Holocene coastal change in the ancient harbor of Yenikap?-?stanbul and its impact on cultural history     

Oya Algan  M. Nam?k Yalç?n  Yücel Y?lmaz  Elmas K?rc?-Elmas  Özlem Bulkan  Cem Gazio?lu  Mehmet Ali Polat 《Quaternary Research》2011,76(1):30-45

An extensive rescue excavation has been conducted in the ancient harbor of ?stanbul (Yenikap?) by the Sea of Marmara, revealing a depositional sequence displaying clear evidence of transgression and coastal progradation during the Holocene. The basal layer of this sequence lies at 6 m below the present sea level and contains remains of a Neolithic settlement known to have been present in the area, indicating that the sea level at ~ 8-9 cal ka BP was lower than 6 m below present. Sea level advanced to its maximum at ~ 6.8-7 cal ka BP, drowning Lykos Stream and forming an inlet at its mouth. After ~ 3 cal ka BP, coastal progradation became evident. Subsequent construction of the Byzantine Harbor (Theodosius; 4th century AD) created a restricted small basin and accumulation of fine-grained sediments. The sedimentation rate was increased due to coastal progradation and anthropogenic factors during the deposition of coarse-grained sediments at the upper parts of the sequence (7th-9th centuries AD). The harbor was probably abandoned after the 11th century AD by filling up with Lykos Stream detritus and continued seaward migration of the coastline.  相似文献   

黔西北天桥铅锌矿床锗地球化学研究   总被引：1，自引：0，他引：1  

赵海燕  黄智龙  李晓彪 《矿物学报》2011,31(3):509-514

天桥铅锌矿床是川一滇一黔铅锌多金属成矿域黔西北铅锌成矿区内很具代表性的中型矿床,赋矿岩石为石炭系碳酸盐岩,矿床严格受构造控制。本次工作利用ICP—MS分析了该矿床主要矿石矿物（黄铁矿、闪锌矿和方铅矿）中锗的含量,初步查明了该区锗的分布规律,探讨了锗在方铅矿和闪锌矿中的富集机制。结果表明：原生矿体中Ge在方铅矿中的含量和富集系数均明显大于闪锌矿,显示本区Ge在方铅矿中的富集特征;Ge在演化晚期的成矿流体中相对富集,流体中的Ge以“2M（I）＋M（Ⅱ）＋M（Ⅲ）=4Zn（Ⅱ）”形式进入方铅矿．Ge在方铅矿中不是以类质同象形式替代Pb、而是替代其中的Zn。  相似文献   

Macrobenthic community changes due to dystrophic events and freshwater inflow: Changes in space and time in a Mediterranean lagoon (Gialova lagoon, SW Greece)     

Georgios ChatzigeorgiouSophia Reizopoulou  Maria MaidanouMaria Naletaki  Eleni OrnerakiEugenia Apostolaki  Christos Arvanitidis 《Estuarine, Coastal and Shelf Science》2011,94(1):111-121

This paper considers the hypothesis that changes in community structure through the control of the larvae maintenance and of the biological traits of the species mostly contribute to the spatio-temporal community pattern. This is supported by the results of the study, the changes to the macrobenthic community pattern deriving from two sampling periods in Gialova lagoon (SW Greece), carried out on a seasonal basis for two yearly periods: 1994-95 and 1998-99. Cognetti’s hypothesis that populations of the tolerant species occupying coastal marine habitats may belong to different species is another alternative hypothesis still to be tested. The importance of alternative management plans aiming at the amelioration of the hydrodynamic conditions of the lagoons and supported by continuous scientific monitoring is highlighted. Two canals bringing fresh water were opened at the beginning of the second sampling period, an intervention among others, suggested by the management plan proposed after the end of the first sampling period. The results show considerable variations in the values of the key environmental variables, for instance long periods with negative Redox potential values, decreased salinity and increased concentrations of the particulate organic matter and of the nutrients. The variables were correlated with the spatio-temporal community pattern, characterized during the second sampling period by: (i) greater dissimilarities among stations/seasons; (ii) disruption of the periodic trend observed on the seasonal scale; (iii) larger relative dissimilarities among the patterns stemming from the macrobenthos and the most abundant groups (polychaetes, molluscs, crustaceans); (iv) significant decrease in abundance or even the disappearance of several marine origin species, along with increased abundance in a few brackish-water species. All of the above changes in the community pattern are considered as early warning signals leading towards degradation, which has not yet been registered in the phylogenetic/taxonomic structure of the macrobenthic community.  相似文献   

Otolith reading and multi-model inference for improved estimation of age and growth in the gilthead seabream Sparus aurata (L.)     

