Potential Impacts of Stream Crossing Traffic On Macroinvertebrate Communities in the Missouri Ozark River

Depending on intensity, physical disturbance can either decrease or increase diversity of stream macroinvertebrate communities. Recreational activities in parks are one component of physical disturbance. Our objective was to evaluate the effects of stream crossings and recreational traffic on macroinvertebrate assemblages. Five stream‐crossing sites were sampled during winter and summer in the Current River, Ozarks National Scenic Riverways, Missouri, USA. Stream‐crossing traffic was assessed using trail cameras. At each site, macroinvertebrates were collected from four locations: riffle upstream of crossing, riffle immediately downstream of crossing and second and third riffles downstream of crossing. We compared sites and locations within sites using standard metrics (taxa richness, Ephemeroptera, Plecoptera and Trichoptera richness, biotic index and diversity) and their composite stream condition index (SCI) plus multivariate analyses (Nonmetric multidimensional scaling and correlations). Stream crossings had no detectable impacts on macroinvertebrate communities in winter, but in summer location, effects were present. Patterns in SCI scores across locations varied among sites, with no consistent declines in macroinvertebrate diversity downstream of crossings. Longitudinal stream effects dominated over potential stream‐crossing effects on macroinvertebrate communities. Overall, high SCI scores indicated that current levels of stream crossings and traffic in this scenic riverway do not pose a threat to macroinvertebrate communities at the spatial and temporal scale of this study. Copyright © 2015 John Wiley & Sons, Ltd.     

Ecological effects of flow regulation on macroinvertebrate and periphytic diatom assemblages in the Hawkesbury–Nepean River,Australia

The effects of flow regulation on macroinvertebrates and periphytic diatoms were examined in the Hawkesbury–Nepean River system in Australia. Regulated sites below eight dams or weirs were compared with unregulated sites above the impoundments and sites on two nearby unregulated streams. The management of the water supply during the study created two types of flow regulation, sites with water supply releases and sites with comparatively small or no releases. The macroinvertebrate communities in three habitats and periphytic diatoms below the storages and weirs differed from the biota at unregulated sites above the weirs and on unregulated systems. The number of macroinvertebrate taxa in riffle and pool‐rock assemblages was significantly lower at regulated sites when compared with unregulated sites and the number of stream edge macroinvertebrate and diatom taxa was unaffected by regulation. Riffle and pool‐rock macroinvertebrate assemblages differed between the two types of regulation. However, periphytic diatom and edge habitat macroinvertebrate assemblages did not differ between the two types of flow regulation. Examination of environmental variables associated with the change in the biota suggested that the principal effect of the management of the water supply system in the Hawkesbury–Nepean River was changed hydrology rather than altered water quality. Copyright © 2001 John Wiley & Sons, Ltd.     

AN ECOLOGICAL STUDY OF A REGULATED PRAIRIE STREAM IN WESTERN MONTANA

Longitudinal and seasonal changes in biophysical variables were examined in this seminal study of an intermountain (Palouse) prairie stream. Hypolimnial releases from an irrigation reservoir controlled discharge, temperature and other habitat variables, thereby influencing distribution and abundance of zoobenthos. Dramatic changes in turbidity and nutrient concentrations occurred during the spring runoff and summer irrigation periods and following wind-driven sediment resuspension in the reservoir. Seasonal changes in the relative dominance of certain macroinvertebrate taxa were correlated with physical and chemical dynamics. Based on detrended correspondence analysis (DCA), specific conductance, temperature, dissolved oxygen and nitrates + nitrites were the variables most associated with seasonal macroinvertebrate biomass. Changes in taxa composition downstream from the dam were mainly related to species additions from site to site. Changes in pH and substratum were associated with longitudinal changes in biomass. For instance, the observed bimodal distribution of Cheumatopsyche sp. was correlated with percentage boulder substratum among the sites. On the other hand, DCA performed on macroinvertebrate densities emphasized pH, total ammonia, discharge and substratum. Species composition throughout the prairie segment of the stream was very different from that in the mountain canyon segment. The effects of regulation ameliorated significantly in a downstream direction from the dam. Presence of warm water species (e.g. Helicopsyche sp.) upstream and downstream of the reservoir were indicative of the native stream fauna of the intermountain prairies. Faunal responses to the ‘recovery’ gradient downstream from the dam provided a basis for the development of remedial management actions.     

