Page 1 - Gambi_Guidetti_1998

Biol. Mar. Mcdir. (1998). 5 ( I ) : 549-552

M.C. GAMBIP,. GUIDETTI

Laboratorio di Ecologia del Benthos. Stazione Zoologica "A. Dohrn" di Napoli,

Punta S. Pietro - 80077 Ischia Porto (Naples). Iialy.

MORPHOLOGICAL OBSERVATIONS ON SEEDLINGS OF
POSIDONIA OCEANICA (L.) DELILE GERMINATED "IN SITU"

OSSERVAZIONI MORFOLOGICHE SU GERMOGLI DI
POSIDONIA OCEANICA (L,) DELILE GERMINATI 'IN SITU"

Abstract

Disiribuiion and morphologicalfeaiures of seedlings of Posidonia oceanica (L.)Delile (Angiospermae,
Poiamogeronaceae) germinated "in siiu" are reporied. Seedlings, observed in Augusi 1995, were seiiled
on hard srrbstraies from 0.5 m io 2 m depih in two siies locaied along ihe souihern coast of ihe Island
of Favignana (Egadi Archipelago, Western Sicily). Mean number of leaves (5.6). of scales (15.5) and
scars (5.6) yielded a ioial mean number of 26.1 leaves produced afier germination. A comparison wiih
literaiure data suggests ihai ihe seedlings found were ai leasi one-year old.

Key-words: Posidonia oceanica, germination, seedlings, morphology, Southem
Tyrrhenian Sea.

Introduction
Records on occurrence of germination and on abundance and distribution of

seedlings of Posidonia oceanica (L.) Delile "in situ" are still too scarce to evaluate
the reproductive success and the role of sexual reproduction in the potential of
colonization at medium and large scale of this key-species. The relatively scanty
information on "in situ" germination actually available (Gambi et al., 1996; Piazzi
et al., 1996 a), seems however to testify an increasing frequency of records in
these last 3-4 years, probably due to an increasing occurrence of flowering events,
evident also along the Italian coasts (Calvo et al., 1995; Balestri et al., 1995;
Boyer et al., 1996), but also to the previous scarcity of observation, generally
lacking in quantitative or phenological data (Giaccone e Sortino, 1974; Brambati
et al., 1980). For this reason it is worthwhile reporting the occurrence of severa1
seedlings of l? oceanica germinated "in situ" in the Island of Favignana (Egadi
Archipelago, Western Sicily), and giving some data on their distribution and
morphological features.

Materials and methods
Seedlings of l? oceanica were observed in middle August 1995 along the

southern coast of the Island of Favignana (37" 58' long. N; 12" 20' lat. E) at
two different sites: Cala Monaci and Cala Rotonda. Both sites are characterized
by rocky shores and by the presence of P. oceanica beds starting at about 3-4
m depth. The bed at Cala Monaci is continuous, while at Cala Rotonda the l?
oceanica meadow shows a patchy distribution. A number of about 50 seedlings
were collected at both sites; some seedlings were still bearing the seed at the