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1.
《Limnologica》2019
Algal assemblages have been widely used as an ecological indicator of aquatic ecosystem health conditions because of their specific sensitivity to a wide variety of environmental conditions. In turbid rivers, as in other aquatic systems, phytoplankton structure plays an important role in structuring aquatic food webs. Worldwide, phytoplankton is less studied in turbid, large tropical rivers compared to temperate river systems. The present study aimed to describe the phytoplankton diversity and abundance in a turbid tropical river (the Red River, northern part of Vietnam from 20°00 to 25°30 North; from 100°00 to 107°10 East) and to determine the importance of a series of environmental variables in controlling the phytoplankton community composition. Phytoplankton community was composed of 169 phytoplankton taxa from six algal groups including Bacillariophyceae, Chlorophyceae, Cryptophyceae, Euglenophyceae, Dinophyceae and Cyanobacteria. Community composition varied both spatially and with season. Sixteen measurement environmental variables were used as input variables for a three-layer backpropagation neural network that was developed to predict the phytoplankton abundance. Phytoplankton abundance was successfully predicted using the tagsig transfer function and the Levenberg-Marquardt backpropagation algorithm. The network was trained to provide a good overall linear fit to the total data set with a slope (R) and mean square error (MSE) of 0.808 and 0.0107, respectively. The sensitivity analysis and neutral interpretation diagram revealed that total phosphorus (TP), flow discharge, water temperature and P-PO43− were the significant variables. The results showed that the developed ANN model was able to simulate phytoplankton abundance in the Red River. These findings can help for gaining insight into and the relationship between phytoplankton and environmental factors in this complex, turbid, tropical river. 相似文献
2.
Alisha L. Steward Jonathan C. Marshall Fran Sheldon Bronwyn Harch Satish Choy Stuart E. Bunn Klement Tockner 《Aquatic Sciences - Research Across Boundaries》2011,73(4):551-566
Dry river beds are common worldwide and are rapidly increasing in extent due to the effects of water management and prolonged
drought periods due to climate change. While attention has been given to the responses of aquatic invertebrates to drying
rivers, few studies exist on the terrestrial invertebrates colonizing dry river beds. Dry river beds are physically harsh
and they often differ substantially in substrate, topography, microclimate and inundation frequency from adjacent riparian
zones. Given these differences, we predicted that dry river beds provide a unique habitat for terrestrial invertebrates, and
that their assemblage composition differs from that in adjacent riparian zones. Dry river beds and riparian zones in Australia
and Italy were sampled for terrestrial invertebrates with pitfall traps. Sites differed in substrate type, climate and flow
regime. Dry river beds contained diverse invertebrate assemblages and their composition was consistently different from adjacent
riparian zones, irrespective of substrate, climate or hydrology. Although some taxa were shared between dry river beds and
riparian zones, 66 of 320 taxa occurred only in dry river beds. Differences were due to species turnover, rather than shifts
in abundance, indicating that dry river bed assemblages are not simply subsets of riparian assemblages. Some spatial patterns
in invertebrate assemblages were associated with environmental variables (irrespective of habitat type), but these associations
were statistically weak. We suggest that dry river beds are unique habitats in their own right. We discuss potential human
stressors and management issues regarding dry river beds and provide recommendations for future research. 相似文献
3.
Benthic macro-invertebrates are vital components of river ecosystems.The effects of fluvial processes and human activities on the distribution of macro-invertebrates were studied through field investigations and experiment.Sixty-one sampling sites on 31 rivers in China were selected to investigate the structures of macro-invertebrate assemblages.The rivers,according to their fluvial conditions,are classified as streams with a stable channel bed,degrading channel bed,aggrading channel bed,and intensive bed load motion.The structures of macro-invertebrate fauna for the four types of rivers are very different.Stable rivers have a large number of individuals,abundant fauna, and high biodiversity;while the density and taxa richness for degrading rivers are small,and those for aggrading rivers are much less;whereas the ecology of rivers with intensive bed load motion are the worst.This paper proposes that streambed stability is the primary influential factor shaping the structure of benthic macro-invertebrate communities.Organic pollution can obviously result in the decrease of biodiversity,in the simplification of macro-invertebrate structures,and in the distortion of functional feeding group composition.In a river with high total nitrogen content,the relative abundance of collector-gatherers is high,and that of collector-filterers,scrapers,shredders,and predators are low.Scrapers,shredders,and predators disappear in severely polluted rivers.The isolation of aquatic habitat results in a distinct decrease of individual numbers and taxa richness.This result demonstrates that the connectivity of aquatic habitat significantly affects macro-invertebrate assemblages.A practical method to calculate a Habitat Suitability Index(HSI) is proposed,integrating the effects of the primary physical(including biotic and abiotic) and chemical factors.The biodiversity and taxa richness increase non-linearly with HSI. 相似文献
4.
