Impact of continental margins in the Mediterranean Sea: Hints from the surface colour and temperature historical record

The surface colour and temperature fields of the Mediterranean Sea, as appearing in time series, of basin-wide images available in the CZCS (1979–1985) and AVHRR (1982–1991) historical archives, differentiate between basin interior and continental margins affected by coastal patterns, river plumes, and mesoscale features. The original data were processed to apply calibration factors, to correct for atmospheric contamination, and to estimate chlorophyll-like pigment concentration and surface temperature. Composites were derived, as monthly and annual means, using a fixed equal-area projection with a 1-km² pixel grid. Enhanced pigment values and lower temperatures along the northern coastal areas (i.e. the Ligurian, Provençal and Balearic basins, as well as the Adriatic, and Aegean Seas) have been associated with the impact of runoff from continental margins (i.e. both a direct impact due to the sediment load and one induced on the planktonic flora by the associated nutrient load) and with vertical mixing due to the prevailing winds (i.e. the Mistral in the northwest, the Bora in the Adriatic, the Etesians in the Aegean). The pattern of increasing pigments and decreasing temperatures in seen to develop in the monthly images from the coastal zone towards the open sea from summer to winter, and then back from winter to summer. The southern coastal areas show different values, namely lower pigments and higher temperatures (except in areas where the data are altered by signal contamination). It is suggested that differences in geomorphology and meteorology of the basin margins have an impact on both water biogeochemistry and dynamics, influencing the biooptical and thermal properties of the various sub-basins, and of the entire Mediterranean region.     

Vertical Distribution and Inventories of 239,240Pu in Deep Sea Sediments of the Mediterranean Sea (Algerian Basin, Ionian Sea)

Deep-sea sediments collected in two areas of the Mediterranean Sea having different sedimentological characteristics have been analyzed to determine present concentrations and inventories of ^239,240Pu and to study the main mechanisms controlling them. Plutonium distribution in the deepest part of a submarine canyon (Taranto Valley, Ionian Sea) is compared to that obtained in an abyssal plain (north Algerian Plain). in the latter case, sedimentation is mainly due to the sinking of biogenic particles, while in the former lateral transport of terrigenous material along the slope of the canyon can significantly contribute to sediment accumulation on the bottom.

^239,240Pu surface concentration in the canyon ranged from 0.2 to 1 Bq kg^-1 (dry weight) and this was lower in the abyssal plain. in this area, plutonium was detectable only in the first 4 cm, while in the canyon it was present down to 11-15 cm. ^239,240Pu inventories are 3 Bq m^-2 in the plain and 45-60 Bq m^-2 in the canyon, indicating considerable input of terrigenous material towards the final part of the Taranto Valley.     

A Comparative Study On the Levels of Trace Metals in Some Mediterranean and Red Sea Fishes

Samples of Mugil cephalus, Liza ramada, Siganus luridus, Siganus rivulatus, Epinephelus alexandrinus, Epinephelus areolatus, Epinephelus fasciatus, Epinephelus chlorostigma, Cephalopholis argus and Cephalopholis sonnerati were collected from the Mediterranean and Red Seas and their muscle and bone analyzed by AAS for some trace metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb). the results showed that these metals accumulate in the bones to a greater extent than in the muscle. the highest accumulated element is cobalt (4.7-20.8 times), while the lowest is lead (1.1-2.5 times). the accumulation is more pronounced in Red Sea species than in Mediterranean species. the elevated levels of lead in Mugil cephalus (2.6-3.0 mg kg^-1) and Epinephelus alexandrinus (3.0-3.9 mg kg^-1) were attributed to the intake in food in the polluted environment of Alexandria coastal water. the relationship between body size and concentration of trace metals using a standard linear regression technique gives a significant positive correlation for cobalt, manganese, iron and lead in the muscle, as well as for lead in the bones of Mugil species from the Red Sea, while the Mediterranean species showed little correlation.

There is a tendency for increased concentrations of the essential metals manganese, iron and copper with increasing trophic level of the fish, while the opposite is true for the toxic metals chromium and lead. Our results indicate that there is no risk from toxic metal concentrations in muscle of fish from the Mediterranean and Red Seas consumed by man even in contaminated areas.     

Gas Transfer Coefficient Evaluation in the Mediterranean Sea Using Bomb Produced Radiocarbon

A study on the carbon dioxide exchange at the water-air interface in the Western Mediterranean Sea was carried out. the attention was focused on the mean air-sea flux estimations by radiocarbon profiles and bomb ¹⁴C concentration atmospheric data. Sampling techniques and analytical methods are reported; mass balance evaluations on data recorded during the MED'92 cruise are presented and discussed briefly.     

