Home About us Contact
|
Home About us Contact | ||
|
|
||
San Francisco Bay (san + francisco_bay)
Terms modified by San Francisco Bay Selected AbstractsThe effect of bidirectional flow on tidal channel planformsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 3 2004Sergio Fagherazzi Abstract Salt marsh tidal channels are highly sinuous. For this project, ,eld surveys and aerial photographs were used to characterize the planform of tidal channels at China Camp Marsh in the San Francisco Bay, California. To model the planform evolution, we assume that the topographic curvature of the channel centreline is a key element driving meander migration. Extraction of curvature data from a planimetric survey, however, presents certain problems because simple calculations based on equally distanced points on the channel axis produce numerical noise that pollutes the ,nal curvature data. We found that a spline interpolation and a polynomial ,t to the survey data provided us with a robust means of calculating channel curvature. The curvature calculations, combined with data from numerous cross-sections along the tidal channel, were used to parameterize a computer model. With this model, based on recent theoretical work, the relationship between planform shape and meander migration as well as the consequences of bidirectional ,ow on planform evolution have been investigated. Bank failure in vegetated salt marsh channels is characterized by slump blocks that persist in the channel for several years. It is therefore possible to identify reaches of active bank erosion and test model predictions. Our results suggest that the geometry and evolution of meanders at China Camp Marsh, California, re,ect the ebb-dominated regime. Copyright © 2004 John Wiley & Sons, Ltd. [source] Relative abundance and diversity of ammonia-oxidizing archaea and bacteria in the San Francisco Bay estuaryENVIRONMENTAL MICROBIOLOGY, Issue 11 2008Annika C. Mosier Summary Ammonia oxidation in marine and estuarine sediments plays a pivotal role in the cycling and removal of nitrogen. Recent reports have shown that the newly discovered ammonia-oxidizing archaea can be both abundant and diverse in aquatic and terrestrial ecosystems. In this study, we examined the abundance and diversity of ammonia-oxidizing archaea (AOA) and betaproteobacteria (,-AOB) across physicochemical gradients in San Francisco Bay , the largest estuary on the west coast of the USA. In contrast to reports that AOA are far more abundant than ,-AOB in both terrestrial and marine systems, our quantitative PCR estimates indicated that ,-AOB amoA (encoding ammonia monooxygenase subunit A) copy numbers were greater than AOA amoA in most of the estuary. Ammonia-oxidizing archaea were only more pervasive than ,-AOB in the low-salinity region of the estuary. Both AOA and ,-AOB communities exhibited distinct spatial structure within the estuary. AOA amoA sequences from the north part of the estuary formed a large and distinct low-salinity phylogenetic group. The majority of the ,-AOB sequences were closely related to other marine/estuarine Nitrosomonas -like and Nitrosospira -like sequences. Both ammonia-oxidizer community composition and abundance were strongly correlated with salinity. Ammonia-oxidizing enrichment cultures contained AOA and ,-AOB amoA sequences with high similarity to environmental sequences. Overall, this study significantly enhances our understanding of estuarine ammonia-oxidizing microbial communities and highlights the environmental conditions and niches under which different AOA and ,-AOB phylotypes may thrive. [source] Water-column concentrations and partitioning of polybrominated diphenyl ethers in the New York/New Jersey Harbor, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2008Archil Zarnadze Abstract Despite the emerging concern regarding polybrominated diphenyl ethers (BDEs), very few measurements of BDE concentrations in ambient water have been published. In the present study, BDEs were measured in water samples from the New York/New Jersey Harbor (USA). Samples were taken in Raritan Bay west of Sandy Hook during four intensive sampling campaigns in 2000 and 2001. Congeners 17, 47, 99, 100, 153, 154, 183, and 209 were detected. Total BDE (,BDE) concentrations (average ± standard deviation) were 175 ± 75 ng/g in the particle phase and 110 ± 72 pg/L in the apparent dissolved phase. The deca-congener, BDE 209, constituted 85 and 9% of ,BDEs in the particle and apparent dissolved phases, respectively. The ,BDE levels are significantly higher than those measured in Lake Ontario, USA, and in The Netherlands, but they are similar to concentrations measured in Lake