Effects of urbanization on streams of the Melbourne region, Victoria, Australia. II. Benthic diatom communities

1. Epilithic and epiphytic diatom community composition were assessed in small streams of the Melbourne region to test the effects of (a) urban density (sub-catchment imperviousness 0–51%) and (b) stormwater drainage intensity (comparing the intensively drained metropolitan area with urban areas of the hinterland, which had open drains and some localized stormwater drainage).
2. Communities separated into three groups: eastern hinterland, western hinterland and a metropolitan group. Separation of eastern and western hinterland groups, and of eastern and western sites within the metropolitan group were best explained by patterns of electrical conductivity, basalt geology and annual rainfall. Separation of metropolitan and hinterland groups, and patterns within the hinterland groups were best explained by nutrient gradients (phosphorus, ammonia and total nitrogen).
3. Nutrient concentrations were not only apparently influenced by urban density but also by effluents from small sewage treatment plants and agricultural activities at a few sites.
4. Species richness did not vary consistently between the metropolitan and hinterland groups but within the western hinterland, sites with low nutrient concentrations tended to be more species-rich than mildly enriched sites.
5. Composition of both diatom and macroinvertebrate communities (assessed in a concurrent study) were sensitive indicators of urban-derived impacts. However, diatoms were better indicators of nutrient enrichment, while macroinvertebrates were better integrative indicators of catchment disturbance.     

Benthic macroinvertebrate distributions in the riffle-pool communities of two east Texas streams

The benthic macroinvertebrate riffle-pool communities of two east Texas streams were sampled monthly for a period of one year. In contrast to previous studies in primarily upland areas, pools in Alazan Creek and Bernaldo Bayou contained significantly higher densities and biomass, as well as a significantly higher diversity and number of taxa. The majority of taxa collected could be characterized as pool adapted organisms, with the Diptera, Ephemeroptera, Coleoptera, and Odonata having greater numbers in pools. Perlesta, Baetis, and Cheumatopsyche were the only genera to have significant numbers in riffles at both sampling sites. A greater number of taxa were restricted to pools at both sampling locations, and although an unstable, sandy substrate was a factor in limiting colonization of riffles, riffles were not as productive as pools even in the presence of suitable substrate conditions. A cluster analysis based on similarity indices indicated that like habitats between streams were more similar to each other, than were adjacent riffle-pool complexes within streams.     

Effects of multiple disturbance on macroinvertebrate communities in the Acheron River,Victoria

In the Acheron River, southern Victoria, patches of riffle substratum (ca 1 m²) were disturbed every 10 days by kicking and raking. After 20 days, i.e. three disturbances, a further set of patches was disturbed once. For the next 70 days macroinvertebrate dynamics were monitored in the two sets of disturbed patches and also in contiguous control patches. There were no differences in the temporal changes in total species richness, number of species per sample, densities of individuals, or species diversity (H’) between the two disturbance regimes. The composition of the fauna colonizing each disturbance regime was similar, and after 33 days the number of species per sample was similar in disturbed and control patches. The fauna appears to be well adapted to physical disturbance and current ideas linking species richness and disturbance cannot be readily applied to stream communities at the temporal and spatial scales of this experiment.     

The organization of macroinvertebrate communities in the major tributaries of the LaTrobe River, Victoria, Australia

SUMMARY.

• 1 Seventeen sites were each sampled six times over 2 years for macroinvertebrates. A range of physicochemical variables was also measured to determine which factors were related to the distribution of species.
• 2 Numerical classification of the faunal data indicated that four groups of sites or communities were distinguishable: lowland sites; sandy upland sites; cobble upland sites from the northern catchment; cobble upland sites from the southern catchment.
• 3 Multiple discriminant analysis and multiple regression analysis demonstrated that particle size of the sediment, concentration of dissolved ions and altitude were the physicochemical features that were most strongly associated with changes in the faunal distribution.
• 4 Abundances of shredders and predators did not vary between the site groups while those of scrapers, gatherers and filterers did: scrapers were most abundant at cobble sites while gatherers and filterers were least abundant on sand and increased in abundance downstream. The distribution of the feeding groups showed some similarity with that predicted by the River Continuum Concept, but the fact that the shredders did not decrease in abundance downstream was a notable difference.
• 5 Abundance of the total fauna at a site was inversely related to the amount of benthic organic matter. This feature is contrary to the pattern usually reported from rivers in the northern hemisphere.

