Persistence and stability of lotic invertebrate communities in New Zealand

1. Persistence and stability of lotic invertebrate communities were determined at an annual time scale over a 9‐year period (1990–98) at 26 river sites over the northern half of New Zealand. In addition, a number of water quality variables were measured monthly and flow information collected continuously over the same period at each site. 2. The aim of the study was to describe the levels of interannual variability in invertebrate communities, and relate community changes to variability in environmental conditions. The consequences of this temporal variability for the sensitivity of predictive models were also investigated. 3. Levels of change in environmental conditions varied significantly between years, but were relatively similar across sites. In contrast, community persistence (similarity between years in species assemblage composition), and stability (similarity between years with respect to relative abundance of species in the community) both varied significantly between sites, but changes between years were similar. Community stability was highest at sites with relatively harsh flow conditions (high coefficient of variation, high relative size of floods), and was also greater in communities dominated by Ephemeroptera. 4. Relationships between change in environmental conditions and changes in community composition and structure were relatively weak for most individual sites. However, when average levels of change for each of the 26 sites were used, communities showed greater persistence under conditions where flow conditions remained relatively constant. Water quality changes had no significant effect on community persistence when assessed for all 26 sites combined. 5. Results from this study suggest that lotic invertebrate communities fluctuate around a relatively stable state, at least over a 9‐year period. However, the extent of interannual variation in community composition and structure observed, along with the relatively low degree of cluster fidelity observed within a single region, suggests that predictive models based on reference site conditions extrapolated over several years should be applied with caution in New Zealand streams.     

Seasonal shifts in the assembly dynamics of benthic macroinvertebrate and diatom communities in a subtropical river

Identifying seasonal shifts in community assembly for multiple biological groups is important to help enhance our understanding of their ecological dynamics. However, such knowledge on lotic assemblages is still limited. In this study, we used biological traits and functional diversity indices in association with null model analyses to detect seasonal shifts in the community assembly mechanisms of lotic macroinvertebrates and diatoms in an unregulated subtropical river in China. We found that functional composition and functional diversity (FRic, FEve, FDis, MNN, and SDNN) showed seasonal variation for macroinvertebrate and diatom assemblages. Null models suggested that environmental filtering, competitive exclusion, and neutral process were all important community assembly mechanisms for both biological groups. However, environmental filtering had a stronger effect on spring macroinvertebrate assemblages than autumn assemblages, but the effect on diatom assemblages was the same in both seasons. Moreover, macroinvertebrate and diatom assemblages were shaped by different environmental factors. Macroinvertebrates were filtered mainly by substrate types, velocity, and COD_Mn, while diatoms were mainly shaped by altitude, substrate types, and water quality. Therefore, our study showed (a) that different biological assemblages in a river system presented similarities and differences in community assembly mechanisms, (b) that multiple processes play important roles in maintaining benthic community structure, and (c) that these patterns and underlying mechanisms are seasonally variable. Thus, we highlight the importance of exploring the community assembly mechanisms of multiple biological groups, especially in different seasons, as this is crucial to improve the understanding of river community changes and their responses to environmental degradation.     

Long-term recovery from mine drainage disturbance of a macroinvertebrate community in the Ichi-kawa River,Japan

The effects of mine drainage on a benthic macroinvertebrate community and its recovery have been investigated for 25 years in the Ichi-kawa River in western Japan, focusing especially on change in community structure. Concentrations of arsenic, copper and zinc in the water were distinctly higher at sites just below the drainage than an upstream reference site before mine closure in 1973. Benthic communities there were severely damaged, as evidenced by reductions in the number of families and biomass. Chironomidae and a mayfly, Epeorus latifolium, predominated at the impacted sites, whereas stenopsychid caddisflies were dominant at the reference site. After mine closure, zinc concentrations significantly decreased downstream, although they remained higher than at the reference site. Following this, family richness and biomass of benthic communities clearly increased. In addition, the percentage of Trichoptera increased and, finally, Stenopsychidae became the dominant family in 1996 at all sites except just below the drainage. Therefore, the dominance of Stenopsychidae at the impacted sites is expected to be an indicator of complete recovery of the benthic community from the effect of mine drainage.     

