Range-wide population structure of shortnose sturgeonAcipenser brevirostrum based on sequence analysis of the mitochondrial DNA control region     

Isaac Wirgin  Cheryl Grunwald  Erik Carlson  Joseph Stabile  Douglas L. Peterson  John Waldman 《Estuaries and Coasts》2005,28(3):406-421

Riverine populations of shortnose sturgeon (Acipenser brevirostrum) once occurred in rivers and estuaries along the east coast of North America from the St. John River, New Brunswick, to the St. Johns River, Florida. Within this range, 19 population segments were identified by the U.S. Federal Shortnose Sturgeon Recovery Team; empirical data supporting this structure is limited. We obtained samples from 11 (12 including a small sample from the Cape Fear River, North Carolina) of these population segments and used PCR and direct sequence analysis of 440 base pairs of the mitochondrial DNA (mtDNA) control region to define the coast-wide genetic population structure of shortnose sturgeon. Collections from most population segments exhibited significant differences in haplotype frequencies with their nearest neighbors, including from the Ogeechee and Savannah Rivers, Georgia (despite the known movement of hatchery-reared offspring from the Savannah into the Ogeechee River). Collections from the Chesapeake Bay and Delaware River exhibited similar haplotype frequencies, suggesting that specimens collected in the Chesapeake Bay had dispersed from the Delaware River. Collections from the Kennebec River and Androscoggin River within a hypothesized single population segment did not exhibit significant differentiation of mtDNA haplotype frequencies. Haplotype frequencies were almost identical between collections from above and below the Holyoke Dam on the Connecticut River, indicating that these aggregations should be managed as a single unit. Our results support the population segment status afforded to shortnose sturgeon in at least the following 9 systems; St. John River, Kennebec-Androscoggin Rivers, upper-lower Connecticut River, Hudson River, Delaware River-Chesapeake Bay, Pee Dee River, Cooper River, Savannah River, and Ogeechee-Altamaha Rivers.  相似文献   

Discrete element modeling of shear wave propagation in carbonate precipitate–cemented particles     

Sun  Meng  Cao  Junnan  Cao  Jingjing  Zhang  Shuai  Chen  Yunmin  Bate  Bate 《Acta Geotechnica》2022,17(7):2633-2649

Bioremediation is widely used to improve ground soil by introducing calcium carbonate (CaCO₃). Shear wave velocity (Vs) is usually adopted to evaluate effect but the microscopic mechanism is unclear. The discrete element method (DEM), a promising tool for simulating the behaviors of cohesive and noncohesive materials, was used in this study to simulate Vs evolution and wave propagation path of sand reinforced by calcite precipitates. Two basic calcite precipitate forms are proposed for representing individual calcite precipitation (CaCO₃-P) and calcite aggregation (CaCO₃-C). Contact cementation between adjacent sand grain pairs was the primary association pattern for calcite precipitates at a low calcite content. At a higher calcite content, the preferential shear wave propagation pathway is the clusters cemented by CaCO₃-C. With calcite content increasing from 0 to 9%, the coordination number and average contact force increased. Vs increased from 169.73 to 2132.64 m/s but had high variability due to the spatial distribution. The results suggest that the calibrated DEM model can elucidate the microscopic mechanisms and evaluate the enhancement effect of microorganism-reinforced soil.

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A review of the plant-based traditions of the Cocoa Panyols of Trinidad     

Cheryl Lans 《GeoJournal》2018,83(6):1425-1454

This paper reviews the plants used by Spanish speakers in Trinidad and Tobago as documented in a 1994 publication. The plant uses were reviewed to determine whether the plants and uses were different from other ethnic groups in Trinidad and the wider region and to draw conclusions from the review. The review covers 148 plants. With few exceptions, the plants were Native and so were the uses. Several plants have been little studied (Ambroisa cumanensis, Aristolochia rugosa, Bauhinia cumanensis, Bauhinia excisa, Begonia humilis, Croton conduplicatus, Croton flavens, Cyperus diffusus, Desmodium incanum, Fleurya aestuans, Heliconia bihai). The Cocoa Panyols retained the knowledge of at least two plants first described in the 1800s that were no longer mentioned to researchers in Trinidad and Tobago after 1981 by the rest of the population. The Cocoa Panyols preserved their cultural and linguistic heritage by concentrating on cocoa growing in rural areas and their movement from place to place to establish cocoa plantations may account for the uniformity of information on ethnomedicine in Trinidad, which additionally is similar to medicinal plant knowledge of the original populations of South America.  相似文献   

