Low reproductive success for copepods during a bloom of the non‐aldehyde‐producing diatom Cerataulina pelagica in the North Adriatic Sea     

Adrianna Ianora  Raffaella Casotti  Mauro Bastianini  Christophe Brunet  Giuliana D’Ippolito  Francesco Acri  Angelo Fontana  Adele Cutignano  Jefferson T. Turner  Antonio Miralto 《Marine Ecology》2008,29(3):399-410

Egg production rates and/or hatching success in the copepods Acartia clausi, Calanus helgolandicus and Temora longicornis were negatively affected by a late spring (May–June 2003) phytoplankton bloom in the North Adriatic Sea, dominated mainly by the large diatom Cerataulina pelagica. Highest total concentrations of 3.3·10⁴ cells·ml^?1 were located in the vicinity of the Po River, which also corresponded to the area where the highest numbers of phaeophorbides were measured (0.779, 0.528 and 0.419 μg·l^?1, respectively, compared to an average of the remaining stations of 0.183 ± 0.049 SD), suggesting some grazing on the bloom. Phytoplankton biomass in terms of carbon was dominated by diatoms, representing on average 42% of total phytoplankton carbon and more than 80% at several stations. Cerataulina pelagica, Cyclotella spp., Chaetoceros spp. and small unidentified centric diatoms dominated the diatom community numerically but C. pelagica was by far the dominant diatom in terms of carbon due to its large cell size. This species represented more than 60% of the diatom biomass at nine of the 14 stations sampled, and was absent only at one station, which was the most offshore station sampled during the cruise. Although polyunsaturated aldehydes (PUAs) were not detected, other oxylipins which are hydroxy and keto derivatives of eicosapentaenoic and docosahexaenoic acids that affect copepod reproduction were found in these samples. Hence, we can attribute the negative impact of diatoms not only to PUAs, as previously believed, but also to these compounds. This is the first direct evidence of the presence of oxylipins other than PUAs in marine blooms dominated by diatoms.  相似文献   

The Relation Among Seismic Activity, Volcanic Rock Emplacement and Bouguer Anomalies in Italy     

Giancarlo Scalera 《Natural Hazards》1997,15(2-3):165-181

A digitization has been performed of all volcanic rock fragments, main thrust fronts and fold axes from the 'Synthetic Structural Kinematic Map' as well as of all intrasedimentary magnetic bodies from the map of Cassano et al. These two maps complement each other, and the buried magnetized bodies fill the gaps of volcanic rocks in various regions e.g. in Tuscany. Some other major gaps can be found along the Northern Apennines, the Central and Southern Apennines and the Calabrian arc. A comparison of a map representing the 'Log C – seismic macrozonation index' to the pattern of all volcanic rocks, reveals that more seismic energy is released in those areas where volcanic rocks are absent or where their continuity in space is interrupted. Furthermore seismic activity is inhibited in those areas where minimum values of Bouguer anomalies are recorded.  相似文献   

Assessment of toxicological status of a SW Mediterranean segment population of striped dolphin (Stenella coeruleoalba) using skin biopsy     

M. Cristina Fossi  Letizia Marsili  Giancarlo Lauriano  Caterina Fortuna  Simone Canese  Stefania Ancora  Claudio Leonzio  Teresa Romeo  Ruben Merino  Esteban Abad  Begoa Jimnez 《Marine environmental research》2004,58(2-5):269

Various studies have revealed high concentrations of contaminants such as organochlorines (OCs) and heavy metals in Mediterranean cetaceans. A geographical trend of contamination (PCBs and DDTs) has been found for striped dolphin (Stenella coeruleoalba). In this study we used a non-lethal approach (skin biopsy) to investigate bioaccumulation of OCs, including polychlorobiphenyls (PCBs), DDTs, polychlorodibenzo-p-dioxins (PCDDs), polychlorodibenzofurans (PCDFs), trace elements (Hg, Cd, Pb) and CYP1A activity (BPMO) in nine striped dolphins sampled in the Aeolian area (Sicily – Italy) in summer 2002. The arithmetic mean value of BPMO activity in this group was 43.46 AUF/g tissue/h. This value is approximately 3 times and 5 times lower, respectively, than the value found in the Ionian and in the Ligurian groups. Skin biopsies of striped dolphins emerged as a suitable material for assessing the toxicological status of the various Mediterranean groups.  相似文献   

