘top-down’
control of these herbivores and thus play a role in the prevention of over-grazing on
rocky bottoms (Sala et al. 1998). The renewal of their assemblages is therefore as
much an economic as an ecological issue. The habitats that play the role of nursery
for juveniles of the white seabream Diplodus spp. (Diplodus sargus, D. puntazzo, and
to a lesser degree D. vulgaris) are the shallow water zones (0–1.5 m depth), gently
sloping, sheltered from hydrodynamic forces and with a heterogeneous substrate of
small rocks, stones, gravel and sand (Fig. 11.3). If the substrate is solely made up
of homogeneous fine fractions (sand), the nursery value of the habitat is severely reduced (Harmelin-Vivien et al. 1995; Bussotti and Guidetti 2010; Garcia-Rubies and
Macpherson 1995; Guidetti 2000; MacPherson 1998; Vigliola and Harmelin-Vivien
2001; Cheminée et al. 2011). In the example of the Calanques Natural Heritage
Site (‘site classé’) from Marseilles (South-east France), Cheminée et al. (2011) have
highlighted that the adult populations of Diplodus spp. of the Calanques are probably
restocked by recruits migrating from nurseries situated not only locally but also, in
the majority, in the bays of Marseille, Cassis and La Ciotat, in other words outside
the protected area. The Calanques National Park, officially founded at the beginning
of 2012, includes a coastline that extends from the southern bay of Marseille to the
bay of La Ciotat and Les Leques. To meet the requirements of the management of
these species, by taking into account all the essential habitats, the statutory zoning
and the contractual protection measures should operate at a spatial scale that goes
beyond the habitat to the scale of a landscape covering half of the coastline of the
‘Bouches-du-Rhˆ one’ district (Fig. 11.4).
11.3.2 Localisation of Nurseries and Presentation of the Zoning
of the Calanques National Park
For the whole of the coast of the Calanques National Park, we have localised and
quantified the stretches of coastline presenting nursery habitats for juveniles of the
white seabream. The coastline studied extends from the roadstead of Marseille (Anse
de Malmousque) to the bay of La Ciotat—Les Lecques and includes the Archipelagos of Frioul and Riou and Ile Verte (Fig. 11.4). It represents a total coastline of
151 km. Using the same method as Cheminée et al. (2011), we have analysed the
ortho-photographs of the coast (MEDDTL et al. 2012; Google_Inc. 2013) in order to
A. Cheminée et al.
11.3 Case Study: The Nurseries of Diplodus spp. and the Zoning
of the Calanques National Park
11.3.1 The Main Issues
The species of the Sparidae belonging to the genus Diplodus are the prey of professional and amateur fishers, in particular for underwater fishing (Coll et al. 2004;
Guidetti et al. 2008). They are of major economic interest throughout the Mediterranean coastal areas. These fishes, that prey on sea urchins, perform ‘top-down’
control of these herbivores and thus play a role in the prevention of over-grazing on
rocky bottoms (Sala et al. 1998). The renewal of their assemblages is therefore as
much an economic as an ecological issue. The habitats that play the role of nursery
for juveniles of the white seabream Diplodus spp. (Diplodus sargus, D. puntazzo, and
to a lesser degree D. vulgaris) are the shallow water zones (0–1.5 m depth), gently
sloping, sheltered from hydrodynamic forces and with a heterogeneous substrate of
small rocks, stones, gravel and sand (Fig. 11.3). If the substrate is solely made up
of homogeneous fine fractions (sand), the nursery value of the habitat is severely reduced (Harmelin-Vivien et al. 1995; Bussotti and Guidetti 2010; Garcia-Rubies and
Macpherson 1995; Guidetti 2000; MacPherson 1998; Vigliola and Harmelin-Vivien
2001; Cheminée et al. 2011). In the example of the Calanques Natural Heritage
Site (‘site classé’) from Marseilles (South-east France), Cheminée et al. (2011) have
highlighted that the adult populations of Diplodus spp. of the Calanques are probably
restocked by recruits migrating from nurseries situated not only locally but also, in
the majority, in the bays of Marseille, Cassis and La Ciotat, in other words outside
the protected area. The Calanques National Park, officially founded at the beginning
of 2012, includes a coastline that extends from the southern bay of Marseille to the
bay of La Ciotat and Les Leques. To meet the requirements of the management of
these species, by taking into account all the essential habitats, the statutory zoning
and the contractual protection measures should operate at a spatial scale that goes
beyond the habitat to the scale of a landscape covering half of the coastline of the
‘Bouches-du-Rhˆ one’ district (Fig. 11.4).
11.3.2 Localisation of Nurseries and Presentation of the Zoning
of the Calanques National Park
For the whole of the coast of the Calanques National Park, we have localised and
quantified the stretches of coastline presenting nursery habitats for juveniles of the
white seabream. The coastline studied extends from the roadstead of Marseille (Anse
de Malmousque) to the bay of La Ciotat—Les Lecques and includes the Archipelagos of Frioul and Riou and Ile Verte (Fig. 11.4). It represents a total coastline of
151 km. Using the same method as Cheminée et al. (2011), we have analysed the
ortho-photographs of the coast (MEDDTL et al. 2012; Google_Inc. 2013) in order to