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61.
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
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In standard hydrodynamical supernova computations many variables are needed to describe the time evolution of the stellar core. A numerical grid of points is usually constructed to attain the desirable accuracy. This fact limits the codes to run in the biggest and fastest computers. A new semi-analytical approach for the problem of the dynamical evolution of the collapse, bounce and explosion of a supernova core is proposed. The relevant coordinates of the dynamical problem are chosen to define an effective Lagrangian. The Lagrangian variables are the radii of the shells, seen now as collective coordinates, which describe the global aspects of the process. An effective Lagrangian with these properties for any number of shells is presented. The equations of motion are obtained from this Lagrangian and then integrated numerically. The potentiality of the method is exemplified for the extreme case in which only two shells are used to describe the stellar core. Even in this instance, it is possible to discuss the circumstances for the occurrence of supernova explosion. 相似文献
64.
The granulites of the Juiz de Fora complex occur within thick basement thrust slices associated with the Pan-African shortening process in the central segment of the Ribeira belt. Five lithological units of the Intermediate tectonic domain of the belt can be identified on the basis of detailed geological mapping: a) orthogranulites, b) orthogneisses; c) kinzigite; d) intrusive garnet charnockite and e) amphibolite facies metasediments of probable Meso to Neoproterozoic age, correlated to the cover of the belt. Petrological data indicate high temperatures and intermediate to low lithostatic pressure conditions for the Paleoproterozoic granulite facies metamorphism. Textures and CO2-rich fluid inclusions are probably related to an IBC path. Geochemical data do not show relevant compositional change as a result of the granulite metamorphism. Two calc-alkaline suites and tholeiitic to alkaline basic rocks can be related to compressional and extensional settings, respectively. The overall composition of the granulites, the lack of substantial LILE depletion as well as the composition of the fluid inclusion points to granulitization process driven by CO2-rich fluids. Orthogranulites gave rise to banded gneisses as a result of the Pan-African retrograde metamorphism and intense deformation. The U and Th depletion detected in few rocks is possibly related with the hydrated conditions of the retrograde reactions. 相似文献
65.
Lopes A. M. G. Duarte N. G. L. Sánchez O. H. Daus R. Koch H. 《Boundary-Layer Meteorology》2021,180(1):27-52
Boundary-Layer Meteorology - The WindStation software package is applied to simulate the wind field over the Bolund hill. The standard, ReNormalization Group (RNG), realizable, and limited-length... 相似文献
66.
The Charisma of Coastal Ecosystems: Addressing the Imbalance 总被引:1,自引:0,他引:1
67.
四川北部米仓山地区下三叠统内部不整合面的发现及其意义 总被引:5,自引:4,他引:1
前人认为四川北部米仓山地区下三叠统内部各组地层之间是整合接触,然而通过构造和沉积学的研究发现下三叠统内部(奥伦尼阶)存在一个区域不整合面。在沉积上表现为环米仓山地区广泛发育的陆相和海相碎屑岩,与下伏地层呈不整合接触。地震剖面上表现为不整合面上下的变形特征不一致、不整合面下部地层被削截、古构造的存在等等,通过对古褶皱和古断裂的平面投影,发现古构造走向为东-西向,与勉略构造带走向一致。综合区域大地构造历史,笔者认为在早三叠世奥伦尼期(约249.7~245.0Ma)南秦岭造山带和上扬子地块就已经发生碰撞,碰撞引起了米仓山地区强烈的构造变形,形成这一区域不整合面。该碰撞时间不一定是南秦岭造山带和上扬子地块在此处的初始碰撞时间。 相似文献
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Iris E. Hendriks Miguel Cabanellas-Reboredo Tjeerd J. Bouma Salud Deudero Carlos M. Duarte 《Estuaries and Coasts》2011,34(1):60-67
We assess the sheltering effect of Posidonia oceanica meadows on drag forces exerted on shells of the fan mussel Pinna nobilis. We examine a range of shell sizes under four unidirectional flow speeds (0.05–0.34 m s−1) and two oscillating regimes. Three meadow densities are evaluated and a control without vegetation. We found that the attenuating
effect of the meadow on drag forces experienced by bivalves is determined by the form of the hydrodynamic energy, e.g., as
unidirectional flow or wave action. In tidal currents, the meadow protects most sizes of bivalves, with a higher efficiency
for dense meadows, while in wave dominant zones the meadow reduces drag forces for bivalves with shell areas below a threshold
of 0.019 m2, whereas larger animals experience increased drag forces within the meadow independent of meadow density. Reduction of shoot
density in seagrass meadows might therefore not affect the effectiveness of the canopy to reduce drag forces on associated
species like the fan mussel in wave-dominated areas while increased storm frequency could result into losses of larger individuals
during periods of high wave action. 相似文献