DNA adducts in mussels and fish exposed to bulky genotoxic compounds     

Dolcetti L  Zuanna LD  Venier P 《Marine environmental research》2002,54(3-5):481-486

Biological and procedural factors can influence DNA adduct detection in aquatic organisms. Among them, functional structure and metabolic traits represent major biological determinants for adducts formed by lipophilic pro-mutagenic contaminants. In detecting DNA adducts through the 32P-postlabelling assay, efficiency in DNA purification, digestion, labelling, as well as adduct enrichment and quantification may explain differences between independent studies. Reference DNA adducts have been used to verify some 32P-postlabelling aspects. Data obtained for mussels and fish treated with benzo[a]pyrene (B[a]P) and environmentally exposed to genotoxins confirm the above assertions. Although the 32P-postlabelling assay cannot be proposed for routine biomonitoring it appears a reliable and very sensitive index of exposure to genotoxic pollutants in both fish and mollusks.  相似文献   

Size matters more than method: Visual quadrats vs photography in measuring human impact on Mediterranean rocky reef communities     

Valeriano Parravicini  Carla Morri  Giada Ciribilli  Monica Montefalcone  Giancarlo Albertelli  Carlo Nike Bianchi 《Estuarine, Coastal and Shelf Science》2009,81(3):359-367

The performances of two commonly used non-destructive sampling procedures for rocky benthic assemblages (i.e. photography and visually assessed quadrats) were compared. A damaging human activity, date mussel (Lithophaga lithophaga) harvesting (DMH), was chosen. Directly impacted sites were compared with reference conditions (controls). Both visual quadrats and photography were equally able to detect differences between impacted situations and controls. However, visual quadrats showed high variability among replicates and estimated higher species richness for controls, while photography did so for impacts. Pooling photos in a ‘sum photo quadrat’ showed that differences between the two methods are due to sampling unit size rather than sampling procedure itself. As a small sampling unit is unavoidable with photography, visual quadrats should be preferred in investigating shallow rocky reefs for their larger size; however, longer working time underwater with quadrats does not allow for numerous replicates. Pooling many photos to reach sampling sizes comparable with those of quadrats may be a valid alternative to reconcile image resolution and areal coverage.  相似文献   

High‐resolution topography and anthropogenic feature extraction: testing geomorphometric parameters in floodplains          下载免费PDF全文

Giulia Sofia  Giancarlo Dalla Fontana  Paolo Tarolli 《水文研究》2014,28(4):2046-2061

In floodplains, anthropogenic features such as levees or road scarps, control and influence flows. An up‐to‐date and accurate digital data about these features are deeply needed for irrigation and flood mitigation purposes. Nowadays, LiDAR Digital Terrain Models (DTMs) covering large areas are available for public authorities, and there is a widespread interest in the application of such models for the automatic or semiautomatic recognition of features. The automatic recognition of levees and road scarps from these models can offer a quick and accurate method to improve topographic databases for large‐scale applications. In mountainous contexts, geomorphometric indicators derived from DTMs have been proven to be reliable for feasible applications, and the use of statistical operators as thresholds showed a high reliability to identify features. The goal of this research is to test if similar approaches can be feasible also in floodplains. Three different parameters are tested at different scales on LiDAR DTM. The boxplot is applied to identify an objective threshold for feature extraction, and a filtering procedure is proposed to improve the quality of the extractions. This analysis, in line with other works for different environments, underlined (1) how statistical parameters can offer an objective threshold to identify features with varying shapes, size and height; (2) that the effectiveness of topographic parameters to identify anthropogenic features is related to the dimension of the investigated areas. The analysis also showed that the shape of the investigated area has not much influence on the quality of the results. While the effectiveness of residual topography had already been proven, the proposed study underlined how the use of entropy can anyway provide good extractions, with an overall quality comparable to the one offered by residual topography, and with the only limitation that the extracted features are slightly wider than the investigated one. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Urban seagrass: status of Posidonia oceanica facing the Genoa city waterfront (Italy) and implications for management     

Montefalcone M  Albertelli G  Morri C  Bianchi CN 《Marine pollution bulletin》2007,54(2):206-213

