The Northern Adriatic Sea
377
Hildenbrandia rubra, Lithoderma sp., Ralfsia verrucosa, Lithophyllum
incrustans) and are shared with the upper sublittoral. Several high-level
spring annuals can likewise join the lowermost stratum of the
associations, such as Bangia a trop urpurea, Ulothrix species, Porphyra
leucosticta, Blidingia minima, dwarf Ulva rigida and various Enteromorpha species.
The level of eulittoral/sublittoral junction, i.e. the intermediate zone
between Fucus virsoides and Cystoseira belts, is usually occupied by
various spring annuals, first of all by Ceramium rubrum, C. diaphanum,
Callithamnion corymbosum, Polysiphonia furcellata, P. elongata, Chylocladia verticillata, Champia parvula, Lomentaria clavellosa, Polysiphonia
sertularioides, Gastroclonium clavatum, Nitophyllum punctatum,
Antithamnion, Aglaothamnion and Griffithsia species. During summer,
this level is usually colonized by Laurencia obtusa, Acetabularia acetabulum and Nemalion helminthoides.
The sublittoral of the northern Adriatic is dominated by associations of
various Cystoseira species, which occur on hard substrata of undisturbed
sites. They were even more prolific before the impact of severe pollution·
(Munda 1979). Cystoseira barbata (Pignatti 1962) is dominant among the
Cystoseira species of the northern Adriatic.!t prefers moderately exposed
sites and its association normally occupies the greater part of the sublittoral
slopes, i.e. between belts of Fucus vir so ides and Sargassum species or other
low-level Cystoseira stands. The biomass within this association was high,
with pronounced summer maxima and ranged from approximately 2800 to
9800 g m -2 on a fresh weight basis (Munda 1973, 1979).
The highest floristic diversity within this as well as other Cystoseira
associations was obvious in the strata of the epiphytes and companion
species, with peaks during spring (Munda 1979). The biomass maxima
during summer usually coincide with minima in species diversity in
most Cystoseira associations from the northern Adriatic. Next in frequency to the Cystoseira barbata association is that of Cystoseira spicata
(c. stricta var. spicata) which is a vicariate to the latter in exposed
habitats. Its zonal position is usually between the high-level Cystoseira
compressa association and that of Sargassum species on rocks or of
Cymodocea nodosa on sandy substrata. A high biomass, upto 7000 g m -2
fresh weight was found in summer. Where the exposure is not too
extreme, a gradual transition, viz. mixed stands of Cystoseira barbata
and C. spicata was found on the mainland coasts. On the islands an
improverishment of floristic diversity was obvious and the understorey
greatly influenced the physiognomy of the settlements.
The vicariate species to the Adriatic Cystoseira spicata are C. stricta
and C. mediterranea in the western Mediterranean and C. amentacea in
377
Hildenbrandia rubra, Lithoderma sp., Ralfsia verrucosa, Lithophyllum
incrustans) and are shared with the upper sublittoral. Several high-level
spring annuals can likewise join the lowermost stratum of the
associations, such as Bangia a trop urpurea, Ulothrix species, Porphyra
leucosticta, Blidingia minima, dwarf Ulva rigida and various Enteromorpha species.
The level of eulittoral/sublittoral junction, i.e. the intermediate zone
between Fucus virsoides and Cystoseira belts, is usually occupied by
various spring annuals, first of all by Ceramium rubrum, C. diaphanum,
Callithamnion corymbosum, Polysiphonia furcellata, P. elongata, Chylocladia verticillata, Champia parvula, Lomentaria clavellosa, Polysiphonia
sertularioides, Gastroclonium clavatum, Nitophyllum punctatum,
Antithamnion, Aglaothamnion and Griffithsia species. During summer,
this level is usually colonized by Laurencia obtusa, Acetabularia acetabulum and Nemalion helminthoides.
The sublittoral of the northern Adriatic is dominated by associations of
various Cystoseira species, which occur on hard substrata of undisturbed
sites. They were even more prolific before the impact of severe pollution·
(Munda 1979). Cystoseira barbata (Pignatti 1962) is dominant among the
Cystoseira species of the northern Adriatic.!t prefers moderately exposed
sites and its association normally occupies the greater part of the sublittoral
slopes, i.e. between belts of Fucus vir so ides and Sargassum species or other
low-level Cystoseira stands. The biomass within this association was high,
with pronounced summer maxima and ranged from approximately 2800 to
9800 g m -2 on a fresh weight basis (Munda 1973, 1979).
The highest floristic diversity within this as well as other Cystoseira
associations was obvious in the strata of the epiphytes and companion
species, with peaks during spring (Munda 1979). The biomass maxima
during summer usually coincide with minima in species diversity in
most Cystoseira associations from the northern Adriatic. Next in frequency to the Cystoseira barbata association is that of Cystoseira spicata
(c. stricta var. spicata) which is a vicariate to the latter in exposed
habitats. Its zonal position is usually between the high-level Cystoseira
compressa association and that of Sargassum species on rocks or of
Cymodocea nodosa on sandy substrata. A high biomass, upto 7000 g m -2
fresh weight was found in summer. Where the exposure is not too
extreme, a gradual transition, viz. mixed stands of Cystoseira barbata
and C. spicata was found on the mainland coasts. On the islands an
improverishment of floristic diversity was obvious and the understorey
greatly influenced the physiognomy of the settlements.
The vicariate species to the Adriatic Cystoseira spicata are C. stricta
and C. mediterranea in the western Mediterranean and C. amentacea in