FIRST SURVEY OF MEIOFAUNAL COMMUNITIES IN PORTO PAONE, NISIDA

Nisida is a volcanic islet of the Flegrean Islands archipelago (A Zone of the Campi Flegrei Regional Park). It lies very close to Cape Posillipo, just north of Napoli and it is now connected to the mainland by a stone bridge. The islet has a circular shape, with a flooded crater forming the bay of Porto Paone. In the 1800s Nisida was the site of a Bourbon prison, then an Italian state penitentiary, and, now, a reformatory for juvenile offenders. Since then the access to the island has been limited and this results in a very preserved area, but in the 1900 Nisida was encroached upon by the unsightly steel industry in Bagnoli affecting the state of health of marine communities. The meiofauna (metazoans between 1000 and 45 µm) are a fundamental component of terrestrial, and marine benthic ecosystems, forming an integral element of food webs, and playing a critical role in nutrient recycling. The presence and the abundance of meiofauna taxa will give then an idea on the environmental status after the stop of industrial activity in 1992. Using a morphological approach (GIERE, 2009) we performed a meiofauna survey in Porto Paone, the natural bay of about 19000 m2 on the southwest side of the islet. Sampling were made from January to June in 12 areas resulting by the division of Porto Paone bay in three concentric loops subdivided in quorters. In each areas we collected 4 samples trying to cover all kind of substrate present. The fauna, narcotized with MgCl2 at 7.0%, was then fixed and preserved in a 10% neutral formalin solution, previously added with Bengal Rose. The extraction, repeated three times, was performed by gradient centrifugation of Ludox AM-30 (d = 1.210), and filtering the supernatant by means of two sieves (1.0 and 0.063 mm) overlapped (PFANNKUCHE and THIEL, 1988), animals retained on the finer sieve were then identified to taxon. Statistical analyses were performed with ANOVA. We found a discrete diversity resulting in the presence of many phyla representatives including very sensitive taxa like Tardigrada. Given that, to date, no data are available on the meiofauna in Porto Paone, beside an old report on the presence of a new Gastrotricha (BODEN, 1965), this work represent a starting point to monitor the environmental recovering of the Flegrean marine area.