The rapid effects of a whole-lake reduction of coarse woody debris on fish and benthic macroinvertebrates

1. Ecosystems can enhance the biodiversity of adjacent ecosystems through subsidies of prey, nutrients and also habitat. For example, trees can fall into aquatic ecosystems and act as a subsidy that increases aquatic habitat heterogeneity. This habitat subsidy is vulnerable in lakes where anthropogenic development of shorelines coincides with a thinning of riparian forests and the removal of these dead trees (termed coarse woody debris: CWD). How the disruption of this subsidy affects lake ecosystems is not well understood.
2. We performed a whole ecosystem experiment on Little Rock Lake, a small (18 ha), undeveloped, and unfished lake in Vilas County, WI, U.S.A., that is divided into two similar-sized basins by a double poly-vinyl chloride curtain that prevents both fish and water exchange between basins. In 2002, we removed about 70% of the littoral CWD in the treatment basin, while the reference basin was left unaltered. We tested for changes in both fish and benthic macroinvertebrate community composition in the two years following the CWD reduction.
3. Yellow perch ( Perca flavescens ) was the most abundant fish species in the lake prior to our experiment, but declined to very low densities in the treatment basin after manipulation. We found no evidence of an effect on macroinvertebrates – the treatment basin's macroinvertebrate community composition, diversity and density did not change relative to the reference basin.
4. Our results indicate that different trophic groups may have differential responses to the loss of a habitat subsidy, even if anthropogenic effects on that subsidy are severe. In the case of Little Rock Lake, fish community responses were evident on a short-time scale, whereas the macroinvertebrate community did not rapidly change following CWD reduction.     

Geometry of biodiversity patterning: assemblages of benthic macroinvertebrates at tributary confluences

We assessed whether tributaries in upland catchments (=watersheds) affected assemblages of benthic macroinvertebrates in mainstems, as has been reported in northern hemisphere systems. Eight confluences of small to medium streams (stream orders 1–4, 2.2–10.8 m wide) were studied in the Acheron River basin in Victoria, Australia. For each confluence, two transects were sampled at each of five zones relative to the confluence: two zones upstream in the mainstem, one zone upstream in the tributary, one zone at the confluence and one zone downstream in the mainstem. Surveys were conducted in both high-flow and low-flow conditions. In mainstems, there was no change in macroinvertebrate density, taxonomic richness or functional feeding group composition downstream relative to upstream of the confluences. While tributaries statistically had distinctive benthic macroinvertebrate assemblages compared to mainstems, these distinctions were small. In low flows, densities in tributaries were substantially lower than in mainstems, but densities during high flows were more similar (albeit only about one-third as high as in low flow) in tributaries and mainstems. An inverse pattern was evident for taxonomic richness, where richness in tributaries and mainstems was similar in low flows but was greater in mainstems than in tributaries in high flows. We found little evidence of tributary effects in macroinvertebrate assemblages in this basin, which is at odds with some previous results from other continents. To explain this divergence, we suggest a conceptual model outlining factors that control variation in effects of tributaries on assemblages of benthic macroinvertebrates in mainstems.     

三峡库区不同水文类型支流大型底栖动物对蓄水的响应

为探究三峡水库修建对库区不同水文类型支流大型底栖动物的影响,于2015年7月和2016年1月对三峡水库四条支流的大型底栖动物进行调研,分别对周期性受蓄水影响支流的非回水区与回水区和长期受蓄水影响支流的非回水区与回水区大型底栖动物群落结构进行比较研究,结果表明:⑴7月份三峡水库145米低水位时期共采集到底栖动物655头计59种(属),在受蓄水影响河段采集到底栖动物4种共40头,优势种为日本沼虾(占受蓄水影响区域的57.5%); 1月份三峡水库175米蓄水时期共采集到底栖动物1123头计69种(属),在受蓄水影响河段采集到16种238头,优势种为锯齿新米虾(占受蓄水影响区域的14.2%)。⑵周期性受蓄水影响支流的非回水区与回水区底栖动物密度、生物量和多样性指数无显著差异(P0.05);长期受蓄水影响支流的非回水区与回水区之间底栖动物密度和Pielou均匀度指数无显著差异(P0.05),但非回水区底栖动物生物量显著高于回水区(P0.05),底栖动物多样性和丰富度极显著高于回水区(P0.01)。⑶7月份影响底栖动物分布的主要环境因子共6个,分别是水深、流速、硝态氮、溶解氧、水温和电导率; 1月份影响底栖动物分布的主要环境因子共7个,分别是水温、溶解氧、总磷、流速、深度、电导率和透明度。     

