Multimetric Assessment of Nutrient Enrichment in Impounded Rivers Based on Benthic Macroinvertebrates

In this investigation we evaluated the performance of multiple metrics, based on benthic macroinvertebrates, to assess nutrient enrichment in impounded rivers. Field studies were conducted in the upper reaches of four impounded mountain rivers (Tormes, Riaza, Eresma and Miraflores Rivers) of Central Spain. The watersheds of these rivers are underlain by siliceous rocks. Two sampling sites, upstream and downstream from the reservoir, were established in stony riffles of each impounded river. We used a total of 34 metrics, representing five different metric groups: measures of abundance and richness, percentages of taxonomic groups, percentages of functional feeding groups, measures of dominance and diversity, and biotic indices. Evaluation of different metrics was mainly based on correlation analyses between concentrations of nutrients (NO3-N, NH4-N, PO4-P) and values of individual metrics. Deep releases from the reservoirs were the primary cause responsible for the nutrient enrichment at downstream sampling sites. Chironomidae density, Gastropoda density, % Chironomidae, % Gastropoda, % collector-gatherers and scrapers, proportion of the two most dominant taxa, and Camargo's dominance index exhibited the highest positive correlation coefficients. Conversely, Plecoptera density, Trichoptera density, EPT richness, % Plecoptera, % Trichoptera, % collector-filterers, % predators, % shredders, Simpson's and Camargo's diversity indices, and the average BMWQ score (biotic index) exhibited the highest negative correlation coefficients. Overall it is concluded that the multimetric approach may be a useful technique for the biological assessment of nutrient enrichment in fluvial ecosystems, particularly in upper reaches of siliceous rivers.     

Testing Bioassessment Metrics: Macroinvertebrate, Sculpin, and Salmonid Responses to Stream Habitat, Sediment, and Metals

The purpose of this article is to report on the testing of responses of multimetric macroinvertebrate and habitat indices to common disturbances to streams: stream habitat alteration, excessive sediment, and elevated metals concentrations. Seven macroinvertebrate community metrics were combined into a macroinvertebrate biotic index (MBI), and 11 channel morphology, riparian, and substrate features were combined into a habitat index. Indices were evaluated by comparing the habitat results to fish population surveys and comparing the macroinvertebrate results to habitat ratings, percent fine sediments measured by Wolman pebble counts, and copper concentrations. Macroinvertebrate scores decreased with increasing percentages of fine sediments measured either across the bankfull or instream channel widths. Macroinvertebrate scores decreased with increasing copper. One metric, richness of Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa, was more responsive to both copper and sediment than was the multimetric MBI. Habitat scores corresponded well with the age class structure of salmonids, but not with that of benthic sculpins. Both salmonid and sculpin age classes declined with increasing percentages of fine sediments. The decline was graded with the sculpin age classes, whether fine sediments were measured across the instream or bankfull channel, whereas salmonids consistently responded only to the instream fine sediments.     

松花江流域大型底栖动物生物完整性指数构建及其适用性

利用生物完整性指数评价河流健康状态,对于水环境管理决策具有重要的实践意义。基于大型底栖动物构建生物完整性指数(B-IBI),并评价松花江流域的水生态系统健康状况。在松花江主要干支流设定37个采样点,分别于2016年6、9月进行环境因子和大型底栖动物调查研究。最终从28个候选参数中确定了种类总数、摇蚊种类数、敏感种百分比、Hilsenhoff指数、Marglef指数作为核心参数构建B-IBI。通过0～10赋分法,计算得到了松花江流域全部采样点的生物完整性评价得分。结果显示,松花江流域内60%区域生物状态存在不同程度的损害。另外,B-IBI能够综合反映松花江大型底栖动物群落多样性、生境质量、理化水质等,具有一定的适用性。     

The influence of suburban land use on habitat and biotic integrity of coastal Rhode Island streams