Organochlorines in the surface sediments of the Bahiret el Bibane lagoon (Tunisia,Southwestern Mediterranean Sea)

Organochlorines (including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs)) were analysed in 10 surface sediment samples collected from the Bahiret el Bibane lagoon, which is one of the most productive lagoons and one of the most important active commercial fish traps in the southern Tunisia. The aim was to obtain information concerning the recent deposition of these compounds in this area, together with the levels, the distribution and any potential biological risk. Total concentrations of OCPs and PCBs in the sediments ranged from below the limit of detection (?1 and from 29.5 to 88.2?ng?g^?1?dw, respectively. The spatial distribution of PCBs suggested that the sources of these contaminants are probably located outside the lagoon and are transported by water currents and atmospheric deposition. Compared with some other regions of the world, the Bahiret el Bibane lagoon exhibited low to moderate levels of PCBs and OCPs. According to established sediment quality guidelines, PCBs and Lindane at most of the study sites would be more concerned for the ecotoxicological risk in the Bahiret el Bibane lagoon. The results of this study could provide a useful aid for the sustainable marine management of the region.     

Dissolved trace-metal concentrations along the Mediterranean Sea, to the north of the Nile Delta Region, Egypt

This work focuses on four marine sites of the Mediterranean Sea, north of the Nile Delta, Egypt. Surface-water samples were collected seasonally during 2003. The aim of this study is to assess the levels of some dissolved trace metals (Fe, Mn, Zn, Cu, and Pb) in two environmental conditions. The metal concentrations in the coastal zone were in the following ranges: 11.92-30.45 μg l^-1 for Fe, 5.79-17.36 μg l^-1 for Mn, 0.87-7.80 μg l^-1 for Zn, 0.40-1.87 μg l^-1 for Cu, and 1.53-10.31 μg l^-1 for Pb. In the sites with continental water input (mixing zone), the metals were scattered in the following ranges: Fe (19.72-60.33 μg l^-1), Mn (12.63-35.60 μg l^-1), Zn (2.67-22.00), Cu (0.83-8.10 μg l^-1), and Pb (1.72-29.7 μg l^-1). The results for the metal concentrations showed a remarkable decrease in the levels of the different metals going from the estuaries and outlets into the coastal sea water. Generally, the levels of the metals in the two zones are higher than the background levels of the unpolluted area. A comparison of the trace-metal levels in the coastal zone of the Mediterranean Sea north of Nile Delta with the minimal risk concentration (reported by water-quality criteria, WQC) showed a significantly lower content at the coastal area of the Mediterranean sea of Egypt. The study also indicated that the impact of anthropogenic inputs was limited in the distribution of the metals, except that the Pb content was slightly higher in the area of the mixing zone than that reported for WQC. The relationships between the different trace-metal concentrations and the other parameters (salinity, chlorophyll a and suspended particulate matter) were discussed, and the simple regressions between them were evaluated.     

Spring and autumn spatial distribution of zooplankton carbon requirement across the Mediterranean Sea

Zooplankton represents a key contributor to the ocean biological pump through its consumption of sinking and suspended carbon. A specific and highly sensitive method to evaluate zooplankton carbon requirement from the sinking flux is through the estimation of the activity of the electron transport system. The present study was carried out from samplings in 2006, and it was focused on the spatial 200–0?m zooplankton carbon demand across 24 sampling stations, along the Mediterranean Sea, from the island of Crete to the Strait of Gibraltar. Its potential day/night variability was evaluated. The zooplankton composition, abundance and biomass were investigated. The carbon demand per unit zooplankton biomass indicates geographical and diel differences among the sampling stations. A higher mean carbon demand was seen for the western Mediterranean with respect to the eastern Mediterranean, which can be justified through the observed ratio of gelatinous:crustacean taxa and the water temperatures recorded. Higher carbon demand was measured in samples collected during the dark hours. The relation to the presence and abundance of actively migrating euphausiids and copepods was discussed. A comparison with data from another of our study carried out in the same study area but in another seasonal period was done.     

Climate change,marine policy and the valuation of Mediterranean intertidal ecosystems

This commentary describes a gap in the qualitative and quantitative knowledge of the provision of benefits to humans from the intertidal ecosystems of the Mediterranean and offers a framework for quantification of the benefits provided by these systems. The identification of such benefits, understanding their spatial distribution and their subsequent quantification will be critical to the design of policy responses to future climate change, sea level rise and seawater acidification. A baseline understanding of the current state of ecosystem functions, as well as of the provision of related ecosystem services, is therefore needed. Further, researchers must strive to generate forecasts of the changes in these functions and services conditional on policy responses and the range of expectations for climate change.     

