Effects of Mediterranean climate annual variability on stream biological quality assessment using macroinvertebrate communities

Data on macroinvertebrates of selected reference sites were compiled from a long-term monitoring programme carried out in the Mediterranean Catalan Basins (NE Spain) that permitted analysis for nine years, from 1996 to 2004, using a homogeneous data collection procedure. This study aims to analyse the differences in composition and structure of macroinvertebrate communities at family level in five Mediterranean river types, and the values of biological quality metrics (IBMWP and IASPT indices, taxon richness and EPT) in reference conditions. Also differences between seasons (spring vs. summer) and between dry and wet periods were analysed. The dry and wet periods were determined using the Standardised Precipitation Index (SPI). A total of 29 reference sites were selected out of 184 sampling sites analysed, and 171 reference samples were available (from 1996 to 2004), of which 88 were sampled in dry periods, whereas 83 correspond to wet periods. Differences on community composition at family level were appreciated, clustering the rivers in three different groups: (1) rivers with a continuous flow regime located in siliceous zones; (2) rivers with a continuous flow regime located in calcareous zones; and (3) temporary rivers regardless of geology. Moreover, our results explain that the characteristics of hydrological periods (dry and wet) characterize the differences between communities better than just the season. The analysis of four biological quality metrics reveals clear differences between values obtained from dry and wet periods concerning taxon richness, EPT values and IBMWP biological indices, whereas the IASPT index does not show significant differences. The median taxonomic richness in wet periods is 32 macroinvertebrate families per sample while in dry periods this value falls to 22. Reference values of IBMWP index, the total number of taxa, and EPT metric are different between dry and wet periods in spring samples, while these differences are not relevant for IASPT index except for temporary streams. Hydrological specific conditions should additionally be considered in order to better calculate biological reference conditions, and to properly apply biological quality metrics used to establish the ecological status in Mediterranean rivers, especially in temporary ones. The use of the dry–wet period classification according to the climate characteristic results is a more accurate application of the Water Framework Directive in Mediterranean rivers. Implications of future climate change should be also considered from our results.     

Towards diagnostic biotic indices for river macroinvertebrates

The construction of biotic indices that use macroinvertebratesto assess pollution and other anthropogenic disturbances ofrivers and streams often requires that each taxon be assigned anumber indicating its level of sensitivity. A problem inconstructing such indices is that individual taxa may varyquite widely in sensivity, depending on the nature of theparticular disturbance. One possible means of overcoming thisproblem is to construct a suite of indices, each assembledusing sensitivity numbers targeted to a particular impact.In order to test this idea, we sampled macroinvertebrates fromrivers in south-eastern Australia subjected to three differenttypes of anthropogenic disturbance: operation of large dams,discharge of effluent from municipal sewage treatment plants,and contamination by metals originating from historical mining.Using macroinvertebrate data from sampling sites with varyinglevels of exposure to disturbance, we developed sensitivitynumbers for macroinvertebrate families for individual riversand combinations of rivers with the same disturbance type.Sensitivity numbers calculated for individual families differedsignificantly according to disturbance type in several cases.Gastropod molluscs (family Thiaridae) were tolerant of dameffects but sensitive to sewage and metals, whereascoenagrionid damselfly nymphs, elmid beetles and ostracods weremost tolerant of sewage. Corydalid alderfly larvae,leptophlebiid mayfly nymphs, lestid damselfly nymphs,libellulid dragonfly nymphs and scirtid beetle larvae weremost tolerant of metals. Indices constructed using sensitivitynumbers for a particular disturbance were generally mostresponsive to that disturbance, but there was considerablegenerality in responses as well as substantial variabilitybetween different rivers with the same disturbance type. Inparticular, macroinvertebrate communities at sites downstreamof dams responded quite variably, probably because ofsubstantial differences in release regimes. We conclude thatthe approach has merit but requires considerable furtherdevelopment and testing, as well as consideration of the levelsof specificity and diagnostic strength that are appropriate orachievable.     

