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41.
Vessels found contaminated with biofouling non-indigenous marine species are predominantly removed from the water and treated in vessel maintenance facilities (i.e., slipways, travel lifts and dry-docks). Using pre-fouled settlement plates to simulate a vessel’s removal from the water for treatment, we demonstrate that a range of mobile organisms (including non-indigenous marine species) may be lost to the marine environment as a consequence of this process. We also determined that different levels of biofouling (primary, secondary and tertiary) and emersion durations (0.5, 5 and 15 min) affected the abundance and composition of mobile taxa lost to the marine environment. Primary biofouling plates lost 3.2% of total animals, secondary plates lost 19.8% and tertiary plates lost 8.2%, while hanging duration had only minor effects. The results suggest that removing vessels contaminated with biofouling non-indigenous marine species from the water for treatment may not be as biosecure as is currently recognised.  相似文献   
42.
Experiments were undertaken to study the nature of granular interaction in running water by examining the influence of fine grain inputs to a coarser sediment bed with a mobile surface. Video recordings of grain sorting by both kinetic sieving and spontaneous percolation are used to diagnose the critical processes controlling the overall bed response. Kinetic sieving takes place in the mobile bed surface, with the finer sediment moving to the bottom of the bedload transport layer at the interface with the underlying quasi‐static coarse bed. We show that the behavior at this interface dictates how a channel responds to a fine sediment input. If, by spontaneous percolation, the fine sediment is able to infiltrate into the underlying quasi‐static bed, the total transport increases and the channel degrades. However, if the fine sediment input rate exceeds the transport capacity or is geometrically unable to infiltrate into the underlying bed, it forms a quasi‐static layer underneath the transport layer that inhibits entrainment from the underlying bed, resulting in aggradation and an increase in bed slope. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
43.
There is still considerable uncertainty about precipitation at high elevation in mountain terrain due to the relatively few in situ measurements available and to the particular variability of the parameter. In this study, several spatialization techniques were tested, some for climatological time scale and others for daily fields, for precipitation over the western Alps for the period of 1990–2012. The study domain and period were chosen for the quality of available in situ observations and density of the network. First, a weather-type classification was established with a technique based on canonical correlation analysis combining large- and regional-scale data. The spatialization techniques applied for the climatological time scale were adapted from the Aurelhy method which uses elevation and principal components of the topography as predictors. The spatialization techniques applied to daily fields were based on kriging of daily rain gauges and used the climatological fields as predictors. This study aims to validate the advantage of using the climatology of the weather type of the day as predictor for daily fields over a monthly climatology. The climatology of the weather type of the day seems to demonstrate some small improvement.Finally, annual means over the period of 1990–2012 were produced using several methods, including some from accumulation of daily fields and others from the spatialization of in situ station means. Precipitation at high elevations and vertical climatological gradients were particularly scrutinized. Annual means based on sums of daily fields seem to have better performances.This paper only presents results for precipitation but temperature was also analysed.  相似文献   
44.
The CASES-99 experimental data are used to analyze turbulence behaviour under a range of stable conditions using an adaptive method based on Hilbert spectral analysis. The characteristic scales of intrinsic mode functions vary between different stratifications. The second-order Hilbert marginal spectra display clear separation between fine-scale turbulence and large-scale motions. After removing the large-scale motions, the statistical characteristics of the reconstructed signals confirm the distinction of different stratifications in the fine-scale range. The correlation coefficient analyses reveal that the Hilbert spectral analysis method separates turbulence from large-scale motions in the stable boundary layer.  相似文献   
45.
The Pitt River is a meandering river channel linking the Fraser River estuary and Pitt Lake. The lake acts as a temporary reservoir for tidally diverted Fraser River flow. Stage level can fluctuate 2 m in Pitt River and as much as 1.2 m in Pitt Lake on a tidal cycle. Stage data from three locations in the system, used in conjunction with velocity measurements (profiles and tethered meter), revealed large tidal and seasonal variations in discharge. Calculations indicate that during the flood, basal shear stress peaks earlier in the cycle and reaches higher values than during the ebb. Thus, sediment moves farther forward on a flood flow than it moves back on the succeeding ebb. An upstream movement of sediment in Pitt River from the Fraser River is indicated by: (1) the identical mineralogy of the two rivers, (2) a decrease in median grain size from the Fraser to Pitt Lake, and (3) a predominance of flood-oriented bedforms in the river channel. A delta, 12 km2 area, has accumulated at the lower (draining) end of the lake. Studies of the river channel using hydrographic charts revealed regular meanders (λM = 6100 m) and evenly spaced riffles and pools which appear to be scaled to the strongest flow, winter flood current (2400 m3/s). The winter flood is thus considered to be the effective discharge. Meander point bars are accreting on the ‘upstream’ side indicating deposition by the flood-oriented flow. The three dimensional geometry of the large-scale bedforms which cover the sandy thalweg of both river and delta channel was determined by echo sounding and side-scan sonar. Three distinct sizes (height/spacing = 0.8 m/10–15 m; 1.5 m/25–30m; 3m/50–60 m) of large-scale bedforms (sand waves) were found; their linear relationship of height vs. spacing on a log-log plot suggests a common genesis. Their occurrence by size does not appear to be related to depth of flow but rather to their position in the channel with respect to large scale features which alter flow.  相似文献   
46.
