Spring Marine Vegetation on Rocky Substrata of the Tremiti Islands (Adriatic Sea, Italy)
247
(lists of species not reported in Tables are available on request to the authors).
The material collected was preserved in sea
water and Formalin (5%) for later study in the
laboratory. Voucher specimens are kept in the
Herbarium of the Department of Botany of the
University of Catania.
Results
Midlittoral Zone
In the upper part of this zone the communities
are characterised by a low mean number of
species: 2.6 and 7 at +30 to +15 cm and at m.s.I.
respectively; while the community occurring at
10 to 15 cm depth shows a higher mean number
of species (20.2).
At +30 to +15 cm a community having
Polysiphonia sertularioides as dominant species
occurs (Table 2). To that species are associated,
according to the stations, Lithophyllum papillosum 1 or Nemalion helminthoides and Ralfsia verrucosa or Gelidiella lubrica and, in a sheltered
station of the island of Caprara (Scoglietti),
Cladophora dalmatica. At the following two stations, Punta Coccodrillo (St Domino) and San
Nicola II (St Nicola), Gelidiella lubrica is the
dominant species instead of R sertularioides. At
m.sJ. (Table 2) a community with Lithophyllum
byssoides and L. papillosum (both species with
high per cent cover values) occurs. In some stations, however, only one of the two species is present. In the lower part of the midlittoral zone
(-15 to -10 cm) a community with Corallina
elongata. Ceramium spp. and Callithamnion
granulatum as dominant species, accompanied
by rhodomelacean species of the genera
Laurencia and Osmundea, generally occurs
(Table 2). At stations with a less steep slope of the
substratum, the last species show high per cent
cover values, e.g. Osmundea truncata and O. verlaquei at Cala Sorrentino and at Punta Secca
(Caprara) respectively. At Grotta del Sale (St
Domino), where Corallina elongata lacks,
Laurencia glandulifera and Osmundea verlaquei
are the dominant species.
Infralittoral Zone
The communities occurring in this zone are
much richer of species than those of the midlittoral zone, having a mean number of species
increasing from near the surface (22.3) to -10 m
(58.4). Then, from 13 to 20 m depth, such a number reduces slightly (54.9) and more markedly
from 22 to 30 m depth (50.8).
In the upper part of this zone (Table 3), a
community with Cystoseira amentacea v. stricta
(with high per cent cover values) and a mean
number of species of 21.6, forms a rather continuous belt in all islands. At Cala Matania (St
Domino) C. amentacea v. stricta is accompanied
by C. compressa which, however, shows a low per
cent cover value. Only at Punta Romito (Caprara)
and at Porto San Nicola (St Nicola) the above
vegetational belt is substituted by a community
with Corallina elongata and by a community
with Ceramium spp., respectively.
Below the belt with Cystoseira amentacea v.
stricta, at about 1 m depth (Table 4), the vegetation is characterised by a community with
Corallina elongata and Laurencia glandulifera
accompanied by some other species (as
Osmundea truncata, O. verlaquei, Ceramium
spp.) with lower per cent cover value. Only at San
Nicola I CSt Nicola) a community with Cystoseira
crinitophylla occurs, while some particular facies
with Ectocarpus siliculosus and with Sphacelaria
cirrosa, at Grotta del Sale (St Domino) and at
Scoglietti (Caprara) occur respectively.
From 3 to 5 m depth (Table 4) a community
with Corallina elongata and some Dictyotaceae
(Dictyota dichotoma v. dichotoma, D. fasciola, D.
spiralis), generally occurs. At Cala Matania (St
Domino), where Corallina elongata lacks, a community with D. fasciola accompanied by
Amphiroa rigida and Haliptilon virgatum occurs.
From 6 to 10 m depth (Table 4) the vegetation is
characterised by a community with Dictyota
dichotoma v. dichotoma often accompanied by
other Dictyotaceae (D. dichotoma v. intricata, D.
fasciola, Taonia atomaria f. ciliata, Padina pavonica), some Sphacelariaceae (Halopteris filicina
and Stypocaulon scoparium) and some large
thalli of Codium bursa. Peyssonnelia squamaria,
According to WoeIkerling et at (1998) the placement of this taxon in Lythophyllum requires confirmation
247
(lists of species not reported in Tables are available on request to the authors).