Assessment of streams of the eastern United States using a periphyton index of biotic integrity

Benthic algae were collected from 272 eastern United States streams and rivers and analyzed for diatom species richness and dominance, the relative abundance of acidobiontic, eutraphentic, and motile diatoms, standing crops of chlorophyll and biomass, and alkaline phosphatase activity. These data were used to calculate a periphyton index of biotic integrity (PIBI), and values of the index were compared among reference, moderately impacted, and disturbed streams. The level of disturbance was based on stream chemistry, riparian disturbance, or a combined classification. Analyses of variance showed that PIBI was significantly higher in reference streams for all classifications. The PIBI and its metrics were correlated with many of the chemistry and habitat variables, and canonical correlation analysis revealed three significant environmental gradients which extracted 84% of the variance in the PIBI and its metrics. We used the mean 75th, 25th, and 5th percentile scores from the reference sites to set thresholds for excellent, good, fair, or poor condition. Applying these criteria to the cumulative distribution of total stream length in the region, we found that 4.3% of the stream length was in excellent condition; 20.8% in good condition; 56.4% in fair condition; and 18.5% in poor condition. The sensitivity of the PIBI and its component metrics to environmental stressors supports the use of this index for monitoring ecological conditions in streams in the eastern United States and as a tool to aid in diagnosing the causes of their impairment.     

EPT昆虫群落分布与环境因子的相关性

为了研究EPT昆虫与水环境因子的相关性,在2006年6-7月和9-10月分季在丹江口水库两条主水源河流上分设5个采样点,对EPT昆虫和水质采样检测。结果共检测到EPT昆虫780头,为12科16种(或种团),水质理化指标7项。简单相关分析与复相关分析都表明,氮浓度、磷浓度、生化需氧量与EPT昆虫密度呈极显著正相关（P<0.01）,与EPT昆虫的种数呈极显著负相关（P<0.01）。典型相关分析表明,EPT昆虫组与环境因子组有极显著的正相关（P<0.0001）,EPT昆虫组主要目为蜉蝣目和襀翅目,环境因子组主要因子为氮浓度、磷浓度、生化需氧量。由此得出：即使在低污染、低营养程度的水环境下,EPT昆虫与环境因子也表现出群体的显著相关性,环境因子对EPT昆虫分布有重要影响。     

Improvement of the ecological water qualification system of rivers based on the first results of the Hungarian phytobenthos surveillance monitoring

Results of an ecological quality ratio-based qualification system, developed on the basis of the analysis of 1,161 benthic diatom dataset of the Hungarian national database, are presented herein. Using Kohonen’s Self Organising Map technique, the 25 Hungarian physiographic river types were pooled into six larger distinct categories (diatom river groups). Diatom metrics were tested for their sensitivity to the targeted stressors (nutrients, COD hydromorphological alteration) in each group. The strongest relationships were found in the case of the IPS, SI and TI indices; therefore the average of these metrics (IPSITI) was proposed as a national multimetric index for Hungarian streams. Based on IPSITI values, the ratio of moderate to worse quality water was the highest in those groups containing small rivers. In the case of large, lowland and mid-altitude rivers with fine sediment, the good and moderate ecological status was more characteristic. Applicability of the IPSITI seems to be very useful in case of small- and medium-sized rivers. For these rivers, the index showed a significant relationship with nutrients and organic pollutants. In the case of very large rivers, the stressor–index relationships were not significant because of the insufficient number of samples and the small range of stressors.     

