Macroinvertebrate communities as bioindicators of water quality in conventional and organic irrigated rice fields in Guanacaste,Costa Rica

The purpose of this study was to compare how aquatic macroinvertebrates are affected by certain management practices and agrochemicals in organic and conventional rice cultivations (treatments) in northwestern of Costa Rica. We sampled macroinvertebrates in both treatments, at the water entrances (irrigation) and exits (drainage) during two cycles (8 months total) of rice field cultivation. We employed a water quality index using macroinvertebrates (BMWP/CR) as bioindicators in both management treatments. Insect family mean (P = 0.0019) and species mean richness (P = 0.0340) were greater in the organic vs. the conventional treatments as well as at the entrances rather than their exits. Both macroinvertebrates mean abundance (P = 0.0281) and insects mean abundances (P = 0.0065) were greater at the organic vs. the conventional treatments. The water quality index (BMWP/CR) was greater in the organic treatment at the entrance (124) comparing with the exit (72), and also at the conventional entrance (92) vs. the exit (66), thus showing that the management practices affected the macroinvertebrate community. The organic treatment showed the settlement of a greater number of families and species of macroinvertebrates both in general and in those considered sensitive to pollution than in the conventional treatment. This sensitive group of macroinvertebrates (Baetis sp., Fallceon sp., Leptohyphes sp., Tricorythodes sp., Farrodes sp., Phyllogomphoides sp., Hydroptila sp., Mayatrichia sp., Neotrichia sp., Oxyethira sp., Nectopsyche sp.1, Nectopsyche sp.2, Oecetis sp.) can be used as a bioindicators of water quality in these agroecosystems. On the contrary, more macroinvertebrates resistant to pollution were found in the conventional compared to the organic treatment, showing that aquatic macroinvertebrates respond to the type of management/products that are applied to the rice field.     

The efficacy of DNA barcoding in the classification,genetic differentiation,and biodiversity assessment of benthic macroinvertebrates

Macroinvertebrates have been recognized as key ecological indicators of aquatic environment and are the most commonly used approaches for water quality assessment. However, species identification of macroinvertebrates (especially of aquatic insects) proves to be very difficult due to the lack of taxonomic expertise in some regions and can become time‐consuming. In this study, we evaluated the feasibility of DNA barcoding for the classification of benthic macroinvertebrates and investigated the genetic differentiation in seven orders (Insecta: Ephemeroptera, Plecoptera, Trichoptera, Diptera, Hemiptera, Coleoptera, and Odonata) from four large transboundary rivers of northwest China and further explored its potential application to biodiversity assessment. A total of 1,144 COI sequences, belonging to 176 species, 112 genera, and 53 families were obtained and analyzed. The barcoding gap analysis showed that COI gene fragment yielded significant intra‐ and interspecific divergences and obvious barcoding gaps. NJ phylogenetic trees showed that all species group into monophyletic species clusters whether from the same population or not, except two species (Polypedilum. laetum and Polypedilum. bullum). The distance‐based (ABGD) and tree‐based (PTP and MPTP) methods were utilized for grouping specimens into Operational Taxonomic Units (OTUs) and delimiting species. The ABGD, PTP, and MPTP analysis were divided into 177 (p = .0599), 197, and 195 OTUs, respectively. The BIN analysis generated 186 different BINs. Overall, our study showed that DNA barcoding offers an effective framework for macroinvertebrate species identification and sheds new light on the biodiversity assessment of local macroinvertebrates. Also, the construction of DNA barcode reference library of benthic macroinvertebrates in Eurasian transboundary rivers provides a solid backup for bioassessment studies of freshwater habitats using modern high‐throughput technologies in the near future.     