《Limnologica》2020
Several studies have shown that fish assemblages are structured by habitat features, most of them have proposed that there is a positive relationship between habitat structural complexity and species diversity. In this study, we aimed to test this positive-relationship idea in three habitats types (creeks, oxbow lakes and river sandbanks) distributed along the Bita River Basin in South America. Standardized surveys were conducted during January and February of 2016 (low water period) in 30 sites distributed along the entire basin. We recorded 23,092 individuals representing 191 species. To investigate possible relationships between habitat structural complexity and species diversity, we calculated the first three Hill’s numbers, and performed a Non-metric Multidimensional Scaling (NMDS), a Principal Component Analysis (PCA) and a Canonical Correspondence Analysis (CCA). Our results showed that river sandbanks and creeks had the highest species richness. Results from the NMDS analysis (stress = 0.19) showed that fish community composition was different in the assessed habitats (ANOSIM < p = 0.001). According to the results of the principal component analysis, sand percentage, dissolved oxygen, and vegetation width separated river sandbanks from the other habitats. Results from the Hill’s numbers, forward selection procedure, and canonical correspondence analysis suggested that species composition and diversity were significantly influenced by the habitat structural complexity index and conductivity. 相似文献
5.
Biological quality in a bay affected by man's activities was evaluated by means of the composition of assemblages of sponges and ascidians. Our results showed that the structure of these two groups of filter-feeders aided in discriminating between undisturbed and disturbed areas, establishing different "environmental health categories" from moderately to strongly disturbed areas, and in ascertaining the extension of the area of each "health category". We were able to divide the bay into four zones based on type of disturbance or anthropogenic source: (1) stations free of any source of disturbance, (2) stations under moderate disturbance, located close to industrial ports, millworks, etc., (3) stations that are under the direct influence of industrial wastes such as a power station and oil refinery, and (4) stations near strongly disturbed areas, influenced directly by harmful steelworks activities. We differentiated clearly between four large species assemblages, and related the composition of these assemblages to different kinds of disturbances. Thus, these species could be used to manage the marine environment in this bay by comparing the observed fauna, with expected fauna in an unstressed site. Moreover, the joint presence of the sponge Cliona vastifica and tunicate Policitor adriaticum seems always to indicate a more or less pristine environmental situation, functioning as bioindicators of normal conditions. We think that the use of specific bioindicators for monitoring disturbance is a valid tool to establish baselines to predict impacts associated with industrial development in many marine ecosystems. The advantages to monitoring communities on hard rocks versus sandy or muddy bottoms are also commented upon. 相似文献
6.
In water-deficient rivers, environmental flows (e-flows) are usually sustained via inter-basin water transfer projects from water-sufficient rivers, but these projects incur tremendous costs and may lead to many negative ecological effects, such as ecological invasion. This research proposed to transfer hydropower instead of water from water-sufficient rivers, because hydropower could substitute for water to promote economic development and reduce water withdrawal from water-deficient rivers (conserved water). In addition, based on the analysis of eco-hydrological processes, the flow regime alteration plays an important role in restoring riverine ecosystem. With the goal of minimum flow regime alternation, we set up two scenarios to distribute the annual conserved water, and determined the optimal amount of transferred hydropower and the optimal use of conserved water, which could effectively sustain the e-flows. Accordingly, this paper established a computable general equilibrium model to analyse the substitution of hydropower for water in a water-deficient river basin, and determined the water withdrawal volume that could be reduced. We adopted a range-of-variability approach to measure the degree of flow regime alteration, and optimized the flow regime management scheme. The Luanhe River Basin was adopted as a study case. The results showed that: the water-hydropower equivalent decreased as the transferred hydropower into the Luanhe River Basin increased; a transferred hydropower amount of 22.46 kWh/s, equivalent to 18.30 m3/s conserved water, was optimal for the river basin; the conserved water should be distributed to the Luanhe River in the proportions of 0.55:0.1:0.35 during the wet, normal and dry seasons, respectively, which is the optimal scheme to sustain the hydrological processes of the river. 相似文献
7.
