Kinetics of vitellogenin protein and mRNA induction and depuration in fish following laboratory and environmental exposure to oestrogens     

Craft JA  Brown M  Dempsey K  Francey J  Kirby MF  Scott AP  Katsiadaki I  Robinson CD  Davies IM  Bradac P  Moffat CF 《Marine environmental research》2004,58(2-5):419-423

Plaice, flounder and sand goby were exposed to ethynylestradiol (EE2) for 21 days and then followed for up to 31 days after removal of the oestrogen. Plasma vitellogenin (VTG) and hepatic VTG mRNA were determined in groups of fish sampled during the induction and post-exposure phases. VTG mRNA increased slightly earlier than plasma protein, but both reached maxima by 21 days. In contrast, VTG mRNA decayed much more rapidly than protein after EE2 exposure was terminated (typical values t(1/2) mRNA 3 days, protein 15-30 days). Vitellogenin and VTG mRNA thus measure different temporal events and this is illustrated by field data of male flounder in which both parameters have been determined. Few fish show co-ordinate increased VTG mRNA and vitellogenin but rather more fish have increased vitellogenin. Low level increases of VTG mRNA (5 X) is observed in some fish without increased vitellogenin and this may represent polymorphic differences between individual fish.  相似文献   

Settling fluxes in Saanich and Jervis Inlets, British Columbia, Canada: sources and seasonal patterns     

David A Timothy  Maureen Y.S SoonStephen E Calvert 《Progress in Oceanography》2003,59(1):31-73

We conducted a multi-year sediment-trap experiment in Saanich and Jervis Inlets, British Columbia, Canada. Moorings with traps positioned at three depths were placed near the mouth and toward the head of each fjord, and deployments were monthly. We present fluxes of total mass, biogenic silica (BSi), particulate organic carbon (POC) and aluminium (Al), as well as the δ¹³C signal of the POC, and we compare the sediment-trap fluxes to primary-production measurements made during the experiment.Diatomaceous silica and aluminosilicates were the primary components of the settling flux, while organic matter from marine (largely diatoms) and terrestrial sources was occasionally a significant portion of the sinking material. Fluxes of BSi and POC were highest in the spring and summer, tracing maxima in local primary production. These fluxes decreased, increased or remained constant with depth due to water-column remineralisation and variability in processes that cause fluxes to increase with depth. Al fluxes followed local precipitation and river runoff at the landward stations, and with remarkable faithfulness in Saanich Inlet. Near the mouths, there was little seasonality in Al flux, and the increases of flux with depth reveal sedimentary plumes at each fjord’s sill. Tidal and deepwater-renewal components of the plumes are evident, and the plume in Saanich Inlet was particularly intense. Fluxes of Al to deep sediment traps associated with renewal flows were also observed toward the head of each fjord.Marine δ¹³C endmembers are estimated from relationships between δ¹³C and BSi concentrations, and measures of soil δ¹³C from each fjord were available. These endmembers are used with the δ¹³C record to quantify marine and terrigenous contributions to the POC flux. Marine POC composed 54-72% of the total POC caught by shallow sediment traps in spring and summer, and 36-54% in fall and winter. Primary production and sediment-trap fluxes are used to estimate annually averaged export ratios (shallow-trap flux:autotrophic assimilation) for marine POC and Si. POC export ratios (0.092-0.14) were low for these productive waters, but they compare with other results based on sediment-trap fluxes from coastal waters where terrigenous OC has been subtracted. Export ratios of Si were calculated using an estimated Si:C assimilation ratio and, therefore, are susceptible to error, but the high results (>0.8) suggest that BSi was exported more efficiently than POC. The possibility that POC was preferentially lost after interception by sediment traps is also considered. Primary production and settling fluxes were higher in Saanich Inlet than in Jervis Inlet, while export ratios of OC and Si were similar in both fjords, away from the nepheloid layer near the sill of Saanich Inlet.  相似文献   

A Holocene record of Pacific Decadal Oscillation (PDO)-related hydrologic variability in Southern California (Lake Elsinore,CA)     

M. E. Kirby  S. P. Lund  W. P. Patterson  M. A. Anderson  B. W. Bird  L. Ivanovici  P. Monarrez  S. Nielsen 《Journal of Paleolimnology》2010,44(3):819-839