太子河大型底栖动物摄食功能群对河岸带土地利用类型的响应

为研究太子河大型底栖动物摄食功能群对河岸带土地利用类型的响应关系,于2012年5月对太子河流域底栖动物和水环境因子和土地利用类型进行野外调查及数据分析。结果表明：1）太子河流域底栖动物群落在4种不同土地利用类型内具有极显著差异,平均丰度、Shannon-Wiener多样性指数和Pielou均匀度指数在森林用地中最高,分别为8.86、0.73和0.94,平均密度在森林耕作用地中最高（782.75个/m²）,除食碎屑者功能群（S）,其他摄食功能群在不同土地利用类型内无差异（P > 0.05）。2）太子河土地利用类型与水环境因子之间的Pearson分析表明,森林用地与EC、TDS、TN、NH₃-N、COD_Mn之间呈显著负相关性,与DO、IOS之间呈显著正相关性;耕地与DO和IOS之间呈显著负相关性;城镇用地与EC、TDS和TN之间呈正相关性。3）太子河土地利用类型与底栖动物功能群之间的Spearman分析表明森林用地与食碎屑者（S）、刮食者（SC）和收集者（GC）呈正相关性。耕地与食碎屑者（S）、滤食者（FC）之间呈负相关性,城镇用地与刮食者（SC）和收集者（GC）之间呈显著负相关性。4）底栖动物功能群和水环境因子之间的典范对应分析表明,食碎屑者（S）功能群主要受底质指数（IOS）驱动,其他功能群与环境因子之间无相关性。因此,水环境因子和底栖动物群落参数比摄食功能群更能反映人类活动对土地利用的改变,水环境和底栖动物群落研究可为河岸带土地利用保护提供理论依据。     

Comparative study of diatoms and macroinvertebrates as indicators of severe water pollution: Case study of the Kebena and Akaki rivers in Addis Ababa,Ethiopia

We assessed the relative performance of diatoms and macroinvertebrates to measure municipal and industrial impacts on the ecological integrity of the three major rivers flowing through Addis Ababa. Both community metric and multivariate statistical techniques were used to analyze the environmental variables and species data along the pollution gradient. This study in the Addis Ababa urban area revealed that three biologically highly stressed rivers are being impacted primarily by physical habitat degradation and both point and nonpoint pollution. The macroinvertebrate composition was liable to severe physical habitat and chemical water quality degradation. Consequently, macroinvertebrates were less diverse and not found at all at the most polluted sites with very low dissolved oxygen levels. Based on community metrics and multivariate analysis results, diatoms more reliably indicated a gradient of pollution than macroinvertebrates. However, both organism groups equally discriminated the two relatively unimpacted upstream sites from all other impacted sites. As diatoms are immobile and ubiquitous (i.e., at least a few can be found under almost any condition), they are good indicators of pollution levels among heavily impacted sites where macroinvertebrates are completely absent or less diverse. Therefore, diatoms are the powerful bioindicators for monitoring urban-impacted and seriously stressed rivers and to examine pollution gradients and impacts of specific pollution sources.     

Effects of in situ phosphorus enrichment on the benthos in a subalpine karst stream and implications for bioassessment in nature reserves

Park managers in nature reserves need scientifically defensible and operationally feasible ecological indicators to better manage protected areas for both nature conservation and tourism. Such needs are much more urgent in karst aquatic ecosystems where spectacular natural scenic wonders attract millions of visitors to natural areas with streams and lakes that are particularly vulnerable to nutrient pollution. To identify a set of biotic indicators of phosphorus (P) pollution in a karst stream, we conducted an in situ P enrichment experiment in a nearly pristine karst stream located at a UNESCO world heritage site in China. Our results show that both benthic algal assemblages and macroinvertebrates were sensitive to P enrichment. Changes in diatoms (e.g., Achnanthidium minutissimum, Delicata delicatula) and macroinvertebrates (e.g., collectors) were indicative of P enrichment. The color change of travertine bryophyte beds from creamy white to green was largely due to increase in filamentous green algae such as Zygnema sp., which may provide a visual cue for P enrichment and pollution. Our findings, in conjunction with further studies that directly link these indicators with human disturbance (e.g., tourist activities) throughout the park, could improve the operation of park managers in minimizing tourist-induced nutrient pollution and in operationalizing these indicators in the current environmental monitoring and assessment program.     