雅鲁藏布江中下游底栖动物物种多样性及其影响因素

雅鲁藏布江流域维系着丰富而独特的生物资源, 是全球生物多样性研究的热点区域。然而, 该流域底栖动物多样性的调查却极不充分。本文于2015年10月和2016年3月对雅鲁藏布江干流(朗县至墨脱段)和主要支流的底栖动物进行了调查, 并采用单因素方差分析(one-way ANOVA)和典范对应分析(canonical correspondence analysis)等对群落多样性格局进行解析。共采集到底栖动物270种, 隶属于5门8纲20目92科, 包括昆虫纲246种, 寡毛纲14种, 腹足纲4种, 其他动物6种。春季和秋季分别采集到底栖动物184种和214种, 优势种均以喜清洁和冷水的水生昆虫为主, 包括四节蜉属一种(Baetis sp.)、花翅蜉属一种(Baetiella sp.)、蚋属一种(Simulium sp.)、小突摇蚊属一种(Micropsetra sp.)和短石蛾属一种(Brachycentrus sp.)等。全流域平均密度为939.1 ind./m²,sp.)等。平均生物量为5.44 g/m²。底栖动物的物种组成、密度和多样性在季节和区域之间存在一定差异, 支流的多样性显著高于干流。典范对应分析显示, 海拔、流速、河宽和底质类型等环境因子是影响雅鲁藏布江流域底栖动物群落结构的关键环境因素, 而大峡谷地区多变的气候类型和地理阻隔是造成群落变化的根本原因。本研究可为雅鲁藏布江流域底栖动物多样性评估和环境监测提供重要的基础和参考。     

Carbon and nitrogen stable isotope ratios of macroinvertebrates in the littoral zone of Lake Biwa as indicators of anthropogenic activities in the watershed

Carbon and nitrogen stable isotope ratios (δ¹³C and δ¹⁵N) of macroinvertebrates inhabiting littoral zones of lakes can serve as useful indicators of material loading from the watershed. We collected snails (Semisulcospira spp.) and bivalves (Unio douglasiae biwae Kobelt) from 29 littoral sites in Lake Biwa near the mouths of river tributaries with various human population density (HPD) and land-use patterns. The δ¹³C and δ¹⁵N signatures were determined for three potential food sources: particulate organic matter in the pelagic zone (PPOM), riverine particulate organic matter from tributaries (RPOM) and epilithic organic matter in the littoral zone (EOM). The stable isotope mixing model revealed that snails relied mainly on EOM, and bivalves on PPOM and RPOM. Multiple regression analysis showed that intersite variation in δ¹⁵N for snails was best explained by HPD, while variation in δ¹⁵N of EOM and nitrate was explained to a lesser extent by HPD. Comparison with isotope signatures of their food sources and riverine nutrients revealed that snails assimilated anthropogenic nitrogen from wastewater in the watershed. Our results also showed that the δ¹³C value of bivalves was marginally related to the fraction of paddy fields in the watersheds. In conclusion, the isotope signatures of macroinvertebrates inhabiting the littoral zone can be useful indicators of anthropogenic impacts from the watershed.     