Watershed land use in suburban areas can affect stream biota through degradation of instream habitat, water quality, and riparian vegetation. By monitoring stream biotic communities in various geographic regions, we can better understand and conserve our watershed ecosystems. The objective of this study was to examine the relationship between watershed land use and the integrity of benthic invertebrate communities in eight streams that were assessed over a 3-year period (2001-2003). Sites were selected from coastal Rhode Island watersheds along a residential land-use gradient (4-59%). Using the rapid bioassessment protocol, we collected biological, physicochemical, habitat, and nutrient data from wadeable stream reaches and compared metrics of structure and integrity. Principal component analyses showed significant negative correlation of indicators for stream physicochemical, habitat, and instream biodiversity with increasing residential land use (RLU) in the watershed. The physicochemical variables that were most responsive to percent RLU were conductivity, instream habitat, nitrate, and dissolved inorganic nitrogen (DIN). The positive correlation of DIN with percent RLU indicated an anthropogenic source of pollution affecting the streams. The biotic composition of the streams shifted from sensitive to insensitive taxa as percent RLU increased; the most responsive biological variables were percent Ephemeroptera, percent Scrapers, percent Insects, and the Hilsenhoff biotic index. These data show the importance of land management and conservation at the watershed scale to sustaining the biotic integrity of coastal stream ecosystems.     

Biomonitoring in the Boulder River Watershed, Montana, USA: Metal Concentrations in Biofilm and Macroinvertebrates, and Relations with Macroinvertebrate Assemblage

Portions of the Boulder River watershed contain elevated concentrations of arsenic, cadmium, copper, lead, and zinc in water, sediment, and biota. We measured concentrations of As, Cd, Cu, Pb, and Zn in biofilm and macroinvertebrates, and assessed macroinvertebrate assemblage and aquatic habitat with the objective of monitoring planned remediation efforts. Concentrations of metals were generally higher in downstream sites compared with upstream or reference sites, and two sites contained metal concentrations in macroinvertebrates greater than values reported to reduce health and survival of resident trout. Macroinvertebrate assemblage was correlated with metal concentrations in biofilm and macroinvertebrates. However, macroinvertebrate metrics were significantly correlated with a greater number of biofilm metals (8) than metals in invertebrates (4). Lead concentrations in biofilm appeared to have the most significant impact on macroinvertebrate assemblage. Metal concentrations in macroinvertebrates were directly proportional to concentrations in biofilm, indicating biofilm as a potential surrogate for monitoring metal impacts in aquatic systems.     

Calibration and validation of a regionally and seasonally stratified macroinvertebrate index for West Virginia wadeable streams

Multimetric indices (MMIs) are routinely used by federal, state, and tribal entities to assess the quality of aquatic resources. Because of their diversity, abundance, ubiquity, and sensitivity to environmental stress, benthic macroinvertebrates are well suited for MMIs. West Virginia has used a statewide family-level stream condition index (WVSCI) since 2002. We describe the development, validation, and application of a geographically- and seasonally partitioned genus-level index of most probable stream status (GLIMPSS) for West Virginia wadeable streams. Natural classification strata were evaluated with reference site communities using mean similarity analysis and non-metric multidimensional scaling ordination. Forty-one metrics spanning six ecological categories (richness, composition, tolerance, dominance, trophic groups, and habits) were evaluated for sensitivity, responsiveness, redundancy, range and variability across seasonal (spring and summer) and regional (mountains and plateau) strata. Through a step-wise metric selection process, 8–10 metrics were aggregated to comprise four stratum-specific GLIMPSS models (mountain/plateau and spring/summer). A comparison of GLIMPSS with WVSCI exhibited marked improvements where GLIMPSS detecting greater stream impacts. A variation of the GLIMPSS, which differs only in the family-level taxonomic identification of Chironomidae (GLIMPSS (CF)), was comparable to the full GLIMPSS. These MMIs are robust yet practical tools for evaluating impacts to water quality, instream and riparian habitat, and aquatic wildlife in wadeable riffle-run streams based on sensitivity, responsiveness, precision, and independent validation. These models may be used effectively to detect degradation of the naturally occurring benthic community, assess causes of biological degradation, and plan and evaluate remediation of damaged stream ecosystems.     

