Preprint volume - SIBM

Pre-print Volume - Posters
BENTHOS COMMITEE
The most abundant macroalgae species were the Phaeophyceae Ascocyclus orbicularis
(J. Agardh) Kjelman and Sphacelaria sp., the Rhodophyta Acrothamnion preissii
(Sonder) E.M. Wollaston and Gayliella flaccida (Harvey ex Kutzing) T.O. Cho & L.J.
McIvor; the most abundant species among the fauna were the Hydrozoa Plumularia
obliqua (Johnston, 1847), the Bryozoa Electra posidoniae (Gautier, 1957),
Fenestrulina malusii (Audouin, 1826) and Tubulipora flabellaris (O. Fabricius, 1780)
and the Foraminifera .
Concerning the red encrusting algae, it was very difficult to define the percentage
cover of each present species (Hydrolithon boreale (Foslie) Y.M. Chamberlain,
Hydrolithon cruciatum (Bressan) Y.M. Chamberlain, Hydrolithon farinosum (J.V.
Lamouroux) D. Penrose & Y.M. Chamberlain, Pneophyllum fragile (Kutzing, 1843),
so we defined one group (Hydrolithon- Pneophyllum spp.) which included all species
of both genera (Giovannetti et al., 2006).
The results showed that the macroalgal epiphytic assemblage (specific percentage
cover) is more developed on transplanted shoots than on natural shoots; the result was
opposite for the animal epiphytic assemblage. Concerning the epiphytic assemblage in
its totality, the results highlighted that the specific richness was more abundant on
transplanted shoots.
ANOVA analysis showed a significant difference between natural and transplanted
shoots only for Foraminifera and Electra posidoniae.
PERMANOVA analysis showed a significant difference among natural and
transplanted shoots and the nMDS ordination of epiphytic assemblage showed 2
separate groups.
Conclusions – The results illustrated a possible difference in the structure of
assemblages of P. oceanica epiphytes between natural and transplanted shoots.
However, it is necessary to highlight the different shoot density in the two studied
conditions. Competition for light plays an important role in structuring marine
communities and there is circumstantial evidence to indicate that light is a primary
factor influencing algal recruitment and growth (Trautman & Borowitzka, 1999): it is
likely that the reduced shoot density of artificial meadow (20 shoots/m 2 ) has permitted
a higher irradiation on the transplanted shoots, which may have influenced the
epiphytic algal community’s abundance and composition.
The results obtained suggest that future studies aimed at detecting epiphytic
community’s difference between natural and transplanted shoots should specifically be
focused on density shoots and seasonality of sampling.
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