Reproductive success of Calanus pacificus during diatom blooms in Dabob Bay, Washington   总被引：1，自引：4，他引：1  

James J. Pierson  Claudia Halsband-Lenk  Andrew W. Leising 《Progress in Oceanography》2005,67(3-4):314

While numerous laboratory studies in the last decade have shown that diatoms can induce reproductive failure in copepods, field evidence for a negative diatom effect is equivocal. To unambiguously elucidate the effects diatoms have on copepod reproduction in situ, we undertook a study of the abundance, distribution, grazing rates, and reproductive success of Calanus pacificus in Dabob Bay, Washington, USA, during two spring bloom periods. We simultaneously measured the phytoplankton composition, abundance, and distribution. Here we present results for the reproductive success of C. pacificus using four measurements: egg production rate, clutch size, egg hatching success, and naupliar survival (to the first feeding stage). Egg production rate was positively correlated with chlorophyll a concentration, and egg hatching success and naupliar survival were usually greater than 80%. However, in February 2002 and 2003 – during blooms of diatoms of the genus Thalassiosira – either egg hatching success, naupliar survival, or both were significantly depressed compared to other times in spring and summer. These effects, combined with evidence that C. pacificus was grazing aldehyde-producing Thalassiosira at the time of their blooms, indicate that diatoms can negatively affect copepod reproduction in the field, albeit only under specific circumstances and for brief periods.  相似文献   

Predicting the optical properties of the West Florida Shelf: resolving the potential impacts of a terrestrial boundary condition on the distribution of colored dissolved and particulate matter   总被引：1，自引：0，他引：1  

W. Paul Bissett  Robert Arnone  Sharon DeBra  Dwight A. Dieterle  Daniel Dye  Gary J. Kirkpatrick  Oscar M. Schofield  Gabriel A. Vargo 《Marine Chemistry》2005,95(3-4):199-233

Predicting the distribution of Inherent Optical Properties (IOPs) in the water column requires predicting the physical, chemical, biological, and optical interactions in a common framework that facilitates feedback responses. This work focuses on the development of ecological and optical interaction equations embedded in a 2D hindcast model of the shallow water optical properties on the West Florida Shelf (WFS) during late summer/fall of 1998. This 2D simulation of the WFS includes one case with a Loop Current intrusion above the 40-m isobath and one with the Loop Current intrusion in addition to a periodic terrestrial nutrient supply below the 10-m isobath. The ecological and optical interaction equations are an expansion of a previously developed model for open ocean conditions (Bissett, W.P., Carder, K.L., Walsh, J.J., Dieterle, D.A., 1999a. Carbon cycling in the upper waters of the Sargasso Sea: II. Numerical simulation of apparent and inherent optical properties. Deep-Sea Research, Part I: Oceanographic Research Papers, 46 (2), 271–317; Bissett, W.P., Walsh, J.J., Dieterle, D.A., Carder, K.L., 1999b. Carbon cycling in the upperwaters of the Sargasso Sea: I. Numerical simulation of differential carbon and nitrogen fluxes. Deep-Sea Research, Part I: Oceanographic Research Papers, 46 (2), 205–269). The expansion includes an increase in the number of elemental pools to include silica, phosphorus, and iron, an increase in the number of phytoplankton functional groups, and a redevelopment of the Dissolved Organic Matter (DOM) and Colored Dissolved Organic Matter (CDOM) interaction equations. It was determined from this simulation that while the Loop Current alone was able to predict the water column conditions present during the summer, the Loop Current alone was not enough to simulate the magnitude of optical constituents present in the fall of 1998 when compared to satellite imagery. Simulating terrestrial inorganic and organic nutrients and CDOM pulses coinciding with significant meteorological events and high freshwater pulses released from the major rivers feeding the WFS were required to accurately predict the distribution and scale of the inherent optical properties at the surface during the fall months. Modeling the in situ light field for phytoplankton growth and community competition requires addressing the CDOM optical constituent explicitly. The majority of the annually modeled CDOM on WFS was created via in situ production; however, it was also rapidly removed via advection and photochemical destruction. A pulse of terrestrial nutrient and organic color was required to simulate the dramatic changes in surface color seen in satellite imagery on the WFS. The dynamics of the biogeochemical portion of the simulation demonstrate the importance of nonstoichiometric supplies of terrestrial nutrients on the WFS to the prediction of nutrient and CDOM fluxes.  相似文献   

Zonal and seasonal variations in zooplankton community structure off the central Oregon coast, 1998–2000     