Mullet and gudgeon liver histopathology and macroinvertebrate indexes and metrics upstream and downstream from a wastewater treatment plant (Febros River—Portugal)

The increased pollution in ecosystems reinforces the importance of both chemical monitoring and biological monitoring of streams and rivers, as an effective water quality-based approach to assess aquatic ecosystem health. In this study, gudgeon (Gobio gobio) and mullet (Mugil cephalus) liver histopathology (biomarker) and some macroinvertebrate community indexes and metrics (bioindicator) were used to evaluate the effect of the wastewater treatment plant (WWTP) of Febros (Avintes) in Febros River water quality and ecosystem health. Regarding macroinvertebrate communities, the Belgian Biotic Index (BBI) and Iberian Biological Monitoring Working Party (IBMWP) indexes suggested that Febros water was slightly polluted, even though the worst situation was found downstream the WWTP discharge. Concerning community metrics, upstream percent of individuals in five numerically dominant taxa (80%) was slightly more superior than the downstream (78%). The presence of intolerant or sensible individuals, determined by percent of Ephemeroptera, Plecoptera, and Trichoptera individuals and number of Ephemeroptera, Plecoptera, and Trichoptera families metrics, was higher upstream WWTP, reflecting a better water quality. The histopathology shows the presence of hepatic lesions in gudgeon and mullet. The statistical analysis of the lesion gradation showed that only necrosis was significantly higher in gudgeon captured downstream the WWTP, while differences were not observed for mullet. The multivariate analysis of data confirmed the existence of differences in hepatic lesions between gudgeon and mullet and between sampling sites. Regarding macroinvertebrate community, this analysis showed that the organic contamination reflected by the BBI and IBMWP indexes values was a determinant factor in the spatial distribution of macroinvertebrates. This work showed that the study of different biological organization levels can be used for a better assessment of ecosystem ecological integrity and can be used as a tool to reveal anthropogenic activity effects in macroinvertebrate diversity and in fish liver pathology from Febros River.     

Dissolved and Total Copper in a Coal Ash Effluent and Receiving Stream: Assessment of In Situ Biological Effects

An in situ chemical and biological study was conducted in the lower Muskingum River (southeast Ohio, U.S.A.) to evaluate potential effects of copper (Cu) discharged from a coal ash effluent. Effluent total Cu, dissolved Cu, TSS and pH measurements were performed monthly during January-December 1995. Benthic macroinvertebrates were sampled at five river locations using artificial substrate samplers, and in situ Cu analyses were conducted. Effluent Cu (total) ranged from 8 to 142 microg L(-1) (mean = 58 microg L(-1)), but dissolved Cu never exceeded 78 microg L(-1) (mean = 20 microg L(-1)). The mean ratio of dissolved Cu to total Cu in these samples was 32%. Total Cu concentrations at the biological sampling sites adjacent to the effluent discharge were higher than levels at ambient sites, but dissolved Cu levels were similar among all sites. The macroinvertebrate community proximal to the coal ash effluent had the highest number of taxa and total number of individuals; a high number of mayfly and caddis fly taxa; and the highest Invertebrate Community Index score. The high water velocity of the discharge (which likely contained particulate organic matter) apparently created a favorable microhabitat that, combined with Cu-complexing constituents in the discharge, superceded potential adverse effects of high Cu levels. This study emphasizes the importance of instream biological data when obtained in conjunction with chemical analyses.     

Sampling Benthic Macroinvertebrates in a Large Flood-Plain River: Considerations of Study Design, Sample Size, and Cost

Estimation of benthic macroinvertebrate populations over large spatial scales is difficult due to the high variability in abundance and the cost of sample processing and taxonomic analysis. To determine a cost-effective, statistically powerful sample design, we conducted an exploratory study of the spatial variation of benthic macroinvertebrates in a 37 km reach of the Upper Mississippi River. We sampled benthos at 36 sites within each of two strata, contiguous backwater and channel border. Three standard ponar (525 cm²) grab samples were obtained at each site ('Original Design'). Analysis of variance and sampling cost of strata-wide estimates for abundance of Oligochaeta, Chironomidae, and total invertebrates showed that only one ponar sample per site ('Reduced Design') yielded essentially the same abundance estimates as the Original Design, while reducing the overall cost by 63%. A posteriori statistical power analysis ( = 0.05, = 0.20) on the Reduced Design estimated that at least 18 sites per stratum were needed to detect differences in mean abundance between contiguous backwater and channel border areas for Oligochaeta, Chironomidae, and total invertebrates. Statistical power was nearly identical for the three taxonomic groups. The abundances of several taxa of concern (e.g., Hexagenia mayflies and Musculium fingernail clams) were too spatially variable to estimate power with our method. Resampling simulations indicated that to achieve adequate sampling precision for Oligochaeta, at least 36 sample sites per stratum would be required, whereas a sampling precision of 0.2 would not be attained with any sample size for Hexagenia in channel border areas, or Chironomidae and Musculium in both strata given the variance structure of the original samples. Community-wide diversity indices (Brillouin and 1-Simpsons) increased as sample area per site increased. The backwater area had higher diversity than the channel border area. The number of sampling sites required to sample benthic macroinvertebrates during our sampling period depended on the study objective and ranged from 18 to more than 40 sites per stratum. No single sampling regime would efficiently and adequately sample all components of the macroinvertebrate community.     

