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At least 19 recordsLinked to original sources
PubMed2005

Bioindicator organisms: heavy metal pollution evaluation in the Ionian Sea (Mediterranean Sea--Italy).

Trace metal concentrations of mercury, cadmium, lead and chromium in Patella caerulea, and Mullus barbatus were investigated to provide information on pollution of Ionian Sea, since these metals have the highest toxic potential. High chromium levels (0.47-0.97 microg g(-1) ww) were registered in limpet samples collected from two station near the Gulf of Taranto, while elevated concentration of mercury (0.31-1.50 microg g(-1) ww) were found in mullet specimens from Sicily. The metal concentrations recorded at the clean stations may be considered as useful background levels to which to refer for comparison within the Mediterranean area. On the contrary, the high levels of chromium and mercury found respectively in the areas near the Gulf of Taranto and at Capo Passero being of concern in terms of environmental health need frequent monitoring.

Animals↗
PubMed2005

Sedimentary humic substances in the northern Adriatic sea (Mediterranean sea).

Humic compounds were determined in sediments collected in an area of the Adriatic sea receiving fresh waters from the river Po. Sediment cores (10 cm) were sectioned into four layers which were analysed separately for redox potential (Eh), total phosphorus (TP), total organic carbon (TOC), humic (HA) and fulvic acid (FA) content. The structure of HA and FA was also investigated. The results showed that the TOC and TP content decreased from the coast to the open-sea stations. Humic and fulvic acid concentrations were also inversely correlated to the distance from the coast. Moreover, the humic and fulvic acids were closely correlated to the total organic content and to the total phosphorus content. The correlations found between humic substances (HS) and TOC and TP, respectively, could be explained both by an in situ formation due to the high content of nutrients and organic matter, and by a common source of HS, TOC and TP, namely the River Po discharge. The predominant presence of aliphatic carbon in the humic structures, the low degree of substitution and the high nitrogen content suggest that primarily humified compounds were formed in situ. Nevertheless, the River Po can act both as supplier of organic matter of which decomposition products lead to the formation of humic compound and as carrier of humified compounds.

Benzopyrans↗
PubMed2004

Sustainable impact of mussel farming in the Adriatic Sea (Mediterranean Sea): evidence from biochemical, microbial and meiofaunal indicators.

We have investigated the impact of a large mussel farm on the benthic environment using a battery of benthic indicators of environmental quality (including biochemical, microbial and meiofaunal parameters). These were analysed through a multi-control sampling strategy over one year. The differences across the seasons are typically higher than those between the impacted and the control stations. No effects are seen in terms of the sediment oxygen penetration and the downward fluxes (as the total mass, organic and phytopigment fluxes). The indicators based on the biochemical compositions of the sediment organic matter and the microbial parameters also show no evidence of the eutrophication process, except as a slight increase in the bacterial density in the sediments beneath the long-lines of the farm during the period of highest mussel stocks. Finally, no effects are observed in terms of the benthic faunal indicators, as the meiofaunal abundance, the community structure and the taxa richness are all indistinguishable between the farm sediments and the controls. These results show that mussel farming in the investigated system is eco-sustainable and does not significantly alter the coastal marine ecosystem, both in terms of the functioning and the trophic state. The battery of indicators selected in this study represents a useful tool for the monitoring of the potential ecological impact of mussel farms, towards guaranteeing the sustainable development of aquacultures in shallow coastal environments.

Analysis of Variance↗
PubMed2004

Polychlorinated biphenyl residues in deep-sea fish from Mediterranean Sea.

Polychlorinated biphenyls including coplanar congeners were measured in the liver of different species of skates and ghostsharks. The mean concentrations of PCBs in skates (314 ng/g wet wt) were comparable with those in ghostsharks (285 ng/g wet wt). The specific analysis of PCB congeners in skates hepatic tissue revealed a profile dominated by hexa-, penta-, and heptachlorinated congeners followed by trichlorobiphenyls, tetra- and decachlorobiphenyls. A different profile dominated by hexa-, tri-, and pentachlorinated congeners, followed by heptachlorobiphenyl and decachlorobiphenyls was found in ghostsharks liver. The estimated 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) of coplanar PCBs in skates and ghostsharks were 0.48 and 0.33 pg/g wet weight, respectively, with mono-ortho congeners PCB105, 118 and 156 contributing more than 90% to the TEQs.

Animals↗
PubMed2001

Microbial communities in the chemocline of a hypersaline deep-sea basin (Urania basin, Mediterranean Sea).