Michigan and San Francisco Bay (both USA). Calculated values of the organic carbon-water partition coefficient (KOC) were strongly correlated with literature values of the octanol-water partition coefficient (KOW). The data suggest that sorption of BDEs to colloids is important in this system, although quantifying the extent of colloid sorption is difficult. [source] Effects of dose and particle size on activated carbon treatment to sequester polychlorinated biphenyls and polycyclic aromatic hydrocarbons in marine sedimentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2005John R. Zimmerman Abstract Recent laboratory studies show that mixing activated carbon with contaminated sediment reduces the chemical and biological availability of hydrophobic organic contaminants. In this study, we test the effects of varying the activated carbon dose and particle size in reducing the aqueous availability of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) and the uptake of PCBs by two benthic organisms. We mixed PCB- and PAH-contaminated sediment from Hunters Point Naval Shipyard, San Francisco Bay (CA, USA), for one month with activated carbon, at doses of 0.34, 1.7, and 3.4% dry mass basis. We found that increasing the carbon dose increased the effectiveness in reducing PCB bioaccumulation. In 56-d uptake tests with the benthic organisms Neanthes arenaceodentata and Leptocheirus plumulosus, PCB bioaccumulation was reduced by 93 and 90%, respectively, with 3.4% carbon. Increasing the dose also increased the effectiveness in reducing PCB and PAH aqueous concentrations and uptake by semipermeable membrane devices and quiescent flux of PCBs to overlying water. Decreasing activated carbon particle size increased treatment effectiveness in reducing PCB aqueous concentration, and larger-sized activated carbon (400,1,700 ,m) was ineffective with a contact period of one month. We invoke a numerical model based on intraparticle diffusion in sediment and activated carbon particles to help interpret our experimental results. This model was useful in explaining the trends for the effect of activated carbon dose and particle size on PCB aqueous concentrations in well-mixed systems. [source] The long-term fate of polychlorinated biphenyls in San Francisco Bay (USA)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2004Jay A. Davis Abstract A simple one-box mass budget model is presented as a first step toward a quantitative understanding of the long-term fate of polychlorinated biphenyls (PCBs) in San Francisco Bay (USA). Sensitivity analysis indicated that the most influential input parameters were degradation half-life in sediment, Kow, outflow, average PCB concentration in sediment, and depth of the active sediment layer. Moderately influential parameters included organic carbon content of suspended solids, sediment burial mass transfer coefficient, and Henry's law constant. If external loading could be eliminated entirely, the mass of PCBs in the bay is predicted to drop to half of the present value in 20 years. The model predicts that sustained loading of 10 kg year,1 would prevent the total PCB mass in the bay from ever dropping below 10% of the present mass. With a sustained loading of 20 kg year,1, the model predicts that the total PCB mass would never fall below about 25% of the present mass. The half-lives in the bay for the individual PCB congeners evaluated in this report ranged from four years for PCB 18 to 30 years for PCB 194. [source] Further evidence and characterization of Artemia franciscana (Kellogg, 1906) populations in ArgentinaJOURNAL OF BIOGEOGRAPHY, Issue 11 2004Francisco Amat Abstract Aim, This paper reports the presence of Artemia franciscana (Kellogg, 1906) in Mar Chiquita (CHI) salt lake and in Las Tunas (TUN) lagoon, as well as at a shallow lake in Salinas Grandes (Province of Córdoba) in Argentina. To date, this species has been considered absent from Argentina. This study also provides further data on the characterization of the A. franciscana populations from this area. Location, Province of Córdoba (Argentina). Methods, The cyst samples collected at the three hypersaline environments were measured to assess its mean diameter with a dissecting microscope. The length of the nauplii hatched from the cysts was also determined with the microscope. The adults raised from these nauplii under strictly controlled conditions were analysed for 12 morphological parameters and compared through multivariate discriminant analysis with other American populations. Fatty acids from the total lipids were analysed by gas chromatography. Reproductive compatibility was evaluated from single-pair intraspecific and