Impact of climate and hydrology on juvenile fish recruitment towards estuarine nursery grounds in the context of climate change   总被引：1，自引：0，他引：1  

Catarina Vinagre  Filipe Duarte Santos  Henrique Nogueira Cabral  Maria José Costa 《Estuarine, Coastal and Shelf Science》2009

Larvae of various coastal fish undergo immigration from spawning grounds towards estuarine nurseries. Several environmental factors can have an important impact on survival at this stage making it crucial for recruitment. Generalized linear models were applied in order to investigate the relation between river drainage, sea surface temperature (SST), NAO index and the North-South wind component intensity, over the two months prior to the estuarine colonization peak, and the densities of Platichthys flesus, Dicentrarchus labrax, Diplodus vulgaris and Diplodus bellottii in the nursery grounds based on a discontinuous historical dataset (from 1978 to 2006), for the Tagus estuary. The relation between SST over the 12 months prior to the estuarine colonization peak and fish densities in the nurseries was also investigated, as it integrates the periods of spawning stock maturation, spawning and larval immigration. While SST over the prior 12 months was negatively correlated with the abundance of P. flesus, it was positively correlated with the abundance of D. bellottii. Abundance of D. vulgaris was positively correlated with SST in the two months prior to the estuarine colonization peak, while the abundance of D. labrax was positively correlated with river drainage. The relations between SST and the abundance of P. flesus, a cold-water species with declining densities, and the subtropical species D. bellottii and D. vulgaris, which are increasing in abundance, are indicative of species abundance alterations related to climate warming. Dicentrarchus labrax will probably also be affected by climate change because of lowered precipitation and consequently river drainage.  相似文献   

On a question of A. Wintner about Jacobi coordinates in the three-body problem     

H. E. Cabral 《Celestial Mechanics and Dynamical Astronomy》1991,52(4):375-379

In his work on the elimination of the nodes in the Three-Body Problem, Jacobi considered a certain straight line (defined below, in the Introduction) which lies always within the invariable plane. Here we settle the question of Wintner on the classification of all motions for which this line fails to exist.  相似文献   

Hydrothermal overprint on Cenozoic sediments in the Quadrilátero Ferrífero of Minas Gerais: implications for precious metals in cratonic terrains     

Alexandre Raphael Cabral  Nikola Koglin 《地学学报》2014,26(2):111-119

Cenozoic sediments deposited in graben‐like basins in the Quadrilátero Ferrífero, southern São Francisco craton, Brazil, have anomalous contents of Hg and Sb. Two localities have been studied: the topaz deposit of Antônio Pereira, and the remains of the old opencast workings at Cata Preta, one of the earliest Au mines of Minas Gerais that dates back to about 1690. At Cata Preta, a brecciated wad‐like rock exhibits geochemical fingerprints that point to fractionation of Pt and Pd from Ag. This metal fractionation, reflected in the Au ingots produced in the region, genetically links Cata Preta to the near‐surface bonanza ore of Serra Pelada, which formed as a result of a Late‐Cretaceous hydrothermal overprint in the Amazon craton. Here, we propose that anorogenic hydrothermal activity in cratonic terrains prepared the ground for the enrichment in precious metals that gave rise to two of the most important Au rushes in Brazilian history.  相似文献   

Estimation of potential failure risks in a mine slope using indicator kriging     

M. S. Lana  I. E. Cabral  A. H. Gripp  M. F. A. Gripp 《国际地质力学数值与分析法杂志》2010,34(16):1725-1742

Indicator kriging has been applied to the study of failure mechanisms in a mine slope in Minas Gerais, Brazil, to estimate potential failure risks in limited areas along this slope. Timbopeba Mine, Vale Company, is an open pit iron mine situated in the Quadrilátero Ferrífero, a very important mining district in Minas Gerais. A slope excavated in quartzite with a maximum height of 200 m at the time of this study, has presented many failure problems involving the sliding of blocks formed by discontinuities. These blocks are of limited size in comparison to the dimensions of the overall slope. They appear along the entire slope, wherever discontinuity orientations have led to the kinematic feasibility of these blocks. Geostatistics permits the estimation of local failure probability distributions associated to these local failures, which would not be possible with traditional statistical models. The geostatistical method employed in this study, indicator kriging, is quite suitable because it is unnecessary to assume a particular global distribution of the phenomena being modeled. The model was used for locating areas with a great tendency for sliding failure, as it considers the local spatial variability of discontinuity orientations. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Fluid-inclusion microthermometry and the Zr-in-rutile thermometer for hydrothermal rutile     