付疃河流域中下游大型底栖动物群落结构与水质生物学评价

2018年12月-2019年10月对山东省日照市付疃河流域中下游大型底栖动物及相应水环境因子进行分季节的监测,并对底栖动物群落组成、多样性特征及与水质因子的相关性进行分析。结果表明,调查共采集底栖动物42种（环节动物14种、节肢动物20种、软体动物8种）,广泛分布物种为霍甫水丝蚓（Limnodrilus hoffmeisteri）、水丝蚓属（Limnodrilus sp.）及摇蚊属（Chironomus sp.）;底栖动物总密度呈春季 > 冬季 > 秋季 > 夏季;CCA （Canonical Correspondence Analysis）分析表明环节动物与COD、TP有显著正相关性,各门类与NH₃-N相关性差异较大;底栖动物多样性分布特征与河流水源结构有关。采用生物多样性指标、指示物种水质生物学指标进行水质评价,Shannon-Wiener指数、Margalef指数评级偏差,Pielou指数评级偏优,而指示物种水质生物学评价（Goodnight-Whitley指数、相对重要性指数及Wright指数）基本一致,整体平均处于中污染,评价过程仍须考虑河流及物种客观属性特征,得到更具适用性的评价管理方法。     

An applied ecological approach for the assessment of anthropogenic disturbances in urban wetlands and the contributor river

An applied ecological approach was used to assess the anthropogenic disturbances on the aquatic systems of the Sorocaba river and its wetlands in the Sorocaba-SP municipality (Southeastern Brazil). Two samplings of water, sediment, macroinvertebrates, and macrophytes were performed in 2017, during the rainy season (February) and dry season (June). Traditional limnological methods were applied to the biological material (macrophytes and macroinvertebrates) and limnological variables. In 2017, domestic wastewater and diffuse pollution were the main anthropogenic impacts on the aquatic ecosystems of the Sorocaba municipality. The used approach allowed the verification of the human disturbances on aquatic systems, sediment, biological communities, and landscape. We found that biochemical oxygen demand, thermotolerant coliforms, total phosphorus, dissolved oxygen, and turbidity are above reference concentrations from the Brazilian guideline CONAMA Resolution 357/05. Four macroinvertebrates orders (Diptera, Oligochaeta, Hirudinea, and Gastropoda) and three macrophytes species (Eichhornia crassipes, Salvinia auriculata and Pistia stratiotes) allowed inferring that Sorocaba river and associated wetlands suffer water quality loss due to organic pollution. The major land use classes were anthropogenic agricultural and non-agricultural (75.42%) disturbances, contributing to limnological alterations and low quality of riparian vegetation. Urban wetlands were similar (e.g. sediment properties, limnological variables, bioindicators) and differed from the contributor river, a situation probably related to the wetlands bimodal pulse. Considering the hydric network of tropical countries in the same geographic region, the similar dynamics of the water bodies, and the context of urbanization, the approach can be applied to assess the human disturbances in the region.     

Multimetric assessment of macroinvertebrate responses to mitigation measures in a dammed and polluted river of Central Spain

In this research, structural and functional responses of benthic macroinvertebrates to mitigation measures (carried out in the dammed and polluted Duraton River, Central Spain, during the 1990s and 2000s) were examined by comparing physicochemical and biological data from the summer of 1987 with data from the summer of 2014. Mitigation measures resulted in significant increases in dissolved oxygen concentrations, as well as in significant reductions of fluoride (F⁻) pollution and short-term flow fluctuations. The macrobenthic community responded positively to improvements in river environmental conditions, exhibiting significant increases in abundance (total density, total biomass and EPT density) and diversity (total family richness and EPT richness) at impacted sampling sites. Furthermore, the presence of relatively sensitive benthic macroinvertebrates after mitigation measures (as indicated by increased values of BMWQ biotic indices) also was the main cause for observed reductions in the environmental impact caused by disturbance points (as indicated by decreased values of the EI index), and for the observed recovering of the trophic structure of the macrobenthic community, with macroinvertebrate scrapers as the functional feeding group most favored. These macroinvertebrate responses to mitigation measures were more marked at sampling sites that initially were more impacted (i.e., nearest to disturbance points), and less apparent at the sampling site that initially was less impacted (i.e., farthest to disturbance points). Within the hydropsychid assemblage, improvements in river environmental conditions clearly favored the presence of Hydropsyche pellucidula and Cheumatopsyche lepida at the expense of the other hydropsychid species. In spite of all monitored environmental improvements and macroinvertebrate positive responses, the need for additional mitigation measures was evident, particularly to reduce high turbidity levels and sedimentation of fine inorganic matter negatively affecting benthic macroinvertebrates downstream from the industrial effluent. Overall, it is concluded that the multimetric approach is an effective technique to assess macroinvertebrate responses to mitigation measures in river ecosystems.     

