Metallothionein in intestine of red mullet, Mullus barbatus as a biomarker of copper exposure in the coastal marine areas

Dietary metal exposure in fish is studied in native red mullet, Mullus barbatus, involving metallothionein (MT) response in the intestine, a primary site for metal uptake. Intestinal MTs (microg mg(-1) proteins), total proteins (mgml(-1) S50), Cu, Zn, Fe, Mn and Cd (microg ml(-1) S50) are considered as indicators of metal exposure in specimens from near-shore and off-shore locations of the Eastern Adriatic Sea. Metallothionein and Cu are statistically significantly higher in 68 specimens from the Kastela Bay, a near-shore area (30.0+/-6.71microg MT mg(-1) proteins; 0.30+/-0.08microg Cu ml(-1) S50), in comparison to 51 specimens from off-shore area, Solta Island (25.9+/-4.21microg MT mg(-1) proteins; 0.26+/-0.09microg Cu ml(-1) S50). Cytosolic Cu, a MT inducer, is significantly correlated (p<0.05, r=0.44) with MT in specimens from the Kastela Bay, independent on fish biometry. Our study indicates that cytosolic intestinal Cu and MT represent a measurable biochemical response in red mullet specimens, dwelling above sediments contaminated with Cu.     

Relationships among predatory fish, sea urchins and barrens in Mediterranean rocky reefs across a latitudinal gradient

Previous studies conducted on a local scale emphasised the potential of trophic cascades in Mediterranean rocky reefs (involving predatory fish, sea urchins and macroalgae) in affecting the transition between benthic communities dominated by erected macroalgae and barrens (i.e., bare rock with partial cover of encrusting algae). Distribution patterns of fish predators of sea urchins (Diplodus sargus sargus, Diplodus vulgaris, Coris julis and Thalassoma pavo), sea urchins (Paracentrotus lividus and Arbacia lixula) and barrens, and fish predation rates upon sea urchins, were assessed in shallow (3-6m depth) sublittoral rocky reefs in the northern, central and southern sectors of the eastern Adriatic Sea, i.e., on a large spatial scale of hundreds of kilometres. No dramatic differences were observed in predatory fish density across latitude, except for a lower density of small D. sargus sargus in the northern Adriatic and an increasing density of T. pavo from north to south. P. lividus did not show any significant difference across latitude, whereas A. lixula was more abundant in the southern than in the central Adriatic. Barrens were more extended in the southern than in the central and northern sectors, and were related with sea urchin density. Fish predation upon adult sea urchins did not change on a large scale, whereas it was slightly higher in the southern sector for juveniles when predation rates of both urchins were pooled. Results show that: (1) assemblages of predatory fish and sea urchins, and barren extent change across latitude in the eastern Adriatic Sea, (2) the weak relations between predatory fish density and predation rates on urchins reveal that factors other than top-down control can be important over large scale (with the caveat that the study was conducted in fished areas) and (3) patterns of interaction among strongly interacting taxa could change on large spatial scales and the number of species involved.     

Numerical Simulation and Observational Analysis of the Bora of Pag’s Ribs

The severe bora case that lasted from 13 to 15 November 2004 has been selected for the analysis of the bora of Pag’s ribs, which occurs in the northern part of the eastern Adriatic coast over the Pag island area (Croatia). According to the measurements from automatic stations, the MM5 numerical model is successful in the 10-min mean wind speed prediction at 10-m height. The vertical analysis of the wind speed and potential temperature also gave satisfactory results. At the commencement of the bora the modelled wind had a magnitude of 20ms⁻¹ at 10-m height in the Pag island area, which sharply attenuated in the cross direction and to the open sea. In this way the model has proved successful in predicting the characteristics of the bora of Pag’s ribs. Potential vorticity (PV) at 600m has lower values within PV banners than during the developed bora. The consequence is a strong jet emanating from the nearest gap. The vertical cross-sections through the centre of the gap point out a permanent hydraulic-like flow. At the time of the bora of Pag’s ribs the highest modelled turbulent kinetic energy is found in the jump-like region above the inversion and within the boundary layer along the lower boundary, ranging from 6–8m² s⁻². It is concluded that the dissipation in the hydraulic jumps and the wave breaking regions are the reasons for PV generation.     