Coral trout (Plectropomus spp.) are the main target species for commercial fishers in the eastern Torres Strait Reef Line Fishery (ETS RLF). The four species of coral trout known to occur in Torres Strait: Plectropomus leopardus, Plectropomus maculatus, Plectropomus areolatus and Plectropomus laevis are currently managed as a single species in Torres Strait, as there is no species-specific biological information available for the region which could be used to assess whether species differ in their response to fishing pressure. The aim of our study was to determine whether it is appropriate (biologically) to manage coral trout in the ETS RLF as a single species group or whether different management arrangements are required for some species. We used catch data and biological data from samples collected by commercial fishers to examine the distribution within Torres Strait and estimate a range of biological parameters for P. leopardus, P. maculatus and P. areolatus. Insufficient P. laevis samples were collected to reliably examine this species. Results indicated that the population biology, particularly the reproductive biology, of P. areolatus was substantially different to both P. leopardus and P. maculatus. Although it is difficult to predict the response to fishing, P. areolatus may be more vulnerable to fishing than P. leopardus and P. maculatus, due to the larger size at sex change observed for this species and the very low proportion of males protected by the current minimum size limit. Therefore, while the common management arrangements for P. leopardus and P. maculatus appear to be adequate for these species, separate management arrangements are needed for the sustainable harvest of P. areolatus populations in the ETS. Specifically, we recommend the introduction of a maximum size limit for P. areolatus, in addition to the current minimum size limit, which may allow a proportion of males some protection from fishing.  相似文献   
47.
The upland planation surface in the Piedmont of central New Jersey consists of summit flats, as much as 130 km2 in area, that truncate bedding and structure in diabase, basalt, sandstone, mudstone and gneiss. These flats define a low‐relief regional surface that corresponds in elevation to residual hills in the adjacent Coastal Plain capped by a fluvial gravel of late Miocene age. A Pliocene fluvial sand is inset 50 m below the upland features. These associations suggest a late Miocene or early Pliocene age for the surface. To assess exposure age and erosional history, a 4·4 m core of clayey diabase saprolite on a 3 km2 remnant of the surface was sampled at six depths for atmospherically produced cosmogenic 10Be. The measured inventory, assuming a deposition rate of 1·3 × 106 atoms cm−2 a−1, yields a minimum exposure age of 227 000 years, or, assuming continuous surface erosion, a constant erosion rate of 10 m Ma−1. Because the sample site lies about 60 m above the aggradation surface of the Pliocene fluvial deposit, and itself supports a pre‐Pliocene fluvial gravel lag, this erosion rate is too high. Rather, episodic surface erosion and runoff bypassing probably have produced an inventory deficit. Reasonable estimates of surface erosion (up to 10 m) and bypassing (up to 50 per cent of total precipitation) yield exposure ages of as much as 6·4 Ma. These results indicate that (1) the surface is probably of pre‐Pleistocene age and has been modified by Pleistocene erosion, and (2) exposure ages based on 10Be inventories are highly sensitive to surface erosion and runoff bypassing. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   
48.
The results of the CCD photometry of the 1995 FG Virginis multi-site campaign, organized by the Delta Scuti Network, are presented. Between March 16 and April 20, 1995 over 120 hours of CCD measurements were obtained. The ten frequencies of FG Vir, known from the previous campaign (1993), range from 9.20 to 34.12 cycles/day (106.5 and 394.9 μHz). Three new frequencies at 16.07, 19.23 and 24.19 c/d (186.0, 222.5 and 279.9 μHz) were detected. The precision of the FG Vir measurements was better than 3.5 mmag per single 1-min integration. It is shown that the present CCD measurements are of similar quality as those obtained simultaneously by photometers with photomultiplier detectors using the three-star observing technique. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
49.
This paper reports on the marine biodiversity and ethnobiodiversity of Bellona, a small island in Solomon Islands inhabited by Polynesians who have, for centuries, depended on biodiversity for their own sustainability. The Bellonese have names for at least 8 whales and dolphins, 7 reptiles, over 500 finfish, 191 molluscs, 48 crustaceans, 29 echinoderms and a range of corals, other invertebrates and marine plants, most of which have commercial, subsistence or cultural value. If conserved, this inheritance will continue to provide a foundation for continuing sustainability in a rapidly globalizing world. The paper highlights the importance of the preservation, and application to development, of ethnobiodiversity for food and subsistence security, and contingent issues of conservation and sustainability in small island developing states. As the current extinction crisis escalates globally, the rate of attrition of the intangible indigenous knowledge that has coevolved with this threatened biodiversity is probably far greater. In itself, the recording of information on biodiversity and related sustainable livelihoods is not sufficient to ensure sustainability. There is a vital need to integrate this into the formal education system and applied scientific activities at all levels to achieve the right balance between agriculture, wild harvest and trade, upon which sustainability and subsistence affluence still depend.  相似文献   
50.
Many countries across the world are experiencing strict austerity measures due to the economic crisis. As a consequence, public financing for stand-alone adaptation to flooding and drought will become scarcer in the (near) future, and this hampers the pursuit of resilience (i.e. the ability to remain functioning under a range of hazard magnitudes). In such times, key challenges for adaptation are further complicated by weaker investment dynamics and an increased tendency to ‘work in silos’. These are: to minimise regret with respect to maladaptation, which results from over- or under-investment in water hazard management; to exploit the opportunities for mainstreaming adaptation to flooding and drought into other investment agendas; and to deliver multiple benefits for society and the economy, such as increased biodiversity, liveability and competitiveness. These common challenges drive the best way in which to adapt to uncertain climate and socio-economic changes. In the Netherlands, the Delta Programme has developed and applied a structured and well-defined approach (called Adaptive Delta Management) for including and acting upon uncertainty around these future changes. This approach allows for greater transparency to decision-makers and stakeholders, because it adheres to four specific steps for strategy development. This paper presents the current understanding of Adaptive Delta Management and an illustration of the approach for the management of flood risk and resilience in Dordrecht. It examines the added value and limitations of Adaptive Delta Management concerning its application in the context of the Delta Programme, with a specific emphasis on the lessons learned from Dordrecht.  相似文献   
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