     

Benthic macroinvertebrate communities of the athabasca river near Ft. Mackay,Alberta

Benthic macroinvertebrates were sampled at six stations in the Athabasca River near Ft. Mackay, Alberta, during the 1977 open water season. Fluctuating discharge of the river effected changes in the nature of the sediments as well as the abundance and composition of invertebrate communities. During most of the summer, coarse sand was dominated by chironomids of the Harnischia complex and an undescribed Orthocladiinae. Stoneflies and mayflies invaded the coarse sand in autumn when decreasing discharge led to greater stability of the substrate. The invertebrate fauna of silt and mud resembled that of similar substrates in lakes. Bedrock supported communities similar to those of stony streams. The average abundances of invertebrates on sand and mud were similar but estimates from mud were somewhat more variable. These results are discussed with respect to substrate stability and compared with published records from other large rivers.     

Benthic macroinvertebrate communities of intermittent streams in the middle reaches of the Guadiana Basin (Portugal)

The Guadiana River has an irregular hydrological regime, with severe droughts and floods, but little is known about how aquatic fauna respond to these natural events. Macroinvertebrate data and environmental information were collected at seven sites from three tributaries in the middle reaches of the Guadiana River, approximately every 3 months from April 1995 to April 1997. Despite considerable annual variation in discharge (related to duration of flood and drought periods), the number of macroinvertebrates found was consistently high. Diptera represented the major proportion of the benthic fauna (73.2%) followed by Ephemeroptera (10.3%), Coleoptera (4.1%) and Trichoptera (3.1%). Canonical correspondence analysis (CCA) was used to evaluate the relationships between taxa density and habitat variables. Generally, Plecoptera and Ephemeroptera were found in the upstream sampling sites. Wider and deeper sites were associated with the presence of Diptera and were least diverse. High values for both the Shannon-Wiener diversity index and the average score per taxon were usually found at upstream sites where Ephemeroptera and Plecoptera predominated. The data suggest that macroinvertebrates have a great capacity to recover rapidly from severe drought periods, both in terms of taxonomic diversity and number of individuals.     

Effect of sediment quality on benthic macroinvertebrate communities in streams in the north of France

The Nord/Pas-de-Calais region located in the North of France has been submitted, for several decades, to important pollution due to intensive industrialization. The present study reports on the effects of the metal and organic content of sediments in different streams on the benthic fauna, using multivariate analyses (PCA, CA, co-inertia analysis). Benthic macroinvertebrate communities present different assemblages along the Canal à Grand Gabarit and the river Aa, both in its natural and in its canalized stretches. These differences are more specifically due to anthropic factors such as the regulation of waterways and urban and industrial contamination. Co-inertia analysis enables to bring to the light the existence of a significant co-structure between environmental and faunistic data. This revised version was published online in September 2006 with corrections to the Cover Date.     

Effects of land use on the structure and function of leaf‐litter microbial communities in boreal streams

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The macroinvertebrate communities of streams draining a small granitic catchment exposed to acidic precipitations (Vosges Mountains,northeastern France)

The physico-chemical characteristics and the macroinvertebrate communities of six streams draining a small granitic catchment located in the Vosges mountains (northeastern France) have been studied. Among the streams, five were affected by acidification and characterised by low pH (mean pH: 4.90 to 5.90), low HCO _inf3 ^sup– concentrations (mean concentration: 0–16 µeq l^–1) and elevated aluminium concentrations (mean concentration: 154–278 µg l^–1). Only one stream was typical of waters draining granitic bedrock (mean pH: 6.90; mean aluminium concentration: 79 µg 1^–1; mean HCO _inf3 ^sup– concentration: 152 µeq l^–1).The macroinvertebrates communities of the acidified streams were strongly affected compared to the non-acidified one. Richness, abundance and diversity (Shannon index) were significantly lower when acidification occurred. All the major taxonomic groups were affected, but Molluscs and Ephemeroptera were the most acid-sensitive or organisms, whereas Plecoptera and Oligochaetes were dominant. However, recolonization of acidified streams was possible during summer low flow when the global water quality slightly increased.