Water quality is the outcome of numerous landscape factors in the catchment. In addition to land use, soil deposits, bedrock and topography are central in different catchment processes and thus important in predicting water quality. In this study, we explored the influence of geomorphological factors at the catchment scale on water quality in 32 boreal rivers in Finland. Water quality was studied through total phosphorus, total nitrogen, pH and water colour, whereas geomorphological factors covered variables from topography, bedrock and surficial ground material (Quaternary soil deposits). Spearman's rank correlation test was used to study the correlations between variables. The relationship between water quality and geomorphology was analysed using novel multivariate methods by fitting of geomorphological vectors and smooth surfaces onto a non‐metric multidimensional scaling (NMDS) scattergram. Hierarchical partitioning (HP) was used to assess the relative importance of geomorphological variables on water quality. Quaternary soil deposits, especially the covers of clay‐silt and till soils, were important factors in relation to phosphorus and nitrogen based on both NMDS and HP analyses. For example, clay‐silt cover explained over 40% of the variation in these nutrients according to HP. The variation in river water pH was best explained by the covers of sand and open bedrock terrain as well as by catchment topography. Geomorphological variables differed in their effect and relative significance, and thus several geomorphological attributes need to be considered when examining variation in water quality. In conclusion, these results demonstrate that geomorphological factors can be used to predict physical–chemical water quality in a cost‐efficient manner in boreal rivers. NMDS was successfully applied in water quality analyses at the catchment scale. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
Structure and seasonal dynamics of bacterial communities in three urban rivers in China 总被引：2，自引：0，他引：2
Although a large number of recent ecological studies have focused on freshwater bacterioplankton populations, knowledge of
the primary factors influencing bacterial communities in urban rivers is limited. Bacterial community structure in three rivers
located in Shanghai city was studied over a 1-year period using denaturing gradient gel electrophoresis (DGGE). Subsurface
samples were collected every 2 months from two study sites in each river. Water was characterized when biological samples
were collected by measuring temperature, pH, chloride ion, total dissolved solids (TDS), total N and total P. complex DGGE
band patterns indicated high bacterial diversity in the rivers. Analysis of similarity (ANOSIM) showed that variation of the
bacterial communities was higher between rivers than it was between samples from the same river. When evaluated using principal
component analysis, samples collected during warmer months from any particular river tended to group together while cold-season
samples generally clustered, suggesting significant seasonal impacts. Redundancy analysis was used to identify relationships
between environmental factors and bacterial community composition in each individual river. Temperature, TDS, pH, TP and salt
concentration were all identified as being related to bacterial community structure, with temperature being the most influential
parameter in all three rivers. Our results indicated that bacterial community composition was different in the three different
rivers. Even though the rivers were located in heavily disturbed urban ecosystems, temperature was the major driver of bacterial
community composition, just as it is in natural systems. 相似文献
9.
10.
The biotic composition, structure, and function of aquatic, wetland, and riparian ecosystem depend largely on the hydrological regime (Poff, N.L., Ward, J.V., 1990. Implications of streamflow variability and predictability for lotic community structure: a regional analysis of streamflow patterns. Can. J. Fisheries Aquat. Sci. 46, 1805–1818; Richter, B.D., Baumgartner, J.V., Wiginton, R., Braun, D.P., 1997 How much water does a river need? Freshwater Biol. 37, 231–249). Available flow data for many rivers in the world can be used to validate these ecological theories. There is a demand for studies that use hydrological indices to establish criteria, which serve to group together regime types at a local level. Once this has been done, these hydrologically similar groups can be used to identify communities of living organisms that are linked to specific aspects of the river's behaviour.
An approach to characterise flow regimes in the river network of the Tagus basin in Spain is presented. The river Tagus (río Tajo) is one of the seven major rivers of the Iberian peninsula. All hydrological data were acquired from the measurements made in the Tagus basin, at 25 gauging stations. Twelve variables were derived for each gauged site to describe variability and predictability of average streamflow conditions, and to describe the frequency, timing and intensity of high flow and low flow extremes.
