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Grace a un effort soutenu de sensibilisation des plngeurs pecheurs et plaisanciers, de nombreuses donnees cartographiques sur Caulerpa taxifolia on ete recueillies en 1997 par les centres nationaux de coordination du suivi de l’invasion. La plupart des colonies connues en 1996 ont ete de nouveau cartographiees pour evaleuer leur expansion. La synthese de l’ensemble des donnees recueillies au cours de l’annee 1997 se resume ainsi: - 99 zones de colonisation independantes ont ete inventoriees. Les 30 nouvelles zones colonisees repertoriees en 1997 ont ete decouvertes essentiellement dans un rayon de 5 km de celles connues en 1996. Seule une colonie eloignee de plus de 50 km de celles connues en 1996 a ete decouverte a proximite du port de Chiavari, a l’est de Genova, - la surgace totale concernee par l’expansion se Caulerpa taxifolia en Mediterranee a ete evaluee a 4630 ha (3052 fin 1996), - 97 % des surfaces concernees se trouvent toujours entre Toulon (France) et Genova (Italie), le lineaire de cote devant lequel on trouve l’algue est de 81,7 km (58 km en 1996). Ce septieme etat de la situation de l’wxpansion de Caulerpa taxifolia montre, comme pour les annees precedentes, que la progression de l’algue est reguliere et importante.

Accidentaly introduced into the Mediterranean sea in 1984, the tropical alga Caulerpa taxifolia did not stop to spread since then. The ecological and economic threats related to this invasion incited scientist to organize a second international campaign of sensitisation, research and prevention. In 1997, 45.000 leaflets published in 6 languages (French, Italian, Castilian, Catalan, Croatian, and English) were distributed to sea users. The aim is to provide the sea users with precise and updated information on results published since 1990. A description of the alga and advice to reduce man-made dissemination are presented. Divers, yachtsmen, fishermen, and port administrators are requested to warn scientists in charge of C.taxifolia about any new sighting of colonies. This campaign enables the establishment and the consolidation of national and international informant networks which are crucial to the yearly assessment of C.taxifolia spreading in the Mediterranean sea. The expansion of the alga is one of the main element to take into account in the elaboration of a prevention strategy to fight C.taxifolia progression.

A model developed for Zostera marina was adapted and used to select suitable areas for Posidonia oceanica transplantation in the Gulf of Palermo, where recent rehabilitation programmes have reduced human pressure. This model consists of three steps: (1) habitat selection, by calculation of the Preliminary Transplant Suitability Index (PTSI); (2) field assessments and test-transplanting, to evaluate the site suitability and to estimate the effects of tearing on transplant units (about 50%); (3) identification of suitable restoration sites, by calculation of the Transplant Suitability Index (TSI). A new parameter was added to the literature model: the number of grids detached, which is linked to factors (hydrodynamic regime, anchoring, fishing) that have a potentially great effect on the final outcome of the transplant. Only one site (TSI = 16) in the Gulf of Palermo was indicated as potentially suitable for restoration with P. oceanica. In this site, a transplant of 40 m2 was implemented. From 2008 to 2014, transplant effectiveness was evaluated in terms of establishment, detachment and mortality of cuttings and shoot density. The long-term monitoring (6 years) allowed us to detect changes in the structural conditions of the transplanted meadow and to identify the possible turning point in P. oceanica recovery (2 years after transplanting). Moreover, 6 years after transplantation the P. oceanica meadow has exceeded the transplant shoot density of about 16%, with a mean and a maximum value of 11.6 and 17 shoots per cutting, respectively.

Di Maida, G., Tomasello, A., Luzzu, F., Scannavino, A., Pirrotta, M., Orestano, C., and Calvo, S. 2011. Discriminating between Posidonia oceanica meadows and sand substratum using multibeam sonar. – ICES Journal of Marine Science, 68: 12–19. High-resolution, multibeam sonar (MBS) (455 kHz) was used to identify two typologies of seabed 8 m deep: Posidonia oceanica meadow and sandy substratum. The results showed that the heterogeneity of the architecture of the P. oceanica canopy and the relatively simple morphology of a sandy substratum can be detected easily by statistical indices such as standard deviation or range-of-beam depth. Based on these indices, an automated classification was performed for seabed mapping. The overall classification accuracy was as high as 99 and 98% in October and January, respectively. The probability that P. oceanica in situ was omitted on the map was

A high-resolution echosounder was used to acquire seismo-acoustic records of P. oceanica dead matte patches in the Gulf of Palermo. Seismo-acoustic profiling enabled detection of dead matte structures that are invisible to visual inspection, being hidden by variable layers of sandy sediment. The thickness of the dead matte measured reaches a maximum of 2.2 m. The mean volume of the matte per unit area of seabed surface (MEIx) varies from 0.2 to 2.2 m 3 /m 2 , with an average value of 1.6 m 3 /m 2 and a total volume estimated at 73,000 m 3 . From literature data and from the volume of dead matte calculated in the present work we estimated that total carbon accumulated in the matte is about 2,484 tons. Seismo-acoustic technologies proves to be a powerful, non-destructive method to measure the thickness, extension, volume of dead matte and its potential carbon content.