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Résumé Les caractéristiques physico-chimiques et les peuplements de macroinvertébrés benthiques de six ruisseaux drainant un bassin versant granitique du massif vosgien ont été étudiés. Parmi les cours d'eau, cinq sont caractérisés par des faibles valeurs moyennes de pH (4.90 à 5.90), et d'alcalinité (HCO _inf3 ^sup– : 0–16 µeq l^–1) et par des concentrations moyennes en aluminium élevées (154–278 µg l^–1) Seul un ruisseau apparaît typique du massif (pH: 6.90; aluminium: 79 g l^–1 et HCO _inf3 ^sup– : 152 µeq l^–1).Les peuplements de macroinvertébrés des ruisseaux acidifiés sont sévèrement affectés. La richesse, l'abondance et la diversité (indice de Shannon) sont alors significativement plus faibles que dans le cours d'eau non acidifié. Tous les groupes faunistiques majeurs sont touchés, mais les Mollusques et les Ephémèroptères sont les organismes les plus sensibles à l'acidification, tandis que les Plécoptères et les Oligochètes sont dominants. Toutefois, il a été mis en évidence une recolonisation possible des rivières acidifiées par certaines espèces, durant la période d'étiage estivale quand la qualité de l'eau s'améliore.

     

The ecology of two intermittent streams in Victoria, Australia. I. Multivariate analyses of physicochemical features

SUMMARY. 1. Amplitudes in physicochemical features in intermittent streams exceed those in nearby permanent streams and strongly influence macroinvertebrate community structure. Hitherto, seasonal variation in the physicochemistry of intermittent streams has been described only anecdotally; there has been no objective attempt to describe phases of flow that could subsequently be compared with patterns in biotic composition.
2. Multivariate techniques of ordination and classification were applied to environmental data collected from pools and riffles at four sites on two intermittent streams in central Victoria during a drought year followed by a wetter year. A cyclical sequence of How phases was usually evident in poo and riffle habitats at all sites over both years: pre-flow, early flow, main flow, diminishing flow and post-flow. Several spates that occurred during the sampling period only briefly distorted the cyclical pattern.
3. No single variable characterized these phases at each site; instead, the phases represented complex combinations of discharge, current velocity, dissolved oxygen, conductivity, water temperature and time-related variables. This highlights the advantages of an integrative, multivariate approach to seek patterns in environmental data, especially since physicochemical features are often highly inter-correlated.     

城市化对森林植被、土壤和景观的影响

用纽约市“城区－郊区－农区”１４０ｋｍ长的森林态样带研究了城市化对森林植被,土壤重金属含量和森林景观的景响,随着距市中心的距离加大,森林植被的类型,种类组成及结构有明显的不同;土壤主要重金属含量逐渐降低。森林景观斑块数量减少,斑块面积在,景观异质性降低,这些变化与交通密度,道路密度,人口密度以及城市土地利用率有显著的相关性。     

城市化对河流大型底栖动物群落的影响研究进展

城市化可以引发一系列"城市溪流综合症",对河流健康造成巨大胁迫。大型底栖动物是河流生态系统的重要组成部分,对环境因子敏感,能够较好的反映流域环境的变化。城市化后,流域人口增加,建设用地比例上升,入河污染物浓度和总量增多,底栖动物中敏感物种比例降低甚至消失,寡毛类、摇蚊等耐污物种成为优势类群;群落多样性显著降低,并且一般与城市化强度成负指数关系;底栖动物总密度普遍大幅度增加,收集者为主要摄食功能群;不透水地表面积比例的增加改变了流域自然的水文过程,群落组成的季节波动减弱,但密度的波动增大;次级生产力明显增加,食物网趋于简化。初步分析了城市化过程中水质污染、水文、生境破坏、流域土地利用等因素影响底栖动物群落的规律和机制,并且根据国内外研究现状提出了进一步研究的方向,以期为我国城市河流生态学研究、流域生态管控和河流生态系统修复提供科学依据。     