Mitigation of impacts of cattle access on stream ecosystems: Efficacy of fencing

Headwater streams can constitute up to 80% of river channel length and are vulnerable to anthropogenic pressures due to their high connectivity to adjacent land, large relative catchment size and low dilution capacity. In these environments, unrestricted cattle access is a potentially significant cause of water quality deterioration, resulting from increases in stream bank erosion, riparian damage and sediment deposition among others. Several studies have reported improvements in the physico-chemical and hydromorphological conditions of streams following the elimination of cattle access; few, however, have focussed on the ecological impacts of such management practices. Here, such impacts are assessed. The study explores the short-term effects of cattle exclusion by comparing habitat conditions, sediment deposition and instream macroinvertebrate communities upstream and downstream of cattle access points prior to, and 1 year following exclusion via fencing. The long-term effects are also measured by reassessing a small stream catchment entirely fenced off from cattle access in 2008 under a dedicated management plan. In the short term, cattle exclusion led to a reduction in deposited sediment downstream of cattle access points and a related homogenisation of macroinvertebrate community structure between upstream and downstream of cattle access points. Increased abundances of specific indicator taxa (Ancylus fluviatilis, Glossosomatidae and Elmidae) in the fenced catchment following 9 years of exclusion highlight the long-term ecological benefits of such mitigation practices. These findings highlight the importance of incentivised agri-environment measures in reducing the negative impacts of cattle access to vulnerable aquatic ecosystems.     

Point source effects on density,biomass and diversity of benthic macroinvertebrates in a Mediterranean stream

We sampled benthic macroinvertebrates above and below a point source effluent in La Tordera stream (NE, Spain) over 2001–2002 to assess the effects of nutrient enrichment on the structure, and taxonomic composition of the benthic macroinvertebrate community. Below the point source, discharge, specific conductance and nutrient concentrations were higher than at the upstream reach, while dissolved oxygen (DO) decreased. Macroinvertebrate density was higher at the downstream reach than at the upstream reach on most dates but the two reaches did not differ in macroinvertebrate biomass. On average, taxa richness at the upstream reach was 20% higher than at the downstream reach. Several taxa, especially mayflies, stoneflies and caddisflies, were present only at the upstream reach. Shannon diversity was similar between the two reaches on 50% of the dates. Ordination analysis clearly separated the samples of the upstream reach from the samples of the downstream reach in the first axis and corroborated the effect of the point source on the benthic community. The two reaches followed a similar temporal pattern with respect to the distribution of taxa along the second axis of the ordination analysis. Higher similarities between the two reaches in taxa composition, densities and biomass after the spates of April and May 2002, suggest that flooding events may act as a reset mechanism for benthic communities and play an important role in stream restoration. Copyright © 2007 John Wiley & Sons, Ltd.     

Using macroinvertebrate biological traits for assessing biotic integrity of neotropical streams

Several recent studies have demonstrated that a functional approach (i.e. analysis of traits indicating species ecological functions) can be successfully used for river biomonitoring. To date this approach has only been applied in temperate rivers, even though it could notably contribute toward the development of an environmental assessment system in developing countries in other climatic zones. Using a multivariate approach (Fuzzy Correspondence Analysis—FCA), we analysed functional invertebrate community characteristics (described by 40 categories of seven biological traits mostly at the family level) at 66 stream sites from neotropical Bolivia with different level of anthropogenic disturbance. We were able to separate the sites on the first FCA axis (F1) (ANOVA test) following the predefined environmental quality classes based on the observed impact. Moreover, the F1 axis scores were significantly related to scores obtained using an independent macroinvertebrate multi‐metric index previously developed to assess streams biotic condition in the same biogeographical region. The F1 axis, which thus represents a gradient of anthropogenic impacts, was significantly correlated to 30 of the 40 studied trait categories. Our results (i) clearly confirm the possible use of functional traits for water quality assessment in neotropical streams, and (ii) provides support to the River Habitat Templet hypothesis since habitat disturbances produced predictable functional changes in macroinvertebrate assemblages. Finally, this study supports the potential worldwide applicability of the species‐trait approach as a biomonitoring tool for stream integrity assessment. Copyright © 2008 John Wiley & Sons, Ltd.     