Alexandre Raphael Cabral  Francisco Javier Rios  Lucilia Aparecida Ramos de Oliveira  Francisco Robério de Abreu  Bernd Lehmann  Thomas Zack  František Laufek 《International Journal of Earth Sciences》2015,104(2):513-519

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Active surface faulting or landsliding in the Lower Tagus Valley (Portugal)? A solved controversy concerning the Vila Chã de Ourique site     

João Manuel Cabral  Fernando Marques  Paula Figueiredo  Luís Matias 《Journal of Seismology》2011,15(2):215-234

The Lower Tagus Valley has experienced significant (M 6–7) historical seismicity, evidencing the presence of seismogenic faults. These are still deficiently known due to the low strain rates and the recent alluvial sedimentation of the Tagus River that buries most of the structures, though Paleoseismic evidence was allegedly found by a research team in the Tagus valley, at a site 60 km N of Lisbon, near Vila Chã de Ourique (VCO). According to this team, trenching at the VCO site exposed an active thrust fault, evidencing the surface rupture of a large earthquake that occurred in 1531. Our studies performed at this site, comprising field observations with a reappraisal of the trench outcrops previously excavated, borehole drilling, soil mechanics laboratory testing, and seismic reflection acquisition, pointed to the alternative interpretation that the outcropping structures are gravitational and not of tectonic origin. The interpretation of new outcrops crosscutting the structures exposed at the trenches, as well as newly acquired high-resolution seismic reflection data, definitely exclude the active thrust fault explanation and support a gravitational slip model for all the observed structures. Gravitational slip in the river bank slope was promoted by low shear strength clays and high pore water pressure coupled with slope toe river erosion. Gravitational slides must have occurred prior to development of the present sedimentation level of the Tagus alluvial plain, which was attained in the last few thousand years as indicated by borehole data and estimations of sedimentation rates.  相似文献   

Iodine and bromine contents in the Palaeoproterozoic Hotazel iron formation, Transvaal Supergroup, South Africa: A reconnaissance study     

Alexandre Raphael Cabral  Harilaos Tsikos  Yasuyuki Muramatsu  Tomoko Sekiya 《Chemie der Erde / Geochemistry》2011,71(3):297-301

A reconnaissance bulk geochemical study was carried out on ten samples from the Palaeoproterozoic Hotazel iron formation, South Africa, with emphasis on iodine and bromine abundances. Very low-absolute contents recorded for both halogens, i.e. 0.08–0.26 μg/g for I and 0.35–1.23 μg/g for Br, indicate that they should largely have been lost during burial diagenesis. Bulk I/Br ratios (0.08–0.50), however, show marginal variation across the selected sample set and broadly resemble those that typify recent marine sediments containing organic matter. The possibility emerges that both elements are organic matter-sourced and may thus provide a potential proxy for the role of biological processes during deposition and diagenesis of Precambrian iron formations.  相似文献   

Assessing food web dynamics and relative importance of organic matter sources for fish species in two Portuguese estuaries: a stable isotope approach     

França S  Vasconcelos RP  Tanner S  Máguas C  Costa MJ  Cabral HN 《Marine environmental research》2011,72(4):204-215