The Urania basin is a hypersaline sulfidic brine lake at the bottom of the eastern Mediterranean Sea. Since this basin is located at a depth of approximately 3,500 m below the sea surface, it receives only a small amount of phytoplankton organic carbon. In the present study, the bacterial assemblages at the interface between the hypersaline brine and the overlaying seawater were investigated. The sulfide concentration increased from 0 to 10 mM within a vertical interval of 5 m across the interface. Within this chemocline, the total bacterial cell counts and the exoenzyme activities were elevated. Employing 11 cultivation methods, we isolated a total of 70 bacterial strains. The 16S ribosomal DNA sequences of 32 of the strains were identical to environmental sequences detected in the chemocline by culture-independent molecular methods. These strains were identified as flavobacteria, Alteromonas macleodii, and Halomonas aquamarina. All 70 strains could grow chemoorganoheterotrophically under oxic conditions. Sixty-six strains grew on peptone, casein hydrolysate, and yeast extract, whereas only 15 strains did not utilize polymeric carbohydrates. Twenty-one of the isolates could grow both chemoorganotrophically and chemolithotrophically. While the most probable numbers in most cases ranged between 0.006 and 4.3% of the total cell counts, an unusually high value of 54% was determined above the chemocline with media containing amino acids as the carbon and energy source. Our results indicate that culturable bacteria thriving at the oxic-anoxic interface of the Urania basin differ considerably from the chemolithoautotrophic bacteria typical of other chemocline habitats.

Colony Count, Microbial↗
PubMed2005

Genetic analysis of housekeeping genes reveals a deep-sea ecotype of Alteromonas macleodii in the Mediterranean Sea.

The genetic diversity of 19 strains belonging to Alteromonas macleodii isolated from different geographic areas (Pacific and Indian Ocean, and different parts of the Mediterranean Sea) and at different depths (from the surface down to 3500 m) has been studied. Fragments of the 16S rRNA gene, the internal transcribed spacer (ITS) between 16S and 23S rDNA genes, the gyrB and the rpoB genes, have been sequenced for each strain. Amplified fragment length polymorphisms were used to characterize similarity at the level of the whole genome. Most of the diversity reflected the existence of a cluster of strains isolated from deep Mediterranean waters and two isolates from the Black Sea. Particularly the isolates from the deep sites were consistently different from all the others indicating the existence of a specific ecotype adapted to these conditions. Amplification of gyrB gene and ITS directly from DNA retrieved from deep Mediterreanean waters and one Atlantic sample showed that presence of this deep-sea ecotype is widespread and is not a product of culture bias. On the other hand, strains isolated from surface tropical waters showed a remarkable level of resemblance to the first isolate of this species obtained from Hawaii in 1972. The results indicate the existence of both lineages of global distribution and ecotypes adapted to specific conditions such as deep or more diluted (the Black Sea) waters.

Alteromonas↗
PubMed1996

Microbial respiratory activity in the euphotic zone of the Mediterranean Sea.

Microplankton respiration in the euphotic zone in the Central Mediterranean Sea was calculated by ETS activity measurements. Distribution of ETSa in the studied area appeared homogeneous and comparable with previous data measured in the Mediterranean Sea. A typical ETSa value for euphotic Mediterranean waters of 0.14 meq O2 h-1 m-3 was calculated. The investigated area supports a metabolic CO2 production of 70 g C m-2 y-1. When compared with regional productivity, the respiration budget in the euphotic zone accounted for 22% of carbon fixed. ETSa appeared a useful assay for the study of evolutive history of the water masses in the Mediterranean Sea.

Animals↗
PubMed2004

Differential population structuring of two closely related fish species, the mackerel (Scomber scombrus) and the chub mackerel (Scomber japonicus), in the Mediterranean Sea.

Population genetic structures of the mackerel (Scomber scombrus) and chub mackerel (Scomber japonicus) were studied in the Mediterranean Sea. Fragments of 272 bp (S. scomber) and 387 bp (S. japonicus) of the 5'-end of the mitochondrial control region were sequenced from spawning individuals collected off the coasts of Greece, Italy, Spain, and Portugal. High levels of mitochondrial control region haplotypic diversity (> 0.98) were found for both Scomber species. Nucleotide diversity was higher in the mackerel (0.022) than in the chub mackerel (0.017). Global F(ST) values were also higher and significant in the mackerel (0.024, P < 0.0001) as opposed to the chub mackerel (0.003, P > 0.05). Molecular variance analyses showed differential genetic structuring for these two closely related species. There is extensive gene flow between Mediterranean Sea and Atlantic Ocean populations of chub mackerel, which are organized into a larger panmictic unit. In contrast, Mediterranean Sea populations of mackerel show some degree of genetic differentiation and are structured along an east-west axis. The analysed eastern Mediterranean Sea mackerel populations (Greece, Italy) are clearly separated from that of the western Mediterranean Sea (Barcelona), which forms a panmictic unit with eastern Atlantic Ocean populations. The genetic structures of both species showed asymmetric migration patterns and indicated population expansion.