Multiple‐stressor effects on stream invertebrates: a mesocosm experiment manipulating nutrients,fine sediment and flow velocity

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Towards rapid bioassessment of wadeable streams in Brazil: Development of the Guapiaçu-Macau Multimetric Index (GMMI) based on benthic macroinvertebrates

We developed a multimetric index based on macroinvertebrates to assess ecological condition of wadeable streams in Rio de Janeiro State, southeast Brazil. To do so we used a set of 12 reference and 12 severely impaired sites sampled in the summer wet season as calibration sites. Nine metrics were selected based on their abilities to distinguish between reference and impaired sites and their independence from other metrics. Metrics retained in the final index were: family richness; Trichoptera family richness; Shannon family diversity; % Plecoptera individuals; % Ephemeroptera, Plecoptera and Trichoptera (EPT) individuals; % mollusk and Diptera individuals; % shredder individuals; proportion Chironomidae/Diptera individuals; and proportion Hydropsychidae/Trichoptera individuals. The final 9 metrics were standardized; then the Guapiaçu-Macau Multimetric Index (GMMI) was calculated, yielding a final index score ranging from 0 to 100. We validated the index through use of 19 sites subject to different levels of impairment, sampled both in summer and in winter. Our final multimetric index distinguished well between different levels of impairment and was strongly correlated with other disturbance measures. Temporal stability was also tested through use of 8 sites that were sampled in both seasons, and results showed no significant changes in the index final score among seasons. Our research represents one of the first initiatives in Brazil to develop a multimetric index for use in a spatially extensive bioassessment program extending across substantial natural and disturbance gradients. It can be a useful tool to help conserve streams in Atlantic forest conservation areas. We suggest that the methodology established here offers a foundation for similar index development and assessments in Brazil.     

Development of a regional macroinvertebrate index for large river bioassessment

Large river bioassessment protocols lag far behind those of wadeable streams and often rely on fish assemblages of individual rivers. We developed a regional macroinvertebrate index and assessed relative condition of six large river tributaries to the upper Mississippi and Ohio rivers, Midwest USA. In 2004 and 2005, benthic macroinvertebrates, water chemistry, and habitat data were collected from randomly selected sites on each of the St. Croix, Wisconsin, Minnesota, Scioto, Wabash, and Illinois rivers. We first identified the human disturbance gradient using principal components analysis (PCA) of abiotic data. From the PCA, least disturbed sites showed strong separation from stressed sites along a gradient contrasting high water clarity, canopy cover, habitat scores, and plant-based substrates at one end and higher conductivity and nutrient concentrations at the other. Evaluation of 97 benthic metrics identified those with good range, responsiveness, and relative scope of impairment, as well as redundancies with other metrics. The final index was composed of Diptera taxa richness, EPT taxa richness, Coleoptera taxa richness, percent oligochaete and leech taxa, percent collector-filterer individuals, predator taxa richness, percent burrower taxa, tolerant taxa richness, and percent facultative individuals. Each of the selected metrics was scored using upper and lower thresholds based on all sites, and averaging across the nine metric scores, we obtained the Non-wadeable Macroinvertebrate Assemblage Condition Index (NMACI). The NMACI showed a strong response to disturbance using a validation data set and was highly correlated with non-metric multidimensional scaling (NMDS) ordination axes of benthic taxa. The cumulative distribution function of index scores for each river showed qualitative differences in condition among rivers. NMACI scores were highest for the federally protected St. Croix River and lowest for the Illinois River. Other rivers were intermediate and generally reflected the mixture of land use types within individual basins. Use of regional reference sites, though setting a high level of expectation, provides a valuable frame of reference for the potential of large river benthic communities that will aid management and restoration efforts.     

Development and application of benthic macroinvertebrate-based multimetric indices for the assessment of streams and rivers in the Taihu Basin,China

