Page 1 - Pardi&al_2006

Marine Ecology. ISSN 0173-9565

ORIGINAL ARTICLE

Spatial variability of Posidonia oceanica (L.) Delile
epiphytes around the mainland and the islands of Sicily
(Mediterranean Sea)

Giuseppina Pardi, Luigi Piazzi, David Balata, Ilaria Papi, Francesco Cinelli & Lisandro
Benedetti-Cecchi

Dipartimento di Biologia, Universita` di Pisa, Pisa, Italy

Keywords Abstract
Epiphytes; Mediterranean Sea; Posidonia
oceanica; Sicily; small islands; spatial This paper investigates patterns of variability in epiphytes of Posidonia oceanica
variability. leaves at various spatial scales around Sicily, including geographical differences
among the Mediterranean basins, differences between the small islands and
Correspondence mainland, and the variability among and within replicated meadows in each of
Giuseppina Pardi, Dipartimento di Biologia, the previous conditions. Data on percentage cover of the most common
Via Volta 6, Pisa, Italy. epiphytic organisms were analysed by univariate techniques. Encrusting red
E-mail: gpardi@biologia.unipi.it algae, encrusting brown algae, filamentous algae, encrusting bryozoans, erect
bryozoans, hydroids and Foraminifera were the most abundant taxa. Significant
Accepted: 12 July 2006 differences in the abundance of taxa were detected among geographical regions,
while no significant differences were found between the islands and mainland.
doi:10.1111/j.1439-0485.2006.00099.x At smaller scales, variability was concentrated mostly among leaves 100s of cen-
timetres apart and among meadows a few kilometres apart. These results sug-
gest that both geographical and local processes are important in structuring the
epiphytes of P. oceanica leaves in this area of the Mediterranean.

Problem bance, as changes in the abundance and composition of
assemblages occur in relation to variation in environmen-
Seagrass meadows are among the most important marine tal conditions (May 1982; Borum 1985; Frankovich &
ecosystems, contributing significantly to the productivity Fourqurean 1997).
of shallow coastal areas of both temperate and tropical
waters (Pergent et al. 1994; Cambridge & Hocking 1997). In P. oceanica, ESL are also more sensitive to environ-
In the Mediterranean Sea, Posidonia oceanica (L.) Delile is mental changes than the plant host (Panayotidis 1980).
the more widespread seagrass, forming broad meadows Delgado et al. (1999) illustrated an increase in the bio-
that may extend from the surface to about 40 m depth. mass of P. oceanica epiphytes sampled close to the sites of
discharge of nutrient and organic matter. Recently, a
Epiphytes of seagrass leaves (ESL) play an important study conducted in the north-west Mediterranean showed
role in ecosystem functioning. The algal epiphytes may different patterns of spatial variability in the epiphytes of
contribute significantly to the primary production of the P. oceanica between disturbed and undisturbed locations,
meadow (Mazzella et al. 1992; Moncreiff et al. 1992; Nel- even if no effects were observed on the structure of entire
son & Waaland 1997; Lepoint et al. 1999), while whole assemblages (Piazzi et al. 2004a).
assemblages including both algae and invertebrates are an
important food resource for many organisms (Buia et al. Understanding the spatial and temporal patterns of
1992; Klumpp et al. 1992). Moreover, ESL are considered variability in populations and assemblages is important to
sensitive indicators of natural and anthropogenic distur- discriminate between natural changes and human-induced
effects (Underwood 1993; Benedetti-Cecchi 2001; Fraschetti

Marine Ecology 27 (2006) 397–403 ª 2006 The Authors. Journal compilation ª 2006 Blackwell Publishing Ltd 397