A system of five adjacent Posidonia oceanica meadows facing the waterfront of Genoa city (Ligurian Sea, NW Mediterranean) was investigated over different spatial scales (meters-kilometers) using three environmental indices: conservation index (CI), substitution index (SI) and phase-shift index (PSI). CI revealed differences mostly at large spatial scale, distinguishing the poor condition of the meadows closest to Genoa centre and harbour from the comparatively healthy condition of the farthest meadows. SI showed differences mostly at small spatial scale (i.e., within meadows), suggesting the influence of local factors in the re-colonisation of regressed meadows by the seagrass Cymodocea nodosa and/or the invasive alga Caulerpa racemosa. Mapping of PSI showed that the meadows closest to Genoa centre and harbour have undergone a nearly total phase shift and have no real potential for recovery: attempts to re-establish P. oceanica there might be a waste of time and money. On the contrary, the meadows farthest from Genoa centre and harbour showed a comparatively low level of phase shift and could still fully recover given specific management actions.  相似文献   

Chemical enrichment in cosmological, smoothed particle hydrodynamics simulations     

Robert P. C. Wiersma  Joop Schaye  Tom Theuns  Claudio Dalla Vecchia  Luca Tornatore 《Monthly notices of the Royal Astronomical Society》2009,399(2):574-600

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Automatic Detection of Limb Prominences in 304 Å EUV Images     

N. Labrosse  S. Dalla  S. Marshall 《Solar physics》2010,262(2):449-460

A new algorithm for automatic detection of prominences on the solar limb in 304 Å EUV images is presented, and results of its application to SOHO/EIT data discussed. The detection is based on the method of moments combined with a classifier analysis aimed at discriminating between limb prominences, active regions, and the quiet corona. This classifier analysis is based on a Support Vector Machine (SVM). Using a set of 12 moments of the radial intensity profiles, the algorithm performs well in discriminating between the above three categories of limb structures, with a misclassification rate of 7%. Pixels detected as belonging to a prominence are then used as the starting point to reconstruct the whole prominence by morphological image-processing techniques. It is planned that a catalogue of limb prominences identified in SOHO and STEREO data using this method will be made publicly available to the scientific community.  相似文献   

Diagenesis of the Khuff Formation (Permian–Triassic), northern United Arab Emirates     

Simone Fontana  Fadi H. Nader  Sadoon Morad  Andrea Ceriani  Ihsan S. Al-Aasm 《Arabian Journal of Geosciences》2010,3(4):351-368

This diagenetic study (including fieldwork, petrographic, fluid inclusion, and stable isotope investigations) deals with the outcrop of Upper Permian–Lower Triassic carbonate rocks, which are equivalent to the Khuff Formation. The studied succession, which outcrops in the Ras Al Khaimah region, northern United Arab Emirates, comprises three formations, including the Bih, the Hagil, and the Ghail formations. The study focuses on unraveling the conditions and fluid compositions encountered during diagenesis of the succession. Emphasize is also made on linking diagenesis to major stratigraphic surfaces and to highlight reservoir property evolution and heterogeneity of the studied rocks. The evolution of fluids and related diagenetic products can be summarized as follows: (1) formation of near-surface to shallow burial, fine-crystalline dolomite (dolomite matrix) through pervasive dolomitization of carbonate sediments by modified marine pore waters; (2) formation of coarse-crystalline dolomite cement by highly evolved marine pore waters (13–23 wt.% NaCl eq.) at elevated temperatures (120–208°C), and (3) calcite cementation by highly saline fluid (20–23 wt.% NaCl eq.) at high temperature (170–212°C). A final calcite cement generation has been formed by the percolation of meteoric fluids during uplift. Fracture- and vug-filling diagenetic minerals are mainly restricted to the mid-Bih breccia marker level, suggesting preferential focused fluid flow through specific stratigraphic surfaces as well as along tectonic-related structures. Reservoir properties have been evolved as result of the interplay of the original sedimentary texture and the diagenetic evolution. Porosity is higher in the Bih Formation, which is dominated by dolomitized packstones and grainstones, than in the Hagil and Ghail formations, consisting mainly of dolomitized mudstones and wackestones. Image analyses were used to quantify the visual porosity in thin sections. The highest porosity values were measured in the Bih Formation, which is characterized by significant amounts of vug- and fracture-filling cements. This feature is attributed to the increase of porosity owing to substantial dissolution of abundant intergranular and vug-filling cements. In contrast, the Hagil and Ghail formations, which consist of finer-grained rock than the Bih Formation, were less cemented, and thus, the porosity enhancement by cement dissolution was insignificant.  相似文献