The development of biological indicators for assessing ecological conditions in streams and rivers is urgently needed in China, particularly in heavily impacted regions. The aim of this study was to develop and apply benthic macroinvertebrate-based multimetric indices (MMIs) for the assessment of streams and rivers in the western hill and eastern plain aquatic ecoregions of the Taihu Basin. MMIs were based on samples collected from October 16 to November 8 2012 at 120 sites in streams and rivers. Least disturbed sites defined the reference conditions. Chemical water quality, physical habitat, and land use were used as criteria to identify reference sites in the basin. Metrics related to benthic macroinvertebrate richness, composition, diversity and evenness, pollution tolerance, and functional feeding groups were screened by range, sensitivity, responsiveness, and redundancy tests. Total number of taxa; percentage of Ephemeroptera, Trichoptera and Odonata (% ETO); Berger–Parker’s index (BP); Biotic index (BI); and percentage of filterers–collectors (% FC) were used to construct the MMI for the western hill aquatic ecoregion (MMI_W). Total number of taxa, percentage of Crustacea and Odonata (% CO), BP, BI, and % FC were used to construct the MMI for the eastern plain aquatic ecoregion (MMI_E). The MMI scores were obtained by combining the rating categories (excellent, good, fair, poor, and very poor). The MMIs were tested using a separate subset of the data, and the results indicated that the newly developed MMIs were robust in terms of percentage of sites correctly classified, coefficient of variation, box-separation ratios, and separation powers. The ecological status was then evaluated based on the MMI scores. The results indicated that the general ecological status of streams and rivers in the Taihu Basin was rated lower than “good”, the western hill aquatic ecoregion was rated “fair” and the eastern plain aquatic ecoregion was rated “poor”. Moreover, the MMIs showed a significant negative response to an increasing gradient of disturbance. Therefore, these preliminary MMIs can be used as assessment tools in ecological biomonitoring and management of the Taihu Basin.     

Ecological response differentials: an alternative benchmark to inform stream and river bioassessment

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Subsidy‐stress and multiple‐stressor effects along gradients of deposited fine sediment and dissolved nutrients in a regional set of streams and rivers

1. Stream managers need to understand relationships between multiple stressors and ecological responses. We examined responses of benthic invertebrates and algae along two land‐use‐related stressor gradients of concern in running waters. Our correlative study of the consequences of augmented deposited fine sediment and nutrient concentrations was conducted in a regional set of streams and rivers monitored by a water management authority in New Zealand and incorporated a wide range of catchment geologies and stream orders. 2. We used multiple linear regression analysis and an information‐theoretic approach to select the best predictive models for our biological response variables by testing multiple competing hypotheses that include nonlinear subsidy‐stress relationships and interactive effects between the two stressors. 3. Patterns consistent with a subsidy‐stress response to increasing dissolved inorganic nitrogen concentration were found for the relative abundances of the common invertebrate genera Pycnocentrodes and Deleatidium and for the relative abundance of total individuals in the EPT orders (Ephemeroptera, Plecoptera, Trichoptera). 4. Fine sediment seemed the more pervasive stressor, apparently counteracting and overwhelming any initial subsidy effect of increased nutrients, and accounting for more of the variance in biological response variables. Relationships with high nutrient concentrations were weaker and modelled with less certainty, probably reflecting the indirect modes of action of nutrients compared to those underlying sediment effects. Nevertheless, in several cases, the models indicated that nutrients interacted synergistically with fine sediment, lending further weight to the conclusion that managers need to address both stressors to achieve the best outcomes.     

A multimetric diatom index to assess the ecological status of coastal Galician rivers (NW Spain)

There are many rivers in northwest Spain as a consequence of the mountainous landscape and the granitic geology subjected to Atlantic influences. Water and epilithic diatoms samples were collected at 72 sites in Galicia flowing into the Atlantic Ocean and Cantabrian Sea in summer 2002–2003 and spring 2004. These sites included minimally disturbed sites, defined as reference sites, and impacted sites which were influenced by different human pressures. We used the diatom assemblages to calculate diatom indices using the Omnidia software, but we also developed new metrics based on the similarity of species composition in reference sites. The response of the metrics was tested in relation to physicochemical variables. We developed a diatom multimetric index (MDIAT) as a combination of metric values. The sensitivity of the MDIAT to organic and nutrient stressors supports the use of this index to classify the ecological status of Galician rivers. The MDIAT showed higher correlations with some variables and nutrients than the individual metrics. According to the MDIAT, 69% of the sites sampled in Galician coastal rivers achieve good ecological status. The MDIAT has been developed specifically for Galician granitic rivers (NW Spain), and has been intercalibrated at the European level in the Central Baltic Rivers GIG. Our study validates the application of this multimetric index to evaluate the water quality in coastal Galician rivers.     

