CHAPTER. 37
Seasonal Trends in the Adriatic Seagrass Communities
of Posidonia oceanica (L.) Delile, Cymodocea nodosa (Ucria)
Ascherson, Zostera marina L.: Plant Phenology,
Biomass Partitioning, Elemental Composition and Faunal Features
P. Guidetti, M.C. Buia, M. Lorenti, M.B. Scipione, V. Zupo, and L. Mazzella
ABSTRACT
Three seagrass systems, represented by Posidonia oceanica(L.) Delile, Cymodocea nodosa (Ucria)
Ascherson and ZosteramarinaL., were studied on a yearly cycle in their seasonal evolution in different sites of the Adriatic Sea. The aim of this studYI conducted in the frame of the programme
PRISMA 2 (Programma diRicerca e Sperimentazione per 10 Salvaguardia del mare Adriatico) was to
follow the temporal patterns of these seagrass ecosystems in the Adriatic Sea, in order to investigate their functional mechanisms. Structural attributes of the meadows (Le. shoot density and
phenological parameters) were measured and biomass contributions of the different plant compartments and associated communities (epiphytes and vagile fauna) were estimated. Analyses
of macro nutrients (carbon and nitrogen) of plant compartments and associated communities
were aimed at identifying their relative proportion within the living part ofthe ecosystem. Shoot
density showed a marked seasonality in C nodosaand in Z marina, while it was constant, as well
known, in P. oceanica. Some phenological and structural parameters (i.e. shoot density, leaf
length, LAO varied seasonally, in the different seagrasses, following patterns in accordance with
plant eco-physiology. Total biomass was highest in P. oceanica. Different plant compartments
(above- vs below-ground) contributed differently to the total biomass in the investigated seagrass species. In P. oceanica and C nodosa, below-ground parts accounted for the highest biomass through the year, while in Z marina above- and below-ground contributions were more
balanced. The study of carbon and nitrogen composition of different seagrass organs showed a
comparative stability of carbon content over time, whereas nitrogen levels followed welldefined seasonal trends in each of the three species, with maxima generally occurring in winter,
except for C nodosa. The patterns observed point to the occurrence of different strategies
among the three species at more than one level.
Introduction
The paramount importance of seagrasses for the
dynamics and productivity of coastal waters has
been largely described for several seas (Larkum
et al. 1989). As regards the Adriatic Sea, early
studies testify to their widespread and functional importance in coastal systems (Benacchio
1938). Marine phanerogams, in fact, are able to
colonize different coastlines and types of substrata, according to their life requirements and
adaptations to the marine and/or estuarine environments. It is interesting that all five species of
marine phanerogams recorded in the
Mediterranean Sea, Posidonia oceanica (L.)
Delile. Cymodocea nodosa (Ucria) Ascherson,
Zostera noltii Hornemann, Zostera marina L.,
Halaphila stipulacea (Forsskal) Ascherson, are
present in the Adriatic Sea, emphasizing the
importance and peculiarity of the basin. The
Adriatic Sea, in fact, is located at the centre of the
Mediterranean basin and extends along a wide
latitudinal gradient. The consequent variety of
climatic conditions and marine environments
highlights the importance of Adriatic seagrass
systems in maintaining marine biodiversity.
On the basis of the spread or the peculiarity
of their distributional patterns, the seagrasses R
oceanica, C. nodosa and Z. marina are of major
interest. R oceanica is distributed along the
Stazione Zoologica "A. Dohrn", Laboratorio di .Ecologia del Benthos, Punta S. Pietro, 80077 Ischia (Napoli), Italy
EM. Faranda, L. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structure& and Processes
o Springer-Verlag ltalia 2001
Seasonal Trends in the Adriatic Seagrass Communities
of Posidonia oceanica (L.) Delile, Cymodocea nodosa (Ucria)
Ascherson, Zostera marina L.: Plant Phenology,
Biomass Partitioning, Elemental Composition and Faunal Features
P. Guidetti, M.C. Buia, M. Lorenti, M.B. Scipione, V. Zupo, and L. Mazzella
ABSTRACT
Three seagrass systems, represented by Posidonia oceanica(L.) Delile, Cymodocea nodosa (Ucria)
Ascherson and ZosteramarinaL., were studied on a yearly cycle in their seasonal evolution in different sites of the Adriatic Sea. The aim of this studYI conducted in the frame of the programme
PRISMA 2 (Programma diRicerca e Sperimentazione per 10 Salvaguardia del mare Adriatico) was to
follow the temporal patterns of these seagrass ecosystems in the Adriatic Sea, in order to investigate their functional mechanisms. Structural attributes of the meadows (Le. shoot density and
phenological parameters) were measured and biomass contributions of the different plant compartments and associated communities (epiphytes and vagile fauna) were estimated. Analyses
of macro nutrients (carbon and nitrogen) of plant compartments and associated communities
were aimed at identifying their relative proportion within the living part ofthe ecosystem. Shoot
density showed a marked seasonality in C nodosaand in Z marina, while it was constant, as well
known, in P. oceanica. Some phenological and structural parameters (i.e. shoot density, leaf
length, LAO varied seasonally, in the different seagrasses, following patterns in accordance with
plant eco-physiology. Total biomass was highest in P. oceanica. Different plant compartments
(above- vs below-ground) contributed differently to the total biomass in the investigated seagrass species. In P. oceanica and C nodosa, below-ground parts accounted for the highest biomass through the year, while in Z marina above- and below-ground contributions were more
balanced. The study of carbon and nitrogen composition of different seagrass organs showed a
comparative stability of carbon content over time, whereas nitrogen levels followed welldefined seasonal trends in each of the three species, with maxima generally occurring in winter,
except for C nodosa. The patterns observed point to the occurrence of different strategies
among the three species at more than one level.
Introduction
The paramount importance of seagrasses for the
dynamics and productivity of coastal waters has
been largely described for several seas (Larkum
et al. 1989). As regards the Adriatic Sea, early
studies testify to their widespread and functional importance in coastal systems (Benacchio
1938). Marine phanerogams, in fact, are able to
colonize different coastlines and types of substrata, according to their life requirements and
adaptations to the marine and/or estuarine environments. It is interesting that all five species of
marine phanerogams recorded in the
Mediterranean Sea, Posidonia oceanica (L.)
Delile. Cymodocea nodosa (Ucria) Ascherson,
Zostera noltii Hornemann, Zostera marina L.,
Halaphila stipulacea (Forsskal) Ascherson, are
present in the Adriatic Sea, emphasizing the
importance and peculiarity of the basin. The
Adriatic Sea, in fact, is located at the centre of the
Mediterranean basin and extends along a wide
latitudinal gradient. The consequent variety of
climatic conditions and marine environments
highlights the importance of Adriatic seagrass
systems in maintaining marine biodiversity.
On the basis of the spread or the peculiarity
of their distributional patterns, the seagrasses R
oceanica, C. nodosa and Z. marina are of major
interest. R oceanica is distributed along the
Stazione Zoologica "A. Dohrn", Laboratorio di .Ecologia del Benthos, Punta S. Pietro, 80077 Ischia (Napoli), Italy
EM. Faranda, L. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structure& and Processes
o Springer-Verlag ltalia 2001