Microbial and macroinvertebrate communities,but not leaf decomposition,change along a mining‐induced salinity gradient

相似文献   

Cover Image

1. Understanding the role of environmental filtering and spatial processes along environmental gradients in assembling and maintaining aquatic communities in rare habitats is crucial for land management and biological conservation. We investigated the relative roles of environmental and spatial factors influencing beta (β) diversity of aquatic macroinvertebrate assemblages in 36 interdunal wetlands from five freshwater sand dune areas across two ecoregions spanning the latitudinal gradient of Lake Michigan. We hypothesised that aquatic macroinvertebrate diversity and composition would vary along the coastline because of an underlying environmental gradient. We predicted high species replacement correlated with environmental (local and regional) conditions and increasing species diversity with decreasing latitude.
2. We calculated sample completeness, obtained diversity estimates based on Hill numbers and used abundance-based β partitioning and multivariate analysis to examine β diversity, and its replacement and nestedness components in relation to local and regional predictors.
3. Despite a short latitudinal gradient, we detected a significant increase in species richness with decreasing latitude, underpinned by a strong temperature and precipitation gradient. Species replacement (balanced variation in abundance) was high at all spatial scales (wetland, dune area, ecoregion and coastline), and correlated with local and regional environmental variables.
4. Community dissimilarity showed no marked increase with spatial extent, which suggests a system where local-scale environmental filtering prevents dispersal driven homogenisation. Both local and bioclimatic factors were correlated with aquatic macroinvertebrate dissimilarity, but local factors played a larger role.
5. This study simultaneously examined the response of alpha and β diversity to geographical and environmental variables. Our results indicate that macroinvertebrates respond to abiotic factors by tracking suitable environmental conditions among locally variable interdunal wetlands. Thus, high dispersal along the coastline conveys resiliency to a hydrologically dynamic wetland system, which allows aquatic macroinvertebrates to contribute an integral portion of sand dune biodiversity within the Laurentian Great Lakes region. The high species turnover found suggests that conservation strategies should consider coastline connectivity among dune areas to maintain freshwater biodiversity.

     

Seasonal patterns of stream macroinvertebrate communities in response to anthropogenic stressors in monsoonal Taiwan

Freshwater ecosystems are affected by a variety of anthropogenic stressors. Temporal variability of biotic communities in these ecosystems makes it difficult to accurately assess the impacts of specific stressors, which has seldom been considered in understudied regions of Asia. We studied the seasonal effects of anthropogenic stressors on stream macroinvertebrates based on sampling every three months over two years at five stream sites in central Taiwan. Several macroinvertebrate metrics (taxon richness, Shannon diversity index, and relative abundance of Trichoptera) were lower during the wet season than the dry season. The presence of dams caused changes in the structure of macroinvertebrate communities, decreased the seasonal variability in relative abundances of Trichoptera, as well as resulted in lower dissolved inorganic nitrogen concentrations and larger substrate size. The presence of urban areas had less or no influence on environmental factors and structural changes. However, significantly lower total abundance, taxon richness, and relative abundance of Trichoptera occurred in the presence of either dams and/or urban areas. One key management implication from the present study is that bioassessment utilizing macroinvertebrates should be facilitated by awareness of the potential role of temporal factors on the effects of anthropogenic stressors, especially in monsoonal Asia.     

Influence of environmental variables on macroinvertebrate community structure in Lianhuan Lake

The structural characteristics of the macroinvertebrate community can effectively reflect the health status of lake ecosystems and the quality of the lake ecological environment. It is therefore important to identify the limiting factors of macroinvertebrate community structure for the maintenance of lake ecosystem health. In this study, the community composition of macroinvertebrate assemblages and their relationships with environmental variables were investigated in 13 small lakes within Lianhuan Lake in northern China. A self‐organizing map and K‐means clustering analysis grouped the macroinvertebrate communities into five groups, and the indicator species reflected the environmental characteristics of each group. Principal component analysis indicated that the classification of the macroinvertebrate communities was affected by environmental variables. The Kruskal–Wallis test results showed that environmental variables (pH, total phosphorus, nitrate, water temperature, dissolved oxygen, conductivity, permanganate index, and ammonium) had a significant effect on the classification of the macroinvertebrate communities. Redundancy analysis showed that mollusks were significantly negatively correlated with pH and chlorophyll a, while annelids and aquatic insects were significantly positively correlated with chlorophyll a and dissolved oxygen. Spearman correlation analysis showed that the species richness and Shannon''s diversity of macroinvertebrates were significantly negatively correlated with total phosphorus, while the biomass of macroinvertebrates was significantly negatively correlated with pH. High alkalinity and lake eutrophication have a serious impact on the macroinvertebrate community. Human disturbances, such as industrial and agricultural runoff, negatively impact the ecological environment and affect macroinvertebrate community structure. Thus, macroinvertebrate community structure should be improved by enhancing the ecological environment and controlling environmental pollution at a watershed scale.     