Assessment of temporary streams: the robustness of metric and multimetric indices under different hydrological conditions

The generalization of ecological results from temporary streams needs the study of those ecosystems across a broad scale of running waters, covering the geographical ecological constraints involved (e.g., precipitation, temperature and geology). For the particular situation of Mediterranean streams in Southern Europe, high changes in water level, with unpredicting flood events, represent an important factor determining the structure and function of Mediterranean streams. This variability, inducing accentuated changes in the macroinvertebrate community, tends to influence the assessment methodologies. A set of metrics commonly used in Europe to assess organic degradation (Shannon–Wiener index, evenness, richness, BBI, IBE, BMWP′, ASPT′, DSFI, EPT, number of Trichoptera families, percentage of Gasteropoda, Oligochaeta and Diptera) and a multimetric index (IM9) developed to assess organic degradation in southern siliceous Portuguese basins were tested to evaluate quality at two contrasting sites (one unimpaired and another impaired by an identified point source of pollution). The multimetric index (IM9) composed by: ASPT′ (average score per taxon); GOLD (one minus percentage of Gasteropoda, Oligochaeta and Diptera); and TRICF (number of Trichoptera families), was the most suitable assessment methodology. IM9 presented a quite stable temporal pattern from February in late winter until June in early summer, even under the effect of episodic floods. A stepwise regression showed that most of tested metrics were significantly related to environmental variables (soluble reactive phosphorous, dissolved inorganic nitrogen and dissolved oxygen). Only richness, IBE and BMWP′ were not significantly influenced by environmental variables. Future research must be done covering the complete gradient of organic degradation, including the extension of multimetric assessment methodologies to temporary streams located in other regions under different geological and climatic conditions.     

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。     

城市溪流中径流式低坝对底栖动物群落结构的影响

调查了浙江省安吉县内具径流式低坝的城市溪流(6个样点)和参照溪流(3个样点)的底栖动物群落,目的是了解城市溪流底栖动物群落结构退化规律和径流式低坝(2—3 m)对城市溪流底栖动物群落组成与结构的影响。结果表明,参照样点的底质组成以大石块(35.92%)和卵石(33.66%)为主,城市溪流以砾石为主(57.97%)。城市溪流水温和电导率显著高于参照溪流,TN和TP高于参照溪流。底栖动物总分类单元数和EPT分类单元数显著低于参照溪流。城市溪流河道内水坝上下游之间的流速(P=0.273)和宽深比(P=3.92)无显著差异。坝下游水体中的TP高于坝上游,电导率、溶解氧、pH值和水温在坝上下游之间几乎一致。除BI指数坝下游高于坝上游外,坝上下游间底栖动物总分类单元数、EPT分类单元数以及多样性指数、优势度和均匀度指数没有显著差异。但坝下游的耐污类群比例显著高于坝上游,敏感类群比例则显著低于坝上游。与坝上游相比,坝下游捕食者比例上升和集食者比例下降。NMDS结果进一步表明,城市溪流内水坝的建设导致坝上下游底栖动物群落物种组成明显改变。     

The life cycle of the Maghrebian endemic Ecdyonurus rothschildi Navás, 1929 (Ephemeroptera: Heptageniidae) and its potential importance for environmental monitoring

Limnology - North African streams and rivers face multiple anthropogenic stressors, and their aquatic fauna is rapidly dwindling before comprehensive knowledge of their distribution and ecology has...     