A comparison of diatom and macroinvertebrate classification of sites in the Kiewa River system, Australia

Diatoms and macroinvertebrates are both commonly used for biological assessment of stream condition. As the use of biological assessment techniques increases, resource managers will need to make decisions on which biological tool to use for a particular study. In a study of the Kiewa River, Victoria, Australia we assessed these two components of the biota—macroinvertebrates and diatoms—using indices and pattern analysis, and comparing them with an a priori landscape classification. We also assessed the relationship exhibited between the biological results and environmental variables which are usually significant in stream ecosystems. To make the data comparable we used categorical abundances for both data sets. The pattern analyses showed complementary results, with diatoms more closely related to water quality variables, whereas macroinvertebrates were primarily related to catchment and habitat features. An analysis of a combined data set (diatoms plus macroinvertebrates) showed no extra information was gained. Using categorisation to create consistency between data sets was shown to reduce the information and affect results from the diatom analyses. The results suggested that the locally derived bioassessment models and indices provided a more accurate assessment of the sites than the overseas-derived diatom index. The outcomes are complicated by issues of data weighting, whereby a presence/absence diatom index may have performed better than abundance-weighted indices due to strong dominance of one or two species at a site. Future comparisons will benefit from an increase in the knowledge of regional diatom taxonomy and autecology.     

Inter-annual patterns in macroinvertebrate communities of wilderness streams in Idaho, U.S.A.

This study examined the inter-annual variation in macroinvertebrate assemblages in six wilderness streams in central Idaho over a 6-year period (1990–1995). Benthic macroinvertebrates and associated environmental correlates were sampled during baseflow each summer. Little environmental change, as assessed using coefficients of variation (CVs) for substrate size and embeddedness, width, depth and periphyton standing crops, occurred in the streams over the period of study. There was also little temporal change in macroinvertebrate assemblages based on the relative abundance of the 10 most abundant taxa, all shredder taxa and all plecopteran taxa. CVs for individual taxa were substantially greater than those of most community measures, with rare taxa contributing 30–50% of the variation for any one stream. Frequency distributions for taxa CVs excluding rare taxa were more normally distributed. Differences in assemblage structure among streams were attributed to stream size (shift in shredder assemblages) and temperature (shift in plecopteran taxa). These data indicate a long-term (multi-year) persistence in the macroinvertebrate composition of these pristine streams, thus supporting the premise that such streams are excellent references for use in long-term biomonitoring programs.     

Temporal patterns in the stability, persistence and condition of stream macroinvertebrate communities: relationships with catchment land-use and regional climate

1. A spatially‐extensive data set of stream macroinvertebrate communities from 49 northern New Zealand sites sampled over a 10‐year period was analysed to assess relationships between the environment (catchment land‐cover, landscape position and regional‐scale weather patterns), and (i) community persistence and stability based on the constancy of species occurrence (presence–absence) and abundance (per cent composition), respectively and (ii) the temporal variability of various community condition metrics. 2. No significant relationship was evident between community stability or persistence within sites and a gradient of increasing land‐use stress (LUS) based on types of upstream land‐cover, with interannual mean similarities at all sites falling within the standard deviations recorded at long‐term reference sites. In contrast, condition metrics were inversely related to LUS. Land‐use appeared to be a key factor influencing community composition among sites whereas climate influenced stability and persistence within sites. 3. Three response trajectories of community variability to increasing LUS were distinguished based on the coefficient of variation of mean interannual similarities, such that (i) persistence and stability appeared to be more variable at developed sites with low LUS and at sites with high stress relative to the variability experienced naturally, but similar to the natural range at intermediate levels of stress (‘sinusoidal response’); (ii) variability in Ephemeroptera, Plecoptera and Trichoptera metrics increased at low‐to‐moderate stress and then accelerated rapidly at highly developed sites (‘stepped‐exponential response’) and (iii) variability in a pollution tolerance metric increased rapidly and then maintained a similar level of variability along the remaining stress gradient (‘plateau response’). 4. The results of this study have implications for biomonitoring approaches that assume high temporal persistence and stability of communities to define site impairment. Misclassifications caused by interannual variability could lead to misinterpretation of site condition, if conclusions are based on single annual surveys. Temporal variability in stability and persistence may help distinguish low levels of impairment where a predominantly healthy fauna experiences increased environmental fluctuations.     