Long-run changes in radiative forcing and surface temperature: The effect of human activity over the last five centuries

We test two hypotheses that are derived from the anthropogenic theory of climate change. The first postulates that a growing population and increasing economic activity increase anthropogenic emissions of radiatively active gases relative to natural sources and sinks, and this alters global biogeochemical cycles in a way that increases the persistence of radiative forcing and temperature. The second postulates that the increase in the persistence of radiative forcing transmits a stochastic trend to the time series for temperature. Results indicate that the persistence of radiative forcing and temperature changes from I(0) to I(1) during the last 500 years and that the I(1) fingerprint in radiative forcing can be detected in a statistically measureable fashion in surface temperature. As such, our results are consistent with the physical mechanisms that underlie the theory of anthropogenic climate change.     

Response of benthic foraminifera to heavy metal contamination in marine sediments (Sicilian coasts,Mediterranean Sea)

To examine the suitability of benthic foraminifera and their test deformations as bioindicators of pollution in coastal marine environments, we studied foraminifera and metal concentrations in 72 marine sediment samples, collected from the inner shelf along the Sicilian coast (Gulfs of Palermo and Termini) and on the south-eastern coast of Lampedusa Island. These areas are characterised by different environmental conditions. On the basis of pollution sources and foraminiferal assemblages, we recognised different zones in the Gulf of Palermo. The most polluted zones showed high metal concentrations, and low diversity of benthic foraminifera with species typical of stressed environments. By contrast, the lowest polluted zones showed a high population density and the highest percentages of epiphytes. Epiphytes were abundant where a Posidonia oceanica meadow was present and decreased in the most polluted zones. Sediments of the Gulf of Termini and Lampedusa exhibited high percentages of benthic foraminifera typical of well-oxygenated waters and low concentrations of metals, with the exception of sites located near sewage outfalls and harbour areas. Furthermore, even though deformed tests are commonly known in natural stressed environmental conditions, this study shows that in the most polluted zones, benthic foraminifera were characterised by the highest percentages of deformed individuals.     

Microbial respiratory and ectoenzymatic activities in the Northern Adriatic Sea (Mediterranean Sea)

The carbon transfer through the microbial community in two areas of the Northern Adriatic Sea was estimated by proteolytic and respiratory activities during four oceanographic surveys carried out in June, 1996, 1997 and February, 1997, 1998. In front of the Po Delta (area A), the mean rates of proteolytic activity range from 4.9 to 9.9 r µg r C r h r l; near Ancona (area B), they range from 3.1 to 7.6 r µg r C r h r l. Respiratory rates vary between 0.19 and 2.29 and between 0.24 and 1.40 r µg r C r h r l in areas A and B, respectively. In general, high rates occur in the surface layers, within the first 10 r m of depth. In area A, proteolytic and respiratory rates undergo seasonal course, with high activity in warm periods. In area B, respiration and bacterioplankton abundance increase from the first to the second year, whilst proteolytic activity decreases. The sequence of metabolic steps in the carbon transfer within the bacteria, from the biotic vs . the abiotic compartment, was drawn in order to define the actual role of bacterial biomass in the biogeochemical fluxes in an ecosystem which often suffers distrophic crises. Respiratory turnover rates, in the upper 10 r m depth, reach low values in cold periods and high values in June, 1997. The carbon transfer versus mineralization flows better in the summer period, in particular in June, 1997. However, the bacterial growth efficiency ranges from 17 to 38% in area A and from 13 to 44% in area B with highest values in February, 1997, when bacteria contribute in a relevant way to the overall respiration.     

Settlement seasonality and temporal changes in hard substrate macrozoobenthic communities of Lesina Lagoon (Apulia, Southern Adriatic Sea)

The macrofauna settling on experimental substrates was studied at two sites of the Lesina Lagoon to test its possible role in monitoring ecological variations in a brackish-water ecosystem. The community settlement was seasonally investigated on 3-month-old wooden poles; the development was monitored from 2001 to 2005. Comparisons with benthic assemblages settled on 10-yr-old poles were also performed. The main hydrological parameters were periodically measured during the study. A total of 38 species were collected. The assemblage reached the highest development in the central lagoon, showing relevant carbonate structures which supported a rich vagile fauna. Close to the sea-water inlet species richness and abundance values were lower, with the disappearance of some brackish-water species. A remarkable salinity drop during 2004 produced some faunistic changes in the assemblages, which however maintained different structures between the study sites, thus confirming macrozoobenthos as an efficient bioindicator of different environmental conditions for transition biotopes and a useful investigation tool in monitoring programmes.     

