Changes in Venice Lagoon dynamics due to construction of mobile barriers

The MoSE project (construction of mobile barrier to safeguard the Lagoon of Venice) entails changes to the structure of the lagoon's inlets. This could have consequences for the areas near the inlets and for the dynamics of the lagoon ecosystem as a whole. In order to predict the effects of the proposed alterations on the hydrodynamics of the lagoon, a well-tested hydrodynamic-dispersion model was applied. Simulations were carried out considering both idealised and realistic tide and wind scenarios.     

Formation and stability of mixed Mg/Ca/phytate species in synthetic seawater media: Consequences on ligand speciation

The results of a potentiometric investigation (by ISE-H⁺, glass electrode) on the speciation of phytate ion (Phy¹²⁻) in an ionic medium simulating the major components (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻ and SO₄²⁻) of natural seawater, at different salinities and t = 25 °C, are reported. The work was particularly aimed at determining the possible formation of mixed Ca²⁺–Mg²⁺–phytate ion pairs, and to establish how including the formation of these mixed species would affect the speciation modeling in seawater media. After testing various speciation models, that considering the formation of the MgCaH₃Phy⁵⁻, MgCaH₄Phy⁴⁻, Mg₂CaH₃Phy³⁻ and Mg₂CaH₄Phy²⁻ species was accepted, and corresponding stability constants were determined at two salinities (S = 5, 10). A discussion is reported both on the choice of the experimental conditions and on the possibility to extend these results to those typical of real seawater. A detailed procedure is also described to demonstrate that the stability of these species is higher than that statistically predicted. As reported in literature, a parameter, namely log X, has been determined in order to quantify this extra stability for the formation of each mixed species at various salinities. For example, at S = 10, log X₁₁₃ = 2.67 and log X₁₁₄ = 1.37 for MgCaH₃Phy⁵⁻ and MgCaH₄Phy⁴⁻ (statistical value is log X_stat = 0.60), and log X₂₁₃ = 6.11 and log X₂₁₄ = 2.15 for Mg₂CaH₃Phy³⁻ and Mg₂CaH₄Phy²⁻ (log X_stat = 1.43), respectively. Results obtained also showed that the formation of these species may occur even in conditions of low salinity (i.e. low concentration of alkaline earth cations) and low pH (i.e., more protonated ligand).     

Active thrust tectonics in western Sicily (southern Italy): the 1968 Belice earthquake sequence

The 1968 Belice earthquake sequence, characterized by six main shocks with 5 < M < 5.4, represents the strongest seismic event recorded in western Sicily in historical times. The epicentral area is located in the Belice Valley, a region lacking any topographic lineament likely to result from a fault with significant offsets of any kind. Instrumental data show that hypocentres of the major shocks are distributed along a roughly N-dipping plane extending from about 36 km to 1 km depth. Fault plane solutions show pure thrusting mechanisms on N-dipping, ENE-trending planes, or oblique slip with a right-lateral component of motion along steep WSW-dipping planes, both as a result of approximate N-S shortening. The observed destruction indicates that isoseismal areas are elongated in an ENE direction. Similarly, the epiccntral distribution of events with M ≥ 4 outlines a roughly elliptical ENE-elongated area located 20 km NW of the Sciacca-Rocca Ficuzza thrust front. This ENE-striking structure, representing the regional morphotectonic feature closest to the epicentral area, consists of two main imbricate fan systems. In the southernmost system, Quaternary deposits (tentatively dated as 1.0–0.7 Myr old) are involved in a large ramp anticline uplifting them to a maximum altitude of 346 m. The occurrence of Holocene lacustrine piggy-back basins on the rear of this structure also indicates late Quaternary activity of the underlying thrust. Seismological, structural and morphotectonic observations suggest that multiple ruptures might have occurred during the 1968 sequence on a blind crustal thrust ramp located beneath the epicentral area. Slip propagated southwards along the shallow ramp-flat system characterizing the thin-skinned foreland fold and thrust belt of southwestern Sicily, being dispersed in flexural folding processes and diffuse strain along this path.     

The role of transcurrent intra-arc tectonics in the configuration of a volcanic arc

Field investigations show that Plio-Quaternary Mexican and Quaternary Ecuadorian volcanic arcs are coeval with intra-arc transcurrent or transtensional tectonics with motions along faults parallel or subparallel to the arc. This relationship can also be observed in the Quaternary Kamchatka arc. These arcs have an anomalously wide distribution of volcanic centres which cannot be explained simply by a low dip in the subducting lithosphere. Comparison with the intra-arc tectonics and geometry of other Quaternary arcs reveals that strike-slip fault zones, parallel to the arc, favour magma rising in a broad surficial zone and may channel magma feeding mainly huge stratovolcanoes.     