Biodiversity loss in Appalachian headwater streams (Kentucky,USA): Plecoptera and Trichoptera communities

Government and academic studies indicate that many streams in the Appalachian Mountains have degraded biological communities stemming from a variety of regional landuses. Headwater stonefly (Plecoptera) and caddisfly (Trichoptera) assemblages were assessed between 1999 and 2004 in relation to pervasive landuse disturbances (coal mining and residential) in mountainous areas of eastern Kentucky, USA. Indicator metrics (richness, abundance, tolerance, and an observed/expected (O/E) null model) were compared among 94 sites with different land use pressures including least disturbed reference, residential, mining, and mixed mining and residential categories. Thirty-three stonefly species from 26 genera and 9 families were identified; Leuctra, Acroneuria, Haploperla, and Isoperla comprised the core genera that commonly decreased with disturbance. Caddisflies were represented by 48 species, 32 genera, and 14 families. Core caddisfly genera (Neophylax, Pycnopsyche, Rhyacophila, Lepidostoma, and Wormaldia) were extirpated from most disturbed sites. Species richness was significantly higher at reference sites and reference site mean tolerance value was lowest compared to all other categories; relative abundance of both orders was variable between disturbance groups. Non-metric multidimensional scaling (for riffle-dwelling stonefly and caddisfly genera) clustered reference sites distinctly from most other sites. The O/E index was highly correlated with individual habitat and chemical stressors (pH, conductivity) and on average, it estimated ~ 70% loss of common stoneflies and caddisflies across all disturbed landuse categories. Expected plecopteran and trichopteran communities were radically altered in streams draining mining and residential disturbance. Long-term impacts incurred by both landuses will continue to depress these vulnerable indigenous fauna.     

Land use impacts on stream community composition and concordance along a natural stress gradient

Most ecosystems are subjected to multiple stressors derived from natural and anthropogenic sources and community responses to human disturbance in naturally stressful habitats may differ from those in more benign habitats. We examined the influence of a natural (geology-driven acidity) vs. human-induced stress (land drainage) and their interaction on the composition and concordance of stream diatom, bryophyte and invertebrate communities. To account for differing drainage impacts in circumneutral (sedimentation) and naturally acid (reduced pH and increased metal concentrations) streams we investigated concordance in three groups of streams: reference (circumneutral and naturally acidic reference), circumneutral (reference and drained) and naturally acidic (reference and drained) streams. We expected diatoms to respond more strongly to anthropogenic acidification and more weakly to sedimentation compared to bryophytes and invertebrates. We expected overall strong concordance among the three taxonomic groups, but especially so in reference streams. All three organism groups had distinct species composition in naturally acidic vs. circumneutral streams. Concordance between communities was overall strong, especially so in the reference streams. All groups responded to drainage disturbance in both types of streams. Invertebrates were slightly less responsive to increased acidification in the naturally acidic streams but were more affected by sedimentation in the circumneutral streams than were the other two groups. The natural stressor affected communities more than the anthropogenic stressors. Naturally stressed communities were affected by an anthropogenic stressor as much as those in more benign habitats, although the additional stressor was similar to the initial stress (further reduction of stream pH). Naturally acid streams may need special concern in bioassessment because models based on circumneutral reference sites will likely produce biased predictions for these streams.     

Macroinvertebrate-based multimetric predictive models for evaluating the human impact on biotic condition of Bolivian streams

We developed and validated a single multimetric index based on predictive models that could evaluate anthropogenic disturbances in streams of three disparate ecoregions of Bolivia. To do so, we examined 45 candidate metrics reflecting different aspects of macroinvertebrate assemblage structure and function gleaned from available literature and for their potential to indicate degradation. More importantly, we integrated functional trait metrics to improve the sensitivity of our index. To quantify possible deviation from reference conditions, we first established and validated statistical models describing metric responses to natural environmental differences in the absence of any significant anthropogenic disturbance. We considered that the residual distributions of these models described the response range of each metric, independently of natural environmental influence. After testing the sensitivity of these residuals to a gradient of anthropogenic disturbance, we retained eight metrics that were used in the final assemblage index, four metrics based on richness and composition and four metrics based on biological traits. Our index performed well in discriminating between reference and disturbed sites, giving a significant negative linear response to a gradient of physical and chemical anthropogenic disturbances. After employing a probability survey design and sampling a relatively small number of sites throughout all major ecoregions of Bolivia, we believe our methodology can be used to develop a monitoring tool to evaluate status and trends in biological condition for streams of the entire country despite its complex and heterogeneous geology and climate.