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256 S. Calvo et al.

man-induced disturbance sources (harbours and urban and industrial sewage) and along southern
and north-eastern coasts of Sicily, due to natural edaphic factors.

Downloaded By: [Furnari, G.] At: 10:31 24 May 2010 5. Leaf biometry

Shoot phenology and leaf biometry are often used to characterise P. oceanica meadows [51,69].
However, to avoid any confounding effect of seasonality these descriptors should be sampled
during a fixed period of the year [70]. In the current study, summer (June–July) foliar biometry
values were selected from data collected in the framework of several research projects of the
last two decades (see Supplementary Table – online only). Altogether, 5372 Posidonia oceanica
shoots were selected in 119 sampling stations from 1 to 27 m depth and >25,000 leaves were
examined (see Table 2).

Mean leaf surface area for Sicilian coasts was from 249.0 ± 89.4 to 306.7 ± 108.2 cm2· shoot−1
(99% CI = 267.1–274.6). The mean number of leaves per shoot ranged from 4.7 ± 1.1 to 5.2 ±
1.2 (99% CI = 4.8–4.9).

Leaf biometry values were comparable among different sectors except for the western coast
of Sicily, where the means were generally ∼10–20% higher than in the other sectors. This is

Table 2. Mean values (SD) of Posidonia oceanica leaf biometry variables in different sectors of Sicilian coasts: 1, western
and north-western; 2, southern; 3, south-eastern; 4, eastern and north-eastern; 5, small islands. Confidence interval (bold)
at 99% of the grand mean for each variable was estimated with sample size = total n stations, leaves or shoots sampled.

No. adult Adult No. intermediate Intermediate No. leaves Shoot
surface
No. Depth leaves leaf length leaves leaf length No. per shoot (cm2)
Sector stations (m) measured (cm) measured (cm) shoots (Ad+Int)

1 38 10.8 5340 68.5 (25.6) 2841 65.9 (32.4) 1660 4.9 (1.0) 306.7 (108.2)
406 54.9 (35.7) 225 5.2 (1.2) 276.3 (95.5)
2 3 7.0 763 62.2 (26.6) 53.3 (33.3) 724 4.7 (1.1) 261.2 (94.1)
1206 57.2 (29.8) 756 4.8 (1.1) 249.0 (89.4)
3 17 7.2 2231 68.3 (27.6) 1314 51.9 (32.9) 4.7 (1.1) 252.2 (110.3)
3045 2007
4 24 8.7 2295 60.0 (23.9)
8,812
5 37 10.2 6421 64.0 (25.9)

Grand

mean 119 8.3 17,050 64.8–65.8 56.6–58.5 5372 4.8–4.9 267.1–274.6

Table 3. Mean values of Posidonia oceanica leaf biometry variables observed in the literature. The confidence interval
(bold) at 99% of grand mean for each variable was calculated by using all mean values recorded per station.

Adult Intermediate No. leaves Shoot
per shoot surface
No. Depth leaf length leaf length No. (Ad+Int) (cm2)
shoots
Locality stations (m) (cm) (cm) Ref.

South of France 97 39.1 34.1 189 4.6 155.3 [75]

Port-Cros (France) 5 13.7 53.3 45.4 200 4.4 – [76]

Banjuls sur Mer (France) 4 8.3 29.5 31.3 160 4.8 –

Urla-Iskele (Turkey) 4 1.8 41.7 22.9 160 5.5 –

Fanals Point (Spain) 1 15 – – 30 – 354.7 [77]

Platja de Mitjorn 6 1.8 – – 60-180 – 153.5 [78]

(Formentera, Balearic

Islands)

Liguria (Italy) 25 – – 54 – 183.3 [79]

Laganas Bay 3 10 – – 30 – 196.6 [80]

(Zakynthos, Greece)

Lacco Ameno 3 16.7 – – 75 – 207.3 [81]

(Ischia, Italy)

Grand mean 7.8 30.5–47.7 25.6–42.6 976–1096 4.4–5.1 148.7–213.8