The role of macroinvertebrates for conservation of freshwater systems

Freshwater ecosystems are the most threatened ecosystems worldwide. Argentinian‐protected areas have been established mainly to protect vertebrates and plants in terrestrial ecosystems. In order to create a comprehensive biodiverse conservation plan, it is crucial to integrate both aquatic and terrestrial systems and to include macroinvertebrates. Here, we address this topic by proposing priority areas of conservation including invertebrates, aquatic ecosystems, and their connectivity and land uses. Location: Northwest of Argentina. We modeled the ecological niches of different taxa of macroinvertebrates such as Coleoptera, Ephemeroptera, Hemiptera, Megaloptera, Lepidoptera, Odonata, Plecoptera, Trichoptera, Acari, and Mollusca. Based on these models, we analyzed the contribution of currently established protected areas in the conservation of the aquatic biodiversity and we propose a spatial prioritization taking into account possible conflict regarding different land uses. Our analysis units were the real watersheds, to which were added longitudinal connectivity up and down the rivers. A total of 132 species were modeled in the priority area analyses. The analysis 1 showed that only an insignificant percentage of the macroinvertebrates distribution is within the protected areas in the North West of Argentina. The analyses 2 and 3 recovered similar values of protection for the macroinvertebrate species. The upper part of Bermejo, Salí‐Dulce, San Francisco, and the Upper part of Juramento basins were identified as priority areas of conservation. The aquatic ecosystems need special protection and 10% or even as much as 17% of land conservation is insufficient for species of macroinvertebrates. In turn the protected areas need to combine the aquatic and terrestrial systems and need to include macroinvertebrates as a key group to sustain the biodiversity. In many cases, the land uses are in conflict with the conservation of biodiversity; however, it is possible to apply the connectivity of the watersheds and create multiple‐use modules.     

Potential importance of lagoons as breeding grounds for bluegill Lepomis macrochirus in Lake Biwa, Japan

Exotic bluegill Lepomis macrochirus have been propagating in the littoral region of Lake Biwa and its tributary lagoons. To investigate the reproductive activity of bluegill in the prespawning season, fish samples were collected from three sites at the littoral region of the lake and their nearby lagoons. The number of females relative to the total number of specimens tended to be higher in lagoons than in the adjacent littoral sites in the lake. The females collected from lagoons had significantly larger ovaries than those from the lake. The means of gonadal somatic index of females in the lake ranged from 1.77 to 3.44, whereas those in lagoons ranged from 4.35 to 12.2. The higher temperature conditions of lagoons appeared to be responsible for the higher maturation of ovaries of the fish in lagoons. The environmental condition of lagoons is potentially suitable for the active growth of larvae, subsequently increasing their overwintering success. Therefore, earlier spawning of bluegill in lagoons might have contributed to the propagation of bluegill in Lake Biwa to some extent.     

Functional Changes in Littoral Macroinvertebrate Communities in Response to Watershed-Level Anthropogenic Stress

Watershed-scale anthropogenic stressors have profound effects on aquatic communities. Although several functional traits of stream macroinvertebrates change predictably in response to land development and urbanization, little is known about macroinvertebrate functional responses in lakes. We assessed functional community structure, functional diversity (Rao’s quadratic entropy) and voltinism in macroinvertebrate communities sampled across the full gradient of anthropogenic stress in Laurentian Great Lakes coastal wetlands. Functional diversity and voltinism significantly decreased with increasing development, whereas agriculture had smaller or non-significant effects. Functional community structure was affected by watershed-scale development, as demonstrated by an ordination analysis followed by regression. Because functional community structure affects energy flow and ecosystem function, and functional diversity is known to have important implications for ecosystem resilience to further environmental change, these results highlight the necessity of finding ways to remediate or at least ameliorate these effects.     

