A benthic mucilage event in North-Western Mediterranean Sea and its possible relationships with the summer 2003 European heatwave: short term effects on littoral rocky assemblages

In this contribution we document an anomalous mucilage growth which occurred in June 2003 along the rocky cliffs of the Portofino Promontory (Ligurian Sea, NW Mediterranean Sea), and we describe its dynamics and its negative effects on many benthic taxa. The zooxanthellate scleractinian Cladocora caespitosa underwent ‘bleaching’ and about 40% of biomass of the erect algae was detached by mucilage ‘lianas’ created and strengthened by bottom currents. The 2003 event differed from any other previously occurred in the northern Tyrrhenian Sea, in that the mucilage aggregates were formed by the free‐living form of the Phaeophyceae Acinetospora crinita (Harvey) Kornmann, a not usually dominant species in mucilage aggregates from the north Tyrrhenian Sea. The damage suffered by the benthic organisms living in this area was curtailed by a severe storm, occurred in July, which removed the mucilage to deeper depths, preventing irreversible damages. Only slow growing, perennant organisms, such as corallinales or scleractinians, were seriously affected, but a survey carried out 1 year later, in June 2004, allowed to appreciate a complete recovery of those organisms. This anomalous mucilage event occurred in coincidence of the 2003 European heatwave, and the anomalous temperature increase of seawater has to be regarded as the major contributing event that led to the mucilage outbreak.     

Monitoring a Marine Coastal Area: Use of Mytilus galloprovincialis and Mullus barbatus as Bioindicators

Abstract. Samples of Mytilus galloprovincialis and Mullus barbatus were collected in eight coastal sites along the South Adriatic and Ionic coasts of Italy in spring 2000 for a survey of coastal pollution in the Mediterranean basin. Specimens were analysed using an integrated approach based on residue analysis of common aquatic pollutants like organochlorines such as hexachlorobenzene (HCB), DDTs and polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), heavy metals and nonylphenols (NPnE) and biomarker responses such as acetylcholinesterase (AChE) activity, and the two specific P450 activities benzo(a)pyrene monooxygenase (BPMO) and 7-ethoxyre-sorufin-(9-deethylase (EROD). Biological and morphological parameters like somatic liver index (SLI), gonadosomatic index (GSI) and gonadal and gamete histology (eggs and sperms) were also evaluated in red mullet samples. A contamination gradient in which several hot spots occur were revealed in this study. The hot spots account for high levels of organochlorines in both species near incinerators and of PAHs in harbour areas. Levels of both NPnE and AChE activity were highest in two protected marine areas and were within detectable limits in others. This finding was confirmed by P450 activities, in which maximum levels were detected in harbours and protected marine areas. No morphological alterations of male and female gonads were observed on the histological level.     

Forecasting the evolution in the mixing regime of a deep subalpine lake under climate change scenarios through numerical modelling (Lake Maggiore,Northern Italy/Southern Switzerland)

Climate Dynamics - The impact of air temperature rise is eminent for the large deep lakes in the Italian subalpine district, climate change being caused there by both natural phenomena and...     

Distribution and population structure of deep‐dwelling red coral in the Northwest Mediterranean

Commercially harvested since ancient times, the highly valuable red coral Corallium rubrum (Linnaeus, 1758) is an octocoral endemic to the Mediterranean Sea and adjacent Eastern Atlantic Ocean, where it occurs on rocky bottoms over a wide bathymetric range. Current knowledge is restricted to its shallow populations (15–50 m depth), with comparably little attention given to the deeper populations (50–200 m) that are nowadays the main target of exploitation. In this study, red coral distribution and population structure were assessed in three historically exploited areas (Amalfi, Ischia Island and Elba Island) in the Tyrrhenian Sea (Western Mediterranean Sea) between 50 and 130 m depth by means of ROV during a cruise carried out in the summer of 2010. Red coral populations showed a maximum patch frequency of 0.20 ± 0.04 SD patches·m^?1 and a density ranging between 28 and 204 colonies·m^?2, with a fairly continuous bathymetric distribution. The highest red coral densities in the investigated areas were found on cliffs and boulders mainly exposed to the east, at the greatest depth, and characterized by medium percentage sediment cover. The study populations contained a high percentage (46% on average) of harvestable colonies (>7 mm basal diameter). Moreover, some colonies with fifth‐order branches were also observed, highlighting the probable older age of some components of these populations. The Ischia population showed the highest colony occupancy, density and size, suggesting a better conservation status than the populations at the other study locations. These results indicate that deep dwelling red coral populations in non‐stressed or less‐harvested areas may diverge from the inverse size‐density relationship previously observed in red coral populations with increasing depth.     

The tropical storm Noel and its effects on the territory of the Dominican Republic

In the period between the end of October and the beginning of November 2007, the Dominican Republic was hit by the tropical storm Noel, then turned into hurricane in its movement toward the Californian coasts. The passage of Noel was accompanied by huge precipitation especially in the south-western part of the country. In some areas, the rainfall registered in 6 days exceeded 700 mm, i.e., more than two-thirds of the mean annual precipitation. The return periods calculated for this rainfall event vary greatly from region to region: while they locally reach 200 years, such as in San José de Ocoa (50 km west of Santo Domingo), in other areas, as for instance in the territory of the capital Santo Domingo, return periods do not exceed 20 years. The tropical storm caused huge damage both in terms of human victims and economic losses, related to diffused inundations and landslide phenomena, which may be attributed only partially to the exceptionality of the event. As a matter of fact, in many regions, the inadequate answer of the territory—widely characterized by serious problems of land degradation and an almost complete lack of territorial planning—appears to be the major responsible for the occurred negative effects. The impact assessment, based on the calculation of an Impact Index, confirms this statement.     

