Page 5 - Balistreri_Mannino_2017

On the occurrence of alien macroalgae in the vermetid reef along the coasts ofFavignana Island (S-Tyrrhenian Sea) 109

Classes of abundance

Taxa
Arre Grotta Cala San San Cala Punta
Faraglione Poz/o Sto niello
Turino Perciata Ro ton da Giuseppe Nicola Azzurra Longa

Junta
R ! 0 1 2 0 ! 4 2 2 0
ruhens

Laurencin
R i 1 1 l 1 0 0 2 1 0
oburnt

Cystoseira
O 4 4 3 4 4 4 2 0 3 3
amentacea

Halopteris
O 0 0 l 0 0 0 2 2 0 0
scoparia

Padina
O 0 1 3 1 0 0 I \ 0 0
pavonka

Caulerpa
C 0 0 1 0 0 ! 3 1 1 3
cylindracea

Table 3. Classes of abundance of Caulerpa cylindracea and the dominant macroalgae in 2015
(R = Rhodophyta, O = Ochrophyta, C = Chlorophyta).

2005; Bulleri et al., 2010, 2011; Katsanevakis et

al., 2010), effective management and conservation
strategies have to be planned within the MPA.
The vermetid reef is a highly vulnerable habitat,
characterised by a delicate balance between two

opposite processes, deposition and erosion, with
the balance generally tilting toward deposition

(Chemello & Silenzi, 2011), even though “the struc-
ture can undergo a kind of ‘suicide leading to its
’
destruction by catastrophic events ” (Antonioli et al.,
1999; Chemello & Silenzi, 2011). Moreover, in-

creases in sedimentation might enhance the invas-
iveness of alien species such as C. cylindracea
(Airoldi & Cinelli, 1997; Piazzi et al., 2007). Indeed,

this alga is able to tolerate high sedimentation rates
and its spread and competitive ability may be en-
hanced by sediment deposition as consequence of
its ability to trap sediments (Piazzi et al., 2005,

2007). As consequence of its active mechanism of
stolonisation it forms compact multilayered mats to-

gether with macroalgae, that traps sediment creating
a relevant decrease of redox potential underneath
(Piazzi et al., 1997, 2005, 2007; Klein & Verlaque,
2008; Mannino & Di Giovanni, 2011; Matijevic et

al., 2013). This mat may negatively affect the
benthic assemblages (in term of diversity and struc-
ture), alters sediment conditions, causes drastic re-
Figure 6. Thalli ofAsparagopsis taxiformis
(San Giuseppe). ductions in diversity of the infaunal compartment