Keywords: Stygofauna; Groundwater; Phreatic traps; Sampling method; Hydrological exchange 相似文献
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Freeze‐coring and bulk sampling are routine methods used to sample subsurface spawning gravel under shallow water. Both methods have limitations. Freeze‐coring is not believed to representatively sample coarse grain sizes and the sample volumes are relatively small. Conversely, when bulk sampling, even within an enclosure, some fine sediment is suspended and washed away from the sample. This paper assesses the biases in sampling performance between the two methods and determines whether the loss of fines that occurs when bulk sampling could be predicted and thus corrected for. At six riffles the spawning substrate was sampled under approximately 50 cm of water with a bulk sample and three adjacent freeze‐cores. For each riffle, data from the two samples were combined using the method of Fripp and Diplas (1993) and the resultant composite sample was compared with the original freeze‐core and bulk samples to assess the relative precision and biases of the two techniques. On average, the D50 of the bulk samples was 4 mm larger and a one‐third loss of the <2 mm fraction occurred compared with the composite samples. In contrast, freeze‐core samples contain on average 32% more sediment >16 mm compared with composite samples. Based on six samples, taken from six riffles, the amount of sediment finer than 0·5 mm lost using our bulk sampling technique with an enclosure appears to be predictable and correctable. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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The relationship between soft-bottom macrobenthic communities and environmental variables in Singaporean waters 总被引：1，自引：0，他引：1
Lu L 《Marine pollution bulletin》2005,51(8-12):1034-1040
Univariate and multivariate methods were used to study soft-bottom macrobenthos collected in December 2002 from the coastal waters of Singapore. The univariate parameters and community structure of benthic communities were related to environmental variables. Three samples were taken with a 0.1 m2 Van Veen grab (33 × 30 × 15 cm) at each station from 12 sampling stations of two different geographical areas. The water depth ranged from 6.5 m to 34.0 m. The mean values of species number, abundance and species diversity (H′) were 24 species/grab, 77 animals/grab and 3.35/grab, respectively. A total of 172 species was recorded. Total petroleum hydrocarbons were strongly negatively related to species number, abundance and species diversity, suggesting that petroleum hydrocarbons have harmful effects on macrobenthic communities. The BIO-ENV analyses for all stations identified median particle size, silt–clay content, salinity and Zn as the major environmental variables influencing the infaunal patterns. However, separate analyses for two areas produced stronger correlations and different best-correlated environmental variable combinations. Total petroleum hydrocarbons were the only common factor in both areas, showing the importance of petroleum contamination in determining the community structure of benthic infauna in Singaporean waters. 相似文献
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Taxonomic level for assessing oil spill effects on soft-bottom sublittoral benthic communities 总被引：6，自引：0，他引：6
Infralittoral soft-bottom macrofauna abundance data collected during four-year surveys after the Aegean Sea (Galicia, Spain) and the Amoco Cadiz oil spill (Brittany, France) at a total of seven sites were analysed at three different taxonomic levels (species, genus, and family). The effects of the spills on macrofauna populations were very similar in the two areas. The post-spill time-courses of Shannon-Weaver diversity values were similar regardless of whether species-, genus- or family-level data were used. Non-metric multidimensional scaling identified well-defined groups of samples corresponding to different times post-spill, and again the results obtained were very similar regardless of the taxonomic level considered. In general, the use of genus- or family-level data did not lead to relevant information loss by comparison with species-level data. In view of these findings and those of previous studies of this type, we conclude that family-level data is generally sufficient for monitoring pollution effects in infralittoral soft-bottom environments. 相似文献
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Rongjiang Yao Jingsong Yang Xiufang Zhao Xiaobing Chen Jianjun Han Xiaoming Li Meixian Liu Hongbo Shao 《洁净——土壤、空气、水》2012,40(9):972-979