Classification of macroinvertebrate communities across drainage basins in Victoria, Australia: consequences of sampling on a broad spatial scale for predictive modelling

1. Spatial scale may influence the interpretation of environmental gradients that underlie classification and ordination analyses of lotic macroinvertebrate communities. This could have important consequences for the spatial scale over which predictive models derived from these multivariate analyses can be applied. 2. Macroinvertebrate community data (identified to genus or species) from edge and main-channel habitats were obtained for sites on rivers from 25 of the 29 drainage basins in Victoria. Trends in community similarity were analysed by carrying out separate multivariate analyses on data from the edge habitats (199 sites) and the main-channel habitats (163 sites). 3. Hierarchical classification (UPGMA) showed that the edge data could be placed into 11 site groups and the main-channel data into 12 site groups. 4. Ordination analysis (hybrid multidimensional scaling) showed no sharp disjunctions between site groups in either habitat; overlap was frequent. Correlation of the ordination patterns with environmental variables showed that edge communities varied longitudinally within a drainage basin and from the east to the west of Victoria. These two trends were superimposed on one another to form a single gradient on the ordination. The taxon richness of edge communities was also related to the species richness of macrophytes at a site. Main-channel communities also displayed a longitudinal and a geographic gradient, but these two gradients were uncorrelated on the ordination. 5. Community similarity only weakly reflected geographic proximity in either habitat. A preliminary subdivision of Victoria into a series of biogeographic regions did not match the pattern of distribution of site groups for the edge habitat, illustrating the difficulties of applying to lotic communities a priori regionalizations based on terrestrial features of the landscape. 6. The longitudinal gradients in the two data sets were commonly observed in data gathered at smaller spatial scales in Victoria. The other gradients (geographic, macrophyte), however, were either not consistently repeated or not evident at smaller spatial scales. At small spatial scales (i.e. within a single drainage basin) gradients were related to variables that varied over restricted ranges, e.g. mean particle size of the substratum. 7. Species richness was very variable when plotted against river slope or distance of site from source; both of these are measures of position on the longitudinal gradients. In contrast to suggestions in the literature, species richness did not show a unimodal trend on these gradients, or any other trend. 8. Environmental gradients (apart from longitudinal gradients) that underlie predictive models of macroinvertebrate distribution are reflections of the spatial scale on which the model has been constructed and cannot be extrapolated to different scales. Models must be suited to the spatial scale over which predictions are required.     

Impacts of acidification on macroinvertebrate communities in streams of the western Adirondack Mountains,New York,USA

Limited stream chemistry and macroinvertebrate data indicate that acidic deposition has adversely affected benthic macroinvertebrate assemblages in numerous headwater streams of the western Adirondack Mountains of New York. No studies, however, have quantified the effects that acidic deposition and acidification may have had on resident fish and macroinvertebrate communities in streams of the region. As part of the Western Adirondack Stream Survey, water chemistry from 200 streams was sampled five times and macroinvertebrate communities were surveyed once from a subset of 36 streams in the Oswegatchie and Black River Basins during 2003–2005 and evaluated to: (a) document the effects that chronic and episodic acidification have on macroinvertebrate communities across the region, (b) define the relations between acidification and the health of affected species assemblages, and (c) assess indicators and thresholds of biological effects. Concentrations of inorganic Al in 66% of the 200 streams periodically reached concentrations toxic to acid-tolerant biota. A new acid biological assessment profile (acidBAP) index for macroinvertebrates, derived from percent mayfly richness and percent acid-tolerant taxa, was strongly correlated (R² values range from 0.58 to 0.76) with concentrations of inorganic Al, pH, ANC, and base cation surplus (BCS). The BCS and acidBAP index helped remove confounding influences of natural organic acidity and to redefine acidification-effect thresholds and biological-impact categories. AcidBAP scores indicated that macroinvertebrate communities were moderately or severely impacted by acidification in 44–56% of 36 study streams, however, additional data from randomly selected streams is needed to accurately estimate the true percentage of streams in which macroinvertebrate communities are adversely affected in this, or other, regions. As biologically relevant measures of impacts caused by acidification, both BCS and acidBAP may be useful indicators of ecosystem effects and potential recovery at the local and regional scale.     

