The Distribution of Amphipoda in a Brackish-Water Lagoon in Greece

Abstract. The distribution of the benthic Amphipoda was studied in the brackish-water lagoon Mazoma of Amvrakikos Bay, Ionian Sea, Greece. Eleven amphipod species typical of the sublittoral zone, some with preference for enclosed bays and lagoons, were identified. Gammarus crinicornis, Microdeutopus bifidus, C. rotundirostris , and Erichthonius difformis are mentioned for the first time for Greek waters. The distribution of amphipods in the lagoon is governed by the vegetation and is probably modified by interspecific relations.     

Impact of sediment organic matter quality on the fate and effects of fluoranthene in the infaunal brittle star Amphiura filiformis

Hydrophobic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) readily adsorb to organic matter. The aim of this study was to determine the importance of the quality of sedimentary organic matter for the uptake, biotransformation and toxicity of the PAH, fluoranthene (Flu), in the infaunal brittle star Amphiura filiformis. Brittle stars were exposed to a base sediment covered by a 2 cm Flu-spiked top layer (30 microg Flu/g dry wt. sed.), enriched to the same total organic carbon content with either refractory or labile organic matter. The labile carbon source was concentrated green flagellate: Tetraselmis spp. The refractory carbon source was lignin from a paper mill. Tissue concentrations of Flu both in disk and arm-fractions were determined as total Flu, parent Flu (i.e. untransformed), aqueous Flu-metabolites, polar Flu-metabolites and tissue residue Flu (i.e. unextractable). Our results showed that sediment particle ingestion is a pathway by which Flu can enter benthic food webs. Flu toxicity (measured as arm-regeneration), but not net accumulation, was dependent on the nutritional quality of the ingested sediment particles. Flu bioaccumulation could not be attributed solely to equilibrium partitioning between organism lipid content and organic content of the sediment. Biotransformation of Flu by brittle stars was very limited and unaffected by organic matter quality. A. filiformis contributed to the downward transport of Flu from the surface sediment to the burrow lining. The limited breakdown of parent Flu by brittle stars and/or microorganisms was relatively higher in burrows compared to surface sediment, and highest in the presence of labile organic matter. Tissue concentrations were higher in disk than in arms, but the proportion of metabolic products relative to parent Flu was higher in arms than in the disk fraction. We estimate that the yearly mobilization of sediment-associated Flu by arm-regeneration in A. filiformis is in the range of 3.8-29.4 microg total Flu eq. m(-2) year(-1) at a sediment concentration of 30 microg Flu/g dry wt. sed.     

A Functional Analysis of the Benthic Macrofauna of the São Sebastião Channel (Southeastern Brazil)

Abstract.  The major problem in coastal areas of developing countries is disturbance caused by anthropogenic influence. This disturbance can be quantified by analysing the distribution and composition of marine communities using uni- and multivariate techniques and the biotic index. A study of benthic macrofauna was carried out along the São Sebastião Channel, northern coast of São Paulo State, Brazil, in an area with a submarine outfall, a petroleum terminal and a commercial harbour. Sampling was undertaken seasonally, by means of a van Veen grab (0.1 m²) at 15 oceanographic stations, from November 1993 to August 1994. A total of 392 species were identified (129 Polychaeta, 127 Mollusca, 98 Crustacea, 28 Echinodermata and 10 other phyla). The sedimentary pattern recorded for the São Sebastião Channel is very heterogeneous, influenced mainly by strong wind-driven currents, and differs from nearby shelf areas. The study area could be divided into three regions based on sediment texture and fauna: one region dominated by medium and coarse sand with low values of organic carbon; a second area where pelitic fractions were dominant with high values of organic carbon and nitrogen; and a third region characterised by fine and very fine sand, presenting intermediate organic carbon values. No temporal significant variation in abundance and species composition was found, except in autumn. The use of the 'marine Biotic Coefficient' showed the same ecological trend as the faunal abundance and demonstrated that the central continental region of the channel is affected by human activities.     