È stato condotto uno studio sulla flora e vegetazione macroalgale dello Stagnone di Marsala (Trapani) con l’obiettivo di fornire una revisione dei dati riportati in letteratura ed esaminare i principali cambiamenti che si sono verificati nell’intera area negli ultimi tre decenni. La flora algale è risultata più povera rispetto al passato (94 taxa contro 108), mostrando un incremento delle Cloroficee e una riduzione delle Rodoficee e delle Feoficee. Solo 48 taxa sono stati riportati precedentemente, mentre 46 sono nuovi per lo Stagnone. Tra questi, è interessante sottolineare sia da un punto di vista floristico che ecologico, il ritrovamento per la prima volta dell’alga bruna Cystoseira compressa (Esper) Gerloff & Nizamuddin e delle alghe invasive Caulerpa cylindracea Sonder e Lophocladia lallemandii (Montagne) F. Schmitz. Al contrario, 60 taxa riportati precedentemente non sono stati trovati nel presente studio. In particolare, si annovera la scomparsa dell’alga verde Lamprothamnium papulosum (Wallroth) Groves e dell’alga bruna Cystoseira barbata (Stackhouse) C. Agardh f. aurantia (Kützing) Giaccone. L’elevato grado di confinamento e la natura del substrato sono stati i principali fattori che hanno influenzato il numero dei taxa e l’abbondanza delle comunità fitobentoniche, con valori massimi nelle stazioni caratterizzate da un buon ricambio idrico e/o dalla presenza di comunità dominate da Cystoseira. Nel presente studio vengono proposte alcune ipotesi per descrivere i cambiamenti nella composizione e struttura delle comunità fitobentoniche all’interno della laguna come conseguenza degli effetti del riscaldamento globale in atto negli ultimi anni. A study of the benthic macroalgal flora and vegetation of the Stagnone di Marsala (Trapani) has been performed in order to provide an up-to-date review of the status of and verify main changes that have occurred in the area over the past three decades. The flora of this study was poorer in taxa than that of literature (94 taxa against 108), with an increase in Chlorophyta and a decrease in Rhodophyta and Phaeophyceae. Only 48 taxa in the present flora have been previously reported, while 46 are new for the Stagnone. Among these, it was noteworthy, from both floristic and ecological point of view, the record for the first time of Cystoseira compressa (Esper) Gerloff & Nizamuddin and the invasive algae Caulerpa cylindracea Sonder and Lophocladia lallemandii (Montagne) F. Schmitz. On the contrary, 60 taxa previously reported have not been detected during the present study. Among these, Lamprothamnium papulosum (Wallroth) Groves and Cystoseira barbata (Stackhouse) C. Agardh f. aurantia (Kützing) Giaccone have been the most significant disappearances. High degree of confinement and sediment composition were the major factors affecting number of taxa and abundance of the phytobenthic communities, with maximum values in the stations characterized by a good water exchange and/or presence of Cystoseira assemblages. As a result of the effects of global warming over the past few years, noticeable changes in composition and structure of phytobenthic communities in the lagoon have been observed and some hypotheses of expected changes are here proposed.

All seagrass species known from the Mediterranean basin have been recorded along the Sicilian coast, where studies have been carried out at a very local scale and information is fragmented or confined to the grey literature. The objective of this article is to summarise and evaluate current knowledge on seagrass species on the Sicilian coasts, providing an overview of species distribution, genetic diversity, biology and ecology, based on the literature and unpublished data. Most literature studies have been carried out on Posidonia oceanica meadows because of their wide distribution, complexity and ecological importance. In this study, the analyses carried out on P. oceanica structural and functional features show that the Sicilian meadows are in good condition with respect to the Mediterranean average, probably because of relatively low anthropogenic pressure and favourable ecological conditions. The available data on this species summarised in this article represent an important starting point from which to build effective plans for understanding levels of environmental threats and for supporting conservation strategies for these important ecosystems. Conversely, the limited information available on other seagrasses only allows the description of some structural and functional features, and does not permit to drive overall conclusions on their general health status.

The Stagnone of Marsala is an oligotrophic lagoon situated on the western coast of Sicily. The area has been under study since the mid-nineteenth century. Research has focused on its physiographic, chemical-physical, biological, ecological features and, particularly, on submerged vegetation. Its main biotic component, a meadow of Posidonia oceanica, is distributed among peculiar reef formations inside and outside the lagoon, which are extremely interesting from an ecological and environmental point of view. The seagrass grows near to its thermal and salinity tolerance level in the inner lagoon, where it is partially replaced by Cymodocea nodosa and Caulerpa prolifera meadows. Algal assemblages are characterised by both attached and/or unattached seaweeds that accumulate in areas of different extension, where they remain lying freely and slowly rolling on the seabed. Over the past few years, as a result of the global climate change, a noticeable reduction in the lagoon biodiversity has occurred due to decreased water exchange, and an increase in both confinement and temperature. Therefore, a consistent, suitable and well organised monitoring plan should be developed for the protection and the recovery of the Stagnone of Marsala lagoon.