Using diatom life-forms and ecological guilds to assess organic pollution and trophic level in rivers: a case study of rivers in south-eastern France

The European Union’s Water Framework Directive has set a target of achieving good ecological status for all aquatic environments in Europe by 2015. In order to determine the quality of aquatic environments, biological indicators such as diatoms are often used. However, biotic diatom indices can be difficult and time consuming to use because of complexity of species determination. We investigated whether the biological traits of diatoms in rivers (life-forms, size classes and ecological guilds) could be used to assess organic pollution and trophic level. We worked on a data set comprising 315 diatom species, determined at 328 river stations of south-east France and a variety of parameters. The abundances of some biological traits differed significantly between the different organic pollution and trophic levels, particularly stalked diatoms, and the motile and low-profile guilds.     

深圳大鹏半岛主要河流底栖动物群落结构及水质生物学评价

2013年5月对深圳大鹏半岛4条主要河流(葵涌河、王母河、鹏城河和东涌河)的大型底栖动物群落结构进行了调查,并利用香农-维纳多样性指数和生物指数(BI)对河流水质进行了生物学评价。在大鹏半岛主要河流的15个样点共采获大型底栖动物35种,隶属3门7纲21科,其中水生昆虫26种,约占底栖动物种类数的74%。但底栖动物的种类组成与分布极不均匀,EPT(蜉蝣目+襀翅目+毛翅目)等对水质变化较敏感的类群主要分布于葵涌河的源头及受人为干扰活动较少的东涌河,而耐污能力较强的摇蚊科幼虫、霍甫水丝蚓和颤蚓等则为葵涌河中、下游样点、王母河和鹏城河的优势物种。生物指数(BI)相较于香农-维纳多样性指数,更适用于水质评价。结果显示,除葵涌河源头、鹏城河和东涌河样点的水质处于清洁至轻污染外,其余大部分样点处于中污染至重污染状态。推测大鹏半岛的王母河及葵涌河中、下游河段的生活污水及工业废水已对底栖动物的群落结构与河流水质造成了一定的影响。     

Influences of native and non-native benthivorous fishes on aquatic ecosystem degradation

Invasive common carp Cyprinus carpio has long been identified as a contributor to water quality deterioration, disrupted ecosystem processes, and shifts in biological assemblage structure. In contrast, little information is available regarding the effects of native benthivorous species on aquatic systems despite their functional similarity to common carp. Effects of common carp and the native black bullhead Ameiurus melas on sediment resuspension, nutrient concentrations, macrophytes, and assemblage structure of zooplankton and macroinvertebrates, were experimentally evaluated. We observed decreased water clarity, increased nutrient concentrations, decreased macrophyte biomass, and decreased benthic macroinvertebrate abundance and biomass associated with common carp, regardless of the presence of black bullhead. In contrast, black bullhead increased total phosphorus, and chlorophyll a concentrations and copepod abundance, but had little or no effect on other measured water quality and biological variables when compared to control conditions. Overall, experimental results suggest that although black bullhead tend to be tolerant of degraded ecosystems, they are not a source of physical changes to the environment known to be responsible for perpetuating degraded water quality (e.g., stable state shifts). Therefore, increased abundance of native species, such as black bullhead, following the invasion of common carp, may serve as an indicator of ecological conditions and should not to be assumed as causative.     

