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排序方式: 共有186条查询结果,搜索用时 15 毫秒
111.
112.
Roberto Carlucci Lembo Giuseppe Maiorano Porzia Capezzuto Francesca Marano Chiara Alessandra Sion Letizia Spedicato Maria Teresa Ungaro Nicola Tursi Angelo Gianfranco D'Onghia 《Estuarine, Coastal and Shelf Science》2009,83(4):529-538
The spatial pattern of the nursery areas of red mullet (Mullus barbatus), hake (Merluccius merluccius) (Linnaeus, 1758) and deep-water rose shrimp (Parapenaeus longirostris) (Lucas, 1846) was studied in the South Adriatic and North Ionian Seas (Eastern-Central Mediterranean) applying geostatistical techniques and data from time series trawl surveys conducted in the area. The analysed variables were: R (number of recruits/km2) and R/Tot (fraction of recruits on the total sampled population). The structural analysis showed a spatial pattern of both variables characterized by continuity on a small scale. Predictions of nursery area localization with probability of finding recruits at different threshold values were obtained through median indicator kriging. For the red mullet the nurseries were mainly identified in the South Adriatic Sea off the Gargano peninsula and between Molfetta and Monopoli within 50 m in depth. The main concentration of hake juveniles was found to be between 100 and 200 m in depth along the Gargano peninsula and between Otranto and Santa Maria di Leuca, where a nursery of deep-water rose shrimp was also detected. An overlapping depth, between 100 and 200 m, was identified for hake and deep-water rose shrimp nurseries. Protection of these areas through limitations of fishing pressure is discussed. 相似文献
113.
114.
Maria Cristina Follesa Cristina Porcu Alice Gastoni Antonello Mulas rea Sabatini & Angelo Cau 《Marine Ecology》2009,30(S1):188-199
Community structure and faunal composition of bathyal decapod crustaceans off South-Eastern Sardinian deep-waters (Central-Western Mediterranean) were investigated. Samples were collected during 32 hauls between 793 and 1598 m in depth over the 2003–2007 period. A total of 1900 decapod specimens belonging to 23 species were collected. Multivariate analysis revealed the occurrence of three faunistic assemblages related to depth: (i) an upper slope community at depths of 793–1002 m; (ii) a middle slope community at depths of 1007–1212 m and (iii) a lower slope community at depths greater 1420 m. In the upper and middle slopes the benthic ( Polycheles typhlops ) and epibenthic–endobenthic feeders (mainly Aristeus antennatus and Geryon longipes ), which eat infaunal prey, were dominant, followed by the macroplankton–epibenthic feeders such as Acanthephyra eximia and Plesionika acanthonotus . In the deepest stratum, the most remarkable feature was the prevalence of macroplankton–epibenthic feeders ( A. eximia and P. acanthonotus ). A small percentage of the benthic deep-sea lobster Polycheles sculptus was also present. The biomass presented higher values in the middle slope and declined strongly in the lower slope. There was no general pattern of mean individual weight/size versus depth among decapods, and the changes seemed to be species-specific with different trends. 相似文献
115.
Francesco Mastrototaro Porzia Maiorano Agostina Vertino Daniela Battista Antonella Indennidate Alessandra Savini Angelo Tursi Gianfranco D'Onghia 《Marine Ecology》2013,34(3):313-320
During a research cruise carried out in April 2010, aimed at updating the knowledge on the biodiversity of the Santa Maria di Leuca (SML) cold‐water coral province (Mediterranean Sea), a facies of the sea pen Kophobelemnon stelliferum (Muller, 1776) was found on mud‐dominated bottoms. This finding represents a new species and a new habitat record from the SML coral province as well as a new bathyal facies in the whole Central Mediterranean Sea. The colonies were collected using an epi‐benthic sledge, at depths between 400 and 470 m. A significant positive relationship between polyp number and colony length was detected. Density of the colonies ranged from 0.003 to 0.038 N·m?2. Differences and affinities between Mediterranean and Atlantic occurrences of K. stelliferum are discussed. 相似文献
116.
Evolutionary polynomial regression to alert rainfall-triggered landslide reactivation 总被引:3,自引:0,他引:3
Angelo Doglioni Francesco Fiorillo Francesco M. Guadagno Vincenzo Simeone 《Landslides》2012,9(1):53-62
The derivation of an alert model for landslide risk management is a paramount problem for those sites which are affected by
complex landslides involving strategic infrastructures as well as towns. This is a quite common scenario all over the world
and then it is a primary problem for the management of geomorphological risk. Along the Adriatic Coast of south Italy, Petacciato
landslide is peculiar, since it showed 11 reactivations between 1924 and 2009. It is a deep-seated landslide, and the history
of its reactivations shows that even if generally related to quite abundant rainfall periods, there is no clear correlation
between rainfall events and reactivations. For this reason, here, an analysis based on a data-driven evolutionary modeling
technique is attempted, in order to identify an alert model based on cumulative rainfall heights. Modeling results are quite
interesting and encouraging, since they are able to provide landslide forecasting whereas no false positive are ever returned.