A hierarchical clustering routine was used to identify similar groups of rivers as defined in terms of similar characteristics of their streamflow regime. The variables were also examined with simple correlations to determine if multicollinearity occurred, in order to reject redundant parameters or to identify similar behaviour trends between pairs of parameters. Some parameters have shown a tendency to increase or decrease along the east–west axis, suggesting that some of the studied characteristics may have a geographical cause.
Cluster analysis, with the values of the 12 parameters, reveals two main groups, each of which splits into two main subdivisions. One of these subgroups contains six rivers with similar characteristics, can be considered to be ‘classic regular rivers’, the stations in this first subgroup are mostly situated geographically close to each other. At the other end, we have found a subgroup, with a high variation of flows over the year and high flood flows; these rivers are highly irregular rivers with great changes. This regular–irregular gradient found between the groups is similar to that observed by others authors (Poff, N.L., Allan J.D., 1995. Functional organization of stream fish assemblages in relation to hydrological variability. Ecology 76, 606–627), and strong associations have been documented with compositions of populations and probably reflect differences in other similar important environmental factors. 相似文献
11.
Constraints on spatial variability in soft-sediment communities affected by contamination from an Antarctic waste disposal site 总被引：1，自引：0，他引：1
A small-scale (<500 m length) transect-based survey was conducted in December 1998 to examine the spatial distribution of soft-sediment communities and of concentrations of heavy metals and hydrocarbons in sediments in Brown Bay, adjacent to an abandoned waste dump, at Casey Station, Antarctica. Samples were taken along three transects at increasing distances (nine stations) from the shore-line waste dump. A gradient of contamination was detected, but concentrations of contaminants were very variable with "hotspots" or high levels of contaminants at some stations. Multivariate analysis revealed that the distribution of soft-sediment communities was distinctly different between the inner, middle and outer stations. Abundances of most taxa were very variable with few patterns apparent, but some fauna displayed an abundance gradient from the inner to the outer part of the bay. Many taxa had maximum abundances at outer stations and minimum at inner stations. Multivariate correlations between environmental variables and soft-sediment communities indicated that combinations of some metals (Cd, Cu, Sn, Pb) and grain size (mainly finer fractions, fine sands and coarse silts) were the variables that best "matched" the community patterns within Brown Bay. This study indicated that there were significant correlations between the presence of contaminants and the distribution and composition of soft-sediment communities over very small spatial scales. 相似文献
12.
《Limnologica》2017
The present study investigates the relationship between hydrological connectivity and species diversity in a by-passed channel section, and in the adjacent water bodies of the Slovak–Hungarian Danube section (1,840.5–1,804.4 rkm). The study was designed to assess long-term temporal trends (from 1991 to 2013) in freshwater copepods assemblages and their ecological indices in different habitats of the Danube floodplain area. One of the purpose of this study was to monitor the species composition of copepods communities and ascertain their shift in various biotopes of the Danube floodplain system. Based on 23 years data, in the first step, the copepods habitat preferences using habitat values (HV) and indicator weights (IW), calculated from data collected over all the years of monitoring of planktonic communities of the Danube floodplain, were quantified. Subsequently, the floodplain index (FI) from a summary of the habitat values and indication weights of the current species was calculated, to evaluate changes in the connectivity of the anabranched section of the Slovak–Hungarian Danube. This confirmed the loss of active hydrological connectivity within the main river channel, ranging from the eupotamal to more or less isolated floodplain water bodies. Out of 50 recorded copepods species, 11 species manifest a preference for eupotamal habitats, 18 taxa preferred eupotamal B/parapotamal habitats and 21 species were found to prefer the plesiopotamal habitat type. The statistical analyses demonstrated that the structure of planktonic copepod communities in this area has changed since the Gabčíkovo hydropower plant was placed into operations. The NMDS analysis revealed shifts in the proportion of euplanktonic and tychoplanktonic species. Reversible community changes were found in the old river bed and in the eupotamal-B side arms. 相似文献
13.