Spatial sampling design based on the variability and distribution of soil properties is an important issue with the progress in precision agriculture and soil ecology. Electromagnetic induction (type EM38) and variance quad‐tree (VQT) method were both applied to optimize the sampling scheme of soil salinity in a coastal reclamation field in north Jiangsu Province, China. Apparent soil electrical conductivity (ECa) measured with EM38 was used as an ancillary variable and the spatial distribution of ECa was used as priori information. The process and result of VQT algorithm analysis was illustrated and the obtained sampling strategy was validated using observed soil salinity. Then the spatial precision and sampling efficiency were evaluated. The result indicated that the spatial distribution of soil salinity produced with the VQT scheme was quite similar to that produced with total sampling sites, while sampling quantity of the former was reduced to approximately 1/2 of the latter. The spatial precision of VQT scheme was considerably higher than that of traditional grid method with respect to the same sampling number, and fewer samples were required for VQT scheme to obtain the same precision level. A 17.3% increase in sampling efficiency was achieved by VQT over grid method at the precision level of 90%. The VQT method was proved to be more efficient and economical because it can sample intensively or sparsely according to variation status in local areas. The associated application of EM38 and VQT method provides efficient tools and theoretical basis for saving sampling cost and improving sampling efficiency in coastal saline region and enriching soil ecology. 相似文献
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Detailed information on vertical variations in hydraulic conductivity (K) is essential to describe the dynamics of groundwater movement at contaminated sites or as input data used for modeling. K values in high vertical resolution should be determined because K tends to be more continuous in the horizontal than in the vertical direction. To determine K in shallow unconsolidated sediments and in the vertical direction, the recently developed direct-push injection logger can be used. The information obtained by this method serves as a proxy for K and has to be calibrated to obtain quantitative K values of measured vertical profiles. In this study, we performed direct-push soil sampling, sieve analyses and direct-push slug tests to obtain K values in vertical high resolution. Using the results of direct-push slug tests, quantitative K values obtained by the direct-push injection logger could be determined successfully. The results of sieve analyses provided lower accordance with the logs due to the inherent limitations of the sieving method. 相似文献
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Environmental monitoring is performed on seafloor communities since these organisms are relatively stationary and integrate the environmental conditions over many years. Standard practices involve sampling by grab. Epifaunal taxa, often missed by grab sampling, are likely to have different ecological functions. We investigate how current environmental assessments represent the benthic community as a whole by comparing taxonomic and functional components sampled by grabs and epibenthic trawls. Faunal communities sampled by trawl (filtrating or predator, epifauna) and grab (infaunal, detrivore) differs widely by sampling distinct functional components, and these may be expected to respond to different human-induced stressors. Neither component appears to be a good surrogate for the community as a whole. We suggest a benthic monitoring by combining both techniques. Sustainable ecosystem functioning is intimately tied to the health of both components of the benthic community, and is recognized as an important goal by signatories of the Convention on Biological Diversity. 相似文献
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Latitudinal changes in larger benthic foraminiferal assemblages in shallow-water reef sediments along the Ryukyu Islands, Japan 总被引：1，自引：0，他引：1
Abstract The taxonomic diversity of hermatypic corals decreases with increasing latitude, which correlates with sea‐surface temperatures. However, little is known about latitudinal changes in the taxonomic diversity and biogeographic patterns of larger benthic foraminifera, although their physiological requirements are similar to those of hermatypic corals because of their symbiotic relationships with microalgae. The present study examined how the abundance and taxonomic composition of larger foraminiferal assemblages in shallow‐water reef sediments change with latitude along the Ryukyu Islands (Ryukyus), which are located near the northern limit of coral‐reef distributions in the western Pacific Ocean. Three islands from different latitudes in the Ryukyus were selected to investigate latitudinal changes in larger foraminiferal assemblages: Ishigaki Island (24°20′N, 124°10′E), Kudaka Island (26°09′N, 127°54′E) and Tane‐ga‐shima Island (30°20′N, 131°E). Four sediment samples were taken at each of three topographic sites (beach, shallow lagoon and reef crest) on the reef flat of each island. Foraminiferal tests of a 2.0‐ to 0.5‐mm size fraction were selected, identified and counted. The variations in foraminiferal abundance in reef sediments from three latitudinally different islands exhibit two contrasting trends along reef flats: a shoreward decrease on Ishigaki and Tane‐ga‐shima Islands and a shoreward increase on Kudaka Island. A total of 25, 24 and 13 foraminiferal taxa were identified in Ishigaki, Kudaka