Time-course evaluation of ROS-mediated toxicity in mussels, Mytilus galloprovincialis, during a field translocation experiment

Harbours can be considered as model environments for developing and validating field monitoring procedures and to investigate mechanistic relationships between different biological responses. In this study several biomarkers were investigated in marine mussels caged for 4 weeks (June-July 2001) into an industrialized harbour of NW Italy. Organisms were collected at different time-intervals to better characterize the sensitivity, temporal variations and interactions of analysed responses. Besides single antioxidants the total oxyradical scavenging capacity (TOSC) assay was used to analyse the capability of the whole antioxidant system to neutralize specific forms of radicals: these data were further integrated by measurement of DNA integrity, oxidized bases and the impairment of lysosomal membrane stability in haemocytes. Results showed a biphasic trend for single antioxidants and TOSC, with an increase during the first 2 weeks of exposure to the polluted site followed by a progressive decrease up to a severe depletion in the final part of the experiment.     

Size matters more than method: Visual quadrats vs photography in measuring human impact on Mediterranean rocky reef communities

The performances of two commonly used non-destructive sampling procedures for rocky benthic assemblages (i.e. photography and visually assessed quadrats) were compared. A damaging human activity, date mussel (Lithophaga lithophaga) harvesting (DMH), was chosen. Directly impacted sites were compared with reference conditions (controls). Both visual quadrats and photography were equally able to detect differences between impacted situations and controls. However, visual quadrats showed high variability among replicates and estimated higher species richness for controls, while photography did so for impacts. Pooling photos in a ‘sum photo quadrat’ showed that differences between the two methods are due to sampling unit size rather than sampling procedure itself. As a small sampling unit is unavoidable with photography, visual quadrats should be preferred in investigating shallow rocky reefs for their larger size; however, longer working time underwater with quadrats does not allow for numerous replicates. Pooling many photos to reach sampling sizes comparable with those of quadrats may be a valid alternative to reconcile image resolution and areal coverage.     

A Bayesian procedure for Probabilistic Tsunami Hazard Assessment

In this paper, a Bayesian procedure is implemented for the Probability Tsunami Hazard Assessment (PTHA). The approach is general and modular incorporating all significant information relevant for the hazard assessment, such as theoretical and empirical background, analytical or numerical models, instrumental and historical data. The procedure provides the posterior probability distribution that integrates the prior probability distribution based on the physical knowledge of the process and the likelihood based on the historical data. Also, the method deals with aleatory and epistemic uncertainties incorporating in a formal way all sources of relevant uncertainty, from the tsunami generation process to the wave propagation and impact on the coasts. The modular structure of the procedure is flexible and easy to modify and/or update as long as new models and/or information are available. Finally, the procedure is applied to an hypothetical region, Neverland, to clarify the PTHA evaluation in a realistic case.     

Volcanic history of the Island of Ischia (South Italy)

New K-Ar dates on Ischia volcanic rocks are reported in order to reconstruct the temporal evolution of volcanic activity and to estimate the rate of associated energy release. The most probable age of eruption of the « green tuff » pumice flows forming the horst in the central part of the island is 0.74 (±0.09) m.y. The formation of the horst occurred in the time span 0.7–0.3 m.y. The subsequent volcanic activity was episodic. The oldest formations (0.37–0.31 m.y.) were formed by lava lake activity with small energy content, whereas formations younger than 0.1 m.y. were formed by eruptions characterized by higher explosivity and energetic content. No ages in the interval 0.31 (±0.02) ?0.10 (±0.07) have been found. Geological considerations also suggest that volcanic activity was very weak or absent in Ischia during this time interval. The different energies and characteristics of the eruption at Ischia in relation to the tectonic pattern are used to evaluate the volcanic risk for the island.     

A thermal model of the magma reservoir feeding Plinian eruptions at Mt. Vesuvius (Italy)

A theoretical thermal model has been worked out for the magma reservoir that would have fed the two last Plinian eruptions of Mt. Vesuvius (Barberi et al., 1981). The effect of convective motions is discussed, and it is shown that the size of convective cells and the efficiency of the process in smoothing out temperature gradients evolves in time due to the progressive viscosity increase produced by the heat lost by conductive heat transfer through the host rock. Although convection will be important throughout the history of the reservoir, until very high viscosities are reached, the pure conductive model seems to account satisfactorily for the cumulative heat loss by the reservoir. Gravitative crystal settling can occur, even in presence of convective motions, mostly during several hundred years after the magma emplacement when viscosity is not yet increased to high values.     