Intensive removal of signal crayfish (Pacifastacus leniusculus) from rivers increases numbers and taxon richness of macroinvertebrate species

Invasive species are a major cause of species extinction in freshwater ecosystems, and crayfish species are particularly pervasive. The invasive American signal crayfish Pacifastacus leniusculus has impacts over a range of trophic levels, but particularly on benthic aquatic macroinvertebrates. Our study examined the effect on the macroinvertebrate community of removal trapping of signal crayfish from UK rivers. Crayfish were intensively trapped and removed from two tributaries of the River Thames to test the hypothesis that lowering signal crayfish densities would result in increases in macroinvertebrate numbers and taxon richness. We removed 6181 crayfish over four sessions, resulting in crayfish densities that decreased toward the center of the removal sections. Conversely in control sections (where crayfish were trapped and returned), crayfish density increased toward the center of the section. Macroinvertebrate numbers and taxon richness were inversely correlated with crayfish densities. Multivariate analysis of the abundance of each taxon yielded similar results and indicated that crayfish removals had positive impacts on macroinvertebrate numbers and taxon richness but did not alter the composition of the wider macroinvertebrate community. Synthesis and applications: Our results demonstrate that non‐eradication‐oriented crayfish removal programmes may lead to increases in the total number of macroinvertebrates living in the benthos. This represents the first evidence that removing signal crayfish from riparian systems, at intensities feasible during control attempts or commercial crayfishing, may be beneficial for a range of sympatric aquatic macroinvertebrates.     

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。     

安宁河中游底栖动物群落结构及其与环境因子的关系

为了解安宁河底栖动物群落结构及其影响因素, 分别于丰水期(2015年7、8月)和枯水期(2016年1、2月)开展了安宁河中游干支流底栖动物的2次调查, 并于2015年7月至2016年6月进行安宁河支流的周年调查。共检出底栖动物5门115属122种, 其中水生昆虫居多(109种)。干流丰、枯水期底栖动物的密度和生物量都明显低于支流, 丰水期干支流底栖动物的密度和生物量都明显低于枯水期。安宁河支流全年优势种为四节蜉(Baetis sp.)、蚋(Simulium sp.)、高翔蜉(Epeorus sp.)、花翅蜉(Baetiella sp.)、扁襀(Peltoperlidae spp.)和小蜉(Ephemerella sp.)。安宁河支流底栖动物密度以12月最高, 7月最低; 生物量以1月最高, 7月最低。典范对应分析(CCA)分析结果显示, 影响丰水期安宁河底栖动物分布的关键环境因子为底质类型和海拔, 影响枯水期底栖动物分布的主要环境因子为流速、海拔和水温; 影响安宁河支流底栖动物群落结构周年变化的主要环境因子为水温与电导。研究为高海拔地区河流生物多样性研究和保护提供科学参考。     

雅鲁藏布江流域底栖动物多样性及生态评价

雅鲁藏布江起源于喜马拉雅山,是世界上海拔最高的河流之一,是流经我国西藏境内重要的国际河流,其河流生态系统具有特殊地貌及生态条件。研究该流域底栖动物多样性分布特征及其影响因子,是科学评价该区域河流生态系统健康状况,实现资源可持续开发利用的基础。2009年10月—2010年6月期间,以底栖动物作为指示物种,对雅江流域干支流及堰塞湖的14个采样断面进行河流生态评价。采用Alpha及Beta生物多样性指数分别指示局部采样河段及全区域的底栖动物多样性。对采样断面底栖动物组成分析发现:14个采样断面共采集到底栖动物110种,隶属57科102属。雅江干流底栖动物种类数最高为29,平均为19。支流年楚河种类数为17。支流拉萨河,尼洋河,帕龙藏布的最高种类数分别为25,33,36;平均种类数分别为21,21,22,生物多样性普遍高于干流。整个流域中底栖动物平均种类数相差不大,但种类组成和密度相差较大。调查区域的Beta多样性指数β高于低海拔地区的相似的山区河流,说明雅江流域内底栖动物群落差异性高于正常海拔地区。对14个采样断面的物种组成进行除趋势对应分析表明:影响雅江流域底栖动物多样性的主要因素为河型,河床阻力结构,堤岸结构,水流流速。保持稳定的阶梯-深潭结构和自然堤岸结构,以及适宜的流速有利于保护雅江河流生态。     