and Tane‐ga‐shima Islands, respectively. Baculogypsina sphaerulata, Neorotalia calcar and Amphistegina spp. were dominant (i.e. >3% of foraminiferal assemblages) in the three islands. Calcarina gaudichaudii and Calcarina hispida were common on Ishigaki and Kudaka Islands but were absent on Tane‐ga‐shima Island. Larger foraminiferal assemblages from three different reef‐flat environments on Ishigaki Island can be distinguished, whereas those from the three environments on Kudaka and Tane‐ga‐shima Islands are similar in composition. These latitudinal changes in larger foraminiferal assemblages in reef sediments may possibly be caused by variations in the topography of reef flats, distributions and standing crops of living foraminifers on reef flats, and the northern limit of some calcarinid species in the northern Ryukyus. 相似文献
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Biodiversity, abundance and taxonomic composition of shallow-water zoobenthos were studied in the W?oc?awek Dam Reservoir (the lower Vistula River, central Poland). The following habitats located near the shore were studied: (1) sandy bottom in the flooded part of the reservoir; (2) sandy bottom close to the main riverine flow in the reservoir and (3) organic-rich bottom covered by a thick layer of plant remnants in a shallow, isolated cove. In each habitat we investigated two sites (ca. 0.5 and 1 m depth). Also examined was the bottom of a phytolittoral site (sandy bottom, with elodeids and nympheids, 1 m depth), located in the flooded zone. In general, the bottom fauna was highly diverse and abundant in these habitats. The highest biodiversity (38 taxa, Shannon-Wiener index=4.3) was found on the bottom rich in organic matter. However, the zoobenthos abundance in this habitat was comparatively low, probably due to periodical oxygen deficiencies. The highest density of bottom fauna (>30,000 individuals per m2), accompanied by its high biodiversity, occurred at the phytolittoral site. The benthic community of the organic-rich sediments was the most distinct, with many taxa occurring exclusively in this area. The composition of the bottom fauna, from the two sandy habitats and phytolittoral, also differed from one another. The differences in taxonomic composition between the shallower and deeper sites were less pronounced. Lower densities at the shallower sandy sites and a very high variability of taxonomic composition among particular samples from these sites indicated lower stability of their environmental conditions. These were certainly due to water level fluctuations and/or destructive wave action. On the other hand, no such differences were found between the sites of various depths from the organic-rich sediments, showing that this substratum provided better protection against adverse hydrodynamical factors. 相似文献
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Peter Haase Susanne Lohse Steffen Pauls Karin Schindehütte Andrea Sundermann Peter Rolauffs Daniel Hering 《Limnologica》2004,34(4):349-365
In the past, no single standardised method for sampling and sorting benthic macroinvertebrates has been implemented in Germany. Therefore, we tested the suitability of two common sorting protocols, RIVPACS and AQEM/STAR, by taking samples with each protocol at 44 sampling sites. Our results reveal that different methods deliver slightly different assessment results. Moreover these two methods differ in costs. Although the AQEM/STAR protocol takes longer than the RIVPACS protocol, we favoured the AQEM/STAR protocol because of its higher level of standardisation. In order to limit costs to an acceptable level, a modification of the AQEM/STAR protocol (MAS method) is developed. This method is highly standardised, gives stable assessment results and is relatively inexpensive (€ 224.00 for processing of an average sample). A detailed protocol of the newly developed method is given. 相似文献
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Fabio Bertasi Francesco Colosio Gianni Gregorio Marco Abbiati Victor Ugo Ceccherelli 《Marine pollution bulletin》2009,58(5):686-694
Sandy shores on the West coast of the North Adriatic Sea are extensively protected by different types of defence structures to prevent coastal erosion. Coastal defence schemes modify the hydrodynamic regime, the sediment structure and composition thus affecting the benthic assemblages. This study examines the effectiveness in detecting changes in soft bottom assemblages caused by coastal defence structures by using different levels of taxonomic resolution, polychaetes and/or bivalves as surrogates and different data transformations. A synoptic analyses of three datasets of subtidal benthic macrofauna used in studies aimed at assessing the impact of breakwaters along the North Adriatic coast has been done. Analyses of similarities and correlations between distance matrices were done using matrices with different levels of taxonomic resolution, and with polychaetes or bivalves data alone. Lentidium mediterraneum was the most abundant species in all datasets. Its abundance was not consistently related to the presence of defence