Comparative study of monitoring South-Finnish rivers and streams using macroinvertebrate and benthic diatom community structure

In southern Finland, most of the rivers are turbid and suffer from eutrophication and leaching of suspended solids from diffuse sources. We first related benthic diatom and macroinvertebrate structure to environmental factors using direct ordination. Second, benthic diatoms and macroinvertebrates were simultaneously sampled in several South-Finnish rivers and streams to compare two monitoring methods. The study sites constituted of some large, moderately nutrient rich rivers and some smaller, less eutrophic streams situated on the south coast of Finland. Diatom species distribution was most affected by conductivity, total P and latitude. Species distribution of macroinvertebrates was mostly related to channel width, conductivity and pH. For diatoms, separation of community structure between sampling stations was clear, but corresponding macroinvertebrate communities were more similar to each other. Correlation between diatom and macroinvertebrate pollution indices was rather low and insignificant (r = 0.28). As a whole, variation of macroinvertebrate index values (CV = 4.7%) among replicate samples was slightly lower than for diatom index (CV = 6.0%). On the contrary, community similarity between the replicate samples was slightly lower among macroinvertebrates (r = 0.770) due probably to their larger local scale spatial variation, sampling of more habitats and lower density compared to diatoms (r = 0.874). In conclusion, multiple pressures affecting the river ecosystems at different spatial and temporal scales should lead to choosing more than one biological monitoring method with clearly identifiable responses.     

Surber and kick sampling: a comparison for the assessment of macroinvertebrate community structure in streams of south-western Australia

Macroinvertebrate community structure was compared in benthic samples taken by Surber and kick methods from a lotic system in south-western Australia. Eleven sites were sampled concurrently in winter, spring and summer 1987.Surber samples contained fewer individuals and more taxa, particularly those with a low frequency of occurrence. This was attributed to the lower surface area, but greater intensity of Surber sampling. It is proposed that the Surber method is more suited to taking cryptic and closely adherent taxa in sites with a highly heterogeneous substratum.Percentage similarity between paired Surber and kick samples was determined by Sorensen's and Czekanowski's coefficients, with mean values of 66% and 60% for June, 61% and 49% for September and 66% and 49% for December respectively. Ordination demonstrated a division of upland from lowland sites on axis 1, with a separation of paired-samples on axis 2. This pattern held across qualitative and quantitative datasets, with and without a downweighting on rare taxa. At each level of classification fewer paired-samples separated in qualitative than quantitative datasets.Kick sampling provided a substantial saving in costs over Surber sampling, particularly when qualitative data were utilised, making the method suitable for routine, biological monitoring. However, the initial use of replicated Surber sampling, particularly in areas that have not been previously sampled is recommended for environmental impact studies to detect rare taxa, that may be endangered.     

Pond permanence is a key determinant of aquatic macroinvertebrate community structure in wetlands

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大型无脊椎动物群落指数和群落数量指数在河流水质评价中的应用

本文介绍了新西兰常用的大型无脊椎动物群落指数(MCI)和大型无脊椎动物群落数量指数(QMCI)的原理及使用方法,并利用MCI和QMCI对新西兰惠灵顿地区40条河流53个监测点进行评价.结果表明:MCI和QMCI均与河流营养指标呈极显著相关关系,可用来监测和评价水体的营养污染状况;二者快速准确地监测出惠灵顿地区河流水质总体良好,但部分河流污染严重,并分析了污染的原因.MCI与QMCI存在极显著相关关系,但MCI与营养指标间的相关关系大于QMCI,可以准确地反映出水体中营养元素的富集状况.     