Impacts of urbanization on stream habitats and macroinvertebrate communities in the tributaries of Qiangtang River,China

The impacts of watershed urbanization on streams have been studied worldwide, but are rare in China. We examined relationships among watershed land uses and stream physicochemical and biological attributes, impacts of urbanization on overall stream conditions, and the response pattern of macroinvertebrate assemblage metrics to the percent of impervious area (PIA) of watersheds in the middle section of the Qiantang River, Zhejiang Province, China. Environmental variables and benthic macroinvertebrates of 60 stream sites with varied levels of watershed urban land use were sampled in April, 2010. Spearman correlation analysis showed watershed urbanization levels significantly correlated with increased stream depth, width, and values of conductivity, total nitrogen, ammonia, phosphate, calcium, magnesium, and chemical oxygen demand for the study streams. There was significant difference in total taxa richness, Empheroptera, Plecoptera, and Trichoptera (EPT) taxa richness, and Diptera taxa richness, percentages of individual abundances of EPT, Chironomidae, shredders, filterers, and scrapers, and Shannon–Wiener diversity index between reference streams and urban impacted streams. In contrast, percentages of individual abundances for collectors, oligochaeta, and tolerant taxa, and biotic index were significantly higher in urban impacted than reference streams. All the above metrics were significantly correlated with PIA. The response patterns of total taxa richness, EPT taxa richness, and Shannon–Wiener diversity index followed a drastic decrease at thresholds of 3.6, 3.7, and 5.5% of PIA, respectively. Our findings indicate that stream benthic macroinvertebrate metrics are effective indicators of impacts of watershed urban development, and the PIA-imperviousness thresholds we identified could potentially be used for setting benchmarks for watershed development planning and for prioritizing high valued stream systems for protection and rehabilitation.     

Scale and the detection of land-use effects on morphology, vegetation and macroinvertebrate communities of grassland streams

1. Land‐use studies are challenging because of the difficulty of finding catchments that can be used as replicates and because land‐use effects may be obscured by sources of variance acting over spatial scales smaller than the catchment. To determine the extent to which land‐use effects on stream ecosystems are scale dependent, we designed a whole‐catchment study of six matched pairs (pasture versus native tussock) of second‐order stream catchments, taking replicate samples from replicate bedforms (pools and riffles) in each stream. 2. Pasture streams had a smaller representation of endemic riparian plant species, particularly tussock grasses, higher bank erosion, a somewhat deeper layer of fine sediment, lower water velocities in riffles, less moss cover and higher macroinvertebrate biodiversity. At the bedform scale, suspendable inorganic sediment (SIS) was higher in pools than riffles and in pasture streams there was a negative relationship between SIS and the percentage of the bed free of overhanging vegetation. Differences between stream reaches (including any interactions between land use and stream pair) were significant for SIS, substrate depth and characteristics of riparian vegetation. There were also significant differences between replicate bedforms in the same stream reaches in percentage exotic species in overhanging vegetation, percentage moss cover, QMCI (Quantitative Macroinvertebrate Community Index – a macroinvertebrate‐based stream health index) and macroinvertebrate density. 3. Significant differences among stream reaches and among replicate bedform units within the same reach, as well as interactions between these spatial units and land‐use effects, are neither trivial nor ‘noise’ but represent real differences among spatial units that typically are unaccounted for in stream studies. Our multi‐scale study design, accompanied by an investigation of the explanatory power of different factors operating at different scales, provides an improved understanding of variability in nature.