Radon anomalies and volcanic eruptions

A well-documented case of ²²²Rn anomaly preceding the eruptive activity of Karymsky volcano (Kamchatka) was recently reported in the literature. Stimulated by this example, we have attempted to utilize the available data on radon emanation from rocks, its solubility, and its circulation in waters to discuss how a ²²²Rn anomaly can be produced by magma approaching the surface. It is shown that the most likely process of radon release is the flushing of gases through pore fluids. Heating of extensive fracture surfaces by high-temperature gases may also be important. In order to survive in detectable amounts after moving distances greater than a few meters, radon must be transported by fast-moving fluids, such as those rising toward the surface through a fracture or in the ascending limbs of fluids convecting in very porous rocks under high temperature gradients. The pattern observed at Karymsky volcano is interpreted on the basis of these relations.     

Fault-plane solutions and seismicity of the Italian peninsula

A new fault-plane solution map of the Italian peninsula is presented in this paper. The earthquakes analyzed are included in the period 1905–1980, with magnitudes ranging 4–7, 75 earthquakes are located in the crust, while 31 are related to the deep and intermediate zone of the Calabrian arc. The large seismic events of the Italian peninsula are generally associated with normal faulting, while strike-slip motion is mostly related to small earthquakes, located along lateral segments of the mountain chain.The deep and intermediate earthquakes of the Tyrrhenian Sea indicate predominant down-dip compression, and strike-slip motion at the boundaries of this Benioff zone. This last is interpreted as a remnant of a subduction zone, active since Oligocene, extending to 500 km depth, with a very small lateral size (about 300 km). The present tectonics of this Benioff zone is strongly conditioned by the lateral bending, more so than the gravitational sinking process.The coexistence of thrust and normal faulting motion associated to the earthquakes, within a few tens of kilometers of each other, seems to be explained by the strong lateral inhomogeneities of the crustal rocks present in this region, more so than to the depth of the seismogenetic zone and the nature of the faulting process.     

Time-course evaluation of ROS-mediated toxicity in mussels, Mytilus galloprovincialis, during a field translocation experiment

Harbours can be considered as model environments for developing and validating field monitoring procedures and to investigate mechanistic relationships between different biological responses. In this study several biomarkers were investigated in marine mussels caged for 4 weeks (June–July 2001) into an industrialized harbour of NW Italy. Organisms were collected at different time-intervals to better characterize the sensitivity, temporal variations and interactions of analysed responses. Besides single antioxidants the total oxyradical scavenging capacity (TOSC) assay was used to analyse the capability of the whole antioxidant system to neutralize specific forms of radicals: these data were further integrated by measurement of DNA integrity, oxidized bases and the impairment of lysosomal membrane stability in haemocytes. Results showed a biphasic trend for single antioxidants and TOSC, with an increase during the first 2 weeks of exposure to the polluted site followed by a progressive decrease up to a severe depletion in the final part of the experiment.     

Probabilistic tsunami hazard assessment for Messina Strait Area (Sicily, Italy)

The general modular Bayesian procedure is applied to provide a probabilistic tsunami hazard assessment (PTHA) for the Messina Strait Area (MSA), Italy. This is the first study in an Italian area where the potential tsunamigenic events caused by both submarine seismic sources (SSSs) and submarine mass failures (SMFs) are examined in a probabilistic assessment. The SSSs are localized on active faults in MSA as indicated by the instrumental data of the catalogue of the Italian seismicity; the SMFs are spatially identified using their propensity to failure in the Ionian and Tyrrhenian Seas on the basis of mean slope and mean depth, and using marine geology background knowledge. In both cases the associated probability of occurrence is provided. The run-ups were calculated at key sites that are main cities and/or important sites along the Eastern Sicily and the Southern Calabria coasts where tsunami events were recorded in the past. The posterior probability distribution combines the prior probability and the likelihood calculated in the MSA. The prior probability is based on the physical model of the tsunami process, and the likelihood is based on the historical data collected by the historical catalogues, background knowledge, and marine geological information. The posterior SSSs and SMFs tsunami probabilities are comparable and are combined to produce a final probability for a full PTHA in MSA.