Growth discontinuity in males of the deep-water giant red shrimp Aristaeomorpha foliacea in the Mediterranean Sea     

Sergio Ragonese  Sergio Vitale  Mark Dimech  Alberto De Santi 《Marine Ecology》2012,33(3):386-392

The deep-water giant red shrimp, Aristaeomorpha foliacea (Risso, 1827) (Decapoda, Aristeidae), represents a highly valuable resource for bottom trawling in the Mediterranean Sea. Recent assessments have described both a worsening of the status of the traditionally exploited stocks and low levels of annual-based instantaneous natural mortality (M 0.4–0.7 year⁻¹) in the unexploited stocks. The mortality (M) figures, however, are in contrast with the longevity (T_max) of 3–4-year males and 4–5-year females, estimated from classical length frequency distribution analysis. Reduced growth (after the onset of sexual maturity) and pile-up of older individuals in the larger size classes have been considered to be reasonable explanations for the contrast between M and T_max. We propose that a discontinuity of the growth models could address this contrast. Because a clear discontinuity in sexual maturity is evident only in males, length frequency distribution data for different sets of males collected from the South of Sicily and the Maltese Islands deep bottoms (400–800 m) were fitted with both the classic (c) and double-phased (d) von Bertalanffy growth formula (VBGF). According to the dVBGF, adult males sharply reduce their growth rate after reaching an age between 1.2 and 1.5 year, which corresponds to the estimates of age at sexual maturity (t_m between 1 and 1.5 years). The reduction in growth determines a higher T_max (7.3–9.5 year) and lower M (0.4–0.6 year⁻¹) than previously derived on the basis of cVBGF estimates (T_max 3–4 years and M 1.2 year⁻¹). The dVBGF results suggest that sexual dimorphism and length–sex segregation in giant red shrimps reflect an alternative life history strategy that is based mainly on growth reduction in adult males and it might be adopted for implementing more conservative assessments.  相似文献   

Can beach dune ridges of the Texas Gulf Coast preserve climate signals?     

James R. Garrison Jr.  Alberto M. Mestas-Nu?ez  Joshua R. Williams  Luz M. Lumb 《Geo-Marine Letters》2012,32(3):241-250

A study of the evolution of North Padre Island (southern Texas Gulf Coast) dunes was carried out using LIDAR topographic data, dune vibracores through the center of the dunes, and grab samples of shoreface sand at four locations along a cross-shore profile. Grain-size analyses of the vibracores show vertical variations in shoreface sand deposition over decimeter depth intervals. A dune ridge growth model is introduced that describes the dune vertical accretion rate as a function of island progradation and freshwater lens expansion. This model allows indirect dating of the dune core samples based on a known island progradation rate (1?m/year), and height and spacing of the dunes calculated from the topographic data. A sand provenance model is also proposed that links the sand deposition in the dunes with sand sourced from various depths along the shoreface profile, depending on storm activity. We present evidence linking the changes in storm-sand deposition in the dune cores with yearly climatic fluctuations in the Gulf of Mexico associated with landfalling tropical storm activity in the period from 1942?C1965. This record of storm-induced sand variability is negatively correlated with El Ni?o-Southern Oscillation (Pacific) sea surface temperature variability, and positively correlated with North Atlantic decadal sea surface temperature variability.  相似文献   

Negligent killing of scientific concepts: the stationarity case   总被引：1，自引：1，他引：0  

Demetris Koutsoyiannis  Alberto Montanari 《水文科学杂志》2015,60(7-8):1174-1183

Abstract

In scientific vocabulary, the term “process” is used to denote change in time. Even a stationary process describes a system changing in time, rather than a static one that keeps a constant state all the time. However, this is often missed, which has led to misuse of the term “nonstationarity” as a synonym of “change”. A simple rule to avoid such misuse is to answer the question: can the change be predicted in deterministic terms? Only if the answer is positive is it legitimate to invoke nonstationarity. In addition, we should have in mind that models are made to simulate the future rather than to describe the past; the past is characterized by observations (data). Usually future changes are not deterministically predictable and thus the models should, on the one hand, be stationary and, on the other hand, describe in stochastic terms the full variability, originating from all agents of change. Even if the past evolution of the process of interest contains changes explainable in deterministic terms (e.g. urbanization), it is better to describe the future conditions in stationary terms, after “stationarizing” the past observations, i.e. adapting them to represent the future conditions.  相似文献   

The Rupture Process and Location of the 2003 Zemmouri–Boumerdes Earthquake (Mw 6.8) Inferred from Seismic and Geodetic Data     

Rúben Santos  Bento Caldeira  Mourad Bezzeghoud  José Fernando Borges 《Pure and Applied Geophysics》2015,172(9):2421-2434

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Advanced Tsunami Numerical Simulations and Energy Considerations by use of 3D–2D Coupled Models: The October 11, 1918, Mona Passage Tsunami     

Alberto M. López-Venegas  Juan Horrillo  Alyssa Pampell-Manis  Victor Huérfano  Aurelio Mercado 《Pure and Applied Geophysics》2015,172(6):1679-1698

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Seismic performance assessment of masonry structures with a modified “concrete” model     

Alberto Maria Avossa  Pasquale Malangone 《Bulletin of Earthquake Engineering》2015,13(9):2693-2718

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Imprint of Climate Variability on Mesozoic Fossil Tree Rings: Evidences of Solar Activity Signals on Environmental Records Around 200 Million Years Ago?     