This work shows the results of this attempt as well as an analysis of the input to the modeling approach, in order to identify
which are those cumulative rainfall heights which are physically sound with respect to the particular landslide. 相似文献
117.
Abstract The problem of identifying and reproducing the hydrological behaviour of groundwater systems can often be set in terms of ordinary differential equations relating the inputs and outputs of their physical components under simplifying assumptions. Conceptual linear and nonlinear models described as ordinary differential equations are widely used in hydrology and can be found in several studies. Groundwater systems can be described conceptually as an interlinked reservoir model structured as a series of nonlinear tanks, so that the groundwater table can be schematized as the water level in one of the interconnected tanks. In this work, we propose a methodology for inferring the dynamics of a groundwater system response to rainfall, based on recorded time series data. The use of evolutionary techniques to infer differential equations from data in order to obtain their intrinsic phenomenological dynamics has been investigated recently by a few authors and is referred to as evolutionary modelling. A strategy named Evolutionary Polynomial Regression (EPR) has been applied to a real hydrogeological system, the shallow unconfined aquifer of Brindisi, southern Italy, for which 528 recorded monthly data over a 44-year period are available. The EPR returns a set of non-dominated models, as ordinary differential equations, reproducing the system dynamics. The choice of the representative model can be made both on the basis of its performance against a test data set and based on its incorporation of terms that actually entail physical meaning with respect to the conceptualization of the system. Citation Doglioni, A., Mancarella, D., Simeone, V. & Giustolisi, O. (2010) Inferring groundwater system dynamics from hydrological time-series data. Hydrol. Sci. J. 55(4), 593–608. 相似文献
118.
The distribution of clasts deposited around a volcano during an explosive eruption typically contoured by isopleth maps provides important insights into the associated plume height, wind speed and eruptive style. Nonetheless, a wide range of strategies exists to determine the largest clasts, which can lead to very different results with obvious implications for the characterization of eruptive behaviour of active volcanoes. The IAVCEI Commission on Tephra Hazard Modelling has carried out a dedicated exercise to assess the influence of various strategies on the determination of the largest clasts. Suggestions on the selection of sampling area, collection strategy, choice of clast typologies and clast characterization (i.e. axis measurement and averaging technique) are given, mostly based on a thorough investigation of two outcrops of a Plinian tephra deposit from Cotopaxi volcano (Ecuador) located at different distances from the vent. These include: (1) sampling on a flat paleotopography far from significant slopes to minimize remobilization effects; (2) sampling on specified-horizontal-area sections (with the statistically representative sampling area depending on the outcrop grain size and lithic content); (3) clast characterization based on the geometric mean of its three orthogonal axes with the approximation of the minimum ellipsoid (lithic fragments are better than pumice clasts when present); and (4) use of the method of the 50th percentile of a sample of 20 clasts as the best way to assess the largest clasts. It is also suggested that all data collected for the construction of isopleth maps be made available to the community through the use of a standardized data collection template, to assess the applicability of the new proposed strategy on a large number of deposits and to build a large dataset for the future development and refinement of dispersal models. 相似文献
119.
Andrea Nanetti Angelo Cattaneo Siew Ann Cheong Chin-Yew Lin 《The Cartographic journal》2013,50(2):159-167
AbstractFor many years geological students have been graduating from universities with little knowledge of how to use the cartographic language of line, letter, symbol and tone by which the distribution and spatial arrangement of earth science data can be best expressed. The author discusses the development of the teaching of geological cartography in the Department of Earth Sciences at the University of Leeds. Details of this innovation are set against the background of data obtained from a recent questionnaire on the practice of cartography as a discipline in departments of geology in British universities. 相似文献
120.
Luciano N. Santos Angelo A. Agostinho Carles Alcaraz Joaquim Carol Alejandra F. G. N. Santos Pablo Tedesco Emili García-Berthou 《Aquatic Sciences - Research Across Boundaries》2011,73(1):43-52
Artificial macrophytes were experimentally deployed in Boadella Reservoir (NE Spain) and assessed for fish use throughout
the first 3 months of the 2007 summer drawdown. In total, 1,832 individuals of seven fish species were recorded through visual
censuses, with introduced perch Perca fluviatilis being the prevalent species. Fish richness and abundance were significantly higher in artificial macrophytes than in rocky
shores and sandy beaches, displaying a unimodal variation through time. P. fluviatilis, Rutilus rutilus and Abramis brama were significantly more abundant in artificial macrophytes than in the other two naturally submersed habitats, where no individuals
of these species were recorded. The abundances of Squalius laietanus, Lepomis gibbosus, Micropterus salmoides and Cyprinus carpio were overall greater in artificial macrophytes than in rocky shores but displayed significant habitat × time interactions.
A decrease in predation risk was apparently the key-factor of the intensive use of artificial macrophytes by small fish (≤100 mm
TL) in Boadella Reservoir, since most species reduced drastically or completely the use of submerged structures when body
size increased. This study demonstrates that adding artificial structures mimicking aquatic macrophytes can be an interesting
tool to mitigate the adverse effects of water level fluctuations on fish assemblages in structure-less and homogeneous ecosystems,
and to understand the mechanisms affecting habitat use and species replacement. 相似文献