An inadvertent transport of the seeding material as a result of cloud modification

Successful seeding of clouds in weather modification experiments essentially depends on the seeding time and dynamics, amount of seeding material and location of the initial seeding area. In the present study, we focus on the influence of the initial seeding zone location on the transport of seeding agent material into the target cloud. In addition, the inadvertent transport of seeding material is analysed. During weather modification activities, a lot of seeding material can be transferred far from the seeding zone in a downwind direction. The primary motivation for this research was to prove this statement. We use a three-dimensional, mesoscale cloud-resolving model to achieve our goal. We performed sensitivity tests with respect to the distance between the mass centres of the initial seeding area and the cloud. Different seeding scenarios are analysed. Our principal findings are as follows: (1) For distances between the mass centres of the initial seeding area and the cloud below 2.5 km, all seeding agent material would be activated after a short time. For distances above 10 km, most of the seeding agent would remain inactivated, because horizontal transport of the seeding agent becomes more important than transport induced by the main updraft. For these scenarios, the seeding agent is injected in the cold peripheral part of the cloud. (2) Sensitivity tests show that the inactivated seeding agent would remain close to the seeding area if the seeding is performed below cloud base. This effect occurs even for large distances between the seeding area and the target cloud (>20 km) due to low-level convergence. Thus, this seeding method suppresses the inert seeding material from being transferred far from the seeding zone. (3) The complete seeding material stays inactivated if the seeding is performed between the ?8 and ?12°C isotherms in front of the increased reflectivity zone. As a consequence, it would be transferred far from its initial area. The cloud would not be able to capture the seeding agent even during its greatest lateral extent.     

Source potential and palynofacies of Late Jurassic “Lemeš facies”, Croatia

Laminated limestone and calcareous shale outcrop samples from the Late Jurassic “Leme?” facies (Croatia) were investigated to characterize their organic facies and palynofacies and their hydrocarbon generative potential. The results indicate that the organic rich sediments of “Leme?” facies were deposited within a relatively shallow marine environment at low redox potential, characterized as an oxygen depleted depositional setting with stratified bottom waters of the carbonate platform (Adriatic Carbonate Platform). The organic rich samples contain a high portion of lipid rich amorphous kerogen of algal/phytoplankton origin, enriched by bacterial biomass. Most of the analyzed samples have total organic carbon contents (TOC) greater than 3%, Rock-Eval S2 >20 mg HC/g rock, yielding Hydrogen Index (HI) values ranging from 509–602 mg HC/g TOC. According to these results, the analyzed samples have very good to excellent oil generative potential. Relatively high sulfur content suggests that the kerogen is best described as Type II-S. Biomarker maturity parameters, as well as the fluorescence of the isolated kerogen, show that the organic matter is at early to peak oil thermal maturity. The observed level of thermal maturity indicates that these samples were once buried to depths of ～5.5–5.8 km before being uplifted in the late Tertiary. The surface outcrops of the “Leme?” facies suggest that these strata have significant source potential and are the likely source of oil in the Croatian External Dinarides.     