High-resolution terrestrial records of Holocene climate from Southern California are scarce. Moreover, there are no records of Pacific Decadal Oscillation (PDO) variability, a major driver of decadal to multi-decadal climate variability for the region, older than 1,000 years. Recent research on Lake Elsinore, however, has shown that the lake’s sediments hold excellent potential for paleoenvironmental analysis and reconstruction. New 1-cm contiguous grain size data reveal a more complex Holocene climate history for Southern California than previously recognized at the site. A modern comparison between the twentieth century PDO index, lake level change, San Jacinto River discharge, and percent sand suggests that sand content is a reasonable, qualitative proxy for PDO-related, hydrologic variability at both multi-decadal-to-centennial as well as event (i.e. storm) timescales. A depositional model is proposed to explain the sand-hydrologic proxy. The sand-hydrologic proxy data reveal nine centennial-scale intervals of wet and dry climate throughout the Holocene. Percent total sand values >1.5 standard deviation above the 150–9,700 cal year BP average are frequent between 9,700 and 3,200 cal year BP (n = 41), but they are rare from 3,200 to 150 cal year BP (n = 6). This disparity is interpreted as a change in the frequency of exceptionally wet (high discharge) years and/or changes in large storm activity. A comparison to other regional hydrologic proxies (10 sites) shows more then occasional similarities across the region (i.e. 6 of 9 Elsinore wet intervals are present at >50% of the comparison sites). Only the early Holocene and the Little Ice Age intervals, however, are interpreted consistently across the region as uniformly wet (≥80% of the comparison sites). A comparison to two ENSO reconstructions indicates little, if any, correlation to the Elsinore data, suggesting that ENSO variability is not the predominant forcing of Holocene climate in Southern California.  相似文献   

Generation of waves in Boussinesq models using a source function method   总被引：4，自引：0，他引：4  

Ge Wei  James T. Kirby  Amar Sinha 《Coastal Engineering》1999,36(4):1027

A method for generating waves in Boussinesq-type wave models is described. The method employs a source term added to the governing equations, either in the form of a mass source in the continuity equation or an applied pressure forcing in the momentum equations. Assuming linearity, we derive a transfer function which relates source amplitude to surface wave characteristics. We then test the model for generation of desired incident waves, including regular and random waves, for both one and two dimensions. We also compare some model results with analytical solution and available experiment data.  相似文献   

Enhanced seamount location database for the western and central Pacific Ocean: Screening and cross-checking of 20 existing datasets     

Valrie Allain  Julie-Anne Kerandel  Serge Andrfouët  Franck Magron  Malcolm Clark  David S. Kirby  Frank E. Muller-Karger 《Deep Sea Research Part I: Oceanographic Research Papers》2008,55(8):1035-1047

Seamounts are habitats of considerable interest in terms of conservation and biodiversity, and in terms of fisheries for bentho-pelagic and pelagic species. Twenty previously compiled datasets including seamount/underwater feature lists, bathymetric maps and emerged feature maps from different sources (ship-derived and satellite altimetry-derived) at different spatial scales (from individual cruise to worldwide satellite data) were gathered in order to compile an enhanced list of underwater features for parts of the western and central Pacific Ocean (WCPO). The KL04 dataset [Kitchingman, A., and Lai, S., 2004. Inferences on potential seamount locations from mid-resolution bathymetric data. Fisheries Centre Research Reports 12 (5), 7–12], listing seamount positions and depths as calculated from satellite altimetry-derived bathymetry, provided the baseline data for this study as it covered the entire region of interest and included summit depth information. All KL04 potential seamounts were cross-checked with other datasets to remove any atolls and islands that had been incorrectly classified as seamounts, to add seamounts undetected by KL04, to update the overall database (geolocation, depth, elevation, and name) and to compile a 12-class typology of the different types of underwater features. Of the 4626 potential seamounts identified in KL04, 719 were multiple identifications of the same large underwater features and 373 (10%) were actually emerged banks, atolls and islands, leaving 3534 actual underwater features. Conversely, 487 underwater features were documented in other datasets but not registered by KL04. The screening of all the potential WCPO seamounts produced a final list of 4021 underwater features with agreed upon position and information. This enhanced list should have many applications in oceanography, biodiversity conservation and studies of the influence of seamounts on pelagic ecosystems and fisheries.  相似文献   

The U.C.S. grain-size comparator disc     

R. Kirby 《Marine Geology》1973,14(3):M11-M14

A perspex disc produced for the purpose of sizing unconsolidated sediment samples in the field has eight segmented compartments where standard samples ranging from granules to clay are sited. The sample to be sized is placed over the clear perspex area of the disc and sized by visual comparison with the fractions in the segments.  相似文献   