Decadal changes in a NW Mediterranean Sea food web in relation to fishing exploitation

We analysed changes in the ecological roles of species, trophic structure and ecosystem functioning using four standardized mass-balance models of the South Catalan Sea (North-western Mediterranean). Models represented the ecosystem during the late 1970s, mid 1990s, early 2000s, and a simulated no-fishing scenario. The underlying hypothesis was that ecosystem models should quantitatively capture the increasing exploitation in the ecosystem from the 1970s to 2000s, as well as differences between the exploited and non-exploited scenarios. Biomass showed a general decrease, while there was an increase in biomass at lower trophic levels (TL) from the 1970s to 2000s. The efficiency of energy transfer (TE) from lower to higher TLs significantly increased with time. The ecosystem during the 1990s showed higher biomass and flows than during the 1970s and 2000s due to an increase in small pelagic fish biomass (especially sardines). Exploited food webs also showed similarities in terms of general structure and functioning due to high intensity of fishing already in the 1970s. This intensity was highlighted with low trophic levels in the catch, high consumption of production by fisheries, medium to high primary production required to sustain the catches and high losses in secondary production due to fishing. Significant differences on ecosystem structure and functioning were highlighted between the exploited and no-fishing scenarios. Biomass of higher TLs increased under the no-fishing scenario and the mean trophic level of the community and the fish/invertebrate biomass ratios were substantially lower in exploited food webs. The efficiency of energy transfer (TE) from lower to higher TLs was lower under the no-fishing scenario, and it showed a continuous decrease with increasing TL. Marine mammals, large hake, anglerfish and large pelagic fish were identified as keystone species of the ecosystem when there was no fishing, while their ecological importance notably decreased under the exploited periods. On the contrary, the importance of small-sized organisms such as benthic invertebrates and small pelagic fish was higher in exploited food webs.     

南中国海地区珊瑚礁资源的破坏现状及保护对策

南中国海具有丰富的浅海和热带的生物多样性,是全球珊瑚礁分布的中心之一。全球34%的珊瑚礁分布在东南亚,该海区拥有全球70个珊瑚属的50个属。东南亚的珊瑚种类有超过一半的分布在南中国海,75种的海绵以及118种的棘皮类动物属于南中国海的地方特有种。珊瑚礁具有重要的生态服务功能,它支持渔业生产、保护海岸、净化空气、提供沿海社区发展的生活资料,在海岸旅游和药物开发等方面具有巨大的潜力。但是由于受人口增加和经济发展的巨大压力,南中国地区珊瑚礁资源破坏严重,退化趋势明显。文章在对南中国海地区珊瑚礁资源的利用现状和退化原因进行分析的基础上,提出南中国海地区珊瑚礁资源保护与管理的建议,以期能在双边或区域的层面上共同协作,采取适当的措施去扭转南中国海地区珊瑚礁生境退化趋势。     

Zooplankton responses to hydrological and trophic variability in a Mediterranean coastal ecosystem (Lesina Lagoon,South Adriatic Sea)

Spatial and temporal variability in zooplankton was studied at eight stations located in the Lesina Lagoon (South Adriatic Sea) Salinity, temperature, dissolved oxygen and chlorophyll a (in the lagoon) at these stations were also assessed. The zooplankton community was characterised by clear seasonal oscillations and mostly represented by copepods and their larvae. The dominant copepod species were Calanipeda aquaedulcis and Acartia tonsa, which exhibited spatial–temporal segregation in the lagoon. C. aquaedulcis copepodites seemed to be better adapted to oligotrophic and oligohaline conditions compared with the A. tonsa population. The invasive species A. tonsa has completely replaced the formerly abundant Acartia margalefi. A positive correlation was found between abundances, total species numbers and trophic state. An increasing abundance trend was shown from the lagoon towards the sea. The highest diversity indices were recorded at the two channel inlets, during high tide due to the absence of a clear dominance of one or more coastal species and the co-occurrence of species of lagoon and marine origin.     