Stream Macroinvertebrate Community Affected by Point‐Source Metal Pollution

The impacts of mining activities on aquatic biota have been documented in many stream ecosystems. In mining streams, point‐source heavy metal pollution often appears in the stream. We hypothesize that this pollution is toxic to macroinvertebrates owing to high concentrations of metals and therefore affects macroinvertebrate community structure. We investigated macroinvertebrate community structure in mountain streams, including heavy metal‐polluted sites and neutral‐pH streams, to determine the relationship between community structure and environmental factors such as low pH and heavy metal concentrations. Based on multidimensional scaling ordination, the macroinvertebrate community at heavy metal pollution sites was remarkably different from that at the other sites. Inductively coupled plasma mass spectrometry revealed high concentrations of aluminum and iron in surface water at the polluted sites. Macroinvertebrate community structure at the metal pollution sites was significantly different from that at other sites in the same stream and in neutral‐pH streams. Thus, point‐source metal pollution may reduce the density and diversity of in situ macroinvertebrates. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Community concordance between fishes and benthic macroinvertebrates among adventitious and ordinate tributaries of a major river system

We examined patterns of concordance between macroinvertebrate and fish communities among adventitious and ordinate tributaries of the Monongahela River in southwestern Pennsylvania in order to determine their efficacy as mutual surrogates for the assessment of ecosystem integrity. Fish, macroinvertebrates, and 19 water quality parameters were sampled from 20 streams. Collected data were analyzed by principal components analysis, redundancy analysis, and Ward’s distance clustering matrices to determine degrees of community concordance and similarity. Fish and macroinvertebrate communities were assessed utilizing Indices of Biotic Integrity (IBI) in order to compare stream ecosystem health as expressed by each index. Adventitious and ordinate macroinvertebrate communities largely clustered in like groups with adventitious tributaries dominated by the crustacean Gammarus sp. and ordinate streams dominated by the trichopteran, Hydropsyche sp. Adventitious communities were strongly influenced by elevated total alkalinity and total suspended solids; ordinate communities by contrast to elevated total organic carbon and specific conductance. Fish communities showed no significant relationship to water quality parameters among either tributary type, but often grouped with their nearest geographic neighbor. The respective indices revealed a discord between the two communities suggesting that neither community serves as a surrogate for the other as an indicator of stream health in this basin. Both communities appeared to be driven by differences in local environmental conditions.     

Impact of water quality on macroinvertebrate assemblages along a tropical stream in Kenya

Prudent management of lotic systems requires information on their ecological status that can be estimated by monitoring water quality and biodiversity attributes. To understand environmental conditions in Gatharaini drainage basin in Central Kenya, a study was carried out to establish the relationship between water quality and macroinvertebrate assemblages between the months of March and September 1996. Six sampling sites, each 25 m long were selected along a 24‐km stretch of the stream, which drained land under agricultural, residential and industrial use. Water physico‐chemical data was explored using multivariate analysis of Principal Component Analysis to detect environmental trends downstream. Both macroinvertebrates and water physico‐chemical data of suggested trends were analysed for variations and correlations. Temperatures and invertebrate densities changed significantly between the dry and wet season (P < 0.01) but the fluctuations were not evident downstream. Water physico‐chemical characteristics (total dissolved solids (TDS), pH, turbidity, dissolved oxygen) and biodiversity indices (species richness, diversity, dominance, evenness) changed markedly downstream (P < 0.01). Biodiversity indices correlated inversely with TDS, pH and turbidity but positively with dissolved O₂. It was evident macroinvertebrate assemblages changed significantly downstream as opposed to functional feeding groups. Diptera was important in most sites whilst Oligochaeta dominance increased downstream corresponding to the deterioration in water quality. Collectors/browsers were the dominant functional feeding groups at most sites. This study showed that significant changes in aquatic macroinvertebrate assemblages were primarily due to water quality rather than prevailing climatic conditions.     

Response of benthic macroinvertebrates to gradients in hydrological connectivity: a comparison of temperate,subtropical, Mediterranean and semiarid river floodplains

相似文献