Page 2 - Buia&al2001

Bio!. Mar. Medi!. (2002), 9 (1): 600-604

M.C. BUIA, M.C. GAMBI, F. BADALAMENTI *

Laboratorio di Ecologia del Benthos, Stazione Zoologica "A. Dohm" di Napoli,
Punta S. Pietro - 80077 Ischia, Napoli, Italia.

* Laboratorio di Biologia Marina, CNR, IRPA, Castellammare del Golfo. Trapani, Italia.

MORPHO-CHRONOLOGICAL OBSERVATIONS ON SEEDLINGS
ANO JUVENILE SHOOTS OF POSIDONIA OCEANICA (L.) DELILE

COLLECTED "IN SITU' IN VARIOUS COASTAL AREAS

OSSERVAZIONI MORFO-CRONOLOGICHE SU GERMOGLI E
GIOVANI PIANTE DI POSIDONIA OCEANICA RACCOLTE

IN SITU IN ALCUNE AREE COSTIERE

Abstract
Morpho-chrono/ogical observalions were carried oul on seedlings and jliVeni/e planls of Posidonia ocea-

nica (L.) De/ile (Monocotyledones) collec/ed in silu in differenl areas a/ong lhe /talian coasts. Seedlings of
differenl age, collec/ed al Ustica and Ischia islands {Tyrrhenian Sea) and al Taranto (Ionian Sea), showed high
phenological variability. Juveni/es shoots ofdifferent age collected al Favignana island (l year o/d) and Ustica
(2 years o/d) showed a wide and comparable range of scale thickness (0.12-1.31 mm), and the first evidence
of the beginning of the lepidochronological cycle, detectab/e in the 2-years-o/d shoots.

Key-words: Posidonia oceanica, jlowering, seedlings, phenology, lepidochronology.

Introduction
In the last decade there was an increasing of records of ftowering and fruiting events

of Posidonia oceanica (L.) Delile along the ltalian coasts (Balestri et al., 1998 a). These
records are probably related to the generai warming trend observed in the Mediterra-
nean, both at local and basin scale (Astraldi et al., 1995). However, germination is stili
considered a rather exceptional event, and morphological features of seedlings in situ
has been reported relatively few times (Buia and Piraino, 1989; Gambi et al., 1996;
Piazzi et al., 1996; Gambi and Guidetti, 1998; Balestri et al., 1998 a). Only in recent
years more attention has been paid to P oceanica seed settlements, in relation also to
the potential that sexual reproduction may have for the genetic structure of this seagrass
and gene ftow among different populations (Procaccini and Mazzella, 1998), and for
the possibility of seedling transplantations to restore meadows (Balestri et al., 1998 b).

The aims of the present paper are to add new records on occurrence and morpho-
logy of P oceanica seedlings, recorded in situ at various sites along the Italian coasts,
and to provide the fìrst data on lepidochronology of juvenile plants, in order to detect
if the pattem of cyclic variation in scale thickness, typical of adult shoots, occurs
even during this early phase of the !ife history. Scale thickness in adult shoots shows
annua! cyclic variations (Pergent et al., 1989) commonly attributed to environmental
or internai factors (Pergent-Martini and Pergent, 1994), but no data were available for
juvenile plants.

Materials and methods
Seedlings of P oceanica were sampled at different sites at the island of Ustica

in September 1997, and in a single site at the island of Ischia in June 1998 (Punta