Factors driving the seasonal dynamics of Pseudo-nitzschia species and domoic acid at mussel farming in the SW Mediterranean Sea

ABSTRACT

The seasonal variations in Pseudo-nitzschia species and domoic acid (DA) concentration were investigated, at three shellfish farms in SW coastal Mediterranean. In parallel, the toxicity of mussels was tested. Two distinct groups of species were enumerated according to morphology and size (Pseudo-nizschia delicatissima and P. seriata groups). DA was detected over a nine-week period from July to October 2012 in the Lagoon, with a maximum concentration recorded in July (12.71?ng?DA?L^?1). DA was positively correlated with the presence of P. seriata-group and P. delicatissima-group and was mostly occurred during P limitation period in seawater. No DA was found in mussels that were collected during the period of DA absence in seawater. Our results suggest that temperature, salinity, inorganic and organic nutrients were significant for the seasonal dynamics of P. seriata and P. delicatissima groups, but that the P limitation was the most driving factor for DA production in these areas. The relative influence of environmental factors should be further studied to better understand the recent surfacing of massive blooms of toxigenic Pseudo-nitzschia in SW Mediterranean coast.     

Variation in biometry and population density of solitary corals with solar radiation and sea surface temperature in the Mediterranean Sea

The correlation between two environmental factors (solar radiation and sea surface temperature), biometry, and population density was assessed along a latitudinal gradient in the zooxanthellate coral Balanophyllia europaea and in the azooxanthellate coral Leptopsammia pruvoti. With increasing polyp size, the oral disc of B. europaea assumed an oval shape, while that of L. pruvoti retained a circular shape. In both species, biometric parameters varied more with temperature than with solar radiation. In the zooxanthellate species, temperature explained a higher percentage of biometric parameter variance than in the azooxanthellate species. While environmental factors did not co-vary with demographic characteristics in L. pruvoti, temperature was negatively related to the population density of B. europaea. It is hypothesized that the negative effect of temperature on biometry and population density of B. europaea depends on photosynthesis inhibition of symbiotic zooxanthellae at high temperatures, which would lower the calcification rate and availability of energetic resources.     

Meio- and macrofauna communities in three sandy beaches of the northern Adriatic Sea protected by artificial reefs

Interactions between meio- and macrofaunal assemblages and food availability were investigated in relation to tourism pressures on three beaches of the northern Adriatic Sea. All beaches were characterised by the presence of artificial reefs, freshwater inputs and tourism pressures. Beach sediments displayed high organic loads and low protein and chlorophyll a contributions to the bulk of the organic matter. Consequently, the organic matter was of mostly refractory composition and, thus, of scarce nutritional quality. Macrofaunal community structure and biomass were related to the quantity and nutritional quality of sedimentary organic matter, whereas meiofauna was apparently not. No relationships were found between physical variables and the metazoan communities. Most likely, the presence of artificial reefs reduced the physical impact of waves on the beach assemblages, whereas the presence of synergistic human impacts, including freshwater inputs and the tourism pressure, negatively influenced both the meio- and the macrofaunal assemblages.     

Climate change and population genetic structure of marine species

Climate change influences populations by reducing or extirpating local populations, by disrupting patterns of migration and by shifting geographical distributions. These events can affect genetic population structure in several ways. Molecular markers have been used in numerous population genetic and phylogeographical studies of marine species and have detected population responses to climate change in the last few decades, such as range expansions, adaptative shifts and declines or increases in abundance. Little is known, however, about the molecular and physiological basis of adaptive responses to climate change in marine Mediterranean species. The Mediterranean Sea ecosystem is a ‘living laboratory’ with native species that are challenged by environmental change and by invasive species and a ‘gene-climate’ approach should be adopted as a way of focusing on the relationship between climate warming and genetic diversity.     

黄渤海表层沉积物中正构烷烃和甾醇的分布及来源研究

在黄海、渤海湾和莱州湾采集64个表层沉积物样品,分析正构烷烃（C15～C33）和甾醇（菜子甾醇、菜油甾醇、谷甾醇和豆甾醇）的质量分数和分子组合特征,探讨其来源,比较物质来源的空间差异。结果表明：（1）黄海表层沉积物中类脂生物标志物主要呈现陆源和海源共同影响的特征,其中北黄海以陆源输入为主,高碳数正构烷烃（〉C24）具有明显的奇碳优势,陆源高等植物的贡献较大;南黄海陆源输入与海洋自身贡献相当;渤海湾与莱州湾接受来自河流的大量陆源物质;（2）来源于陆源高等植物的甾醇（包括菜油甾醇、谷甾醇和豆甾醇）在黄海表层沉积物中的质量分数远小于渤海湾和莱州湾,但指示硅藻来源的菜子甾醇在整个研究区域均具有较高的质量分数。