Seasonality and interannual variability of freshwater inflow to a large oligohaline estuary in the Northern Gulf of Mexico     

Y. Jun Xu  Kangsheng Wu 《Estuarine, Coastal and Shelf Science》2006,68(3-4):619

Quantity, timing, duration, and fluctuation of freshwater inflow are important factors affecting the development and health of aquatic and adjacent wetland ecosystems in coastal estuaries. This study assessed six decades of freshwater inflow from the Amite River, Tickfaw River, and Tangipahoa River watersheds to Lake Pontchartrain, a large oligohaline estuary in the Northern Gulf of Mexico, whose flood waters caused recent damage to the city of New Orleans in the aftermath of Hurricane Katrina. By utilizing the long-term (1940–2002) river discharge and climatic data from the three major tributary watersheds, monthly and annual freshwater inflows have been quantified and their spatial and temporal variations have been analyzed. On average, the three rivers discharged (±standard error) 0.27 ± 0.04 km³ freshwater monthly and 3.29 ± 0.15 km³ freshwater annually into the lake estuarine system, with the highest inflow from the Amite River (0.16 ± 0.03 m³ mon⁻¹, and 1.91 ± 0.09 km³ yr⁻¹) and the lowest inflow from the Tickfaw River (0.03 ± 0.00 km³ mon⁻¹, and 0.34 ± 0.02 km³ yr⁻¹). A distinct seasonality was evident with over 69% of the total annual inflow occurring during December and May (wet months) and with a low flow period from August to November (dry months). The monthly inflow during the wet months was positively correlated with the monthly precipitation (r² = 0.64), while the monthly inflow during the dry months was subject to evapotranspiration. Furthermore, the study found a 20-year low flow period from 1954–1973 (2.76 ± 0.24 km³ yr⁻¹) and a 24-year high flow period from 1975–1998 (3.84 ± 0.24 km³ yr⁻¹), coinciding with both the climate variation and population growth in the watersheds.  相似文献   

Spatial and temporal variations of mesozooplankton in the Pearl River estuary, China   总被引：10，自引：0，他引：10  

K.Z. Li  J.Q. Yin  L.M. Huang  Y.H. Tan   《Estuarine, Coastal and Shelf Science》2006,67(4):543-552

This paper examines spatial and temporal variations of mesozooplankton abundance, biomass and community structure during three cruises of July 2002 (summer), January 2003 (winter), and April 2003 (spring) in the Pearl River estuary, China. Zooplankton abundance and biomass fluctuated widely and showed distinct heterogeneity in the Pearl River estuary. A total of 154 species were identified during three surveys. The number of zooplankton species richness was strongly linked to salinity. Hierarchical cluster analysis identified three zooplankton groups during this study. Estuarine, neritic and pelagic groups corresponded to the upper, middle and lower reaches in the Pearl River estuary. The difference among groups could be mainly ascribed to changes in the relative contributions of the dominant species. The fluctuations in the zooplankton abundance, biomass and community structure were determined by the interactive effects of freshwater inflow, tidal and coastal currents, chlorophyll a, salinity and temperature. Significant spatial variability in the distribution of zooplankton species, abundance and biomass can be ascribed to the virtual presence of a horizontal gradient in salinity.  相似文献   