Marcela Mrquez-García Irma Vila Luis Felipe Hinojosa Marco A. Mndez Jos Luis Carvajal María Catalina Sabando 《Limnologica》2009,39(4):314-318
We compared the distribution and seasonal fluctuations in the aquatic biota in relation to chemical and physical water variables in the Altiplano watersheds of the Ascotán, Carcote and Huasco salars; Chungará and Cotacotani lakes; Isluga and Lauca Rivers and the Parinacota wetland. We sampled during the austral autumn–winter of 2006 and in the spring–summer of 2006–2007, using three sampling stations for each system. We used canonical correspondence analysis to establish relations between frequency of taxa and environmental variables.We demonstrate that the structure and composition of the aquatic biota in humid areas of the Altiplano is determined by physical and chemical variables of the water. The most relevant one is total nitrogen, which is also the limiting nutrient for phytoplankton production in tropical systems.Benthos and zooplankton showed significant associations with the set of environmental variables (Monte Carlo test, p<0.05); however, the association was not significant for phytoplankton. Lake Chungará showed the greatest variation in composition and abundance of zooplankton between autumn-winter and spring-summer, while in the Huasco salar the physical and chemical characteristics were related to the composition and abundance of the benthonic fauna. Thus, changes in the water volume of these systems would have repercussions in chemical and physical variables, altering the species assemblage and possibly the efficiency and stability of ecosystem functions. 相似文献
14.
自然流淌的支流在维持建坝河流水生生物多样性中起着重要作用。补远江是澜沧江下游的重要一级支流,保持了较为天然的河流状态,人类活动干扰相对较少,是流域土著鱼类保护区和水生生物重要栖息地。在澜沧江流域水电开发的背景下,掌握补远江大型底栖动物群落结构的时空分布及其影响因素,对澜沧江乃至西南河流的水生生物多样性保护和恢复具有重要参考意义。于2019年4月(旱季)和2019年10月(雨季)对补远江的大型底栖动物进行了详细调查,共检出大型底栖动物150个分类单元,隶属于5门7纲68科,其中水生昆虫121种,软体动物20种,蛭类3种,寡毛类2种,甲壳类2种,涡虫、线虫各1种。毛翅目和蜉蝣目为全流域优势类群。补远江底栖动物密度和生物量在旱季和雨季均表现为上游大于中下游,物种丰富度和Shannon-Wiener多样性指数在雨季显著高于旱季。功能摄食类群中,滤食者(41.09%)和收集者(31.81%)占绝对优势,其次为刮食者(11.00%)、捕食者(11.21%),撕食者(4.89%)较少。Mantel检验分析表明,河宽(RW)、硝态氮(NO3--N)、化学需氧量(CODMn)是影响补远江大型底栖动物群落结构的主要环境因子;不同功能摄食类群所受到的环境影响因素不同。生物指数(BI)和生物监测工作组记分(BMWP)系统评价显示,补远江大部分样点处于良好及以上水平,少数样点处于中等及以下水平,总体水生态状况良好。 相似文献
15.
《Limnologica》2021
The conservation and restoration of freshwater ecosystems require the understanding of potential biota of the target area. My ultimate study goal was to clarify the potential fauna of the watershed unit of the Japanese archipelago, a hotspot of biodiversity. Here, I attempted to classify the macroinvertebrate community of the major rivers within the Japanese archipelago, thereby elucidating its biogeography, and to investigate the extent to which environmental factors drive the watershed’s macroinvertebrate community. I classified the rivers located in the northern region of the Japanese archipelago geographically, but did not group the geographically adjacent rivers in the western region together. Differences in watershed size, geological history (including river conflict), and paleo-drainage systems seem to affect the classification results. Moreover, Indicator Species Analysis results suggest that river groups in the northern part of the Japanese archipelago had highly endemic species, whereas, the river groups in the western part of the Japanese archipelago had few highly endemic species. The result of the canonical correspondence analysis indicated that topographic factors, the flow regime, geology, water quality, and anthropogenic factors were significantly correlated with macroinvertebrate classification and distribution. The results of the decision tree model indicated that water temperature and maximum specific discharge were explanatory factors in the classification of the macroinvertebrate community. Further, my results also suggest that environmental factors at a smaller scale than that of the watershed were needed to explain further subdivisions in classification of the macroinvertebrate community. 相似文献
16.