Analysis of Variance↗
PubMed2005

Hydrocarbons in surface sediments from the Sfax coastal zone, (Tunisia) Mediterranean Sea.

The Semi-enclosed Mediterranean Sea records various signals of high anthropic pressures from surrounding countries and the industrialized European countries. This is particularly true for oil pollution. Although accounting for 1% of the world's ocean surface, it receives about 25% of the petroleum inputs to the ocean. To achieve a global budget we need to collect information from different parts of the Mediterranean. Particularly, we focus in this paper on the Southern Mediterranean, where data are presently very scarce. In this context, the University of Sfax has undertaken an estimation of hydrocarbon pollution along the coasts of Sfax and Gabès Gulf. Non-aromatic hydrocarbons were analysed in 8 surface sediments by FT/IR and GC/MS. Non-aromatic hydrocarbon concentrations vary in the range 310-1406 microg g(-1) sediments dry weight, which is high, compared to other Mediterranean sites. GC/MS data indicate a large group of unresolved compounds suggesting a petroleum contamination, confirmed by the identification of hopanes with predominant C29 and C30alpha,beta compounds and steranes with predominance of C27 over C28) and C29 compounds.

Environmental Monitoring↗
PubMed1979

Seasonal and geographic distribution of luminous bacteria in the eastern mediterranean sea and the gulf of elat.

Luminous bacteria in the Mediterranean Sea and the Gulf of Aqaba-Elat have different distribution patterns. In the Mediterranean Sea, Beneckea harveyi is present all year round, with different subtypes alternating in summer and winter; Photobacterium fischeri was only present during the winter. In the Gulf of Elat, P. leiognathi is present throughout the water column in similar densities during the entire year. This constancy in distribution is presumably due to the near-constancy in water temperature. In summer, Photobacterium leiognathi is replaced by B. harveyi in coastal surface waters. In the hypersaline Bardawil lagoon, only B. harveyi types are present. P. fischeri, a major component of the Mediterranean Sea winter communities, is absent from the lagoon. Luminous Beneckea strains show a great diversity in properties, e.g. temperature range for growth, sensitivity to infection by phages, sensitivity to attack by Bdellovibrio strains, and differences in tolerance to high-salinity shock. Therefore, subdivision of the taxonomic cluster of B. harveyi into subtypes is indicated. The composition of the luminous bacteria communities may serve as indicators of different marine water bodies. The symbiotic luminous bacteria of the light organ of the common Gulf of Elat fish, Photoblepharon palbebratus steinitzi, is different from any of the types described.

Journal Article↗
PubMed2004

Heavy metals monitoring using bivalves from Mediterranean Sea and Red Sea.

The concentrations of heavy metals (Cd, Co, Cu, Fe, Mn, Ni, Pd and Zn) were measured in the Bivalves (Modiolus auriculatus and Donax trunculus) collected from the Egyptian coasts of Mediterranean Sea and Brachiodonates sp. from the Egyptian coasts of Red Sea. The average concentrations of the heavy metals analyzed exhibited the following decreasing order: Fe > Zn > Cu > Mn > Ni > Co > Pb > Cd for both Mediterranean Sea and Red Sea. The analyses of Cd, Co, Ni, Pb, and Zn showed higher average concentrations for samples collected from Red Sea than that collected from Mediterranean Sea, while Fe, Cu and Mn showed the reverse results. Fe was used as a normalizing agent for all studied metals and exhibited presence of two locations from each of Mediterranean Sea and Red Sea have anthropogenic inputs of heavy metals. These results suggest that the coastal area in both Mediterranean Sea and Red Sea of Egypt might be considered relatively unpolluted with heavy metal.

Animals↗
PubMed2003

The role of the exchanges through the Strait of Gibraltar on the budget of elements in the Western Mediterranean Sea: consequences of human-induced modifications.