Evaluation Score and Interpretation Index for the Ecological Quality of Running Waters in Central and Northern Hellas

The present study aims at creating an evaluation system for the quality of running waters, based on the analysis of benthic macroinvertebrate records from Hellenic rivers (473 samples from 8 river basins). The proposed evaluation system (Hellenic Evaluation Score and its Interpretation Index) may be used for waters sampled with the cost effective semi-quantitative sampling method of “3 min kick-sweep” and requires benthic macroinvertebrates to be identified to the taxonomic level of family. Though resulting from a modification of the Spanish score BMWP, it differs from it in the following characteristics: a) it includes the relative abundance of benthic macroinvertebrates and b) it takes into consideration the habitat diversity of the studied site, classifying it as “poor” or “rich”, based on some parameters of the System B of the Water Framework Directive (2000/60/EU). Its interpretation is also based on a five-scaled classification system, consistent with the provisions of the same Directive.     

Spatiotemporal variation of macroinvertebrates in relation to canopy cover and other environmental factors in Eriora River, Niger Delta, Nigeria

Canopy cover is well known to influence the distribution of macroinvertebrates in temperate streams. Very little is known about how this factor influences stream communities in Afrotropical streams. The effects and possible interactions of environmental factors and canopy cover on macroinvertebrate community structure (abundance, richness, and diversity) were examined in four stations in Eriora River, southern Nigeria bimonthly from May to November 2010. The river supported diverse macroinvertebrates in which the upstream sampling stations with dense canopy cover were dominated by Decapoda, Ephemeroptera, Odonata, Gastropoda, Trichoptera, and Coleoptera while Diptera and Coleoptera were the benthic organisms found predominant at downstream stations with less canopy cover. Some caddisfly species such as Agapetus agilis, Trichosetodes species and the stonefly Neoperla species were present upstream and were found to be potential bioindicators for a clean ecosystem. The blood worm Chironomus species and Tabanus sp. were abundant at the downstream of the river and are considered potential bioindicators for an organically degrading ecosystem. Some environmental factors varied temporally with significantly higher macroinvertebrate abundance and richness in May. We found out that canopy cover and environmental factors affected macroinvertebrates abundance, diversity, and richness and that the individual taxon had varying responses to these factors. These results help identify the mechanisms underlying the effects of canopy cover and other environmental factors on Afrotropical stream invertebrate communities.     

A bioassessment approach for mid-continent great rivers: the Upper Mississippi, Missouri, and Ohio (USA)

The objectives of the Environmental Monitoring and Assessment Program for Great River Ecosystems (EMAP-GRE) are to (1) develop and demonstrate, in collaboration with states, an assessment program yielding spatially unbiased estimates of the condition of mid-continent great rivers; (2) evaluate environmental indicators for assessing great rivers; and (3) assess the current condition of selected great river resources. The purpose of this paper is to describe EMAP-GRE using examples based on data collected in 2004-2006 with emphasis on an approach to determining reference conditions. EMAP-GRE includes the Upper Mississippi River, the Missouri River, and the Ohio River. Indicators include biotic assemblages (fish, macroinvertebrates, plankton, algae), water chemistry, and aquatic and riparian physical habitat. Reference strata (river reaches for which a single reference expectation is appropriate) were determined by ordination of the fish assemblage and examination of spatial variation in environmental variables. Least disturbed condition of fish assemblages for reference strata was determined by empirical modeling in which we related fish assemblage metrics to a multimetric stressor gradient. We inferred least disturbed condition from the y-intercept, the predicted condition when stress was least. Thresholds for dividing the resource into management-relevant condition classes for biotic indicators were derived using predicted least disturbed condition to set the upper bound on the least disturbed condition class. Also discussed are the outputs of EMAP-GRE, including the assessment document, multimetric indices of condition, and unbiased data supporting state and tribal Clean Water Act reporting, adaptive management, and river restoration.     