interspecific crosses of adult specimens. Results, The results endorse the morphometric assimilation of the Artemia populations of this area to other American populations of the A. franciscana,super-species', together with its morphometric differentiation from the species A. persimilis (Piccinelli & Prosdocimi, 1968). The more conspicuous population from CHI shows cross-fertility with A. franciscana original from San Francisco Bay (California, USA). Both populations from CHI and TUN show cross-fertility between them and reproductive isolation with A. persimilis from Hidalgo (Province of La Pampa), which to date is considered to be endemic or exclusive of hypersaline ecosystems in Argentina. The reproductive characteristics displayed by the population from TUN lagoon suggest the existence of an occasional hybridization between A. franciscana and A. persimilis (Papeschi et al., 2000). Artemia cysts from CHI and TUN show a fatty acid profile rich in eicosapentaenoic acid differing markedly from the fatty acid profiles found in A. persimilis cysts. Main conclusions:,Artemia franciscana is present in Argentina at 36° S and north of this latitude. Artemia persimilis is confined to the south of latitude 37°10, S. There are different pieces of evidence that point to a certain level of hybridization of the two species taking place in the land belt between these parallels. [source] Stakeholder Perspectives about Marine Oil Spill Response Objectives: A Comparative Q Study of Four RegionsJOURNAL OF CONTINGENCIES AND CRISIS MANAGEMENT, Issue 2 2009Seth Tuler Marine oil spills can cause major social, economic, and ecological disruptions. Spill response managers must weigh different options and objectives when deciding what to do. We investigated the ways in which preferences for spill response objectives vary among those who are responsible for oil spill contingency planning and response in Buzzards Bay, Delaware Bay, San Francisco Bay, and Washington State regions. We begin this paper with a discussion of the research method used in the study: the Q method. In Buzzards Bay, Delaware Bay, and San Francisco Bay three perspectives were identified in each case. In Washington State, two perspectives were identified. An analysis of the 11 case-specific perspectives reveals that they can be described by four ,composite' perspectives that describe how different stakeholders prioritize spill response objectives. These four perspectives are compared on several themes, including the emphasis they placed on mitigating economic impacts, protecting health and safety, mitigating ecological impacts, implementing a coordinated and timely response, addressing the needs and concerns of the affected public/communities, gaining public support for the response, mitigating cultural impacts, and mitigating social nuisance impacts. The implications for spill response planning and spill response evaluation are discussed. [source] Extreme population subdivision throughout a continuous range: phylogeography of Batrachoseps attenuatus (Caudata: Plethodontidae) in western North AmericaMOLECULAR ECOLOGY, Issue 20 2007IÑIGO MARTÍNEZ, SOLANO Abstract Low-vagility species with deep evolutionary histories are key to our understanding of the biogeographical history of geologically complex areas, such as the west coast of North America. We present a detailed study of the phylogeography of the salamander Batrachoseps attenuatus (Caudata: Plethodontidae) using sequences of the mitochondrial gene cob from 178 individuals sampled from throughout the species' range. Sequences of three other mitochondrial genes (16S, cox1, nad4) and a nuclear gene (RAG-1) were used to investigate the deeper evolutionary history of the species. We found high levels of genetic diversity and deep divergences within a mostly continuous distribution, with five genetically well-differentiated and geographically structured mitochondrial DNA clades. Significant association between geographical and genetic distances within these clades suggests demographic stability, whereas Fu's FS tests suggest demographic expansions in three of them. Mantel tests identify two biogeographical barriers, the San Andreas Fault and the Sacramento,San Joaquin Delta, as important in the diversification of lineages. The timing of the main splitting events between intraspecific lineages was estimated by applying relaxed molecular clock methods combining several mutation rates and a fossil calibration. The earliest splitting events are old (Pliocene/Miocene), with more recent (Pleistocene) subdivisions in some clades. Disjunct populations distributed along the western foothills of the Sierra Nevada colonized this area