The role of the Strait of Gibraltar on the exchanges of substances between Mediterranean Sea and the Atlantic Ocean is reviewed. The previous estimations have been recalculated by using a similar water flux and compared with the river and atmospheric inputs to the Western Mediterranean Sea. The man-induced changes in the dimensions of the Strait of Gibraltar increasing (planning the sill) or reducing of the cross-section by a total or partial dam are discussed. A total dam will control the sea-level rise in the Mediterranean Sea, but an annual increase of major nutrient concentrations of 1-2% could be expected, lower than the rate of increase of the river and atmospheric inputs in the Western Mediterranean Sea. The increase of the cross-section of the Strait by increasing the depth (planning) at the sill could compensate the increase of the external nutrient inputs.

Carbon↗
PubMed2004

Microsatellite and mitochondrial DNA analyses of Atlantic bluefin tuna (Thunnus thynnus thynnus) population structure in the Mediterranean Sea.

Genetic variation was surveyed at nine microsatellite loci and the mitochondrial control region (868 bp) to test for the presence of genetic stock structure in young-of-the-year Atlantic bluefin tuna (Thunnus thynnus thynnus) from the Mediterranean Sea. Bluefin tuna were sampled over a period of 5 years from the Balearic and Tyrrhenian seas in the western basin of the Mediterranean Sea, and from the southern Ionian Sea in the eastern basin of the Mediterranean Sea. Analyses of multilocus microsatellite genotypes and mitochondrial control region sequences revealed no significant heterogeneity among collections taken from the same location in different years; however, significant spatial genetic heterogeneity was observed across all samples for both microsatellite markers and mitochondrial control region sequences (FST=0.0023, P=0.038 and PhiST=0.0233, P=0.000, respectively). Significant genetic differentiation between the Tyrrhenian and Ionian collections was found for both microsatellite and mitochondrial markers (FST=0.0087, P=0.015 and PhiST=0.0367, P=0.030, respectively). These results suggest the possibility of a genetically discrete population in the eastern basin of the Mediterranean Sea.

Animals↗
PubMed1999

Polyphasic classification of 0.2 microm filterable bacteria from the western Mediterranean Sea

The 0.2 microm filtration of sea water samples from the Mediterranean Sea (Bay of Calvi, Corsica), collected from 10 m and 35 m depth led to the isolation of several gram-negative bacterial strains able to grow on full-strength media as well as on diluted media. The analysis of the 16S rRNA gene sequences and estimation of the phylogenetic relationships of these facultative oligotrophic bacteria indicated that they grouped into two phylogenetic branches. The strains RE10F/2, RE10F/5 (10 m depth samples) and RE35/F12 (35 m depth samples) were assigned to the gamma-subclass, while RE35F/1 (35m depth sample) was assigned to the alpha-4-subclass of the Proteobacteria. The strains RE10/F2 and RE10/F5 were most closely related to species and strains of the Pseudoalteromonas group, whereas the strain RE35F/12 placed adjacent to the family Vibrionaceae. The phylogenetic analysis of strain RE35F/1 revealed that this bacterium clusters with marine strains and species of the aerobic anoxygenic phototrophic bacteria Erythrobacter as well as Erythromicrobium and more distantly to Sphingomonas spp. Supplementary to those genotypic classifications the chemotaxonomic signatures including the major respiratory lipoquinone systems, the cellular fatty acid compositions as well as the polyamine contents of the bacteria were investigated. The isolated organisms displayed differences in their physiological and biochemical properties to already described strains belonging to the same genera or families, as revealed by the comparative 16S rRNA analysis. Despite the fact that these bacteria were isolated from a 0.2 microm filtrate, the cultured organisms which were all rod-shaped, displayed width dimensions ranging from 0.4 up to 0.7 microm, indicating that these bacteria were starvation forms at the time of isolation and not ultramicrobacteria as defined by Torella and Morita (1981) or by Schut et al. (1993). Because our isolated strains represent potentially new taxa, this first investigation on 0.2 pm filterable bacteria from the Western Mediterranean Sea supports the hypothesis that this bacterial fraction contributes to the diversity of marine bacteria.

Journal Article↗
PubMed2005

Trace element (Cd, Cu, Hg, Se, Zn) accumulation and tissue distribution in loggerhead turtles (Caretta caretta) from the Western Mediterranean Sea (southern Italy).