Species turnover in lake littorals: spatial and temporal variation of benthic macroinvertebrate diversity and community composition

Aims Despite wide consensus that ecological patterns and processes should be studied at multiple spatial scales, the temporal component of diversity variation has remained poorly examined. Specifically, rare species may exhibit patterns of diversity variation profoundly different from those of dominant taxa. Location Southern Finland. Methods We used multiplicative partitioning of true diversities (species richness, Shannon diversity) to identify the most important scale(s) of variation of benthic macroinvertebrate communities across several hierarchical scales, from individual samples to multiple littorals, lakes and years. We also assessed the among‐scale variability of benthic macroinvertebrate community composition by using measures of between‐ and within‐group distances at hierarchical scales. Results On average, a single benthic sample contained 23% of the total regional macroinvertebrate species pool. For both species richness and Shannon diversity, beta‐diversity was clearly the major component of regional diversity, with within‐littoral beta‐diversity (β₁) being the largest component of gamma‐diversity. The interannual component of total diversity was small, being almost negligible for Shannon index. Among‐sample (within‐littoral) diversity was related to variation of substratum heterogeneity at the same scale. By contrast, only a small proportion of rare taxa was found in an average benthic sample. Thus, dominant species among lakes and years were about the same, whereas rare species were mostly detected in a few benthic samples in one lake (or year). For rare species, the temporal component of diversity was more important than spatial turnover at most scales. Main conclusions While individual species occurrences and abundances, particularly those of rare taxa, may vary strongly through space and time, patterns of dominance in lake littoral benthic communities are highly predictable. Consequently, many rare species will be missed in temporally restricted samples of lake littorals. In comprehensive biodiversity surveys, interannual sampling of littoral macroinvertebrate communities is therefore needed.     

Species aggregation: the influence of detritus in a benthic invertebrate community

Species aggregation with detritus was examined in a zoobenthic stream community. Detritus was quantified (dry weight in particle size categories) in contiguously arranged quadrats along four transects within a 40m stream section. Total organism density was found to be positively related to increasing detrital biomass (dry weight) in all transects, although the magnitude of this association was influenced by the detrital particle size distribution in each quadrat. Eliminating certain particle size categories of detritus resulted in substantial changes in the magnitude of association. For example, in one transect, total organism density and total detrital biomass showed no association. However, when one particle size category (greater than 10 mm) was removed a highly significant relationship was found. Total detrital biomass was found to be a useful predictor of organism distribution, however, inordinately high detrital biomass and variance within larger particle size categories can mask a relationship. This result suggests that the use of discrete size categories is necessary when considering species/ detrital relationships.Significant associations were found between the density of particular species and total biomass of detritus. The magnitude, as well as significance, of these associations were found to vary when correlations were calculated with restricted particle size categories of detritus. Species associations were often not consistent between transects, possibly due to local characteristics of detritus or overriding environmental factors. Current velocity was found to be unimportant in determining the detrital biomass held in the substrate. Likewise, few associations were found between current velocity and organism density in three out of four transects. Results of this study suggest that habitat selection by some taxa is influenced by local variation in detrital biomass, as well as detrital particle size composition.     

Effects of stream-crossing by a pipeline on the benthic macroinvertebrate communities of a small mountain stream

Aquatic environmental impact associated with stream-crossing by a pipeline was monitored at Archibald Creek, B.C. for two years. Water chemistry and benthic macroinvertebrates were used as monitoring tools. Results indicated that impacts arising from stream-crossing were short-term and non-residual.Funded by a contract from Canadian Arctic Gas Study Limited, calgary, to Aquatic Environments Limited, Calgary.Aquatic Environments Limited, Calgary.Aquatic Environments Limited, Calgary.     

Habitat complexity as a determinate of benthic macroinvertebrate community structure in cypress tree reservoirs

We analyzed benthic samples (n = 128) collected from four cypress-tree population areas within a large, shallow Arkansas reservoir over a 2-year period to investigate macroinvertebrate community distribution patterns and their relation to physical and chemical parameters. The calculated biomass, abundance and diversity of the benthic macroinvertebrate community varied significantly both temporally and spatially. Variations of these variables are most likely explained by significant differences in the concentration of carbon and nitrogen in sediments across lake sites, and on a smaller scale, the presence or absence of cypress trees. Benthic macroinvertebrate abundance, biomass, and diversity significantly decreased with distance from tree.     