Lny Mercier  Jacques Panfili  Christelle Paillon  Awa N'diaye  David Mouillot  Audrey M. Darnaude 《Estuarine, Coastal and Shelf Science》2011,92(4):534-545

Accurate knowledge of fish age and growth is crucial for species conservation and management of exploited marine stocks. In exploited species, age estimation based on otolith reading is routinely used for building growth curves that are used to implement fishery management models. However, the universal fit of the von Bertalanffy growth function (VBGF) on data from commercial landings can lead to uncertainty in growth parameter inference, preventing accurate comparison of growth-based history traits between fish populations. In the present paper, we used a comprehensive annual sample of wild gilthead seabream (Sparus aurata L.) in the Gulf of Lions (France, NW Mediterranean) to test a methodology improving growth modelling for exploited fish populations. After validating the timing for otolith annual increment formation for all life stages, a comprehensive set of growth models (including VBGF) were fitted to the obtained age–length data, used as a whole or sub-divided between group 0 individuals and those coming from commercial landings (ages 1–6). Comparisons in growth model accuracy based on Akaike Information Criterion allowed assessment of the best model for each dataset and, when no model correctly fitted the data, a multi-model inference (MMI) based on model averaging was carried out. The results provided evidence that growth parameters inferred with VBGF must be used with high caution. Hence, VBGF turned to be among the less accurate for growth prediction irrespective of the dataset and its fit to the whole population, the juvenile or the adult datasets provided different growth parameters. The best models for growth prediction were the Tanaka model, for group 0 juveniles, and the MMI, for the older fish, confirming that growth differs substantially between juveniles and adults. All asymptotic models failed to correctly describe the growth of adult S. aurata, probably because of the poor representation of old individuals in the dataset. Multi-model inference associated with separate analysis of juveniles and adult fish is then advised to obtain objective estimations of growth parameters when sampling cannot be corrected towards older fish.  相似文献   

Feeding ecology of Ammothella longipes (Arthropoda: Pycnogonida) in the Mediterranean Sea: A fatty acid biomarker approach     

Anna Soler-Membrives  Sergio Rossi  Toms Munilla 《Estuarine, Coastal and Shelf Science》2011,92(4):819-597

Fatty acid analysis has proved valuable in determining seasonal trophic links and the feeding behavior in organisms in which these diet and trophic links cannot be inferred from stomach content analyses. Seasonal variations in total free fatty acid content (TFFA) and fatty acid composition of seston (<250 μm), the brown macroalgae Stypocaulon spp., polychaetes (Nereididae) and the pycnogonid Ammothella longipes have been used to establish their trophic links, with particular focus on seasonality and feeding ecology of A. longipes. Samples were collected in a coastal environment (NW Mediterranean Sea) at 7–10 m depth, in five different periods (August and October 2008, February, June and September 2009). Seston and Stypocaulon spp. samples did not show significant seasonal variations in TFFA content, while nereids showed a significant variation. Analysis of fatty acid profile showed high similarities of fatty acid composition between seston and Stypocaulon spp. Nereids were closer to seston and Stypocaulon spp. than A. longipes, which seemed to follow a seasonal trend. The results of this study reveal that A. longipes may change its feeding behavior depending on the season and available food. This pycnogonid species appears to be carnivore during spring and early summer but seems to feed on detritus when availability of prey diminishes during winter. Notable high amounts of odd-chain fatty acids are found in summer–autumn for this species, which may come from bacteria acquired from the detrital diet or from de novo biosynthesis from propionate. The results obtained provide new and valuable data on the understudied feeding biology of pycnogonids in general, and contribute to the understanding of their functioning of Mediterranean shallow oligotrophic systems and their trophic links.  相似文献   