山地河流浅滩生境潜流层大型无脊椎动物群落拓殖

通过包埋人工基质法研究大型无脊椎动物在山地河流潜流层中的拓殖过程。结果表明:群落个体密度在7—29 d呈"J"型增长,在29 d后骤然降低,55 d后呈波动趋势;物种丰富度在1—29 d呈增加趋势,29 d后呈波动状态;群落的生物量总体呈增加趋势。群落的物种丰富度、密度和生物量在第29、71和83天时没有显著性差异(P0.05),Shannon-Wiener多样性指数和Pielou均匀度指数在第55、71、83天没有显著性差异(P0.05),综合不同拓殖时间段物种的主成分分析,表明潜流层大型无脊椎动物群落在55 d后趋于稳定。群落优势种为摇蚊(Camptochironomus sp.)、河蚬(Corbicula fluminea)、四节蜉(Baetis sp.)、动蜉(Cinygmina sp.)、纹石蛾(Hydropsyche sp.)和扁泥甲科的一种(Psephenidae)。滤食者和收集者在整个拓殖过程中均是优势功能摄食群。群落拓殖过程是一个群落自身恢复能力和外部环境影响相互作用的过程,拓殖初期潜流层的结构是影响着无脊椎动物迁入的主要因素,中期动物的生活史特征起主要作用,稳定期之后群落可能受到各因素的综合影响。     

Ecological health of the Usuthu and Mbuluzi rivers in Swaziland based onselected biological indicators

Biological monitoring, using coliform bacteria and macroinvertebrate populations and diversity, was carried out monthly from August 2004 to January 2005 to determine the ecological health of the Usuthu and Mbuluzi rivers in Swaziland. Water temperature and pH were not significantly different between sites, but differed significantly between months. Bacterial species identified from both rivers were Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris, with no significant differences in mean colony counts between the two rivers. Average colony counts were significantly different between months. A total of 926 macroinvertebrates, representing 28 families, were collected from both rivers and were significantly different between sites, rivers and months. Macroinvertebrate populations and diversity were negatively correlated with bacterial colony counts. Compliance with regulated water quality standards did not necessarily indicate acceptable water quality for biological communities, and thus there is a need for an integrated approach in water quality monitoring.     

松花江流域大型底栖动物群落结构与水质评价

【目的】松花江流域是中国最早的工业基地之一,其水生态环境遭到严重破坏,环境保护工作面临巨大挑战。开展松花江流域水质评价及典型生物类群多样性状况调查,可为松花江流域生态系统的保护和修复提供依据。【方法】于2016年7月调查整个松花江流域近岸的大型底栖动物群落组成和测定水质理化指标,开展其水质理化特征评价和生物指数评价,并探讨底栖动物群落分布与水环境因子间的关系。【结果】理化指标评价结果显示,南源松花江水质状况最差,处于中度污染;北源松花江处于轻度污染;梧桐河水质最好,处于良好状态。松花江流域3个河段的底栖动物群落结构存在空间差异性。另外,梧桐河的物种多样性最高,北源松花江次之,南源松花江最低。溶解氧和营养元素K的浓度是驱动底栖动物群落组成发生显著性差异的主要环境因子。生物指数评价结果显示,3个河段水质均处于轻度污染状态。【结论】松花江流域水质处于轻度到中度污染状态。有机污染是松花江流域面临的主要水质环境问题,对松花江流域底栖动物群落结构产生了显著影响。因此,控制有机质的输入是维持松花江流域水生态系统平衡的重要举措之一。     

Application of European biomonitoring techniques in China: Are they a useful tool?

This paper focuses on the application of various biomonitoring techniques in China. We report a study in the Pearl River Basin (Guangzhou) based on the application of diatom indices as well as a study on the waterways in Wuhan based on evaluation of toxicity (using phytotoxicity, Daphnia magna and Microtox™ tests) and the Extended Biotic Index (EBI). Regarding the diatom indices, acceptable results were obtained based on comparison of the chemical water quality level and the European and Japanese indices, despite a lack of taxonomic information. The toxicity tests applied to the Wuhan waterways (Yangtze and Han Rivers) produced interesting results and can be considered to represent a useful tool for water pollution control in this area. Application of the EBI in Wuhan produced results that were contradictory to the toxicological analyses, as there were no indications of toxicity, whereas EBI indicated poor water quality. It can be concluded that in principle, certain European biological indicators can be considered to represent feasible tools to be applied in China. However, further studies will have to be carried out to develop bioindices based on Chinese data sets. The use of bioindices based on macroinvertebrates is limited to less polluted and smaller rivers with a lithic river substratum, whereas diatom indices are also applicable under extreme conditions (e.g., under high pollution loads or in large river streams with sandy riverbed sediments through installing artificial substrates).     