Estimating vertebrate,benthic macroinvertebrate,and diatom taxa richness in raftable Pacific Northwest rivers for bioassessment purposes

The number of sites sampled must be considered when determining the effort necessary for adequately assessing taxa richness in an ecosystem for bioassessment purposes; however, there have been few studies concerning the number of sites necessary for bioassessment of large rivers. We evaluated the effect of sample size (i.e., number of sites) necessary to collect vertebrate (fish and aquatic amphibians), macroinvertebrate, and diatom taxa from seven large rivers in Oregon and Washington, USA during the summers of 2006–2008. We used Monte Carlo simulation to determine the number of sites needed to collect 90–95% of the taxa 75–95% of the time from 20 randomly located sites on each river. The river wetted widths varied from 27.8 to 126.0 m, mean substrate size varied from 1 to 10 cm, and mainstem distances sampled varied from 87 to 254 km. We sampled vertebrates at each site (i.e., 50 times the mean wetted channel width) by nearshore-raft electrofishing. We sampled benthic macroinvertebrates nearshore through the use of a 500-μm mesh kick net at 11 systematic stations. From each site composite sample, we identified a target of 500 macroinvertebrate individuals to the lowest possible taxon, usually genus. We sampled benthic diatoms nearshore at the same 11 stations from a 12-cm² area. At each station, we sucked diatoms from soft substrate into a 60-ml syringe or brushed them off a rock and rinsed them with river water into the same jar. We counted a minimum of 600 valves at 1,000× magnification for each site. We collected 120–211 diatom taxa, 98–128 macroinvertebrate taxa, and 14–33 vertebrate species per river. To collect 90-95% of the taxa 75-95% of the time that were collected at 20 sites, it was necessary to sample 11–16 randomly distributed sites for vertebrates, 13–17 sites for macroinvertebrates, and 16–18 sites for diatoms. We conclude that 12–16 randomly distributed sites are needed for cost-efficient sampling of vertebrate richness in the main stems of our study rivers, but 20 sites markedly underestimates the species richness of benthic macroinvertebrates and diatoms in those rivers.     

Development of rapid bioassessment approaches using benthic macroinvertebrates for Thai streams

Thailand currently lacks formal bioassessment approaches and protocols to assist management decisions for water quality. The aim of this research is to develop a practical method of rapid bioassessment for a professional level by using benthic macroinvertebrate assemblages for streams in Thailand. Eleven reference and nine test sites were sampled in the headwater streams of the Loei River and adjacent areas to explore the development of a practical protocol. Specific physico-chemical parameters were selected to provide ecological information supplemental to the biological indicators. The biological research was designed around the USEPA Rapid Bioassessment Protocols (RBPs) using the multi-habitat approach. Four fixed-count subsamplings (100, 200, 300 and 500 organisms) were randomly conducted using a standardized gridded pan to evaluate an appropriate level for bioassessment in Thai streams. A 300 organism subsample is adequate for bioassessment purposes in Thai stream (evaluated by calculating dissimilarity values and ordination techniques). A systematic selection of candidate reference sites, metric selection, and index calibration was part of this research. Multimetric and multivariate analyses were examined as a foundation for bioassessment in Thailand. The multimetric approach appears to be more practical for a rapid bioassessment technique. Nine core metrics were identified for biological index score including number of total taxa, Diptera taxa, Ephemeroptera, Plecoptera, Trichoptera, and Coleoptera taxa, (%) Plecoptera, (%) Tolerant organisms, Beck's Biotic Index, (%) Intolerant organisms, Shredders taxa and Clingers taxa were calibrated for the final index. As a result of multimetric and multivariate analyses, family level identification data effectively discriminated reference condition and broad-scale environmental gradients. Hampered by incomplete taxonomic knowledge of benthic macroinvertebrates in Thailand, family-level identification may be sufficient taxonomic resolution for rapid bioassessment in Thailand.     