Effects of stream diversion on riffle macroinvertebrate communities in a Maui,Hawaii, stream

The continual demand for freshwater by industry (e.g. tourism) and agriculture, a growing population, and increasing development over the past 100 years has resulted in the construction of diversions within many streams of Hawaii. The main objective of this study was to evaluate the impact of stream diversions on riffle macroinvertebrate communities. Benthic macroinvertebrate larval populations were compared above and below a diversion in Iao Stream, Maui, Hawaii, from April to August 2000. During this summer approximately 92–97% of daily stream flow was diverted from Iao Stream. Three taxa, Procanace sp. (Diptera: Canacidae), Atyoida bisulcata (Crustacea: Decapoda), and Amphipoda (Crustacea), were only collected above the diversion. However, the most numerous taxa, Chironomidae (63–64% of the total macroinvertebrate community), Hydroptila arctia (Trichoptera: Hydroptilidae; 15%), and Cheumatopsyche pettiti (Trichoptera: Hydropsychidae; 8%), were found both above and below the diversion. The relative percentage abundance of these dominant taxa remained relatively consistent above and below the diversion over the study period. However, the mean total density of individual dominant taxa was greater above the diversion. The mean total macroinvertebrate density above the diversion was 46% greater than below the diversion (Student t‐test: df = 30, t = ?3.22, p > 0.01). No correlation was found between temperature and density. A positive correlation was detected between Froude number and mean total macroinvertebrate density. Overall, the reduction in macroinvertebrate diversity and in individual and total density below the diversion suggest that trophic interactions, and thus energy flow, could be affected by reduced flow in Hawaiian streams. The information gained from this study will contribute to knowledge on Hawaiian stream ecosystems, help to create minimum instream flow standards for stream restoration, and will provide information for future freshwater management issues on the Hawaiian islands. Copyright © 2002 John Wiley & Sons, Ltd.     

The role of riparian vegetation and woody debris in the development of macroinvertebrate assemblages in streams

Riparian vegetation development and macroinvertebrate assemblages were studied in 16 streams formed between 35 and 230 years ago, following glacial recession in Glacier Bay National Park, southeast Alaska. Riparian vegetation established most rapidly in streams where flow variation in downstream reaches was buffered by a lake. Riparian vegetation development was positively correlated with lower bank stability, but was independent of stream age. Roots and branches of riparian vegetation trailing into streams (trailing riparian habitat—TRH) were shown to be an important habitat for a number of macroinvertebrate taxa. In young and unstable streams, TRH was colonized mainly by Plecoptera whereas in more stable lake‐influenced streams Simuliidae dominated. Significant coarse woody debris (CWD) accumulations were not observed until after approximately 130 years of stream development had occurred when certain channel features, such as gravel bars, were stabilized by dead wood. Where dead wood was present, opportunistic wood taxa were abundant, even in the younger streams. However, a xylophagous species, Polypedilum fallax, was not recorded until streams were over 100 years old. Two‐way indicator species analysis (TWINSPAN) using presence/absence of macroinvertebrate taxa on TRH, initially divided streams into lake and non‐lake systems, but subsequent divisions were consistent with differences in stream age. TWINSPAN of macroinvertebrate assemblages on dead wood again highlighted differences in stream age. Canonical correspondence analysis indicated that bed stability and stream age were the most important environmental variables influencing macroinvertebrate distribution on TRH. Trailing riparian habitat was most abundant in moderately unstable streams where it facilitates invertebrate colonization. CWD contributes markedly to channel stabilization, provides habitat for invertebrate xylophages, and confers additional habitat complexity. Maximum levels of CWD are predicted to occur in non‐lake streams after approximately 300 years, but at least a further 100 years will be required in stable streams below lakes where dead wood entrainment is not enhanced by flooding, channel migration and bank undercutting. A conceptual model summarizing the role of TRH and CWD on stream development in Glacier Bay is presented. Copyright © 2005 John Wiley & Sons, Ltd.     

The use of palaeoecological and contemporary macroinvertebrate community data to characterize riverine reference conditions

Defining reference conditions is a crucial element in quantifying the extent of anthropogenic modification and for identifying restoration targets in riverine ecosystems. Despite palaeoecological approaches being widely applied in lakes to establish reference conditions, their use in lotic ecosystems remains limited. In this study, we examine contemporary, historical (1930 and 1972), and palaeoecological macroinvertebrate biodiversity and biomonitoring scores in Eastburn Beck, a headwater tributary of the River Hull (UK) to determine if palaeoecological approaches can be used to characterize lotic system reference conditions. Palaeoecological samples comprised a greater gamma diversity (18 taxa) than contemporary samples (8 taxa), samples taken in 1972 (11 taxa) and 1930 (8 taxa). Palaeoecological samples supported taxonomically different Gastropoda, Trichoptera, and Coleoptera (GTC) communities compared with contemporary and historical samples (1930 and 1972). Results from biomonitoring indices using the GTC community indicated that the palaeochannel had (a) similar invertebrate biological quality, (b) a less energetic flow regime, and (c) increased fine sediment deposits compared with the contemporary channel. The results clearly illustrate that palaeoecological data can provide a suitable method to characterize reference conditions for lotic habitats. However, it is important to recognize that faunal data from palaeochannel deposits provide a short‐term “snapshot” of the conditions within the river immediately prior to its hydrological isolation. River restoration activities should therefore draw on multiple lines of evidence, including palaeoecological information where possible, to characterize a range of reference conditions to reflect the highly dynamic nature of lotic ecosystems.     

