Page 3 - First assessment of the vermetid
P. 3
First assessment of the vermetid reefs along the coasts of Favignana Island (Southern Tyrrhenian Sea) 373
Data analysis Height of Height of Slope of Slope of
Differences in reef topographic complexity Study Width the inner the outer the inner the outer
were analysed using permutational multivariate
analysis of variance (PERMANOVA, Anderson, Areas (m) margin margin margin margin
2001). For the topographic complexity, the design
consisted of three factors: Coastal exposure (Sd; (cm) (cm) (°) (°)
two levels, fixed factor), Area (Ar; three levels,
random, nested in Sd) and Site (St; three levels, Grotta 7.31 ± 10.33 ± 15.66 ± 27.5 ± 42.5 ±
random, nested in ArxSd). All multivariate analyses Perciata 0.23 0.23 0.23 0.23 0.23
were based on Bray-Curtis dissimilarities of log(x
+ 1) transformed data and each term in the analyses Stor- 5.10 ± 8.33 ± 8 ± 33.3 ± 29.16 ±
was tested using 9999 random permutations of the nello 0.23 0.23 0.23 0.23 0.23
appropriate units. The analyses were performed
using the software package PRIMER 6 (Clarke & Pattern 3: Arre Turinu (northern side) and Cala
Gorley, 2006). Rotonda (southern side, Figs. 10–13).
RESULTS The reef is damaged. OUTER MARGIN: it has a
variable height and sometimes it is absent. Some
Reef typology crevices can also be present together with regrowth
areas. INNER MARGIN: Dendropoma petraeum is
All the vermetid reefs are consistent with a true absent. CUVETTES: many and sometimes very deep.
reef (according to Antonioli et al., 1999), displaying
at least three local patterns, distinguishable for Height of Height of Slope of Slope of
width, height of the outer and of the inner margin
and number, width and depth of cuvettes. A descrip- Study Width the inner the outer the inner the outer
tion of the different patterns are reported below.
Areas (m) margin margin margin margin
Pattern 1: Pozzo and Faraglione (northern side,
Figs. 2–5). (cm) (cm) (°) (°)
OUTER MARGIN: wide, flattened and irregular. In Arre 6.38 ± 26 ± 17 ± 26.6 ± 45 ±
the inner side, crevices were also present. Some- Turinu 0.23 0.23 0.23 0.23 0.23
times at Faraglione are present two outer margins.
INNER MARGIN: Dendropoma petraeum is absent. CalaRo- 2.30 ± 12 ± 7.6 ± 41.6 ± 38.3 ±
CUVETTES: not many, not deep and with a variable tonda 0.23 0.23 0.23 0.23 0.23
width. At Faraglione they are mainly present near
the outer margin. At Pozzo some of them are Reef topographic complexity
fullfilled of sediment.
The PERMANOVA on the reef topographic
complexity provided an evidence of significant
differences in topographic complexity among the
areas whereas no differences were recorded between
the two coastal exposures (Fig. 14; Table 1).
Height of Height of Slope of Slope of Source df SS MS Pseudo-F P(MC)
Study Width the inner the outer the inner the outer
Areas (m) margin margin margin margin Sd 1 8627 8627 0.349 0.771
(cm) (cm) (°) (°)
Fara- 7.03 ± 8.66 ± 18 ± 38.3 ± 45 ± Ar(Sd) 4 98876 24719 9.1486 0.0001
glione 0.23 0.23 0.23 0.23 0.23 12 32423 2701.9 1.8084 0.0098
St [Ar 36 53789 1494.1
Pozzo 15.46 ± 17.33 ± 15.33 ± 45 ± 45 ± (Sd)]
0.23 0.23 0.23 0.23 0.23 Res
Pattern 2: Grotta Perciata and Stornello (south- Total 53 1.9372E5
ern side, Figs. 6–9).
Table 1. PERMANOVA on the topographic
OUTER MARGIN: thin and not continuously ar- complexity data.
ranged. INNER MARGIN: Dendropoma petraeum is
absent. CUVETTES: not many and not deep.
