Changes in body condition and fatty acid composition of wild Mediterranean horse mackerel (Trachurus mediterraneus, Steindachner, 1868) associated to sea cage fish farms     

Fernandez-Jover D  Jimenez JA  Sanchez-Jerez P  Bayle-Sempere J  Casalduero FG  Lopez FJ  Dempster T 《Marine environmental research》2007,63(1):1-18

Net-cage fish farms attract a great number of wild fishes, altering their behaviour and possibly their physiology. Wild Mediterranean horse mackerel (Trachurus mediterraneus), sampled from populations aggregated around two Mediterranean fish farms and from two natural control populations, were analyzed for differences in body condition, stomach content and fatty acid composition. Pellets used to feed caged fish in both farms were also analyzed to identify their relationship with the fatty acid composition of tissue of wild fish. T. mediterraneus aggregated around the farms throughout the year although large seasonal changes in abundance and biomass occurred. Wild fish aggregated at farms mainly ate food pellets while control fish fed principally on juvenile fish and cephalopods. Wild fish that fed around the cages had a significantly higher body fat content than the control fish (7.30+/-1.8% and 2.36+/-0.7%, respectively). The fatty acid composition also differed between farm-associated and control fish, principally because of the significantly increased levels of linoleic (C18:2omega6) and oleic (C18:1omega9) acids and decreased docosahexaenoic acid (C22:6omega3) in farm-associated fish. The increased condition of wild fish associated with farms could increase the spawning ability of coastal fish populations, if wild fish are protected from fishing while they are present at farms. The fatty acids compositions could also serve as biomarkers to infer the influence of a fish farm on the local fish community, helping to better describe the environmental impact of fish farming.  相似文献   

The Cenomanian/Turonian oceanic anoxic event in the Razzak Field, north Western Desert, Egypt: Source rock potential and paleoenvironmental association     

Mohamed K. Zobaa  Francisca E. Oboh-IkuenobeMohamed I. Ibrahim 《Marine and Petroleum Geology》2011,28(8):1475-1482

The Western Desert of Egypt is one of the world’s most prolific Jurassic and Cretaceous hydrocarbon provinces. It is one of many basins that experienced organic-rich sedimentation during the late Cenomanian/early Turonian referred to as oceanic anoxic event 2 (OAE2). The Razzak #7 oil well in the Razzak Field in the northern part of the Western Desert encountered the Upper Cretaceous Abu Roash Formation. This study analyzed 23 samples from the upper “G”, “F”, and lower “E” members of the Abu Roash Formation for palynomorphs, particulate organic matter, total organic carbon (TOC) and δ¹³C_org in order to identify the OAE2, determine hydrocarbon source rock potential, and interpret the depositional environment. The studied samples are generally poor in palynomorphs, but show a marked biofacies change between the lower “E” member and the rest of the studied samples. Palynofacies analysis (kerogen quality and quantity) indicates the presence of oil- and gas-prone materials (kerogen types I and II/III, respectively), and implies reducing marine paleoenvironmental conditions. Detailed carbon stable isotopic and organic carbon analyses indicate that fluctuations in the δ¹³C_org profile across the Abu Roash upper “G”, “F”, and lower “E” members correspond well with changes in TOC values. A positive δ¹³C_org excursion (∼2.01‰) believed to mark the short-term global OAE2 was identified within the organic-rich shaly limestone in the basal part of the Abu Roash “F” member. This excursion also coincides with the peak TOC measurement (24.61 wt.%) in the samples.  相似文献   

Mid to late Holocene constraints for continental shelf mud deposition in association with river input: the Guadiana Mud Patch (SW Iberia)   总被引：1，自引：1，他引：0  

Francisca Rosa  J. A. Dias  I. Mendes  ��. Ferreira 《Geo-Marine Letters》2011,31(2):109-121

This study correlates Holocene sedimentation with regional environmental changes for the Guadiana middle shelf, SW Iberia, based on a detailed sedimentological analysis combined with radiocarbon and amino acid racemization dating. The sedimentary record of vibrocore CRIDA16 (307 cm) from the mud patch off the Guadiana River is characterized by a transgressive signature. Terrigenous sand–gravel dominates the core base up to ca. 5,000 cal. years b.p., enriched in schist/greywackes and non-reworked quartz. The shelf area was under the direct influence of Guadiana bed load discharges, as sea level was lower than today but rising, favouring the entrapment of fines during the Guadiana estuary infilling in the early Holocene. Core upwards, fines dominate the record. Sea-level stabilization at ca. 5,700–3,700 cal. years b.p. led to estuary infilling by coarser sediments and export of suspended sediment to the middle shelf. After ca. 900–700 cal. years b.p., the formation of the Guadiana Mud Patch signifies deposition in a marine environment dominated by suspended material from the Guadiana River. Comparison with earlier publications showed that a similar evolutionary mechanism of middle shelf mud deposition occurred in other parts of the Iberian Margin, pointing to a generalized establishment of this type of sedimentary body in Iberia since the mid to late Holocene. This suggests that the formation of mud belts on the north and south Iberian Margin was to a large extent synchronous. It is likely that the evolution of the Guadiana Mud Patch on the shelf was controlled foremost by the overall climate trends identified for several parts of Iberia during the Holocene (i.e. increased aridity punctuated by significant humidity stages), and less by human occupation of the region. Enhanced humidity stages led to higher rainfall and intensified floods, with a consequent increase of discharges to the shelf which ultimately were responsible for the Guadiana Mud Patch formation. It is expected that this pattern of sedimentary dynamics has been strongly disturbed since 2002, when the closing of the Alqueva Dam (the biggest on the Iberian Peninsula) was completed in the Guadiana River basin.  相似文献   

