Geodynamic evolution of ophiolites from Albania and Greece (Dinaric-Hellenic belt): one, two, or more oceanic basins?

All the geological constraints for an exhaustive reconstruction of the Triassic to Tertiary tectonic history of the southern Dinaric-Hellenic belt can be found in Albania and Greece. This article aims to schematically reconstruct this long tectonic evolution primarily based on a detailed analysis of the tectonic setting, the stratigraphy, the geochemistry, and the age of the ophiolites. In contrast to what was previously reported in the literature, we propose a new subdivision on a regional scale of the ophiolite complexes cropping out in Albania and Greece. This new subdivision includes six types of ophiolite occurrences, each corresponding to different tectonic units derived from a single obducted sheet. These units are represented by: (1) sub-ophiolite mélange, (2) Triassic ocean-floor ophiolites, (3) metamorphic soles, (4) Jurassic fore-arc ophiolites, (5) Jurassic intra-oceanic-arc ophiolites, and (6) Jurassic back-arc basin ophiolites. The overall features of these ophiolites are coherent with the existence of a single, though composite, oceanic basin located east of the Adria/Pelagonian continental margin. This oceanic basin was originated during the Middle Triassic and was subsequently (Early Jurassic) affected by an east-dipping intra-oceanic subduction. This subduction was responsible for the birth of intra-oceanic-arc and back-arc oceanic basins separated by a continental volcanic arc during the Early to Middle Jurassic. From the uppermost Middle Jurassic to the Early Cretaceous, an obduction developed, during which the ophiolites were thrust westwards firstly onto the neighboring oceanic lithosphere and then onto the Adria margin.     

First evidence of altered vitellogenin-like protein levels in clam Tapes philippinarum and in cockle Cerastoderma glaucum from the Lagoon of Venice

Possible xenoestrogenic effects were investigated, for the first time, in two bivalve species from the Lagoon of Venice (Italy): the clam Tapes philippinarum and the cockle Cerastoderma glaucum. Bivalves were collected far from their reproductive phase at the very early stage of gametogenesis (January), and in the pre-spawning period (June) in six sites. Vitellogenin (Vg)-like proteins (a biomarker of exposure to estrogenic compounds) were measured by the alkali-labile phosphate method (ALP), in both haemolymph and digestive gland from males and females (when it was possible to distinguish sex by microscopic observation of gonadal tissue). Haemolymph calcium concentrations (a parameter considered closely related to the presence of Vg-like proteins) and the bivalve condition index (CI) were also measured. In both seasons, bivalves collected at Campalto (near a sewage treatment plant) and Marghera (a highly contaminated area) had higher Vg-like protein levels, particularly in haemolymph, than animals from the other sampling sites. Interestingly, CI had high values in these polluted sites. In June only, Vg-like proteins and Ca(2+) levels in haemolymph exhibited similar trends in both bivalve species at most sampling sites. The responsiveness of bivalves to environmental xenoestrogens was higher in June, allowing better discrimination among sites. The present study demonstrates that animals from highly polluted areas have increased Vg-like protein levels. As endocrine disruption due to exposure to estrogenic compounds may cause fertility reduction, alterations in the sex ratio, and a decrease in reproductive rate, a condition of potential risk for bivalve populations in estuarine areas is highlighted.     

Effects of 4-nonylphenol exposure in mussels (Mytilus galloprovincialis) and crabs (Carcinus aestuarii) with particular emphasis on vitellogenin induction

Since it is often difficult to estimate possible adverse effects due to contamination in selected ecosystems, multi-species biomonitoring may provide more information, taking into account different routes of exposure, ecological roles and metabolic capabilities of animals. In this context, we exposed for 7 days the mussel Mytilus galloprovincialis and the crab Carcinus aestuarii to 4-nonylphenol (NP), a well-known xenoestrogen. In mussels (0-0.2 mg NP l(-1)), we measured NP bioaccumulation in soft tissues and vitellogenin (Vg)-like protein levels in digestive glands from both males and females by the alkali-labile phosphate assay (ALP). As no reference data were available for crab exposure, the NP 96-h LC(50) value was previously determined. Then, in sublethally exposed (0-1.0 mg NP l(-1)) male crabs, NP bioaccumulation and Vg levels were measured in hemolymph, gonads and digestive gland. Bioaccumulation of NP increased from 43 to 371 microg g(-1) d.w. in mussels, and from 3.6 to 37 microg g(-1) d.w. in crabs, depending on the NP concentration in water. Dose-dependent Vg-like protein induction was observed in both species, appearing to be related to NP bioaccumulation, although a partial decrease was recorded at the highest concentration tested. A similar trend was observed in both digestive gland and gonad of exposed crabs; Vg increased to a lesser extent, although significantly, in hemolymph. Results demonstrated that NP induces Vg synthesis both in male and female mussels, as well as in male crabs. On the basis of the responsiveness of both species investigated, a multi-species approach is indicated in biomonitoring programmes.