Organic matter features, degradation and remineralisation at two coastal sites in the Ligurian Sea (NW Mediterranean) differently influenced by anthropogenic forcing

Organic matter (OM) features, degradation and remineralisation were studied in the seawater of a natural coastal site (Marine Protected Area of Portofino) and at an urbanised coastal site (Quarto, Genoa city) of the Ligurian Sea. The accumulation of low trophic value OM and the persistence of phytoplanktonic biomass throughout the year were observed only at the urbanised site. Efficient OM degradation and remineralisation via high-activity (two times higher than at the Portofino site) hydrolytic enzymatic activities (alkaline phosphatase and leucine aminopeptidase) were recorded. This active degradation indicated a generally good resistance of the Quarto system to environmental pressures (coastal inputs and anthropogenic influence). However, the high potential release of recycled inorganic nutrients and the favourable environmental conditions (i.e. higher seawater temperature at the Quarto site and allochthonous inputs), could encourage unpredictable development of the autotrophic fraction, including an already observed dystrophic blooming of toxic microalgae.     

Seasonal and spatial variability of water quality parameters in the Port of Genoa, Italy, from 2000 to 2007

This paper presents the results of the statistical analysis of a set of physico-chemical and biological water quality parameters, monthly collected from 2000 to 2007 in the Genoa Harbour area (Ligurian Sea). We applied multivariate methods, such as principal component analysis (PCA) and dynamic factor analysis (DFA) for investigating the spatial and temporal variability and for providing important background information on pollution problems in the region. PCA evidenced the role of the sewage and river discharges and of the exchanges with the open sea in determining the harbour water quality. DFA was used to estimate underlying common trends in the time series. The DFA results partly show a general improvement of water quality over the 8-years period. However, in other areas, we found inter-annual variations but no significant multi-annual trend. Furthermore, we included meteorological variables in our statistical analyses because of their potential influence on the water quality parameters. These natural forcings explain part of the variability in water quality parameters that are superimposed on the dominating anthropogenic pollution factors.     

The coral assemblages of an off‐shore deep Mediterranean rocky bank (NW Sicily,Italy)

In this study we characterized the deep assemblages dwelling at 200–250 m depth on a large shoal off Capo St. Vito Promontory (Northwestern coast of Sicily, South Tyrrhenian Sea) by means of ROV‐imaging. Two assemblages of suspension feeders, dominated by the gorgonian Callogorgia verticillata and by the black coral Leiopathes glaberrima, together with a tanatocoenosis of the colonial yellow scleractinian coral Dendrophyllia cornigera, were examined. The three main species were significatively distributed into two areas corresponding to different habitat preferences: a more elevated hardground hosting black corals and a gently sloping, silted rocky bottom hosting the other coral species. The study area is subjected to a heavy pressure from the professional fishery, resulting in the mechanical damage of numerous colonies, some of which are then overgrown by various epibionts including a parasitic bioluminescent zoanthid, new for the Mediterranean fauna, and tentatively identified as Isozoanthus primoidus. In the Mediterranean Sea, these deep off‐shore rocky banks are widely known among recreational and professional fishermen due to their rich fish fauna. However, there has been still little effort into quantifying and characterizing the extent of the impact and its consequences on the benthic communities, which may represent, as in this case, only a partial picture of their original structure and extent.     

Local Site Effects in the Town of Benevento (Italy) from Noise Measurements

— The study of ground motion amplification produced by surface geology is extremely interesting in the Benevento area, Southern Italy, as it is characterized by high seismic hazard. The present moderate-to-low seismicity makes the noise method appropriate to estimate the seismic site response in the area. The three components of seismic noise have been recorded in five sites in the Benevento metropolitan area characterized by different surface geology, in order to estimate the seismic site response. In evaluating site amplification effects we used the direct interpretation of amplitude spectra and standard spectral ratio techniques, evaluating sediment-to-bedrock, sediment-to-average and H/V spectral ratios. The temporal evolution of the noise spectra is analysed within one day, in order to assess the stationarity of the noise signal. The noise wavefield properties have been studied through polarization analyses in selected bands of frequency, where spectral peaks are observed to dominate, to better understand the real nature of those peaks. Results give evidence of low amplification levels, missing any correlation between spectral amplitudes and sediment thickness over the basement. We interpret this result as due to the poor impedance contrast between sediments and basement, which is characterized by low values of shear waves velocity. Moreover, sharp amplitude peaks are observed in the raw spectra of the sediment-sites, in the 2–4 Hz frequency band; a numerical simulation interprets this effect as possibly associated with a wide-scale structure, invoking the presence of a sharper impedance contrast at greater depth. At high frequencies the action of ambient noise sources, mainly active on horizontal components of motion, is retained dominant to generate the prominent peaks observed in the H/V spectral ratios; in some cases the presence of a near-surface low-velocity layer can contribute to amplify the seismic motion generated at these frequencies.     

Comments about the drag laws used in hail growth simulations

The values of the drag coefficient (C_D), experimentally obtained by different authors for graupels and hailstones, are carefully analyzed, in order to investigate how the numerical simulations of hail trajectories, which markedly depend on the C_D values assigned to the growing particle, can be improved. It is found that new measurements of C_D should be performed in the whole range of the Reynolds number (Re) of the cloud ice particles. These measurements should be carried out applying the same criterion to define the characteristic variables (particle cross section and dimensions) used to calculate C_D and Re. Furthermore, it is found that the C_D fitting curves should be expressed as a function not only of Re but also of other parameters which represent the particle surface roughness and the departure from the spherical form. Based on this finding, a plausible definition of these variables and the way to introduce them in a hail trajectory calculation are proposed.