Pb²⁺对青蛤的急性毒性及对其血淋巴液中免疫相关酶活性的影响     

王瑞  黄雨辰  熊德东  黄亚  田甜  孟彬  梁健 《海洋科学》2020,44(3):59-65

采用静态急性毒性实验研究了重金属Pb~(2+)对青蛤(Cyclina sinensis)的生物急性毒性效应,测定了在96 h Pb~(2+)半致死浓度的1/10(TC组)和1/100(SC组)两个浓度胁迫下,血淋巴液中酸性磷酸酶(ACP)、碱性磷酸酶(AKP)和溶菌酶(LSZ)活性的变化。结果显示:Pb~(2+)的96 h LC50为7.938 mg/L; SC组ACP活性表现为诱导-抑制趋势,除4 d外均与对照组差异显著(P0.05), TC组为抑制趋势,为3个组中的最低,与对照组差异显著(P0.05);实验组SC组和TC组的AKP、LSZ活性均表现为前期为诱导中后期受抑制的趋势,与对照组差异显著(P0.05),且TC组活性始终低于SC组,表现出Pb~(2+)的胁迫浓度越高酶活性受到的抑制作用越大。以上结果表明,重金属Pb~(2+)对青蛤的毒性级别为高毒级,能造成青蛤免疫相关酶的活性受到抑制,影响青蛤的免疫能力,而且这种抑制作用随着环境中Pb~(2+)浓度增加而增加。  相似文献   

Sedimentology of a subtidal,tide-dominated sand body in the Yellow Sea,southwest Korea     

George DeVries Klein  Y.A. Park  J.H. Chang  C.S. Kim 《Marine Geology》1982,50(3):221-240

Odanam Satoe, a subtidal, tide-dominated sand body in the Yellow Sea, Korea, is linear in plan and asymmetrical in cross-section. It consists of fine- to medium-grained, well-sorted subangular sand. Bedforms consist of high-amplitude (1–2 m) sandwaves on the lower flanks of the gentler-sloping bar surface, and medium-amplitude (0.5-1 m) sandwaves on the sand body trough adjoining the steeper face, the bar crest and shallower parts of the gently sloping bar surface. Bedforms are absent on the relatively steeper bar surface, which is characterized by 2° slopes. Bedform orientation on the gentler slope is oblique by 30° to the bar crest, parallel to the sand-body crest on the crest itself, and opposite to the steeper sand-body face in the trough below the steeper slope of the bar.Bottom current velocity data show that tidal currents are semi-rotary with a flood time—velocity asymmetry over the gentler slope, and ebb time—velocity asymmetry over the steeper slope during most of the tidal cycle. Tidal-current flow parallels bar elongation over the steeper slope, whereas over the gentler slope, tidal-current flow is directed at 30° to the bar crest and changes to normal to the crest one hour prior to low tide. Bedform orientation mapped with side-scan sonar shows agreement with these flow directions.Sand dispersal around the sand body is controlled by time—velocity asymmetry and partial rotary flow directions of tidal currents. This circulation causes not only a trapezoidal mode of grain dispersal, but also westerly migration of the sand body documented from comparative bathymetric surveys in 1964 and 1980.  相似文献   

Wind-induced eddy motion in the lower St. Lawrence Estuary     

G. Mertz  V.G. Koutitonsky  Y. Gratton  M.I. El-Sabh 《Estuarine, Coastal and Shelf Science》1992,34(6)

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Algorithm for non-hydrostatic dynamics in the Regional Oceanic Modeling System     

Y. Kanarska  A. Shchepetkin  J.C. McWilliams 《Ocean Modelling》2007,18(3-4):143-174

A non-hydrostatic algorithm for the Regional Oceanic Modeling System (ROMS) is proposed. It is based on a decomposition technique for hydrostatic and non-hydrostatic pressure. The algorithm has a pressure-correction scheme with split-explicit time-stepping for baroclinic and barotropic vertical modes with a free surface. The algorithm implementation requires solving a Poisson equation for a non-hydrostatic pressure that has a non-symmetric matrix in discrete form. The efficiency of a different class of solvers and preconditioners were tested. The algorithm is successfully implemented with several examples where non-hydrostatic effects are important. These include standing external gravity waves; strongly nonlinear internal wave generation and transformation; stratified shear instability and its associated mixing; and nonlinear internal tidal generation over a ridge. The corresponding changes in the pre-processing and post-processing infrastructure in the existing hydrostatic ROMS code were performed to implement parallel elliptic solvers and a new set of dynamical equations.  相似文献   

Food and feeding ecology of juvenile albacore, Thunnus alalunga, off the Bay of Biscay: a case study     