Julie E. Keister  William T. Peterson 《Progress in Oceanography》2003,57(3-4):341

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Marsh expansion at Calaveras Point Marsh, South San Francisco Bay, California   总被引：1，自引：1，他引：0  

Elizabeth Burke Watson   《Estuarine, Coastal and Shelf Science》2008,78(4):593-602

Studies of shoreline progradation along low-energy vegetated shorelines have been limited, as these environments are generally experiencing erosion rather than deposition, with extreme erosion rates frequently found. This study examined yearly changes along a vegetated shoreline at Calaveras Point Marsh, South San Francisco Bay, California, using aerial photography, to determine the roles of climatic, watershed, and coastal process in driving shoreline changes. In addition, sediment accumulation was monitored on a yearly basis at 48 locations across the marsh to determine the role of geomorphic factors in promoting accumulation. Calaveras Point Marsh was found to have expanded from 49.26 ± 5.2 to 165.7 ± 4.7 ha between 1975 and 2005. Although the rate of marsh expansion was not positively correlated with yearly variability in precipitation, local streamflow, delta outflow, water level observations, population growth, or ENSO indices, marsh growth was greater during years of higher than average temperatures. Warmer temperatures may have promoted the recruitment and growth of Spartina foliosa, a C₄ grass known to be highly responsive to temperature. Other factors, such as the formation of a coastal barrier, a recent change in the location of the mouth of the Guadalupe River, and channel readjustment in response to diking are credited with driving the bulk of the marsh expansion. Sediment accumulation was found to be high closest to channels and to the shoreline, at low elevations and in recently vegetated marsh. Globally, the pace of sea level rise exerts the primary control on wetland development and persistence. However, at local geographic scales, factors such as tectonic events, modifications to natural sediment transport pathways or land use changes may overwhelm the effects of regional sea level rise, and allow for wetlands to develop, expand and persist despite rapid sea level rise.  相似文献   

GRAPES_Meso背景误差特征及应用   总被引：2，自引：0，他引：2       下载免费PDF全文

庄照荣  王瑞春  王金成  龚建东 《应用气象学报》2019,30(3):316-331

基于2015年6月—2016年5月GRAPES_Meso有限区域中尺度数值预报模式产品,采用美国国家气象中心（NMC）方法和高斯函数拟合方案统计中国区域的背景误差和水平相关尺度随纬度、高度和季节的变化特征。结果表明:控制变量的背景误差与水平相关尺度不仅随高度和纬度有明显变化,其中非平衡Exner气压和比湿具有明显的局地性和季节变化特征。非平衡Exner气压的背景误差在青藏高原地区较大,且冬季最大,夏季最小。比湿背景误差在低纬度热带季风区较大,且夏季最大,冬季最小。非平衡Exner气压和比湿的水平相关尺度在冬季最大,夏季最小。同时文中采用随高度变化的水平相关尺度替换GRAPES-3DVar中单一尺度参数,1个月的分析和模式预报试验表明,6 h的位势高度预报在对流层有明显改进;风场分析及其12 h内的预报在平流层改进明显;对24 h不同量级降水的预报有显著正贡献,也显著改善24 h内的小雨、中雨和大雨的空报现象,明显改善12~24 h特大暴雨的漏报现象。  相似文献   

Potential climate-change impacts on the Chesapeake Bay   总被引：1，自引：0，他引：1  

Raymond G. Najjar  Christopher R. Pyke  Mary Beth Adams  Denise Breitburg  Carl Hershner  Michael Kemp  Robert Howarth  Margaret R. Mulholland  Michael Paolisso  David Secor  Kevin Sellner  Denice Wardrop  Robert Wood 《Estuarine, Coastal and Shelf Science》2010

We review current understanding of the potential impact of climate change on the Chesapeake Bay. Scenarios for CO₂ emissions indicate that by the end of the 21^st century the Bay region will experience significant changes in climate forcings with respect to historical conditions, including increases in CO₂ concentrations, sea level, and water temperature of 50–160%, 0.7–1.6 m, and 2–6 °C, respectively. Also likely are increases in precipitation amount (very likely in the winter and spring), precipitation intensity, intensity of tropical and extratropical cyclones (though their frequency may decrease), and sea-level variability. The greatest uncertainty is associated with changes in annual streamflow, though it is likely that winter and spring flows will increase. Climate change alone will cause the Bay to function very differently in the future. Likely changes include: (1) an increase in coastal flooding and submergence of estuarine wetlands; (2) an increase in salinity variability on many time scales; (3) an increase in harmful algae; (4) an increase in hypoxia; (5) a reduction of eelgrass, the dominant submerged aquatic vegetation in the Bay; and (6) altered interactions among trophic levels, with subtropical fish and shellfish species ultimately being favored in the Bay. The magnitude of these changes is sensitive to the CO₂ emission trajectory, so that actions taken now to reduce CO₂ emissions will reduce climate impacts on the Bay. Research needs include improved precipitation and streamflow projections for the Bay watershed and whole-system monitoring, modeling, and process studies that can capture the likely non-linear responses of the Chesapeake Bay system to climate variability, climate change, and their interaction with other anthropogenic stressors.  相似文献   