Local disturbance history affects patchiness of benthic river algae

1. Recent research has shown that high‐flow events in streams leave a small‐scale mosaic of bed patches that have experienced scouring, sediment deposition (fill), or remained stable. Few studies have investigated if this ‘local disturbance history’ contributes to the patchy distribution of benthic organisms in streams and rivers. 2. In the present research, we demonstrate that local disturbance history in a mid‐sized river can have both short‐ and long‐term effects on epilithic algae. Chains buried vertically in the substratum of the river bed (236 in a 800‐m reach) indicated that two floods (return periods ≤1 year) caused a mosaic of bed patches with different disturbance histories. Once after the first and twice after the second flood, we sampled epilithic algae (mainly diatoms) in replicate patches that had been scoured, filled, or remained stable during the respective event. Algal biomass and cell density per substratum area were determined. 3. Three months after the first flood, algal biomass, total diatom density, diatom taxon richness, and densities of six of nine most common taxa were highest in fill patches. Six days after the second flood, biomass was highest in stable patches, indicating a refugium function of these patches. The refugium patches consisted of average‐sized stones, in contrast to previous studies of flood refugia for benthic algae in which these refugia were always large and/or immobile substrata. Four weeks after the second flood, diatoms tended to be most abundant in scour patches. With one exception, these differences between patch types could not be attributed to differences in local near‐bed current velocity or water depth. 4. The effects of disturbance history were more complex than a simple refugium function of stable patches because algal patterns changed with time since the last disturbance, possibly depending on the successional state of the algal mats.     

Lotic meiofaunal community dynamics: colonisation, resilience and persistence in a spatially and temporally heterogeneous environment

1.  The spatial and temporal dynamics of lotic meiofaunal communities were examined with a focus on colonisation, maintenance of populations in lotic environments and persistence of meiofaunal communities.
2.  Lotic meiofaunal colonisation of new habitats may take place via a number of mechanisms and is rapid at both the patch scale (within hours–days) and the drainage basin scale (within 20 years). Successional patterns in lotic meiofaunal communities are evident although data are extremely limited.
3.  Lotic meiofaunal communities appear to be resilient to high flow disturbances. Resilience is moderated by the availability of in-stream refugia and habitat hydrology. Lotic meiofauna may also adopt a 'refuge as habitat' approach to such disturbances.
4.  Lotic cyclopoid copepods possess a common suite of life history characteristics that confers resilience to disturbances. Compared to pelagic planktonic species they have short generation times, many descendants per reproductive cycle and long lifespans. Females in 'source' populations are likely to survive disturbances and so could continuously reproduce over a long period of time producing large numbers of offspring which develop rapidly and recolonise 'sink' areas of the stream.
5.  Persistence of lotic meiofaunal communities is highly variable. Meiofaunal persistence does not increase with increasing proportions of in-stream flow refugia.     

Effects of pulsed and pressed disturbances on the benthic invertebrate community following a coal spill in a small stream in northeastern USA

In September 1999, a coal-carrying train derailed and spilled 180,000–270,000 kg of coal into the Cayuga Inlet near Ithaca, New York. This study determined the immediate effects of the coal spill and the clean up procedures on the aquatic invertebrate community, and whether the stream recovered from this event after 2 years. Benthic invertebrate samples were taken both upstream and downstream of the coal spill immediately following clean-up efforts and two years later. Just after the coal spill, the total abundance and species richness of aquatic invertebrates were significantly lower downstream of the spill, suggesting that the disturbance caused increased mortality and/or emigration compared to a reference site upstream. Taxa affected most were grazers and turbidity-susceptible invertebrates. Two years later the invertebrate communities were similar upstream and downstream of the spill, except for an increase in the percent of the dominant genus, Hydropsyche(Trichoptera: Hydropsychidae). We speculate that long-term effects of channelization of the stream that occurred during the clean-up prevented the invertebrate assemblage from returning to the conditions observed in a reference site upstream of the coal spill. We propose that large scale environmental clean-ups should be designed to avoid altering ecosystems permanently, and that streams should be allowed to recover naturally without destructive human intervention.     

