Page 14 - Bioconstructions_2018

74 Gianmarco Ingrosso et al.

in detail (Canessa et al., 2017; Ca ´novas Molina et al., 2013, 2014, 2016). The
western and eastern coasts followed different formation patterns, leading to
two major geological systems (Cattaneo-Vietti et al., 2010). Along the eastern
coast, coralligenous formations develop mainly on vertical cliffs with parallel
series of horizontal rims, from 25–30m to 80–100m depth. Along the western
side, vertical cliffs are not so common and the coast has a different geomor-
phology, with a wider sandy platform. The Western Ligurian Riviera has been
poorly studied and rarely characterized due to its patchy distribution of
isolated rocky outcrops and their limited extent.
Sardinia hosts a notable variety and abundance of coralligenous forma-
tions due to the complexity of the coast and to the shape of the sublittoral
slope. In the Marine Protected Area (MPA) of Tavolara Punta Coda Cavallo
five typologies were recognized: (i) enclaves within infralittoral assemblages
on vertical walls, either carbonatic or granitic; (ii) on limestone pinnacles
between 25 and 40m depth; (iii) on granite inselbergs and other erosional
remnants from 38 to 56m depth; (iv) organogenic platforms at 42–44m;
and (v) on beach rocks at 27, 40 and 54m (Bianchi et al., 2007). Five major
coralligenous communities have been recognized and mapped: (1) associa-
tion with C. zosteroides; (2) facies with A. polypoides; (3) facies with Eunicella
cavolini (Koch, 1887); (4) facies with Eunicella singularis (Esper, 1791); and
(5) facies with P. clavata (Vassallo et al., 2018). Other rare and endangered
species "typical" of the coralligenous populations can be found along the
Sardinian coast, such as the exuberance of the Mediterranean red coral
Corallium rubrum (Linnaeus, 1758) whose populations dwell on steep rocky
walls free from sediments (Cau et al., 2015a, 2016). Dense E. cavolini facies
have been documented along with rich and diverse animal forests dominated
by gorgonian and black corals dwelling both in rocky outcrops arising
from soft bottoms of the continental shelf and in submarine canyons dis-
secting the Sardinian continental margin, at a depth range comprised
between 100 and 180m (Bo et al., 2015; Cau et al., 2015b, 2017a,b). This
condition, together with the existence of a nursery area for catsharks within
the coral ramifications and the occurrence of a meadow of the now rare soft
bottom alcyonacean Isidella elongata (Esper, 1788) in small surviving muddy
enclaves, indicates that this ecosystem have to be considered a pristine Med-
iterranean deep-sea coral sanctuary that would deserve special protection
(Cau et al., 2017c).
Distribution of coralligenous formations along the Campania coast has
been investigated since the end of XVIIIth century, mostly for economic
reasons (red coral banks exploitation, Cattaneo-Vietti et al., 2016). More