Stable carbon and nitrogen isotopes (δ13C, δ1?N) were used to analyse food web dynamics of two of the main estuaries of the Portuguese coast: Tejo and Mira. The ultimate sources of organic matter supporting production of some of the most abundant and commercially important fish species were determined; and seasonal, inter- and intra- estuarine differences in the trophic relations among producers and consumers were identified. Stable isotope analysis was performed in different producers, primary consumers (main prey items for fish) and fish species (Solea solea, Solea senegalensis, Pomatoschistus microps, Dicentrarchus labrax, Liza ramada, Diplodus vulgaris and Atherina presbyter) of two areas in each estuary, in July and October 2009. Model calculations showed that the main prey for the fish species in the Tejo estuary used mostly salt marsh-derived organic matter as nutritional sources, with no marked differences between the sampled months. Trophic levels of fish species from the same estuary differed at multiple scales: inter-species, seasonally and spatially (both between and within estuaries). Significant differences in isotopic composition of fish species were more pronounced spatially (between the two sampled areas in the estuary) than seasonally (between sampled months). Trophic relationships in both estuaries demonstrated that organic matter is transferred to higher trophic positions mainly through benthic pathways. This shows the flexibility of these species to share resources and to exploit temporary peaks in prey populations. The present results showed that extensive disturbance in intertidal habitats from both estuaries may potentially change the balance of organic matter in the base of these complex food webs.  相似文献   

Effect of body size and body mass on δC and δN in coastal fishes and cephalopods     

C. Vinagre  C. Máguas  H.N. Cabral  M.J. Costa 《Estuarine, Coastal and Shelf Science》2011

Carbon and nitrogen isotopes have been widely used in the investigation of trophic relations, energy pathways, trophic levels and migrations, under the assumption that δ¹³C is independent of body size and that variation in δ¹⁵N occurs exclusively due to ontogenetic changes in diet and not body size increase per se. However, several studies have shown that these assumptions are uncertain. Data from food-webs containing an important number of species lack theoretical support on these assumptions because very few species have been tested for δ¹³C and δ¹⁵N variation in captivity. However, if sampling comprises a wide range of body sizes from various species, the variation of δ¹³C and δ¹⁵N with body size can be investigated. While correlation between body size and δ¹³C and δ¹⁵N can be due to ontogenetic diet shifts, stability in such values throughout the size spectrum can be considered an indication that δ¹³C and δ¹⁵N in muscle tissues of such species is independent of body size within that size range, and thus the basic assumptions can be applied in the interpretation of such food webs. The present study investigated the variation in muscle δ¹³C and δ¹⁵N with body size and body mass of coastal fishes and cephalopods. It was concluded that muscle δ¹³C and δ¹⁵N did not vary with body size or mass for all bony fishes with only one exception, the dragonet Callionymus lyra. Muscle δ¹³C and δ¹⁵N also did not vary with body size or mass in cartilaginous fishes and cephalopods, meaning that body size/mass per se have no effect on δ¹³C or δ¹⁵N, for most species analysed and within the size ranges sampled. The assumption that δ¹³C is independent of body size and that variation in δ¹⁵N is not affected by body size increase per se was upheld for most organisms and can be applied to the coastal food web studied taking into account that C. lyra is an exception.  相似文献   

How much are the Bolinao-Anda coral reefs worth?     

Annabelle Cruz-Trinidad  Rollan C. Geronimo  Reniel B. Cabral  Porfirio M. Aliño 《Ocean & Coastal Management》2011,54(9):696-705

The Total Economic Value of the estimated 200 km² of coral reef area straddling the municipalities of Alaminos, Anda, Bani and Bolinao in Pangasinan, Philippines is estimated to reach US$38 million per year consisting mainly of indirect benefits from shoreline protection. Direct use from fisheries, aquaculture, and tourism was valued at US$6 million based on the coral reef interaction index. Non-use values for coral reef conservation were based on estimates of willingness to pay across the three economic sectors plus the general public as a fourth sector. Results varied across sectors and municipalities although the ranges were not wide, especially for fishers. Fishers’ willingness to pay averaged at US$0.25 per individual per year. Except for aquaculture operators in Bolinao, which yielded willingness to pay values reaching US$3 per individual per year, the range of conservation funding was narrow for the three other municipalities for all sectors. Using binary logistic regression (logit model), differences in willingness to pay among fishers are explained by the age, number of children, and employment status.  相似文献