Antarctic Intermediate Water influence on Mediterranean Sea Water outflow     

Essyllt Louarn  Pascal Morin 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(9):932-942

This study of the mixing of Mediterranean Sea Water (MW) with the surrounding waters was made possible by the Semane 2002 cruise (Sortie des Eaux Meditérranéennes dans l'Atlantique Nord-Est) that took place in the Gulf of Cadiz in July 2002. Potential temperature, salinity, oxygen, nutrients and CFC data are used to describe the water masses present in the Gulf. In the southern part of the basin, a water mass characterised by low oxygen, high nutrient and low CFC concentrations occurs along the African continental slope. This water has been identified as the modified Antarctic Intermediate Water (AAIW). It has been previously observed south of this section, at the latitude of the Canary Islands, as a northward flow between the African shelf and the islands. The modified AAIW found in the Gulf of Cadiz is situated at a density of 27.5 kg m⁻³. Above, at 27.3 kg m⁻³, the lower limb of the North Atlantic Central Water is observed as a salinity minimum. The modified AAIW enters the Gulf of Cadiz along the south-western part of the continental shelf. It flows cyclonically and exits north-westward. In the northern part of the gulf, due to the presence of the Mediterranean Undercurrent (MU), the AAIW flows off the coast. An optimum multiparameter analysis was conducted to evaluate the influence of the AAIW on the MW northwest of the basin. We show that the AAIW is present in the lower core of the MU at a proportion of 12.9±8.2% and is absent in the upper core.  相似文献   

Do abyssal scavengers use phytodetritus as a food resource? Video and biochemical evidence from the Atlantic and Mediterranean     

Rachel M. Jeffreys  Marc S.S. LavaleyeMagda J.N. Bergman  Gerard C.A. DuineveldRob Witbaard 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(4):415-428

Deep-sea benthic communities derive their energetic requirements from overlying surface water production, which is deposited at the seafloor as phytodetritus. Benthic invertebrates are the primary consumers of this food source, with deep-sea fish at the top of the trophic hierarchy. Recently, we demonstrated with the use of baited cameras that macrourid fish rapidly respond to and feed vigorously on large plant food falls mimicked by spinach (Jeffreys et al., 2010). Since higher plant remains are scarce in the deep-sea, with the exception of canyons, where terrestrial material has been observed, these results led us to ask if a more commonly documented plant material i.e. phytodetritus might form a food source for deep-sea fish and mobile scavenging megafauna. We simulated a phytodetritus dump at the seafloor in two contrasting environments (1) the NE Atlantic where carpets of phytodetritus have been previously observed and (2) the oligotrophic western Mediterranean, where the deposition of phytodetritus at the seafloor is a rare occurrence. We recorded the response of the scavenging fauna using an in situ benthic lander equipped with baited time-lapse cameras. In the NE Atlantic at 3000 m, abyssal macrourids and cusk-eels were observed ingesting the phytodetritus. The phytodetrital patch was significantly diminished within 2 h. Abundance estimates calculated from first arrival times of macrourids at the phytodetrital patch in the Atlantic corresponded with abundance estimates from video-transect indicating that fish were attracted to the scent of phytodetrital bait. In contrast to this, in the western Mediterranean at 2800 m a single macrourid was observed investigating the phytodetrital patch but did not feed from it. The phytodetrital patch was significantly diminished within 6.5 h as a result of mainly invertebrate activity. At 1900 m, Lepidion lepidion was observed near the lander and the bait, but did not feed. The phytodetrital patch remained intact until the end of the experiment. In the deployments in the Mediterranean abundance estimates from first arrival times at the bait, corrected for their body size, were lower than estimates obtained from video-transects and trawl catches. This suggests that the Mediterranean fish were not readily attracted to this food source. In contrast, invertebrates in the Balearic Sea were observed ingesting the phytodetritus bait despite the rare occurrence of phytodetritus dumps in the Mediterranean. Stable isotope values of the fish at both study sites, set within the context of the benthic food web, did not demonstrate a strong trophic link to phytodetritus. Fatty acid profiles of these fish indicated a strong link between their lipid pool and primary producers i.e. phytoplankton, which may be attributed to trophic transfer. The usefulness of fatty acid biomarkers in ascertaining deep-sea fish diets is discussed. Our study suggests that the abyssal grenadier C. armatus on the Atlantic Iberian margin is attracted to phytodetritus. However the exact contribution of this food source to the diet of macrourids in this area remains unresolved.  相似文献   