The Mesolithic–Neolithic transition in southern Iberia     

Miguel Cortés Sánchez  Francisco J. Jiménez Espejo  María D. Simón Vallejo  Juan F. Gibaja Bao  António Faustino Carvalho  Francisca Martinez-Ruiz  Marta Rodrigo Gamiz  José-Abel Flores  Adina Paytan  José A. López Sáez  Leonor Peña-Chocarro  José S. Carrión  Arturo Morales Muñiz  Eufrasia Roselló Izquierdo  José A. Riquelme Cantal  Rebecca M. Dean  Emília Salgueiro  Rafael M. Martínez Sánchez  Nuno F. Bicho 《Quaternary Research》2012,77(2):221-234

New data and a review of historiographic information from Neolithic sites of the Malaga and Algarve coasts (southern Iberian Peninsula) and from the Maghreb (North Africa) reveal the existence of a Neolithic settlement at least from 7.5 cal ka BP. The agricultural and pastoralist food producing economy of that population rapidly replaced the coastal economies of the Mesolithic populations. The timing of this population and economic turnover coincided with major changes in the continental and marine ecosystems, including upwelling intensity, sea-level changes and increased aridity in the Sahara and along the Iberian coast. These changes likely impacted the subsistence strategies of the Mesolithic populations along the Iberian seascapes and resulted in abandonments manifested as sedimentary hiatuses in some areas during the Mesolithic–Neolithic transition. The rapid expansion and area of dispersal of the early Neolithic traits suggest the use of marine technology. Different evidences for a Maghrebian origin for the first colonists have been summarized. The recognition of an early North-African Neolithic influence in Southern Iberia and the Maghreb is vital for understanding the appearance and development of the Neolithic in Western Europe. Our review suggests links between climate change, resource allocation, and population turnover.  相似文献   

BaMn[CO3]2 – a previously unrecognized double carbonate in low-temperature environments: Structural,spectroscopic, and textural tools for future identification     

Michael E. Böttcher  Herta S. Effenberger  Peer-Lennart Gehlken  Georg H. Grathoff  Burkhard C. Schmidt  Patrizia Geprägs  Rainer Bahlo  Olaf Dellwig  Thomas Leipe  Vera Winde  André Deutschmann  Alexander Stark  David Gallego-Torres  Francisca Martinez-Ruiz 《Chemie der Erde / Geochemistry》2012,72(1):85-89

Following a tentative evidence for the occurrence of low-temperature barium manganese(II) carbonates in brackish sediments of the Baltic Sea, a stoichiometric double carbonate, BaMn[CO₃]₂, was synthesized from aqueous solutions at ambient temperature for the first time. Here we report the results of a multi-method approach, including scanning electron microscopy (SEM–EDX) investigations, the chemical composition, and, in particular, the diagnostic powder X-ray diffraction pattern, as well as diagnostic parts of the FT infrared absorption and Raman spectra for future identification of this new carbonate in low-temperature environments, like brackish sediments.  相似文献   

Ensemble Spatial Interpolation: A New Approach to Natural or Anthropogenic Variable Assessment     

Egaña  Alvaro  Navarro  Felipe  Maleki  Mohammad  Grandón  Francisca  Carter  Francisco  Soto  Fabián 《Natural Resources Research》2021,30(5):3777-3793

Natural Resources Research - This paper presents a novel and versatile framework for building ensemble spatial interpolation functions. As with all ensemble methods, the central idea is to assemble...  相似文献   

Comparative toxic effects of copper-based nanoparticles and their microparticles in Daphnia magna by using natural freshwater media     

Francisca Arratia  Pamela Olivares-Ferretti  Alba García-Rodríguez  Ricard Marcos 《新西兰海洋与淡水研究杂志》2019,53(3):460-469