美国新墨西哥州钾盐矿床及其开发   总被引：2，自引：0，他引：2  

魏东岩 《化工矿产地质》2001,23(1):31-38

新墨西哥州卡尔斯巴德 (Carlsbad)钾盐矿床是美国最早发现的古钾盐矿床 ,该矿床一直是美国钾盐的主要供给地。含钾蒸发岩系产出于得克萨斯州西部、新墨西哥州东南部Delaware盆地上二叠统海相地层中。含钾蒸发岩系可分为 4个建造。由下向上分别为 :①Castile建造 ,由石盐岩和其夹层硬石膏岩或石灰岩构成 ;②Salado建造 ,由钾盐、石盐岩、含泥石盐岩、硬石膏岩、杂卤石岩、白云岩、泥岩构成 ;③Rustler建造。由石盐岩、石膏岩、硬石膏岩、硅质岩、白云岩及石灰岩构成 ;④DeweyLake红层建造 ,由红色泥岩和砂岩构成。其中 ,Salado建造 ,厚 6 70m ,含 12个矿带 ,面积为 492 0km2 ,钾盐矿体主要由钾石盐和无水钾镁矾以及石盐等矿物所组成。次生的钾盐矿物有 :钾盐镁矾和钾镁矾等  相似文献   

Radiocarbon dating of dissolved inorganic carbon in groundwater from confined parts of the Upper Floridan aquifer, Florida, USA   总被引：3，自引：1，他引：3  

Niel L. Plummer  Craig L. Sprinkle 《Hydrogeology Journal》2001,9(2):127-150

Geochemical reaction models were evaluated to improve radiocarbon dating of dissolved inorganic carbon (DIC) in groundwater from confined parts of the Upper Floridan aquifer in central and northeastern Florida, USA. The predominant geochemical reactions affecting the ¹⁴C activity of DIC include (1) dissolution of dolomite and anhydrite with calcite precipitation (dedolomitization), (2) sulfate reduction accompanying microbial degradation of organic carbon, (3) recrystallization of calcite (isotopic exchange), and (4) mixing of fresh water with as much as 7% saline water in some coastal areas. The calculated cumulative net mineral transfers are negligibly small in upgradient parts of the aquifer and increase significantly in downgradient parts of the aquifer, reflecting, at least in part, upward leakage from the Lower Floridan aquifer and circulation that contacted middle confining units in the Floridan aquifer system. The adjusted radiocarbon ages are independent of flow path and represent travel times of water from the recharge area to the sample point in the aquifer. Downgradient from Polk City (adjusted age 1.7 ka) and Keystone Heights (adjusted age 0.4 ka), 14 of the 22 waters have adjusted ¹⁴C ages of 20–30 ka, indicating that most of the fresh-water resource in the Upper Floridan aquifer today was recharged during the last glacial period. All of the paleowaters are enriched in ¹⁸O and ²H relative to modern infiltration, with maximum enrichment in δ¹⁸O of approximately 2.0‰. Electronic Publication  相似文献   

Contrasts between source parameters of M 5.5 earthquakes in northern Baja California and southern California     

Diane I. Doser 《Geophysical Journal International》1994,116(3):605-617

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Coincidence of cadmium and antibiotic resistance in New York Bight apex benthic microorganisms     

M.A Devanas  C.D Litchfield  C McClean  J Gianni 《Marine pollution bulletin》1980,11(9):264-269

Microorganisms resistant to 1–500 ppm cadmium were isolated over an 11 month period from sediments at the sewage sludge, dredge spoils and industrial acid waste disposal sites, as well as at an estuarine outflow to the New York Bight apex. Tests for antibiotic resistance in these isolates revealed that 94% of the isolates were resistant to one or more antibiotics and that 91% of the original isolates could be characterized by multiple drug resistance. Different selective pressures may account for the various genera and antimicrobial resistance patterns observed. The possibility of extrachromosomal linkage of cadmium and streptomycin resistance is discussed.  相似文献