Geochemical investigation and characterisation of Neogene sediments from Valjevo-Mionica Basin (Serbia)

Sediments from the Valjevo-Mionica Basin of Neogene age were investigated in this study using different geochemical methods. The results of the inorganic part analyses suggest that during genesis of the sediments, the contents of Na₂O, B and As changed the most, which indicates that genesis of the investigated sediments was followed by climate changes and volcanic activity. The quantity of other macro- and microelements did not vary significantly. Investigations of the organic substance showed that it is native organic matter, which has been preserved to a significant extent, formed predominantly of algal precursor organisms, which provided good quality, deposited under reducing conditions and that it is at a low maturity level. As it has been established that genesis of the investigated sediments was mostly affected by an arid climate with more intensive salinity, the aim of this study, was also to identify the processes which were the most affected by the change in salinity, as well as biomarkers which are the most sensitive to this change. The results led to the conclusion that the salinity increase in the depositional environment had a primary effect on the preservation of the organic substance and the formation of the mineral searlesite. In addition, it was noticed that besides the Sq/nC₂₆ ratio, the parameters nC₁₇/nC₂₇, CPI and Ph/nC₁₈, are also significantly sensitive to salinity change in a depositional environment in case of immature organic substance deposited under reducing conditions.     

Trace metals (Cd,Pb, Cu,Zn and Ni) in sediment of the submarine pit Dragon ear (Soline Bay,Rogoznica, Croatia)

Vertical profiles of trace metal (Cd, Pb, Zn, Cu, Ni) concentrations, organic matter content, carbonate content and granulometric composition were determined in two sediment cores from the submarine pit Dragon Ear (Middle Adriatic). Concentrations of the analyzed metals (Cd: 0.06–0.12 mg kg⁻¹, Pb: 28.5–67.3 mg kg⁻¹, Zn: 17.0-65.4 mg kg⁻¹, Cu: 21.1–51.9 mg kg⁻¹, Ni: 27.8–40.2 mg kg⁻¹) were in usual range for Adriatic carbonate marine sediments. Nevertheless, concentrations of Cu, Zn, and especially Pb in the upper layer of sediments (top 12 cm) were higher than in bottom layer, while Cd and Ni concentration profiles were uniform. Regression analysis and principal component analysis were used to interpret distribution of trace metals, organic matter and carbonate content in sediment cores. Results of both analysis showed that concentrations of all trace metals in the core below the entrance to the pit were significantly positively correlated with organic matter and negatively correlated with carbonate, while in the core more distant from the entrance only Pb showed significant positive correlation with organic matter. Obtained results indicated that, except for lead which was enriched in surface sediment, in the time of sampling (before the building of the nautical marina) investigated area belonged to unpolluted areas.     

The conspicuous red “impact” layer of the Fish Clay at Højerup (Stevns Klint,Denmark)

The marine Cretaceous-Paleogene boundary (KPB) section at Højerup-Fish Clay consists of a very thin red smectite-rich carbonate-poor (“impact”) layer overlain by a thick black marl. Similar red layers are found in the KPB sections at Agost in Spain and El Kef in Tunisia.Smectite of the red layer of the KPB section at Højerup is probably detrital and redeposited from adjacent coastal or marine areas. This clay mineral is likely mixed with a small amount of smectite derived from impact glasses. Most of the microspherules and nano-size glasses of the red layer at Højerup are probably detrital and simultaneously redeposited with smectite. The deposition of the red layer occurred for several decades to a century at most.     

Discriminant function model as a tool for classification of stratigraphically undefined radiolarian cherts in ophiolite zones

Two discriminant function models are constructed in order to distinguish major- and trace-element geochemical patterns characteristic for radiolarian cherts from the Zagorje–Mid-Transdanubian Zone ophiolite mélange of NW Croatia. The models are subsequently used to assign new samples from the adjacent magmatic–sedimentary complex extending from the Central Dinaridic Ophiolite Belt in NW Bosnia and thereby to test their applicability in similar cases when clear field relations are absent. In both models the first discriminant function explains the most part of the system variability. However, between the two, the trace-element model proves itself as a more helpful predictive tool presenting a straightforward example of correct classification of samples into three pre-defined groups (Triassic-basin, Triassic-slope and Jurassic radiolarian cherts). This result is extended further, with allocation of all samples from the test region into a single group (Jurassic) according to their trace-element geochemistry.