Plio-Quaternary continental deposits of the Castellamonte area, between Orco and Dora Baltea Basins (Torino Province, Italy)

New geologic mapping of the area near Castellamonte (Torino Province) describes a wide Plio-Quaternary continental succession, up to about 100-m thick. This sequence is distinguished according to allostratigraphic criteria. Altitude, degree of pedogenesis and sediment supply from different basins are also used. Within a single alloformation, several lithofacies are described.Fine-grained fan-delta sediments (Vespia Alloformation) are described in the lower part of the continental succession. The fossil plant remains indicate an Early–Middle Pliocene age. These sediments show an evident deformation and fill ancient lacustrine basins, likely associated with the Canavese Line trend. Their wide distribution and considerable thickness suggest subsidence.Coarse-grained glacial, outwash and fluvial sediments (Colleretto Castelnuovo, S. Defendente, Case Musso, Pagliero, Serra and Piverone Alloformations) are described in the upper part of the continental succession. They consist of undeformed sediments deposited during Middle to Late Pleistocene. These sediments indicate the presence of small local glaciers along the current valley trends. The terracing ratios among the different units and their small thicknesses indicate subsequent differential uplift.     

The tectonic regime in Italy inferred from borehole breakout data

In Italy, the horizontal stress directions are well constrained in many regions, but the tectonic regime is not well known because the stress magnitudes are unknown. Our intention is to improve the knowledge of crustal stress in Italy, both at shallow depth and in low seismicity areas. Therefore, we inferred the tectonic regime from the comparison between the depth of breakout occurrence and the physical properties of the rocks in 20 boreholes. The critical value of the maximum horizontal stress, for which the effective tangential stress at the borehole wall overcomes the rock strength to form breakouts, could be computed from rock strength and density. Comparing the theoretical stress distributions for different tectonic regimes with the depth distribution of breakout occurrence, it is possible to infer the tectonic regime that fits best to the breakout depth distribution. We investigated boreholes up to 6 km deep located in different tectonic environments over the Italian peninsula: the Po Plain, the Apenninic chain, the Adriatic foredeep and the Tyrrhenian Quaternary volcanic region. These wells are characterised by breakout data of good quality (A, B and C, according to World Stress Map quality ranking system). The results are in general agreement with the style of faulting derived from earthquake focal mechanisms and other stress indicators. Our results show a predominance of a normal faulting (NF) regime in the inner Apennines and both normal faulting and strike–slip faulting (SS) style in the surrounding regions, possibly also associated with changes in the tectonic regime with depth.     

The impact of hydrological changes on travertine deposits related to thermal springs in the Pamukkale area (SW Turkey)

Pamukkale thermal waters (35 °C), exhibiting calcium-bicarbonate-sulfate composition and high carbon dioxide concentration, are of a predominantly meteoric origin. The meteoric fluid, circulating through faults and fractures, is heated by magmatic intrusions at great depth, and ascends from deep reservoirs to the surface. Mixing with relatively cold groundwater in the near surface zone promotes different saturation conditions with respect to calcium carbonate that later precipitates at depth and/or the surface. Dissolution-deposition processes of calcium carbonate both at surface and depth environments may help to reconstruct past climate direction in the field. During wet climate conditions a high-rate of calcium carbonate accumulation would be expected to occur at the surface because thermal fluid would be under-saturated with respect to calcium carbonate at depth because of a relatively higher mixing ratio with cold groundwater. During dry climate conditions the thermal fluid would be super-saturated at depth because of the highly acidic environment. Hydrometeorological studies reveal that the annual precipitation at the Pamukkale hydrothermal field tends to decrease with time. This climatic change in the area was also detected from geological records. While humid climate conditions prevailed during the late Quaternary, the area has recently been affected by arid/semi-arid climate conditions, followed by some episodic transitions. This study has shown how the system has possibly reacted to different climate conditions since antiquity.