Cadmium (Cd), copper (Cu), mercury (Hg), selenium (Se) and zinc (Zn) were determined in the liver, kidney and muscle of 29 loggerhead turtles, Caretta caretta, from the South Tyrrhenian Sea (Western Mediterranean). No significant differences (p>0.05) were detected between males and females. Trace element concentrations were not influenced by the size of the specimen except Se in the liver, which was negatively correlated with the curved carapace length (p<0.001). Muscles generally displayed the lowest trace element burdens, with the exception of Zn which contained concentrations as high as 176 microgg-1dwt. Kidneys displayed the highest Cd and Se mean concentrations (57.2+/-34.6 and 15.5+/-9.1 microgg-1dwt, respectively), while liver exhibited the highest Cu and Hg levels (37.3+/-8.7 and 1.1+/-1.7 microgg-1dwt, respectively). Whichever tissue is considered, the toxic elements had elevated coefficients of variation (i.e. from 60% to 177%) compared to those of the essential ones (i.e. from 14% to 65%), which is a consequence of homeostatic processes for Cu, Se and Zn. Globally, the concentrations of Hg remained low in all the considered tissues, possibly the result of low trophic level in sea turtles. In contrast, the diet of loggerhead turtles would result in a significant exposure to Cd. Highly significant correlations between Cd and Cu and Zn in the liver and kidney suggest that efficient detoxification processes involving MT occur which prevent Cd toxicity in loggerhead turtles.

Animals↗
PubMed1998

Population genetic structure of North Atlantic, Mediterranean Sea and Sea of Cortez fin whales, Balaenoptera physalus (Linnaeus 1758): analysis of mitochondrial and nuclear loci.

Samples were collected from 407 fin whales, Balaenoptera physalus, at four North Atlantic and one Mediterranean Sea summer feeding area as well as the Sea of Cortez in the Pacific Ocean. For each sample, the sex, the sequence of the first 288 nucleotides of the mitochondrial (mt) control region and the genotype at six microsatellite loci were determined. A significant degree of divergence was detected at all nuclear and mt loci between North Atlantic/Mediterranean Sea and the Sea of Cortez. However, the divergence time estimated from the mt sequences was substantially lower than the time elapsed since the rise of the Panama Isthmus, suggesting occasional gene flow between the North Pacific and North Atlantic ocean after the separation of the two oceans. Within the North Atlantic and Mediterranean Sea, significant levels of heterogeneity were observed in the mtDNA between the Mediterranean Sea, the eastern (Spain) and the western (the Gulf of Maine and the Gulf of St Lawrence) North Atlantic. Samples collected off West Greenland and Iceland could not be unequivocally assigned to either of the two areas. The homogeneity tests performed using the nuclear data revealed significant levels of divergence only between the Mediterranean Sea and the Gulf of St Lawrence or West Greenland. In conclusion, our results suggest the existence of several recently diverged populations in the North Atlantic and Mediterranean Sea, possibly with some limited gene flow between adjacent populations, a population structure which is consistent with earlier population models proposed by Kellogg, Ingebrigtsen, and Sergeant.

Animals↗
PubMed2001

Allozyme and microsatellite loci provide discordant estimates of population differentiation in the endangered dusky grouper (Epinephelus marginatus) within the Mediterranean Sea.

The dusky grouper, Epinephelus marginatus, inhabits coastal reefs in the Mediterranean Sea and Atlantic Ocean. A decline in the abundance of this long-lived protogynous hermaphrodite has led to its listing as an endangered species in the Mediterranean, and heightened management concerns regarding its genetic variability and population substructure. To address these concerns, we analysed genetic variation at seven microsatellite and 28 allozyme loci in dusky groupers sampled from seven areas (for microsatellites) and three areas (for allozymes) in the west-central Mediterranean. Levels of genetic variability were higher for microsatellites than for allozymes (mean H(E) = 0.78 and 0.07, respectively), but similar to those observed in other marine fishes with comparable markers. Both microsatellites and allozymes revealed significant genetic differentiation among all areas analysed with each class of marker, but the magnitude of differentiation revealed by allozymes over three locales (F(ST) = 0.214) was greater than that detected with microsatellites over seven areas, or over the three areas shared with the allozyme analysis (F(ST) = 0.018 and approximately 0, respectively). A large proportion of the allozyme differentiation was due to a single locus (ADA*) possibly influenced by selection, but allozyme differentiation over the three areas was still highly significant (F(ST) = 0.06, P < 0.0001), and the 95% confidence intervals for allozyme and microsatellite F(ST) did not overlap when this locus was excluded. There was no evidence of isolation by distance with either class of markers. Our results lead us to conclude that dusky groupers are not panmictic in the Mediterranean Sea and suggest that they should be managed on a local basis. However, more work is needed to elucidate genetic relationships among populations.

Animals↗