Anthropogenic CO₂ fluxes in the Otranto Strait (E. Mediterranean) in February 1995     

Evangelia Krasakopoulou  Ekaterini Souvermezoglou  Catherine Goyet 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(11):1103-1114

This study presents the distribution and fluxes of dissolved inorganic carbon (C_T), total alkalinity (A_T) and anthropogenic carbon (C_ant) along the Otranto strait, during February 1995. Based on a limited number of properties (temperature, dissolved oxygen, total alkalinity and dissolved inorganic carbon), the composite tracer TrOCA was used to estimate the concentration of anthropogenic CO₂ in the Otranto strait.Total alkalinity exhibits high values and weak variability throughout the water column of the strait, probably associated with the dense water formation processes in the Adriatic basin that induce a rapid transport of the coastal alkalinity to the deep waters. Elevated C_ant concentrations and high anthropogenic pH variations are observed in the bottom layer of the strait, associated with the presence of Adriatic Deep Water (ADW). The study shows that large amounts of C_ant have penetrated the highly alkaline Eastern Mediterranean waters, thereby causing a significant pH reduction since the pre-industrial era.Estimates of the transports of C_T and C_ant through the strait indicate that during February 1995, the Adriatic Sea imports through the Otranto strait natural and anthropogenic carbon and acts as a net sink of carbon for the Ionian Sea. The anthropogenic carbon that is imported to the Adriatic Sea represents less than 1% of the net C_T inflow. The Levantine Intermediate Water (LIW) contributes to about one-third of the total C_T and C_ant inflow. Although the amounts of C_ant annually transported by LIW and ADW are almost equal, the contribution of C_ant to the C_T transported by each water mass is slightly higher in ADW (3.1%) than in LIW (2.6%), as a result of its higher mean C_ant concentration. The ADW, despite its weak contribution to the total outflow of C_ant, has a vital role for the sequestration and storage of the anthropogenic carbon, as this water mass is the main component of the Eastern Mediterranean Deep Waters and, thus, the anthropogenic CO₂ is transferred in the deep horizons of the Eastern Mediterranean, where it remains isolated for many years.  相似文献   

Impact of the Eastern Mediterranean Transient on the distribution of anthropogenic CO₂ and first estimate of acidification for the Mediterranean Sea     

Franck Touratier  Catherine Goyet 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(1):1-15