A record of the Messinian salinity crisis in the eastern Ionian tectonically active domain (Greece,eastern Mediterranean)

This integrated study (field observations, micropalaeontology, magnetostratigraphy, geochemistry, borehole data and seismic profiles) of the Messinian–Zanclean deposits on Zakynthos Island (Ionian Sea) focuses on the sedimentary succession recording the pre‐evaporitic phase of the Messinian salinity crisis (MSC) through the re‐establishment of the marine conditions in a transitional area between the eastern and the western Mediterranean. Two intervals are distinguished through the palaeoenvironmental reconstruction of the pre‐evaporitic Messinian in Kalamaki: (a) 6.45–6.122 Ma and (b) 6.122–5.97 Ma. Both the planktonic foraminifer and the fish assemblages indicate a cooling phase punctuated by hypersalinity episodes at around 6.05 Ma. Two evaporite units are recognized and associated with the tectonic evolution of the Kalamaki–Argassi area. The Primary Lower Gypsum (PLG) unit was deposited during the first MSC stage (5.971–5.60 Ma) in late‐Messinian marginal basins within the pre‐Apulian foreland basin and in the wedge‐top (<300 m) developed over the Ionian zone. During the second MSC stage (5.60–5.55 Ma), the PLG evaporites were deeply eroded in the forebulge–backbulge and the wedge‐top areas, and supplied the foreland basin's depocentre with gypsum turbidites assigned to the Resedimented Lower Gypsum (RLG) unit. In this study, we propose a simple model for the Neogene–Pliocene continental foreland‐directed migration of the Hellenide thrusting, which explains the palaeogeography of the Zakynthos basin. The diapiric movements of the Ionian Triassic evaporites regulated the configuration and the overall subsidence of the foreland basin and, therefore, the MSC expression in this area.     

Modeling the influence of hydroperiod and vegetation on the cross-sectional formation of tidal channels

The evolution of the cross section of a salt-marsh channel is explored using a numerical model. Deposition on the marsh platform and erosion and deposition in the channel affect the tidal prism flowing through the cross section, such that the model captures the evolution of the stage–discharge relationship as the channel and marsh platform evolve. The model also captures the growth of salt-marsh vegetation on the marsh platform, and how this vegetation affects flow resistance and the rate of sedimentation. The model is utilized to study the influence of hydroperiod and vegetation encroachment on channel cross section. Numerical results show that a reduction in hydroperiod due to the emergence of the marsh platform causes an infilling of the channel. Vegetation encroachment on the marsh surface produces an increase in flow resistance and accretion due to organic and mineral sedimentation, with important consequences for the shape of the channel cross section. Finally, modeling results indicate that in microtidal marshes with vegetation dominated by Spartina alterniflora, the width-to-depth ratio of the channels decreases when the tidal flats evolve in salt marshes, whereas the cross-sectional area remains proportional to the tidal peak discharge throughout channel evolution.     

Multistatic Sonar Localization

This paper develops bistatic contact-localization statistics as a function of source-target-receiver geometry, source and receiver location errors, sound-speed errors, time and bearing errors, and array-heading errors. We verify the analysis through Monte Carlo simulation and illustrate localization accuracy for some representative choices of source-target-receiver geometry and measurement error assumptions. We examine the improved localization accuracy of multistatic contacts that result from the fusion of multiple sonar contacts     

Linking marine protected areas to integrated coastal and ocean management: A review of theory and practice

If managed in isolation, coastal and marine protected areas (MPAs) are vulnerable to natural resource development and exploitation occurring outside these areas—in particular, overfishing, alteration and destruction of habitats, and water pollution. Thus, protection of coastal and marine areas—of species, habitats, landscapes, and seascapes—should be integrated into spatial development strategies for larger areas, under the umbrella of integrated coastal and ocean management (ICM). This is typically easier said than done, since the actors involved in MPA networks and in ICM programs are often different, reflecting different cultures, networks of relationships, ministries, and goals and motivations.This article reviews the ecological, social and economic linkages between MPAs and the governance of broader ocean and coastal areas; sets forth nine guiding principles for managing MPAs within an ICM context; reviews work conducted under the Convention on Biological Diversity to operationalize the linkages between ICM and MPAs; and develops strategic guidance for addressing these linkages. The article ends with a call to bring together the diverse communities involved in marine protected areas, coastal and ocean management, and watershed management to collaborate in national-level ocean and coastal planning, including in the designation of networks of marine protected areas.