Diversity as a measure of benthic macroinvertebrate community response to water pollution

The assumption that water pollution causes a depression in the diversity of benthic macroinvertebrates as measured by the Shannon index and similar diversity indices is questioned. An interpretation of the community response of benthic macroinvertebrates to pollution in the Millers River, Massachusetts is developed from species presence-absence and abundance data in conjunction with published information on the species' environmental tolerances as compared to chemical water quality data. This interpretation is compared with one derived solely from diversity index values. The interpretations are quite different; the differences may be attributed to other environmental factors such as impoundments and flow reductions which influence the fauna and thus the diversity index value, but which are not related to pollution. In addition, several intrinsic features of the diversity indices increase their bias.Contribution No. 47 of the Massachusetts Cooperative Fishery Unit jointly supported by the U.S. Bureau of Sport Fisheries and Wildlife, the Massachusetts Division of Fisheries and Game, the Massachusetts Division of Marine Fisheries, and the University of Massachusetts.     

Revitalization of a northcentral Texas river,as indicated by benthic macroinvertebrate communities

Macrobenthic communities were surveyed in 1987–88 as part of acomprehensive study of fish kills and water quality in the upper TrinityRiver. The purpose was to characterize macrobenthic integrity in relation toambient and storm-associated water quality and other environmental factors.No physical habitat features were found to be substantially limiting toaquatic life. Water and sediment quality generally were good, andmacrobenthic communities typically were healthy. Ecological conditions werevastly improved compared to the recent past, attributable mainly todecreased contaminant loading from wastewater treatment plants and reducedincidence of raw sewage bypassing. Nonetheless, some impact was evident incertain reaches. Deleterious effects at Beach St. evidently resulted frompesticides derived from urban runoff. Slight impacts by dissolved metalswere suggested for Grand Prairie and Continental Ave.; possible sourcesincluded urban runoff and wastewater treatment plant effluents. Moderateimpacts at S. Loop 12 were attributed to low-flow toxicity induced by awastewater treatment plant discharge; ammonia and chlorine were consideredprimarily responsible, with metals and pesticides possibly involved.Macrobenthic communities were somewhat degraded from Trinidad to US 79, dueto storm-related stresses by DO depression, pesticides, and metallic oxides.Overall impacts were relatively slight on a long-term basis, however, and ahigh aquatic life use was attained at most sites. The degree of macrobenthicintegrity was considered remarkable for an effluent-dominated system withsuch extensive urbanization in the watershed.     

Seasonal variation in benthic invertebrate recolonization of small-scale disturbances in a subtropical Florida lake

Approximately 11.5% of the littoral zone of a hypereutrophic Florida lake is disturbed by the construction of spawning beds by the cichlid fish, Sarotherodon aurea, during a single spawning season. Simulations of these beds were created during three seasons of the year to test for variation in recolonization rates and patterns in the benthic macroinvertebrate community.The seasonal variation in densities of benthic invertebrate populations suggests a direct relationship between reproductive activity and recolonization rate. Recolonization rates of the numerically dominant species, Polypedilum halterale (Diptera: Chironomidae), were much more rapid in the spring and summer than in the winter. In contrast, Hyalella azteca and Glyptotendipes paripes attained peak population densities during the winter season when Polypedilum was present in low densities. These organisms invaded the disturbed area in unusually high abundances and later declined to background levels. The final result was a winter population with densities comparable to the control (undisturbed) area, but the species composition was different.Similarity between disturbed and control communities during the winter season only reached 67% a month after disturbance, while communities during the warmer months attained nearly 90% similarity in less than 15 days. This lack of similarity during the winter indicates that disturbance, at the appropriate time, may play a role in community organization.     