江苏省太湖流域大型底栖无脊椎动物完整性业务化评价指数构建

为支撑流域水生态目标的业务化管理,提高水生态监测和评价的可操作性,突破物种分类鉴定的技术瓶颈,以大型底栖无脊椎动物为研究对象,在江苏省太湖流域布设120个采样点,于2013年1—3月、7—8月和10—11月开展3次监测。以最小干扰为参照状态,对涉及物种丰度、物种多度组成、耐污能力和摄食类群的72个候选指数进行分布范围、判别能力及相关性分析,结合指数获取的便利性及物种分类的难易程度,最终筛选出3个核心指数构成大型底栖无脊椎动物完整性业务化评价指数,其中湖荡、河流和水库的指数为软体动物分类单元数、优势分类单元相对多度和BMWP指数,溪流的指数为ETO分类单元数、前三位优势分类单元相对多度和BMWP指数。经验证,业务化指数与环境梯度有较好的响应关系,且可操作性强,具备开展业务化应用的前景。但目前的流域水生态目标管理尚处于摸索阶段,技术体系还须在业务化过程中不断修正和完善。     

Relations between macroinvertebrates, nutrients, and water quality criteria in wadeable streams of Maryland, USA

In an ongoing effort to propose biologically protective nutrient criteria, we examined how total nitrogen (TN) and its forms were associated with macroinvertebrate communities in wadeable streams of Maryland. Taxonomic and functional metrics of an index of biological integrity (IBI) were significantly associated with multiple nutrient measures; however, the highest correlations with nutrients were for ammonia-N and nitrite-N and among macroinvertebrate measures were for Beck’s Biotic Index and its metrics. Since IBI metrics showed comparatively less association, we evaluated how macroinvertebrate taxa related to proposed nutrient criteria previously derived for those same streams instead of developing nutrient–biology thresholds. We identified one tolerant and three intolerant taxa whose occurrence appeared related to a TN benchmark. Individually, these taxa poorly indicated whether streams exceeded the benchmark, but combining taxa notably improved classification rates. We then extracted major physiochemical gradients using principal components analysis to develop models that assessed their influence on nutrient indicator taxa. The response of intolerant taxa was predominantly influenced by a nutrient-forest cover gradient. In contrast, habitat quality had a greater effect on tolerant taxa. When taxa were aggregated into a nutrient sensitive index, the response was primarily influenced by the nutrient-forest gradient. Multiple lines of evidence highlight the effects of excessive nutrients in streams on macroinvertebrate communities and taxa in Maryland, whose loss may not be reflected in metrics that form the basis of biological criteria. Refinement of indicator taxa and a nutrient-sensitive index is warranted before thresholds in aquatic life to water quality are quantified.     

Combined use of rapid bioassessment protocols and sediment quality triad to assess stream quality

Physical, chemical and biological conditions at five stations on a small southeastern stream were evaluated using the Rapid Bioassessment Protocols (RBP) and the Sediment Quality Triad (SQT) to assess potential biological impacts of a municipal wastewater treatment facility (WWTF) on downstream resources. Physical habitat, benthic macroinvertebrates and fish assemblages were impaired at Stations 1 and 2 (upstream of the WWTF), suggesting that the degraded physical habitat was adversely impacting the fish and benthic populations. The SQT also demonstrated that Stations 1 and 2 were degraded, but the factors responsible for the impaired conditions were attributed to the elevated concentrations of polycylclic aromatic hydrocarbons (PAHs) and metals (Mn, Pb) in the sediments. The source of contaminants to the upper reaches of the stream appears to be storm-water runoff from the city center. Increased discharge and stabilized base flow contributed by the WWTF appeared to benefit the physically-altered stream system. Although the two assessment procedures demonstrated biological impairment at the upstream stations, the environmental factors identified as being responsible for the impairment were different: the RBP provided insight into contributions associated with the physical habitat and the SQT contributed information on contaminants and sediment quality. Both procedures are important in the identification of physical and chemical factors responsible for environmental impairment and together they provide information critical to the development of appropriate management options for mitigation.     