An application of different bioindicators for assessing water quality: a case study in the rivers Alfeios and Pineios (Peloponnisos, Greece)

A number of bioindicators and biotic indices and scores based on benthic macroinvertebrates, diatoms, fishes, aquatic and riparian vegetation in relation to physicochemical parameters have been applied in assessing the water quality of the rivers Alfeios and Pineios (Peloponnisos, Greece). According to the findings, the water quality in both rivers varied from very poor to very good. Among the bioindicators used, the benthic macroinvertebrates seem to be the most reliable. The BBI and IBE were the most applicable indexes while the applicability of the IBMWP and IASPT in the Greek region can be enforced with the inclusion of the Diptreran family Rhagionidae and the Coleopteran family Elminthidae.     

Effects of water temperature on freshwater macroinvertebrates: a systematic review

Water temperature is one of the main abiotic factors affecting the structure and functioning of aquatic ecosystems and its alteration can have important effects on biological communities. Macroinvertebrates are excellent bio-indicators and have been used for decades to assess the status of aquatic ecosystems as a result of environmental stresses; however, their responses to temperature are poorly documented and have not been systematically evaluated. The aims of this review are: (i) to collate and summarize responses of freshwater macroinvertebrates to different temperature conditions, comparing the results of experimental and theoretical studies; (ii) to understand how the focus of research on the effects of temperature on macroinvertebrates has changed during the last 51 years; and (iii) to identify research gaps regarding temperature responses, ecosystem types, organism groups, spatiotemporal scales, and geographical regions to suggest possible research directions. We performed a comparative assessment of 223 publications that specifically consider freshwater macroinvertebrates and address the effects of temperature. Short-term studies performed in the laboratory and focusing on insects exposed to a range of temperatures dominated. Field studies were carried out mainly in Europe, at catchment scale and almost exclusively in rivers; they mainly investigated responses to water thermal regime at the community scale. The most frequent biological responses tested were growth rate, fecundity and the time and length of emergence, whereas ecological responses mainly involved composition, richness, and distribution. Thermal research on freshwater macroinvertebrates has undergone a shift since the 2000s when studies involving extended spatiotemporal scales and investigating the effects of global warming first appeared. In addition, recent studies have considered the effects of temperature at genetic and evolutionary scales. Our review revealed that the effects of temperature on macroinvertebrates are manifold with implications at different levels, from genes to communities. However, community-level physiological, phenological and fitness responses tested on individuals or populations should be studied in more detail given their macroecological effects are likely to be enhanced by climate warming. In addition, most field studies at regional scales have used air temperature as a proxy for water temperature; obtaining accurate water temperature data in future studies will be important to allow proper consideration of the spatial thermal heterogeneity of water bodies and any effects on macroinvertebrate distribution patterns. Finally, we found an uneven number of studies across different ecosystems and geographic areas, with lentic bodies and regions outside the West underrepresented. It will also be crucial to include macroinvertebrates of high-altitude and tropical areas in future work because these groups are most vulnerable to climate warming for multiple reasons. Further studies on temperature–macroinvertebrate relationships are needed to fill the current gaps and facilitate appropriate conservation strategies for freshwater ecosystems in an anthropogenic-driven era.     

Biodiversity of constructed wetlands for wastewater treatment

Constructed wetlands are often built for wastewater treatment to mitigate the adverse effects of organic pollution in streams and rivers caused by inputs of municipal wastewater. However, there has been little analysis of biodiversity and related factors influencing the ecosystem functioning of constructed wetlands. The purpose of this study was to evaluate the biodiversity of two free-water-surface integrated constructed wetlands in subtropical Taiwan by analyzing the water quality, habitat characteristics, and biotic communities of algae, macrophytes, birds, fish, and aquatic macroinvertebrates in the treatment cells. Our results indicated that the two integrated constructed wetlands (Hsin-Hai II and Daniaopi Constructed Wetlands) achieved good performance in reducing the concentrations of total nitrogen (TN) and total phosphorus (TP), and loadings of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) from municipal sewage. In total, 58 bird species, 7 fish species, and 34 aquatic macroinvertebrate taxa were recorded in the two wetlands. The results of stepwise multiple regressions showed that the richness, abundance, and diversity of birds increased with wetland area. Fish richness and abundance respectively increased with wetland area and dissolved oxygen, while the diversity decreased with increases in TP concentrations. The richness and density of aquatic macroinvertebrates increased with the cover of aquatic macrophytes, while the diversity increased with wetland area. Ordination analyses indicated that variations in the community structures of birds, fishes, and aquatic macroinvertebrates were respectively best explained by water temperature, wetland area, and species richness of fish. Our results suggest that wetland area, cover of aquatic macrophytes, and water quality were the most important factors governing the diversity in the constructed wetlands, and that the factors influencing community structures varied among different taxonomic groups. In addition to improving water quality, this study implied that the biodiversity of constructed wetlands for wastewater treatment can be enhanced through proper design and management.     