A. Prestes  N. R. Rigozo  D. J. R. Nordemann  E. Echer  L. E. A. Vieira  M. P. Souza Echer  C. M. Wrasse  F. L. Guarnieri 《Pure and Applied Geophysics》2014,171(8):1983-1991

Evidence of the solar activity modulation of the Earth’s climate has been observed on several parameters, from decadal to millennial time scales. Several proxies have been used to reconstruct the paleoclimate as well as the solar activity. The paleoclimate reconstructions are based on direct and/or indirect effects of global and regional climate conditions. The solar activity reconstructions are based on the production of the ¹⁴C isotope due to the interaction of cosmic ray flux and the Earth’s atmosphere. Because trees respond to climate conditions and store ¹⁴C, they have been used as proxies for both for climate and solar activity reconstructions. The imprints of solar activity cycles dating back to 10,000 years ago have been observed on tree-ring samples using ¹⁴C data, and those dating back to 20 million years ago have been analyzed using fossil tree-growth rings. All this corresponds to the Cenozoic era. However, solar activity imprints on tree rings from earlier than that era have not been investigated yet. In this work, we showed that tree rings from the Mesozoic Era (of ~200 million years ago) recorded 11- and 22-year cycles, which may be related to solar activity cycles, and that were statistically significant at the 95 % confidence level. The fossil wood was collected in the southern region of Brazil. Our analysis of the fossils' tree-ring width series power spectra showed characteristics similar to the modern araucaria tree, with a noticeable decadal periodicity. Assuming that the Earth’s climate responds to solar variability and that responses did not vary significantly over the last ~200 million years, we conclude that the solar–climate connection was likely present during the Mesozoic era.  相似文献   

A kriging approach based on Aitchison geometry for the characterization of particle-size curves in heterogeneous aquifers   总被引：2，自引：0，他引：2  

Alessandra Menafoglio  Alberto Guadagnini  Piercesare Secchi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(7):1835-1851

We consider the problem of predicting the spatial field of particle-size curves (PSCs) from a sample observed at a finite set of locations within an alluvial aquifer near the city of Tübingen, Germany. We interpret PSCs as cumulative distribution functions and their derivatives as probability density functions. We thus (a) embed the available data into an infinite-dimensional Hilbert Space of compositional functions endowed with the Aitchison geometry and (b) develop new geostatistical methods for the analysis of spatially dependent functional compositional data. This approach enables one to provide predictions at unsampled locations for these types of data, which are commonly available in hydrogeological applications, together with a quantification of the associated uncertainty. The proposed functional compositional kriging (FCK) predictor is tested on a one-dimensional application relying on a set of 60 PSCs collected along a 5-m deep borehole at the test site. The quality of FCK predictions of PSCs is evaluated through leave-one-out cross-validation on the available data, smoothed by means of Bernstein Polynomials. A comparison of estimates of hydraulic conductivity obtained via our FCK approach against those rendered by classical kriging of effective particle diameters (i.e., quantiles of the PSCs) is provided. Unlike traditional approaches, our method fully exploits the functional form of PSCs and enables one to project the complete information content embedded in the PSC to unsampled locations in the system.  相似文献   

Mapping the environmental risk of a tourist harbor in order to foster environmental security: Objective vs. subjective assessments     

Petrosillo Irene  Vassallo Paolo  Mensa Jean Alberto  Fabiano Mauro 《Marine pollution bulletin》2010,60(7):1051-1058

A new definition of environmental security gives equal importance to the objective and subjective assessments of environmental risk. In this framework, the management of tourist harbors has to take into account managers’ perceptions. The subject of the present study is a tourist harbor in southern Italy where six different managers are present. This paper aims to assess subjectively and objectively the environmental risks associated with the harbor, and to compare the results to provide estimates of environmental security. Hereby managers have been interviewed and a simple model is used for making preliminary assessment of environmental risks. The comparison of the results highlighted a common mismatch between risk perception and risk assessment. We demonstrated that the old part of the harbor is less secure than the new part. In addition, one specific manager representing a public authority showed a leading role in ensuring the environmental security of the whole harbor.  相似文献   

DIRDOP: a directivity approach to determining the seismic rupture velocity vector     

Bento Caldeira  Mourad Bezzeghoud  José F. Borges 《Journal of Seismology》2010,14(3):565-600

Directivity effects are a characteristic of seismic source finiteness and are a consequence of the rupture spread in preferential directions. These effects are manifested through seismic spectral deviations as a function of the observation location. The directivity by Doppler effect method permits estimation of the directions and rupture velocities, beginning from the duration of common pulses, which are identified in waveforms or relative source time functions. The general model of directivity that supports the method presented here is a Doppler analysis based on a kinematic source model of rupture (Haskell, Bull Seismol Soc Am 54:1811–1841, 1964) and a structural medium with spherical symmetry. To evaluate its performance, we subjected the method to a series of tests with synthetic data obtained from ten typical seismic ruptures. The experimental conditions studied correspond with scenarios of simple and complex, unilaterally and bilaterally extended ruptures with different mechanisms and datasets with different levels of azimuthal coverage. The obtained results generally agree with the expected values. We also present four real case studies, applying the method to the following earthquakes: Arequipa, Peru (M _w = 8.4, June 23, 2001); Denali, AK, USA (M _w = 7.8; November 3, 2002); Zemmouri–Boumerdes, Algeria (M _w = 6.8, May 21, 2003); and Sumatra, Indonesia (M _w = 9.3, December 26, 2004). The results obtained from the dataset of the four earthquakes agreed, in general, with the values presented by other authors using different methods and data.  相似文献