Biological responses to sediment remediation based on thin layer placement near a former pulp mill in Ward Cove, AK (USA)

In 2001, 28 acres of the bottom of Ward Cove, AK (USA) were remediated using thin layer placement, to enhance the natural recovery of contaminated sediments. The remediated areas were part of an 80-acre area of concern identified offshore from the site of a former sulfite pulp mill. The primary chemicals of concern were those commonly associated with organic enrichment near pulp mills: ammonia and 4-methylphenol. The primary remedial objectives were to reduce the toxicity of the contaminated sediments and to stimulate colonization of the remediated areas by benthic macroinvertebrates. In 2004, the initial monitoring event for the remediated areas was conducted, and included evaluations of physical/chemical sediment variables (i.e., total organic carbon, grain size distribution, ammonia, and 4-methylphenol), sediment toxicity (i.e., using the 10-day amphipod survival test with Eohaustorius estuarius), and in situ benthic macroinvertebrate communities. Results of the monitoring event showed that conditions in the remediated areas had improved considerably in the 3 years since thin layer placement had occurred. At most stations, concentrations of both ammonia and 4-methylphenol were very low, and amphipod survival was >or=90%. In addition, benthic macroinvertebrates appeared to be rapidly colonizing the remediated areas, based on evaluations of several community metrics (i.e., taxa richness, diversity, and dominance), as well as key indicator species of organic enrichment and associated transitional areas (i.e., primarily the polychaetes Capitella capitata and Nephtys cornuta, and the bivalve molluscs Axinopsida serricata and Parvilucina tenuisculpta). In general, colonization was consistent with the patterns identified for areas recovering from organic enrichment on the continental shelf of southern California and elsewhere. Based on these results, thin layer placement was considered successful in enhancing the natural recovery of the remediated sediments in Ward Cove.     

2012—2019年松花江干流底栖动物群落变化及其对水环境因子的响应

底栖动物是水生态系统的重要组成部分,其群落特征通常用来评价水生态环境质量。研究了2012—2019年松花江干流水生态环境质量状况、变化趋势,并应用冗余分析(RDA)探究底栖动物群落结构特征与水环境因子之间的响应关系。结果表明:8年间共鉴定出底栖动物246个分类单元,隶属于4门、9纲、25目、58科、69属,其中水生昆虫的EPT物种为99个分类单元,占总物种数的40.24%;水生昆虫的其他物种为68个分类单元,占总物种数的27.64%;软体动物为36个分类单元,占总物种数的14.63%;环节动物为25个分类单元,占总物种数的10.16%;甲壳动物为18个分类单元,占总物种数的7.32%。底栖动物密度总体呈上升趋势,种类组成总体有所增多,其中环节动物、软体动物和甲壳动物有向水生昆虫转变的趋势,群落结构相对稳定且主要以水生昆虫占比最多,底栖动物密度平均值为5.97×10³个/m²,变化范围为2.86×10³~8.98×10³个/m²,优势科(属)主要为小蜉属Ephemerella、小寡脉蜉属Oligoneuriella、扁蜉属Heptagenia、等蜉属Isonychia、纹石蛾科Hydropsychidae、缺叉多距石蛾属Polycentropus、摇蚊科Chironomidae和圆田螺属Cipangopaludina等。生物指数评价结果多数为"中等"及以上,评价结果趋于稳定,且下游评价结果好于上游。松花江干流的水环境质量变化阶段性明显,溶解氧含量升高,氨氮呈下降趋势,其余指标呈波动变化。冗余分析(RDA)结果表明:影响松花江干流底栖动物群落结构变化的主要环境因子是随时间推移而变化的,其中溶解氧、生化需氧量、化学需氧量、总磷、氨氮和总氮等指标是影响该监测区域底栖动物群落分布的重要环境因子。     

江苏地表水体大型底栖无脊椎动物生物多样性状况研究

大型底栖无脊椎动物群落结构与水体水质和水生态系统健康状况关系密切,其受外界干扰后群落结构的变化趋势可以反映水体受污染的性质和程度。2008年,对江苏省主要饮用水源地,长江、京杭大运河等主要河流及太湖等重点湖泊开展底栖动物调查与评价研究,共设置调查点位154个。江苏主要饮用水源地底栖动物的物种数量为78种,主要河流发现底栖动物96种,主要湖泊底栖动物发现65种。从物种多样性指数评价结果看,主要湖泊的底栖生物多样性状况优于地表水源地和主要河流,丰富和较丰富所占比例合计达58%;主要河流的评价结果最差,丰富和较丰富所占比例合计仅达30.7%,存在11.3%物种多样性极贫乏的点位,且大部分水体底栖动物组成以耐污种为主,优势种为极耐污的霍甫水丝蚓,水质状况劣于饮用水源地和主要湖泊。