structures. Moreover, distribution patterns of L. mediterraneum were masking the structure of the whole macrofaunal assemblages. Removal of L. mediterraneum from the datasets allowed the detection of changes in benthic assemblages due to coastal defences. Analyses on different levels of taxonomic resolution showed that the level of family maintained sufficient information to detect the impacts of coastal defence structures on benthic assemblages. Moreover, the outcomes depended on the transformation used. Patterns of distribution of bivalves, used as surrogates, showed low correlations with the patterns of the total macrofaunal species assemblages. Patterns of polychaetes, if identified to the species or genus level showed higher correlations with the whole dataset. However, the identification of polychaetes to species and genus level is as costly as the identification of all macrobenthic taxa at family level.This study provided additional evidences that taxonomic sufficiency is a useful tool in environmental monitoring, also in investigations on the impacts of coastal defence structures on subtidal macrofauna. The use of coarser taxonomic level, being time-efficient, would allow improving sampling designs of monitoring programs by increasing replication in space and time and by allowing long term monitoring studies. 相似文献
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Benthic Ecological Quality Ratios (EQR) are important tools for assessing the ecological status of coastal and transitional water bodies. Here, we use spatial and time-series data from Kinsale Harbour, Ireland to examine the effects of sample processing methodologies on the outputs of two EQRs: Multivariate AMBI (M-AMBI) and Infaunal Quality Index (IQI).Both EQRs were robust to changes in sieve size from 1 mm to 0.5 mm, and to changes in the taxa identified in spatial calibration. Both EQRs classified habitat quality in Kinsale as generally Good or High with no evidence of significant change over the time series (1981-2006). IQI classified the ecological status as higher than M-AMBI.There was a significant relationship between IQI and M-AMBI in spatial calibration, but no significant relationship between them in time series. Further research into the behaviour of EQRs in relation to natural variability over long time-scales is needed to discriminate anthropogenic impacts reliably. 相似文献
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eDNA (environmental DNA)是指从环境样品（水体、土壤、沉积物、空气、混合物等）中提取的DNA,是各种生物的DNA混合物,区别于传统从单物种样品中提取的DNA。eDNA监测是指从环境样品中提取DNA,用物种特异性引物或特定DNA metabarcoding引物对其进行扩增测序、分类学分析、相对丰度分析、功能预测等,以监测环境中是否存在某特定物种,或者获得环境中物种组成、群落结构、生态功能等相关信息。eDNA监测主要应用在特定物种监测检出、生物多样性调查评估、群落结构和功能分析、生态系统过程分析评估等领域。eDNA监测可以应用在陆地、水体、空气、器物表面、生物（内）表面等任何有可能存在不确定DNA的场景。因为eDNA监测的非侵入性、灵敏检出、大类群检出、易标准化方法与结果、低人力物力时间成本、结果可核查等特点,未来很有希望发展成为一种常规的物种监测、群落功能预测、生态过程分析的方法,对象可涵盖所有生境条件下的所有生物类群。但要实现这个图景,需要从普遍性和特殊性层面完成eDNA监测技术链条中10个关键环节的技术标准化：样品重复数设计、采样时间设计、采样点设计、采样方法设... 相似文献
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Taxonomic sufficiency (TS) involves the identification of taxa only to a level of taxonomic resolution sufficient to permit the detection of changes in stressed assemblages. Recently, however, TS has been proposed also for conservation issues as a tool to estimate biodiversity over large areas and in poorly known environments. This paper briefly reviews the use of TS in environmental impact studies and the effects of TS on sampling procedures and data analyses. The risk of possible loss of information depending on TS and the studied environment are discussed. Concluding remarks deal with the dangers of loss of taxonomic expertise in marine biological studies and assess critically the proposal of TS as a tool to describe biodiversity at a taxonomic level higher than species. 相似文献
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- (1) A new method of sampling stygofauna is presented, along with some data derived from applications in the field. Numerous bores were sampled for fauna, water and bacteria, down to a depth of 7.50 m. Two or 3 unbaited traps were fixed to a central pole within the bore. The traps consist of an inert plastic chamber with holes in the upper parts and gaskets near the bottom and near the lid of each trap. The content of the traps was emptied monthly using a pump.
(2) While the taxonomic composition of the trap samples seemed to be comparable to the surrounding groundwater, estimation of abundances in the traps might differ, with a potential over-estimation in the traps, in particular in sparsely populated aquifers. Detailed comparative studies on the performance of the method are, as yet, lacking.
(3) Trap data of invertebrate communities reflect hydraulic changes, and highest abundances and taxa richness were found near the water table. They decreased rapidly with depth, implying that small-scale stratified sampling is possible.
(4) The technique is cheap, reliable, simple and rapid to use, and allows simultaneous sampling of hydro-chemical, faunal and microbial samples. The method seems to be suitable for a wide range of sub-surface waters, where the water table is shallower than 8 m.
