378
LM. Munda
the eastern Mediterranean. They form similar associations under comparable ecological conditions.
The Cystoseira compressa association appeared in two different variants. Whereas the high-level variant is characteristic of exposed sites, the
sublittoral one is common in sheltered habitats and is situated higher up
the sublittoral than Cystoseira barbata. Nitrophilous codominants (Dictyota dichotoma, Halopteris scoparia, Ulva rigida) were already found
within this association before the impact of severe pollution.
Further Fucacean associations, characteristic of undisturbed habitats,
are those of Cystoseira adriatica, and C. crinita, which can tolerate a wide
scale of exposure conditions and are found at different levels throughout
the sublittoral. C. corniculata usually grows in deeper water layers. The
low sublittoral Cystoseira species, viz. C. ercegovichii and C. fucoides,
appear usually in patches or as single specimens in between Sargassum
stands and do not deserve an association rank in the northern Adriatic.
Characterisitc of deeper water layers of undisturbed habitats, and
apparently most sensitive, are settlements of Sargassum species, viz. Sargassum acinarium and S. hornschouchii. Their associations were
described by Munda (1979). It is obvious that seasonal variations in
biomass and floristic composition of the low-level Fucacean associations
are less pronounced than in those occupying the upper sublittoral slopes.
It is noteworthy, however, that several tropical floristic elements were
found in the lower sublittoral of the northern Adriatic, such as Halimeda
tuna, Udotea petiolata, Anadyomene stellata along with several Codium
species and the prostrate green alga Palmophyllum crassum.
A scheme of the zonal distribution of main algal belts in undisturbed
sites is presented in Fig. 16.3. A clear zonal distribution of the main
fucoids is obvious along with an intermediate red algal belt at the level of
the eulittoral/sublittoral junction, and the dominance of crustose floristic
elements in deeper water layers (crustose corallines, Peyssonnelia
polymorpha P. rubra, P. squamaria, Zanardinia prototypus). Corallina
officinalis was characteristic for undisturbed sites under conditions of
extreme surf, mainly on steep rocky surfaces around the eulittoral/sublittoral junction and in the upper sublittoral.
16.4 Changes of the Benthic Algal Vegetation
Under the Influence of Eutrophication
By the late 1970s, profound changes in the benthic algal vegetation had
become obvious. They comprised a disappearance of the main Fucacean
LM. Munda
the eastern Mediterranean. They form similar associations under comparable ecological conditions.
The Cystoseira compressa association appeared in two different variants. Whereas the high-level variant is characteristic of exposed sites, the
sublittoral one is common in sheltered habitats and is situated higher up
the sublittoral than Cystoseira barbata. Nitrophilous codominants (Dictyota dichotoma, Halopteris scoparia, Ulva rigida) were already found
within this association before the impact of severe pollution.
Further Fucacean associations, characteristic of undisturbed habitats,
are those of Cystoseira adriatica, and C. crinita, which can tolerate a wide
scale of exposure conditions and are found at different levels throughout
the sublittoral. C. corniculata usually grows in deeper water layers. The
low sublittoral Cystoseira species, viz. C. ercegovichii and C. fucoides,
appear usually in patches or as single specimens in between Sargassum
stands and do not deserve an association rank in the northern Adriatic.
Characterisitc of deeper water layers of undisturbed habitats, and
apparently most sensitive, are settlements of Sargassum species, viz. Sargassum acinarium and S. hornschouchii. Their associations were
described by Munda (1979). It is obvious that seasonal variations in
biomass and floristic composition of the low-level Fucacean associations
are less pronounced than in those occupying the upper sublittoral slopes.
It is noteworthy, however, that several tropical floristic elements were
found in the lower sublittoral of the northern Adriatic, such as Halimeda
tuna, Udotea petiolata, Anadyomene stellata along with several Codium
species and the prostrate green alga Palmophyllum crassum.
A scheme of the zonal distribution of main algal belts in undisturbed
sites is presented in Fig. 16.3. A clear zonal distribution of the main
fucoids is obvious along with an intermediate red algal belt at the level of
the eulittoral/sublittoral junction, and the dominance of crustose floristic
elements in deeper water layers (crustose corallines, Peyssonnelia
polymorpha P. rubra, P. squamaria, Zanardinia prototypus). Corallina
officinalis was characteristic for undisturbed sites under conditions of
extreme surf, mainly on steep rocky surfaces around the eulittoral/sublittoral junction and in the upper sublittoral.
16.4 Changes of the Benthic Algal Vegetation
Under the Influence of Eutrophication
By the late 1970s, profound changes in the benthic algal vegetation had
become obvious. They comprised a disappearance of the main Fucacean