The material collected was preserved in sea
water and Formalin (5%) for later study in the
laboratory. Voucher specimens are kept in the
Herbarium of the Department of Botany of the
University of Catania.
Results
Midlittoral Zone
In the upper part of this zone the communities
are characterised by a low mean number of
species: 2.6 and 7 at +30 to +15 cm and at m.s.I.
respectively; while the community occurring at
10 to 15 cm depth shows a higher mean number
of species (20.2).
At +30 to +15 cm a community having
Polysiphonia sertularioides as dominant species
occurs (Table 2). To that species are associated,
according to the stations, Lithophyllum papillosum 1 or Nemalion helminthoides and Ralfsia verrucosa or Gelidiella lubrica and, in a sheltered
station of the island of Caprara (Scoglietti),
Cladophora dalmatica. At the following two stations, Punta Coccodrillo (St Domino) and San
Nicola II (St Nicola), Gelidiella lubrica is the
dominant species instead of R sertularioides. At
m.sJ. (Table 2) a community with Lithophyllum
byssoides and L. papillosum (both species with
high per cent cover values) occurs. In some stations, however, only one of the two species is present. In the lower part of the midlittoral zone
(-15 to -10 cm) a community with Corallina
elongata. Ceramium spp. and Callithamnion
granulatum as dominant species, accompanied
by rhodomelacean species of the genera
Laurencia and Osmundea, generally occurs
(Table 2). At stations with a less steep slope of the
substratum, the last species show high per cent
cover values, e.g. Osmundea truncata and O. verlaquei at Cala Sorrentino and at Punta Secca
(Caprara) respectively. At Grotta del Sale (St
Domino), where Corallina elongata lacks,
Laurencia glandulifera and Osmundea verlaquei
are the dominant species.
Infralittoral Zone
The communities occurring in this zone are
much richer of species than those of the midlittoral zone, having a mean number of species
increasing from near the surface (22.3) to -10 m
(58.4). Then, from 13 to 20 m depth, such a number reduces slightly (54.9) and more markedly
from 22 to 30 m depth (50.8).
In the upper part of this zone (Table 3), a
community with Cystoseira amentacea v. stricta
(with high per cent cover values) and a mean
number of species of 21.6, forms a rather continuous belt in all islands. At Cala Matania (St
Domino) C. amentacea v. stricta is accompanied
by C. compressa which, however, shows a low per
cent cover value. Only at Punta Romito (Caprara)
and at Porto San Nicola (St Nicola) the above
vegetational belt is substituted by a community
with Corallina elongata and by a community
with Ceramium spp., respectively.
Below the belt with Cystoseira amentacea v.
stricta, at about 1 m depth (Table 4), the vegetation is characterised by a community with
Corallina elongata and Laurencia glandulifera
accompanied by some other species (as
Osmundea truncata, O. verlaquei, Ceramium
spp.) with lower per cent cover value. Only at San
Nicola I CSt Nicola) a community with Cystoseira
crinitophylla occurs, while some particular facies
with Ectocarpus siliculosus and with Sphacelaria
cirrosa, at Grotta del Sale (St Domino) and at
Scoglietti (Caprara) occur respectively.
From 3 to 5 m depth (Table 4) a community
with Corallina elongata and some Dictyotaceae
(Dictyota dichotoma v. dichotoma, D. fasciola, D.
spiralis), generally occurs. At Cala Matania (St
Domino), where Corallina elongata lacks, a community with D. fasciola accompanied by
Amphiroa rigida and Haliptilon virgatum occurs.
From 6 to 10 m depth (Table 4) the vegetation is
characterised by a community with Dictyota
dichotoma v. dichotoma often accompanied by
other Dictyotaceae (D. dichotoma v. intricata, D.
fasciola, Taonia atomaria f. ciliata, Padina pavonica), some Sphacelariaceae (Halopteris filicina
and Stypocaulon scoparium) and some large
thalli of Codium bursa. Peyssonnelia squamaria,
According to WoeIkerling et at (1998) the placement of this taxon in Lythophyllum requires confirmation