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Isabel Díez Alberto Santolaria José María Gorostiaga 《Marine pollution bulletin》2010,60(10):1779-1789
The effects of using reduced sampling resolutions to study macroalgal vegetation patterns have not been studied sufficiently. Here, we test the influence of taxonomic resolution level, removal of occasional species, aggregation of species abundances into functional groups and data transformation in the detection of a long-term recovery process by phytobenthic intertidal assemblages. Results indicate that the aggregation of species data into the genus level has very little influence. Likewise, almost any significant information is lost when occasional algae are removed. Analyses at the level of families and orders still clearly detect differences between highly degraded and reference vegetation. By contrast, analyses based on class and functional group abundances capture quite different information. The effect of transformation is similar at the different taxonomic levels. Most surrogate measures properly reflect changes in diversity. It is concluded that genus level is the most appropriate surrogate approach for detecting the recovery process. 相似文献
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An in situ monitoring of the sediment characteristics and macrobenthic communities was undertaken at a marine fish culture site in subtropical waters of Hong Kong before and after the deployment of biofilters which were made of cement concrete artificial reef (AR) structures. According to the distance to the boundary of the fish cages, 6 points were selected as sampling stations: 2 at the fish cages, 2 near the boundary of the fish culture area, and 2 reference sites further away from the culture area. Bimonthly sediment samples were collected for analysis of silt-clay fraction (SCF), moisture content (MC), total organic carbon (TOC), total Kjeldahl nitrogen (TKN) and total phosphorus (TP). The macrobenthos (>0.5mm) present in the sediment were sorted, identified and enumerated. TOC, TKN and TP levels at the fish cage stations were consistently higher than those at the reference stations over the 1-year pre-AR and 2-year post-AR deployment monitoring period. The diversity of macrofauna was significantly reduced at the fish cage stations relative to the reference sites. The intermediary stations near the fish culture area showed a transitional state of disturbance. Over the 2-year post-AR deployment period, TOC, TKN and TP showed a decreasing trend at the fish cage and intermediary stations. More diverse macrofaunal communities were recorded at the fish cage stations, with species diversity H'increasing from 0-1 at the beginning of the AR deployment to H'>2 at the end of the study. The present results demonstrated that artificial reefs can improve the benthic abiotic environment and biotic conditions beneath fish rafts which are deteriorated due to farming activities. 相似文献
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The design and the management of pump-and-treat (PAT) remediation systems for contaminated aquifers under uncertain hydrogeological settings and parameters often involve decisions that trade off cost optimality against reliability. Both design objectives can be improved by planning site characterization programs that reduce subsurface parameter uncertainty. However, the cost for subsurface investigation often weighs heavily upon the budget of the remedial action and must thus be taken into account in the trade-off analysis. In this paper, we develop a stochastic data-worth framework with the purpose of estimating the economic opportunity of subsurface investigation programs. Since the spatial distribution of hydraulic conductivity is most often the major source of uncertainty, we focus on the direct sampling of hydraulic conductivity at prescribed locations of the aquifer. The data worth of hydraulic conductivity measurements is estimated from the reduction of the overall management cost ensuing from the reduction in parameter uncertainty obtained from sampling. The overall cost is estimated as the expected value of the cost of installing and operating the PAT system plus penalties incurred due to violations of cleanup goals and constraints. The crucial point of the data-worth framework is represented by the so-called pre-posterior analysis. Here, the tradeoff between decreasing overall costs and increasing site-investigation budgets is assessed to determine a management strategy proposed on the basis of the information available at the start of remediation. The goal of the pre-posterior analysis is to indicate whether the proposed management strategy should be implemented as is, or re-designed on the basis of additional data collected with a particular site-investigation program. The study indicates that the value of information is ultimately related to the estimates of cleanup target violations and decision makers’ degree of risk-aversion. 相似文献
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Geomorphological studies often require precise devices to measure surface roughness or variations with high precision and good repeatability. A digital measurement device is described, which provides these features and can be linked to a small, light and portable recorder and processor. Such an arrangement allows rapid, accurate data recording by a single operator and can be used in the laboratory or field. With interchangeable measurement rods the vertical range of the instrument is 150 mm, with an actual measured range of 30 mm per rod. The potential accuracy is 0·001 mm with an operating temperature range of+5 to +40°C. Its light weight, relatively low cost and precision make it a useful measuring device which can be adapted for many tasks simply by modification of the stand. 相似文献