Cellular diagnostics and coral health: declining coral health in the Florida Keys     

Downs CA  Fauth JE  Robinson CE  Curry R  Lanzendorf B  Halas JC  Halas J  Woodley CM 《Marine pollution bulletin》2005,51(5-7):558-569

Coral reefs within the Florida Keys are disappearing at an alarming rate. Coral cover in the Florida Keys National Marine Sanctuary declined by 38% from 1996 to 2000. In 2000, populations of Montastraea annularis at four sites near Molasses Reef within the Florida Keys National Marine Sanctuary and one reef within Biscayne National Park were sampled on a quarterly basis. Anecdotal observations showed corals at Alina's Reef in Biscayne National Park appeared healthy in March, but experienced an acute loss of coral cover by August. Cellular Diagnostic analysis indicated that Alina's Reef corals were in distress: they had been afflicted with a severe oxidative damaging and protein-denaturing stress that affected both the corals and their symbiotic zooxanthellae. This condition was associated with a significant xenobiotic detoxification response in both species, reflecting probable chemical contaminant exposure. These results demonstrate that applying a Cellular Diagnostic approach can be effective in helping to identify stress and its underlying causes, providing diagnostic and prognostic biomarkers of coral health.  相似文献   

Characterizing aquatic sediment-oil aggregates using in situ instruments     

Sterling MC  Bonner JS  Ernest AN  Page CA  Autenrieth RL 《Marine pollution bulletin》2004,48(5-6):533-542

The effects of emulsified crude oil and salinity (15, 30 per thousand ) on the steady state aggregate volume distributions and fractal dimensions were determined for a range of mean velocity gradients, (G(m) =5-50 s(-1)). Aggregation was performed in a 40-L cylindrical tank with a 4-blade paddle mixer. Three-dimensional fractal dimensions (D3) and volume distributions were determined using a procedure integrating data from an electrozone and an in situ light scattering instrument. Two-dimensional fractal dimensions (D2) and derived volume distributions were determined using a recently developed submersible flow cytometer equipped with a digital camera and image analysis software. For latex beads or emulsified crude oil systems, the above listed instruments yielded consistent size distributions and fractal dimensions (D2=1.92 +/- 0.16, D3=2.94 +/- 0.12). Mean volume aggregate diameters determined using the FlowCAM were consistently larger that those determined using the LISST-100 or Coulter Multisizer due to aggregate orientations during measurements. With increasing G(m) values, all colloidal aggregates showed increasing D3 values due to reduced aggregate length. Because of the compactness of all the aggregates (D3 >2), D2 values remained constant at 2. Neither salinity nor sediment type significantly affected D2 values calculated for sediment-crude oil aggregates. However, clay-oil aggregates showed higher D3 values than clay aggregates. This suggests that colloidal oil and mixing shear are the more dominant factors influencing aggregate morphology in nearshore waters. Overall, the data suggests that the analysis methods provide consistent size distribution results. However, because of the shear and salinity of coastal waters, resulting aggregates are too compact to estimate their D3 values using image analysis alone.  相似文献   

Cytochrome P4501A1 induction in Kenai River sculpin (Cottus spp.) as a monitor of freshwater pollution effects     

Cheryl E. Paige  John M. Kennish 《Marine environmental research》1995,39(1-4)

Freshwater sculpin were taken from various locations in the Kenai River to determine their in-vivo response to pollution exposure. The specific activity of cytochrome P4501A1 was determined using fluorescence detection of the 7-ethoxyresorufin-O-dealkylase (EROD) reaction. The EROD specific activity was found to be independent of river miles but appeared to relate to specific sites of urban runoff. Glutathione-S-transferase (GST) activities were also measured but showed no significant difference between sites. Cytochrome P450 laboratory induction studies were carried out on individuals collected from a pristine site. Five groups of 10 fish were dosed from 10–150 mg β-Naphthoftavone (βNF)/kg body weight. The response was linear from 10–50 mg βNF/kg body weight. Sculpin appear to have excellent potential as a sensitive indicator of xenobiotic exposure in a freshwater benthic habitat.  相似文献   

The generation and preservation of multiple hurricane beds in the northern Gulf of Mexico   总被引：1，自引：0，他引：1  