In the Mediterranean Sea the carbon chemistry is poorly known. However, the impact of the regional and large-scale anthropogenic pressures on this fragile environment rapidly modifies the distribution of the carbonate system key properties like C_T (total dissolved inorganic carbon), A_T (total alkalinity), C_ANT (anthropogenic CO₂), and pH. This leads inexorably to the acidification of its waters. In order to improve our knowledge, we first develop interpolation procedures to estimate C_T and A_T from oxygen, salinity, and temperature data using all available data from the EU/MEDAR/MEDATLAS II database. The acceptable levels of precision obtained for these estimates (6.11 ??mol-kg⁻¹ for C_T and 6.08 ??mol kg⁻¹ for A_T) allow us to draw the distribution of C_ANT (with an uncertainty of 6.75 ??mol kg⁻¹) using the Tracer combining Oxygen, inorganic Carbon, and total Alkalinity (TrOCA) approach. The results indicate that: 1) all Mediterranean water bodies are contaminated by anthropogenic carbon; 2) the lowest concentration of C_ANT is 37.5 ??mol kg⁻¹; and 3) the western basin is more contaminated than the Eastern basin. After reconstructing the distribution of key properties (C_T, A_T, C_ANT) for four periods of time (between 1986 and 2001) along a west-east section throughout the whole Mediterranean Sea, we analyze the impact of the Eastern Mediterranean Transient (EMT). Not only has the concentration of C_ANT increased (especially in the intermediate and the bottom layers of the eastern basin, during and after the EMT), but also the distribution of all properties has been considerably perturbed. This is discussed in detail. For the first time, the level of acidification is estimated for the Mediterranean Sea. Our results indicate that for the year 2001 all waters (even the deepest) have been acidified by values ranging from −0.14 to −0.05 pH unit since the beginning of the industrial era, which is clearly higher than elsewhere in the open ocean. Given that the pH of seawater may affect a very large number of chemical and biological processes, our results stress the necessity to develop new programs of research to understand and then predict the evolution of the carbonate system properties in the Mediterranean Sea.  相似文献   

Food web structure of the epibenthic and infaunal invertebrates on the Catalan slope (NW Mediterranean): Evidence from ��C and ��N analysis     

E. Fanelli  V. PapiolJ.E. Cartes  P. RumoloC. Brunet  M. Sprovieri 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(1):98-109

The food-web structure of the epibenthic and infaunal invertebrates on the continental slope of the Catalan Sea (Balearic basin, NW Mediterranean) was investigated using carbon and nitrogen stable isotopes on a total of 34 species, and HPLC pigment analyses for three key species. Samples were collected close to Barcelona (NE Iberian Peninsula), between 650 and 800 m depth and between February 2007 and February 2008. Mean ??¹³C values ranged from −21.0‰ (small Calocaris macandreae and Amphipholis squamata) to −14.5‰ (Sipunculus norvegicus). Values of ??¹⁵N ranged from 4.0‰ (A. squamata) to 12.1‰ (Molpadia musculus). The stable isotope ratios of benthic fauna displayed a continuum of values (e.g. ??¹⁵N range of 8‰), confirming a wide spectrum of feeding strategies (from active suspension feeders to predators) and complex food webs. According to the available information on diets of benthic fauna, the lowest values were found for surface deposit feeders (small C. macandrae and the two ophiuroids A. squamata and Amphiura chiajei) and active suspension feeders (Abra longicallus and Scalpellum scalpellum) feeding on different sizes of particulate organic matter (POM), among which small particles may exhibit lower ??¹⁵N. High annual mean ??¹⁵N values were found among sub-surface deposit feeders, exploiting refractory or frequently recycled organic matter that is enriched in ??¹⁵N. Carnivorous polychaetes (Nephtys spp., Oenonidae and Polynoidae) and large decapods (Geryon longipes and Paromola cuvieri) also displayed high ??¹⁵N values. ??¹³C ranges were particularly wide among surface deposit feeders (ranging from −21.0‰ to −16.4‰), suggesting exploitation of POM of both terrigenous and oceanic origins. Correlation between ??¹³C and ??¹⁵N was generally weak, indicating multiple carbon sources, likely due to the consumption of different kinds of sinking particles (e.g. marine snow, phytodetritus, etc.), sedimented and frequently recycled POM, together with macrophyte remains. The stronger ??¹³C-??¹⁵N correlations found in February and April suggest that during the period of water column homogeneization (winter-spring), the benthic community was sustained by phytodetritus inputs originating from the peak of surface primary production in February. Conversely, weaker ??¹³C-??¹⁵N correlations were observed during the period of water column stratification (beginning in June-July), suggesting that the benthic community in this period was sustained, with a delay of ca. 2/3 months, by multiple carbon sources including continental inputs from river discharge (with the maxima in April-May). Thus both advective and vertical fluxes seem to be food sources for benthos on the Catalonian slope. Pigments in the guts of key species were generally degraded, and only the active suspension feeder A. longicallus ingested fresh chlorophyll during periods of high primary production at the surface (February and April 2007).  相似文献