Pusineri  C.; Vasseur  Y.; Hassani  S.; Meynier  L.; Spitz  J.; Ridoux  V. 《ICES Journal of Marine Science》2005,62(1):116-122

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Jason-1: Assessment of the System Performances     

J. Perbos  P. Escudier  F. Parisot  G. Zaouche  P. Vincent  Y. Menard  F. Manon  G. Kunstmann  D. Royer  L. -L. Fu 《Marine Geodesy》2003,26(3):147-157

On 7 December 2001, Jason-1 was successfully launched by a Boeing Delta II rocket from the Vandenberg Air Force Base, California. The Jason-1 satellite will maintain the high accuracy altimeter service provided since 1992 by TOPEX/Poseidon (T/P), ensuring the continuity in observing and monitoring the Ocean Dynamics (intraseasonal to interannual changes, mean sea level, tides, etc.). Despite one-fourth the mass and power, the Jason-1 system has been designed to have basically the same performance as T/P, measuring sea surface topography at a centimetric level. This new CNES/NASA mission also provides near real-time data for sea state and ocean forecast. The first two months of the Jason-1 mission have been dedicated to the assessment of the overall system. The goals of this assessment phase were:

1. To assess the behavior of the spacecraft at the platform and payload levels (Jason-1 being the first program to call on the PROTEUS versatile multimission platform for Low and Medium Earth Orbit Missions developed in partnership between Alcatel Space and CNES);

2. To verify that platform performance requirements are met with respect to Jason-1 requirements;

3. To verify that payload instruments performance requirements evaluated at instrument level are met;

4. To assess the performance of the Jason-1 Ground System.

This article will display the main outputs of the assessment of the system. It will demonstrate that all the elements of the onboard and ground systems are within the specifications. Provision of data to the Jason-1 Science Working Team started at the end of March 2002. This is the goal of a six-month phase after closure of the initial assessment phase to derive the error budget of the system in terms of altimetry user products.  相似文献   

Short period internal waves over the Huanghe (Yellow River) delta front   总被引：4，自引：0，他引：4  

L. D. Wright  Z. -S. Yang  B. D. Bornhold  G. H. Keller  D. B. Prior  W. J. Wiseman Jr.  Y. B. Fan  Z. Su 《Geo-Marine Letters》1986,6(2):115-120

Internal waves with periods of about 5 minutes and trough to crest heights of up to 6.2 m were observed acoustically over the actively accreting delta front of the Huanghe (Yellow River) in the western portion of the Gulf of Bohai, Peoples Republic of China. The radian frequency of the internal waves was close to the locally-observed Brunt-Vaisala frequency. Through the relatively short (one hour) duration of an internal wave train, the amplitude was observed to decrease progressively with time. These internal waves may cause resuspension of delta-front sediments.  相似文献   

Distribution and Diversity of Ibla cumingi Darwin [Crustacea, Cirripedia) from the Gulf of Elat (Red Sea)     

Y. Achituv  W. Klepal 《Marine Ecology》1981,2(4):295-305

Abstract. The distribution of Ibla cumingi DARWIN on different types of hard substrata along 30 km of coast in the Gulf of Elat was studied. I. cumingi was found among and underneath Tetraclita squamosa rufotincta , in oyster beds, underneath slabs of beachrock, and in fissures in igneous rocks. In the Tetraclita belt, I. cumingi is most frequent in empty shells of dead Tetraclita while in the oyster bed it is common inside the meshwork made by the oysters. The distribution is regarded as clustered distribution. The density and size of the clusters of I. cumingi is determined by the available sheltered space within the midlittoral zone. The form of the habitat determines the shape of the animals. Those found in the oyster bed and fissures are usually longer than those found in the Tetraclita belt due to the depth of the fissures or to the bigger spaces within the oyster bed. I. cumingi is orientated so that the capitulum with the cirri is projecting towards the open water, and the water current. It is concluded that I. cumingi can withstand the physical stress encountered in a tropical intertidal zone, but that the distribution pattern is caused by predation.  相似文献