Macroinvertebrate assemblages at mesohabitat scale in small sized volcanic siliceous streams of Central Italy (Mediterranean Ecoregion)

According to the guidelines of the European Water Framework Directive, assessment of the ecological quality of streams and rivers should be based on type-specific reference conditions. Moreover to support biological indicators an hydromorphological analysis is also requested for each river type. The rationale for including an habitat assessment in biomonitoring study is that a biological community can be influenced by habitat quality just as water chemistry.In the present work benthic macroinvertebrates were analysed in a specific river type of Central Italy (small-sized streams, volcanic-siliceous), to identify taxa assemblages at the mesohabitat scale and to test how common measures of benthic community used in biomonitoring differ between riffles and pools in order to evaluate if differences may influence water quality classification.Macroinvertebrates were collected in 10 selected streams, covering the whole quality range present in the geographic area from ‘reference sites’ to human-impacted sites, along a pool–riffle sequence following a multihabitat sampling protocol.We compared assemblage of macroinvertebrates found in different mesohabitats using principal component analysis (PCA). Similar site grouping was obtained in riffle, pool and abiotic analysis.The measures of diversity and abundance were used as replicates in ANOVA analysis to test differences between pools and riffles within the groups of sites. There were no significant differences in terms of taxa richness and total abundance.When we compared the abundance of each taxon we found significant differences only in the group of reference sites with 18 taxa (about 25%) that showed a significant habitat preference.Our findings support that macroinvertebrates assemblages reflected primarily the environmental conditions and differences at mesohabitat scale are strongly correlated to hydromorphological condition and are maximized in reference sites. However such differences do not influence the ecological status assessment in this typology.     

Environmental gradients determining the distribution of benthic macroinvertebrates in Lake Takkobu, Kushiro wetland, northern Japan

Effects of environmental variables on the distribution of benthic macroinvertebrates inhabiting sediments were studied at 25 sites along the shoreline of Lake Takkobu in the Kushiro wetland of northern Japan in summer 2003. During the last decade, the lake’s status has undergone a drastic shift from clear water dominated by submerged macrophytes to turbid water dominated by phytoplankton. The canonical correspondence analysis showed that four environmental variables explained the significant variation in the macroinvertebrate species composition: submerged plant biomass, bottom sediment organic matter content (OMC), distance from the mouth of the Takkobu River, and bottom-layer pH. Five species of Chironomidae [Chironomus sp. (except plumosus group), Psectrocladius sp., Corynoneura sp., Parachironomus sp. arcuatus group, and Zavreliella sp.] occurred in sites with relatively lower pH and a high submerged plant biomass, whereas three species of Tubificidae (Tubifex tubifex, Aulodrilus limnobius and Aulodrilus sp.) and two of Chironomidae (Nanocladius sp. and Monodiamesa sp.) occurred in sites with high pH and little vegetation. The three Tubificidae species also preferred organic-rich sediments. Irrespective of aquatic vegetation, Sphaerium sp. (Bivalvia) and Monodiamesa sp. (Chironomidae) occurred in low-OMC sites, whereas Tanypus sp. (Chironomidae) preferred high-OMC sites. The number of macroinvertebrate taxa showed the highest correlation with the number of submerged plants, suggesting that macroinvertebrate species richness was related mostly to submerged plant species diversity in this lake. The quantity and species richness of submerged plants and OMC are thus important determinants of the community structure of macroinvertebrates inhabiting sediments in Lake Takkobu.