Trends of macroinvertebrate community structure in glacier-fed rivers in relation to environmental conditions: a synthesis

1. Generalized additive models (GAMs) were used to predict macroinvertebrate taxonomic richness and individual taxon diversity at the reach level across seven European glacier-fed river sites from a set of 11 environmental variables. Maximum water temperature and channel stability were found to explain the most deviance in these models.
2. Using this information, and data from other recent studies of glacier-fed rivers, a modified conceptual model based on Milner & Petts (1994) is presented which predicts the occurrence of macroinvertebrate families and subfamilies as determined by maximum water temperature ( T _max) and channel stability. This deterministic model only applies to the summer meltwater period when abiotic variables drive community structure.
3. Where maximum water temperature is below 2 °C, Diamesinae chironomids are typically the sole inhabitants, but where T _max >2 °C but <4 °C Orthocladiinae are found and, where channels are more stable, Tipulidae and Oligochaeta also occur. Above 4 °C Perlodidae, Taeniopterygidae, Baetidae, Simuliidae and Empididae can be expected to be part of the glacier-fed river community, particularly in Europe.
4. At other times of the year when environmental conditions ameloriate, glacial rivers support higher macroinvertebrate abundance and diversity, with a number of taxa present that are not found during the summer melt period.
5. Dispersal constraints influence macroinvertebrate assemblages of many glacier-fed rivers located on islands and in some alpine areas.     

Individual and combined effects of fish predation and bed disturbance on stream benthic communities: a streamside channel experiment

1. The composition and spatiotemporal dynamics of biological communities are influenced by biotic processes, such as predation and competition, but also by physical disturbances, such as floods in running waters. However, the interplay of disturbance with predation is still poorly understood, especially in frequently disturbed streams. Further, different predator species can affect prey communities in different ways depending on their feeding mode and efficiency. 2. We investigated the individual and combined effects of flood‐induced bed disturbance and fish predation on the benthos for 4 weeks in 18 streamside channels fed by a flood‐prone New Zealand river. Bed movements caused by floods were simulated by tumbling the substratum in half the channels. Six channels each were stocked with introduced brown trout (Salmo trutta) or native upland bully (Gobiomorphus breviceps) or had fish excluded. We studied algal biomass and both invertebrate density and daytime activity on surface stones on several dates after the disturbance, invertebrate community composition in the substrata of the entire channels on day 28 and leaf decomposition rates over the 28‐day period. 3. Disturbance affected algal biomass and density, richness and activity of surface stone invertebrates, and overall density and richness of channel invertebrates. Presence or absence of fish, by contrast, did not influence overall invertebrate standing stocks when subsurface substrata were included but did affect invertebrate densities on surface stones in 45% of all analysed cases and invertebrate activity on surface stones in all cases. Leaf decomposition rates were not influenced at all by the experimental manipulations. 4. Native upland bullies featured more often than exotic brown trout in causing invertebrate density changes and equally often in causing changes to grazer behaviour. Overall, our results imply that fish predation can have strong effects on the benthic invertebrate community in frequently disturbed streams, especially via behavioural changes.     

香溪河大型底栖无脊椎动物群落结构季节动态研究

研究香溪河大型底栖无脊椎动物群落结构和季节动态特征情况,发现高翔蜉、萝卜螺、河蚬、湖沼股蛤、四节蜉为香溪河水系优势分类单元,各季节底栖动物优势种的组成存在显著差异。冬季的生物密度、生物量、生物多样性指数显著高于其他季节,说明冬季的河流生境最适宜大型底栖无脊椎动物生存。香溪河刮食者丰度最高,撕食者最低,表明香溪河着生藻类丰富;固着型底栖动物在香溪河底栖类群中丰度最高,说明香溪河河流流速较快,生境更适宜固着型动物栖居。不同季节环境因子对大型底栖动物群落结构有显著影响。