Copper-based nanoparticles (NPs) are being widely used in different application fields and their health impacts to aquatic environments represent a current concern. Few studies are available about their comparative toxicity with their bulks and ions under natural exposition in aquatic organisms. Thus, the toxicity of Cu and CuO NPs and their microparticle and ionic forms was assayed in the acute immobilisation test of Daphnia magna by using freshwater media. Electronic microscopy, laser doppler velocimetry, and dynamic laser scattering methodologies were used to NPs characterisation. The results indicated that CuNPs and CuONPs were more toxic than their microparticles. Among NPs, CuNPs showed higher toxicity than CuONPs. Copper-based nanoparticles showed similar hydrodynamic particle size and were agglomerated in culture media, suggesting toxic-ionic release relationship and corroborated by the high toxicity induced by CuSO₄. Additionally, water chemistry of natural freshwater used in the experiments also favoured the ion release of these NPs.  相似文献   

A Forward Modeling Approach for Interpreting Impeller Flow Logs     

by Alison H. Parker  L. Jared West  Noelle E. Odling  Richard T. Bown 《Ground water》2010,48(1):79-91

A rigorous and practical approach for interpretation of impeller flow log data to determine vertical variations in hydraulic conductivity is presented and applied to two well logs from a Chalk aquifer in England. Impeller flow logging involves measuring vertical flow speed in a pumped well and using changes in flow with depth to infer the locations and magnitudes of inflows into the well. However, the measured flow logs are typically noisy, which leads to spurious hydraulic conductivity values where simplistic interpretation approaches are applied. In this study, a new method for interpretation is presented, which first defines a series of physical models for hydraulic conductivity variation with depth and then fits the models to the data, using a regression technique. Some of the models will be rejected as they are physically unrealistic. The best model is then selected from the remaining models using a maximum likelihood approach. This balances model complexity against fit, for example, using Akaike's Information Criterion.  相似文献   

A late paleo-Indian/Early archaic water well in Mexico—Possible oldest water-Management feature in the new world     

S. Christopher Caran  James A. Neely  Barbara M. Winsborough  Francisca Ramirez Sorensen  Salvatore Valastro 《Geoarchaeology》1996,11(1):1-35

A filled prehistoric water well discovered at the village of San Marcos Necoxtla, Puebla, Mexico, may be the oldest directly dated water-management feature in the Americas. The ∼10 m stratigraphic section exposed at this remarkable site records 18,000+ yr of deposition, erosion, water-table and hydrochemical fluctuations, and ≥10,000 yr of continual occupation. Temporal control is afforded by a multicomponent cultural chronology and radiocarbon assays by conventional and experimental techniques. The ∼10 m wide, ∼5 m deep well was excavated, utilized, maintained, and filled with cultural material between <9863 and ≫5950 yr B.P., a span of ≪3913 yr. Ages of other reported Late Pleistocene(?) to Middle Holocene wells in the New World are based on indirect or questionable dating, or are ≤6600 yr. Because of its age and continuity of occupation, the San Marcos Necoxtla well site may help define the nature of the peopling of the Americas and the advent of New World agriculture. © 1996 John Wiley & Sons, Inc.  相似文献   

Magnetic characterization of Cretaceous‐Tertiary boundary sediments     

Víctor Villasante‐Marcos  Francisca MartÍNez‐Ruiz  María Luisa Osete  Jaime Urrutia‐Fucugauchi 《Meteoritics & planetary science》2007,42(9):1505-1527

Abstract— Rock magnetic properties across several K‐T boundary sections have been investigated to reveal any possible magnetic signature associated with the remains of the impact event at the end of the Cretaceous. Studied sections' locations vary in distance to the Chicxulub structure from distal (Agost and Caravaca, Spain), through closer (ODP Hole 1049A, Blake Nose, North Atlantic), to proximal (El Mimbral and La Lajilla, Mexico). A clear magnetic signature is associated with the fireball layer in the most distal sections, consisting of a sharp increase in susceptibility and saturation isothermal remanent magnetization (SIRM), and a decrease in remanence coercivity. Magnetic properties in these sections point to a distinctive ferrimagnetic phase, probably corresponding to the reported Mg‐ and Ni‐rich, highly oxidized spinels of meteoritic origin. At closer and proximal sections magnetic properties are different. Although there is an increase in susceptibility and SIRM associated with a rusty layer placed on top of the siliciclastic deposit in proximal sections, and with a similar limonitic layer on top of the spherule bed that defines the boundary at Blake Nose, the magnetic properties indicate a mixture of iron oxyhydroxides dominated by fine‐grained goethite. Based on previous geochemical studies at Blake Nose and new geochemical and PGE abundance measurements performed in this work at El Mimbral, this goethite‐rich layer can be interpreted as an effect of diagenetic remobilization and precipitation of Fe. There is not enough evidence to assert that this Fe concentration layer at proximal sections is directly related to deposition of fine meteoritic material. Magnetic, geochemical, and iridium data reject it as a primary meteoritic phase.  相似文献