relatively recently from a single refugium east of San Francisco Bay. The combination of fine-scale, comprehensive sampling with phylogenetic, historical demographic and hypothesis-based tests allowed delineation of a complex biogeographical scenario with general implications for the study of codistributed taxa. [source] Reciprocal hybrid formation of Spartina in San Francisco BayMOLECULAR ECOLOGY, Issue 6 2000C. K. Anttila Abstract Diversity in the tRNALEU1 intron of the chloroplast genome of Spartina was used to study hybridization of native California cordgrass, Spartina foliosa, with S. alterniflora, introduced to San Francisco Bay , 25 years ago. We sequenced 544 bases of the tRNALEU1 intron and found three polymorphic sites, a pyrimidine transition at site 126 and transversions at sites 382 and 430. Spartina from outside of San Francisco Bay, where hybridization between these species is impossible, gave cpDNA genotypes of the parental species. S. foliosa had a single chloroplast haplotype, CCT, and this was unique to California cordgrass. S. alterniflora from the native range along the Atlantic coast of North America had three chloroplast haplotypes, CAT, TAA, and TAT. Hybrids were discriminated by random amplified polymorphic DNA (RAPD) phenotypes developed in a previous study. We found one hybrid that contained a cpDNA haplotype unknown in either parental species (TCT). The most significant finding was that hybridization proceeds in both directions, assuming maternal inheritance of cpDNA; 26 of the 36 hybrid Spartina plants from San Francisco Bay contained the S. foliosa haplotype, nine contained haplotypes of the invading S. alterniflora, and one had the cpDNA of unknown origin. Furthermore, cpDNA of both parental species was distributed throughout the broad range of RAPD phenotypes, suggesting ongoing contributions to the hybrid swarm from both. The preponderance of S. foliosa cpDNA has entered the hybrid swarm indirectly, we propose, from F1s that backcross to S. foliosa. Flowering of the native precedes by several weeks that of the invading species, with little overlap between the two. Thus, F1 hybrids would be rare and sired by the last S. foliosa pollen upon the first S. alterniflora stigmas. The native species produces little pollen and this has low viability. An intermediate flowering time of hybrids as well as pollen that is more vigourous and abundant than that of the native species would predispose F1s to high fitness in a vast sea of native ovules. Thus, spread of hybrids to other S. foliosa marshes could be an even greater threat to the native species than introductions of alien S. alterniflora. [source] Paleoepidemiological patterns of interpersonal aggression in a prehistoric central California population from CA-ALA-329AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Robert Jurmain Abstract Interpersonal aggression is assessed paleoepidemiologically in a large skeletal population from the CA-ALA-329 site located on the southeastern side of San Francisco Bay, California. This comprehensive analysis included all currently recognized skeletal criteria, including craniofacial fracture, projectile injury, forearm fracture, and perimortem bone modification. Craniofacial injury is moderately common, showing an adult prevalence of 9.0% with facial lesions accounting for >50% of involvement. Clinical studies suggest that such separate evaluation of facial involvement provides a useful perspective for understanding patterns of interpersonal aggression. In this group male facial involvement is significantly greater than in females, paralleling the pattern found widely in contemporary populations as well as in African apes. When compared to other North American skeletal samples the prevalence of adult cranial vault injury (3.3%) and especially projectile injury (4.4%) are quite high. However, well documented populations from southern California show markedly higher prevalence for both types of skeletal markers of aggression. Forearm fracture is also assessed using a rigorous radiographic methodology and results suggest that these injuries are not reliable indicators of interpersonal aggression. Lastly, perimortem bone modification was not observed in this population, although it has been recorded from other (older) sites nearby. This study provides an evaluation of multiple skeletal markers of interpersonal aggression in the largest sample from a single site yet reported in North America and, joined with consideration of cultural context, helps further illuminate both geographic and temporal patterns of interpersonal aggression in California. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||