Timothy R. Keen  Samuel J. Bentley  W. Chad Vaughan  Cheryl Ann Blain 《Marine Geology》2004,210(1-4):79-105

Cores collected from Mississippi Sound and the inner shelf of the northeast Gulf of Mexico have been examined using ²¹⁰Pb and ¹³⁷Cs geochronology, X-radiography, granulometry, and a multi-sensor core logger. The results indicate that widespread event layers were probably produced by an unnamed hurricane in 1947 and by Hurricane Camille in 1969. Physical and biological post-depositional processes have reworked the event layers, producing regional discontinuities and localized truncation, and resulting in an imperfect and biased record of sedimentary processes during the storms. The oceanographic and sedimentological processes that produced these event beds have been simulated using a suite of numerical models: (1) a parametric cyclone wind model; (2) the SWAN third-generation wave model; (3) the ADCIRC 2D finite-element hydrodynamic model; (4) the Princeton Ocean Model; (5) a coupled wave–current bottom boundary layer-sedimentation model; and (6) a model for bed preservation potential as a function of burial rate and bioturbation rate. Simulated cores from the Mississippi Sound region are consistent with the observed stratigraphy and geochronology on both the landward and seaward sides of the barrier islands.  相似文献   

Nature’s laboratory should be included in the fight against Ebola     

Cheryl Lans 《GeoJournal》2016,81(1):1-3

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Mangrove Range Expansion Rapidly Increases Coastal Wetland Carbon Storage     

Cheryl?L.?DoughtyEmail author  J.?Adam?Langley  Wayne?S.?Walker  Ilka?C.?Feller  Ronald?Schaub  Samantha?K.?Chapman 《Estuaries and Coasts》2016,39(2):385-396

The climate change-induced expansion of mangroves into salt marshes could significantly alter the carbon (C) storage capacity of coastal wetlands, which have the highest average C storage per land area among unmanaged terrestrial ecosystems. Mangrove range expansion is occurring globally, but little is known about how these rapid climate-driven shifts may alter ecosystem C storage. Here, we quantify current C stocks in ecotonal wetlands across gradients of marsh- to mangrove-dominance, and use unique chronological maps of vegetation cover to estimate C stock changes from 2003 to 2010 in a 567-km² wildlife refuge in the mangrove-salt marsh ecotone. We report that over the 7-yr. period, total wetland C stocks increased 22 % due to mangrove encroachment into salt marshes. Newly established mangrove stands stored twice as much C on a per area basis as salt marsh primarily due to differences in aboveground biomass, and mangrove cover increased by 69 % during this short time interval. Wetland C storage within the wildlife refuge increased at a rate of 2.7 Mg C ha^?1 yr.^?1, more than doubling the naturally high coastal wetland C sequestration rates. Mangrove expansion could account for a globally significant increase of terrestrial C storage, which may exert a considerable negative feedback on warming.  相似文献   

Predicting the properties of binary stellar systems: the evolution of accreting protobinary systems     

Matthew R. Bate 《Monthly notices of the Royal Astronomical Society》2000,314(1):33-53

We investigate the formation of binary stellar systems. We consider a model where a 'seed' protobinary system forms, via fragmentation, within a collapsing molecular cloud core and evolves to its final mass by accreting material from an infalling gaseous envelope. This accretion alters the mass ratio and orbit of the binary, and is largely responsible for forming the circumstellar and/or circumbinary discs.
Given this model for binary formation, we predict the properties of binary systems and how they depend on the initial conditions within the molecular cloud core. We predict that there should be a continuous trend such that closer binaries are more likely to have equal-mass components and are more likely to have circumbinary discs than wider systems. Comparing our results with observations, we find that the observed mass-ratio distributions of binaries and the frequency of circumbinary discs as a function of separation are most easily reproduced if the progenitor molecular cloud cores have radial density profiles between uniform and 1/ r (e.g., Gaussian) with near-uniform rotation. This is in good agreement with the observed properties of pre-stellar cores. Conversely, we find that the observed properties of binaries cannot be reproduced if the cloud cores are in solid-body rotation and have initial density profiles which are strongly centrally condensed. Finally, in agreement with the radial-velocity searches for extrasolar planets, we find that it is very difficult to form a brown dwarf companion to a solar-type star with a separation ≲10 au, but that the frequency of brown dwarf companions should increase with larger separations or lower mass primaries.  相似文献