Small mountain water streams are lately more interesting from the aspect of hydroenergetic exploitation. Catchments area of smaller rivers and creeks are mostly not enough researched from hydroenergetic aspect, so the most difficult task for small hydropower plant designers is to determine hydroenergetic potential of discussed water streams, from short period of hydrological observations. Very often happens that existing measurement stations on discussed water streams are placed few kilometers from potentially place of water intake and the value of flow is drastically different on these two locations. In this work, two methods for determination of hydrological picture for the chosen location of water intake on discussed river are shown, correlation method and analogy method. Using these methods it is possible to use data that describes measured values of discharge from the old measurement stations, that is exists on the same or adjacent river, to determine flow duration curve on the place of interests. Results given from these two methods are compared with measured values of discharge and precipitation from last period that are collected from location of planed intake. Based on the good agreement of theoretical and measured values, it was concluded that these two methods can be also applied to the adjacent basins. Suggestion of hydroenergetic utilization of discussed water stream and its economic justification is also presented in this work. 相似文献
17.
Mollusc death assemblages were recovered in 98 subtidal sampling stations on the seafloor of the shallow Pertuis Charentais Sea (Atlantic coast of France). Taxonomic composition and spatial distribution of death assemblages were investigated, as well as their response to sediment grain size (field data), bottom shear stress (coupled tide and wave hydrodynamic modelling), and sediment budget (bathymetric difference map). Results showed that molluscs are likely to be reliable paleoenvironmental indicators since death assemblages were able to acquire ecological changes within years (decadal-scale taphonomic inertia), and live–dead agreement inferred from existing data on living benthic communities was high, except close to river mouths and intertidal mudflats that provide terrestrial and intertidal species to subtidal death assemblages, respectively. Taxonomic composition of these within-habitat death assemblages strongly depended on sediment grain size and bottom shear stress, similarly to living subtidal communities. Post-mortem dispersal of shells, owing to relatively low bottom shear stress in the area, was only of a few 10s to 100s of meters, which shows that death assemblages preserved environmental gradients even at a fine spatial scale. Sediment budget had also a significant influence on death assemblages. Thick-shelled epifaunal species were correlated with erosion areas on one side, and thin-shelled infaunal species with deposition on the other, showing that mollusc fossil assemblages could be used as indicators of paleo-sedimentation rate. This new proxy was successfully tested on a previously published Holocene mollusc fossil record from the same area. It was possible to refine the paleoenvironmental interpretation already proposed, in accordance with existing stratigraphic and sedimentological data. 相似文献
18.
We present the process of developing a macrophyte based index (River Macrophyte Index – RMI) for assessing river ecological status, that would be applicable for rivers with moderate to high water alkalinity, flowing over low slope terrain. A reference value and boundary values were determined for five ecological classes. The relation between the developed index and two existing indices, the Reference Index (RI) and the Trophic Index of Macrophytes (TIM), and selected environmental variables was established. The RMI is based on species composition and abundance from 208 sampling sites being in reference or good hydromorphological conditions and differing in the catchment land use. The percentage of natural areas in the sub-catchment was used for classifying macrophyte taxa into 5 ecological groups. 65 plant taxa, of which 47 were identified as indicator taxa, were included in the analysis. To assess the ecological status of a river site, the presence of at least 3 indicator taxa is necessary, otherwise the assessment is considered inconclusive. RMI is expected to indicate multiple pressures on the river, including trophic level. The developed index and RI and TIM indices differed in relation to slope, distance to source and catchment size. 相似文献
19.
20.
位于四川省甘孜藏族自治州康定市内大渡河干流的长河坝-黄金坪水电站,为大渡河流域开发中,以长河坝、大岗山、瀑布沟等形成主要梯级格局开发方案中,"三库22级"水电站中的第10和11级电站,其地震监测台网也采用梯级设计方式,长河坝-黄金坪上下游水库地震监测台网统一设计、建设及监测,共享同一地震监测能力。通过对监测设备的技术指标、台基地噪声水平和震级-频度对数关系的分析,结果表明,长河坝-黄金坪水库区域地震固定台站建成后,地震监测能力达到并优于设计的理论监测能力,地震监测震级达到下限为ML 0.5的设计要求。 相似文献