Paolo Breber

Environmental heterogeneity patterns and assessment of trophic levels in two Mediterranean lagoons: Orbetello and Varano, Italy

The management of coastal lagoons is of particular interest due to their high economical importance. In spite of their great productivity, coastal lagoons are often impacted by human pressure which produces water eutrophication. The aim of this paper is to assess the trophic state of the two Mediterranean lagoons taking into account chemical-physical parameters, nutrient concentrations and biological parameters. Two Italian lagoons, Orbetello and Varano (respectively located in Tyrrhenian and Adriatic coast, Italy) were studied between May 2003 and April 2005. Both these systems receive treated urban outflows, agricultural effluents and rivers freshwater inputs. Field collected data showed that studied lagoons were characterized by different human and natural pressures. Orbetello showed the highest water eutrophication, highlighted by the trophic index values, while Varano showed lower eutrophication levels except for the summertime. The values of physical, chemical and biological parameters measured in Orbetello and Varano lagoons indicate that a wide spatial and seasonal gradient of the water characteristics was established during the study period, but in particular in winter. This gradient, typical of estuarine systems, was essentially due to the mixing of freshwater, seawater and anthropogenic inputs. Orbetello lagoon seemed much more affected by the urban impact and the fish-farming activities than Varano lagoon, but the latter showed a greater agriculture activities impact as showed by the remote sensing images.

Introduction and Acclimatisation of the Pacific Carpet Clam, Tapes Philippinarum, To Italian Waters

In 1983 the exotic clam Tapes philippinarum was introduced to the lagoons of the north Adriatic as an aquaculture project. The purpose was to surrogate the insufficient production of the nearly identical native T. decussatus. Seed was obtained from European and North American hatcheries. Loose sediment in shallow, non-turbulent but well-flushed waters constitutes the habitat of the species. By 1986 there was evidence that the species was breeding freely and colonising all suitable areas. By 1990 the commercial yield from the culture parcs and natural beds had reached 20,000 tons year-1 furnishing the livelihood to a labour force of about 4,000 units. In the most productive areas densities of > 1,000 ind m-2 are common. Acclaimed as a great success by the fisheries sector, this initiative has been condemned by scientists and environmentalists as infringing the general principle of keeping out alien species and more specifically because the exotic clam is thought to have caused the disappearance of the native sympatric counterpart and generally upsetting the indigenous benthos. Field surveys carried out before and after the arrival of the alien clam show that the accusations are unfounded or cannot be demonstrated.

Distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of some Italian lagoons exploited for aquaculture and fishing activities.

The concentrations of 16 PAHs in surface sediments collected from four Italian lagoons, exploited for aquaculture and fishing activities, during the period 2004–2007, were analysed. Some molecular ratios and Pearson correlations were used in order to estimate the origin of the pollution and similar transport of PAH sources. Principal Component Analysis (PCA) and Cluster Analysis were used in order to highlight dissimilarities among sampling sites. Concentrations of total 16 PAHs varied significantly among the lagoons as well as within the same basin. Sediments of Orbetello lagoon showed the highest level of contamination (mean of 98.78 ng g−1), followed by that in Santa Giusta (48.15 ng g−1), Lesina (31.06 ng g−1) and Varano (25.19 ng g−1). These results were linked to the greater industrialisation and urbanisation of the catchment area of both Orbetello and Santa Giusta compared with Lesina and Varano. A considerable predominance of 4-rings PAHs was observed for Lesina (52%,), Varano (77%), Orbetello (50%) and Santa Giusta (57%) and Pyrene was the dominant compound. On the other hand, phenanthrene is the dominant compound of low molecular weight contaminants for all the studied lagoons. A meaningful pyrolytic contribution to pollution was found in the sediments of Lesina lagoon, dominated by benzo[a]pyrene (7.27 ng g−1) and benz[a]anthracene (4.14 ng g−1), due to intensive traffic. For Varano, an evident petrogenic contamination was observed along the western area, due probably to accidental oil spillage. All 16 PAHs were found to be correlated in Orbetello and Santa Giusta lagoons and the compounds present in Santa Giusta sediments, near the urban centre, were shown to be mainly of pyrolytic origin. A much more complex situation was observed in Orbetello, where a mixed pattern of pyrolytic and petrogenic inputs was observed.

Trace elements in sediments and bioaccumulation in European silver eels (Anguilla anguilla L.) from a Mediterranean lagoon (SE Italy)

Samples of surface sediments and tissues (liver and muscle) of commercially available European silver eels (Anguilla anguilla L.) collected from Varano lagoon (Italy) were analysed to determine trace element contents. Univariate and multivariate analyses were performed to highlight both the differences between sampling sites and the influence of channel discharges. Atomic ratios indices for sediment data and biological enrichment factors (BEF) for eel tissues were calculated in order to evaluate the enrichment factor due to human activities. The highest levels of As (11.9 µg g−1) and Zn (14.1 µg g−1) were observed in the south-eastern zone of the lagoon, which is influenced by urban and agricultural discharges. The low levels of Hg observed in this study (0.04 µg g−1) led us to exclude both natural and human local sources of this element. Trace element concentrations of all elements were lower in muscle than in liver tissue. Significant enrichment of Cu and Zn was found in livers.