Groundwater–surface water connectivity in a chain-of-ponds semiarid river     

Sébastien Lamontagne  Jason Kirby  Caroline Johnston 《水文研究》2021,35(4):e14129

Semiarid rivers are often characterized by chains of small pools connected by riffles and wet meadows. The pools can be maintained by wet season surface runoff, groundwater discharge, or some combination thereof. Using synoptic surveys for several environmental tracers (δD and δ¹⁸O of H₂O, specific electrical conductance at 25°C [EC], chloride and ²²²Rn), we evaluated the groundwater—surface water connectivity of the Light River (South Australia) along an 8 km section in the vicinity of a proposed mining development. In all three surveys (representing spring, summer and winter conditions), the pools were maintained by regional groundwater discharge based on an elevated surface water EC (9–12 dS m⁻¹) similar to regional groundwater, elevated radon-222 activities (0.09–3.0 Bq L⁻¹) and low rainfall. Most pools were perennial, either because they directly received groundwater discharge or, indirectly, had an inflow originating from upstream groundwater-fed pools. The elevated salinity of regional groundwater is a key factor for the maintenance of perennial pools in the Light River because the potential for baseflow depletion by groundwater pumping is more limited.  相似文献   

Lava-ice interaction on a large composite volcano: a case study from Ruapehu,New Zealand     

C. E. Conway  D. B. Townsend  G. S. Leonard  C. J. N. Wilson  A. T. Calvert  J. A. Gamble 《Bulletin of Volcanology》2015,77(3):1-18

  相似文献   

Subgrid modeling of salt marsh hydrodynamics with effects of vegetation and vegetation zonation          下载免费PDF全文

Guoxiang Wu  Huajun Li  Bingchen Liang  Fengyan Shi  James T. Kirby  Ryan Mieras 《地球表面变化过程与地形》2017,42(12):1755-1768

Vegetation plays a critical role in modifying inundation and flow patterns in salt marshes. In this study, the effects of vegetation are derived and implemented in a high‐resolution, subgrid model recently developed for simulating salt marsh hydrodynamics. Vegetation‐induced drag forces are taken into account as momentum sink terms. The model is then applied to simulate the flooding and draining processes in a meso‐tidal salt marsh, both with and without vegetation effects. Marsh inundation and flow patterns are significantly changed with the presence of vegetation. A smaller area of inundation occurs when vegetation is considered. Tides propagate both on the platform and through the channels when vegetation is absent, whereas flows concentrate mainly in channels when vegetation is present. Local inundation on vegetated platforms is caused mainly by water flux spilled from nearby channels, with a flow direction perpendicular to the channel edges, whereas inundation on bare platforms has contributions from both local spilled‐over water flux and remote advection from adjacent platforms. The flooding characteristics predicted by the model showed a significant difference between higher marsh and lower marsh, which is consistent with the wetlands classification by the National Wetlands Inventory (NWI). The flooding characteristics and spatial distribution of hydroperiod are also highly correlated with the vegetation zonation patterns observed in Google Earth imagery. Regarding the strong interaction between flow, vegetation and geomorphology, the conclusion highlights the importance of including vegetation in the modeling of salt marsh dynamics. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

New insights into the structure and evolution of the Isle of Wight Monocline     

D.J. Evans  G.A. Kirby  A.G. Hulbert 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(5):764-780

High quality seismic reflection data acquired during hydrocarbon exploration activities provide evidence for the subsurface structure and evolution of one of England's most well known structures at outcrop: the Isle of Wight Monocline. It is generally seen as a major northerly verging monoclinal structure linked to the Purbeck Monocline to the west. The Isle of Wight Monocline is the result of the interplay between two inverted east-west trending, southerly dipping and overlapping down-to-the-south major syndepositional normal faults that were active during Triassic and Jurassic times: the Needles and Sandown faults. The area between the two faults tips forms an easterly-dipping relay ramp, down which sequences of all ages thicken. Both of these major normal faults were inverted during Cenozoic (Miocene: Alpine) compressional events, folding the overlying post-rift sequences of early Cretaceous to early Cenozoic (Palaeogene) age. Interpretation of the seismic reflection data suggest that previously unknown high angle, down-to-the-north reverse faults cut the northern limbs of both anticlines forming the composite monocline and are likely to come to crop in the steeply-dipping Chalk and/or the drift-covered Cenozoic sequences. Their identification marked a period of discussions and testing of the model by detailed field mapping. The existence and location of such faulting was proved through an iterative process with the result that a reverse fault zone is now mapped along the northern limb of the northern Sandown Anticline section of the Monocline. The main reverse faults on the Brighstone and Sandown anticlines result in up to circa 550 m of displacement at top Chalk level. It is thought that a series of smaller footwall short-cut faults affect the Cenozoic strata to the north of the main reverse fault, producing up-faulted sections of flatter-lying Cenozoic strata. Reverse displacements and the severity of folding on the inverted faults decreases on each fault segment in a complementary fashion in the area of the relay ramp as one fault takes up the movement at the expense of the other. The swing in strike of the Chalk in the area of shallowly dipping strata between Calbourne and Garstons is a result of deformation of the post-rift sequences across the relay ramp established between the overlapping fault tips of the Needles and Sandown faults and the interaction of the folds developed at the tips of the reverse faults.  相似文献