Effects of Passive and Structural Stream Restoration Approaches on Transient Storage and Nitrate Uptake

Understanding nitrogen dynamics in headwater streams is important for ascertaining how they influence downstream nutrient loads and identifying strategies for reducing loading through stream restoration. We compare nitrate uptake associated with two restoration approaches in headwater streams, Sheep Creek and Nunn Creek, of northern Colorado, USA. Segments of Sheep Creek were exclosed (fenced off) from open rangeland cattle grazing in the 1950s, allowing riparian corridors of these segments to naturally revegetate (passive approach), while other segments have been continually grazed. In 2003, restoration structures including cross vanes, J‐hook vanes, rootwads, log vanes, and bank riprap (structural approach) were installed along portions of Nunn Creek for trout habitat enhancement and local bank stabilization. We performed detailed physical characterizations and multiple nutrient injections of Br^? and NO₃^? to estimate transient storage and nitrate uptake in four reaches along Sheep Creek (two reaches exclosed from grazing and two grazed reaches) and two reaches along Nunn Creek (one with restoration structures and one without structures). Parameters of transient storage and nitrate uptake were estimated with the one‐dimensional transport with inflow and storage model run through universal inverse modelling code for optimization. Responses of transient storage and nitrate uptake to restoration techniques depended upon the type and extent of restoration implemented, as well the context and physical setting of each study reach. For example, in the higher‐gradient pair of Sheep Creek reaches, the restored reach showed greater nitrate uptake, while in the lower‐gradient pair of reaches, the non‐restored reach had greater uptake. At Nunn Creek, the reach with instream wood but without restoration structures exhibited more transient storage and nitrate uptake when compared with the reach with extensive J‐hook vane structures. Copyright © 2016 John Wiley & Sons, Ltd.     

Macroinvertebrate assemblages in streams of interior Alaska following alluvial gold mining

Alluvial gold mining, or placer mining, represents a major disturbance to stream ecosystems in interior Alaska. This process typically involves re‐routing the stream to one side of the valley while the gravels are removed across the floodplain for processing. The stream is then re‐directed back into a reclaimed new channel after mining has ceased in that section of stream. Macroinvertebrate colonization of reclaimed stream reaches is necessary for benthic community recovery following mining. Macroinvertebrate community assemblages at 36 sites on six streams in interior Alaska were examined. Sites with different mining histories were compared to control sites. TWINSPAN classification and ordination of sites using macroinvertebrate abundance indicated a greater similarity of sites within watersheds than between watersheds even though each watershed had a history of mining including recently mined sites. Significant differences were found for total invertebrate abundance, percentage dominant taxon and mean total biomass of macroinvertebrates between control sites and sites that were recently mined (≤10 years) and sites mined 12–50 years ago. Total macroinvertebrate abundance and biomass was lower and taxon dominance higher in both groups of sites with a history of mining. No significant difference in these or other measures was found for sites where mining occurred upstream. There was also no significant relationship between time since mining and the biotic measures used to summarize macroinvertebrate community structure. Although taxon richness recovered rapidly, no individual taxon was found to be a specific indicator of macroinvertebrate recovery since mining. Copyright © 2004 John Wiley & Sons, Ltd.     

Seasonal differences in diversity of macroinvertebrate and fish taxa in a Midwestern stream

Most biomonitoring projects focus on single species groups at time scales either too short or too coarse to detect intra‐annual oscillations in biodiversity. Using a multifaceted approach, we compared diversity indices of larval macroinvertebrate families and fish species in a Midwestern stream during spring and fall of 2009–2013 and discovered contrasting patterns in α and β diversities between the seasons for the two taxa groups. Compared with spring, both α and β diversities were significantly higher during fall for macroinvertebrates; on the contrary, only α diversity differed between the seasons for fishes. For both taxa, we partitioned the overall β diversity to identify contributions of temporal and spatial β diversities on the observed differences. The observed patterns for macroinvertebrates were likely the result of season acting as environmental filter, but stochastic dispersal and recruitment processes were likely more important in driving fish diversity patterns. In light of widespread conservation and restoration efforts in the Midwestern streams, it seems prudent to study community composition frequently so that baseline α and β diversities can be obtained for organisms at different taxonomic levels and during different seasons.     

Structural and functional changes of tropical riffle macroinvertebrate communities associated with stream flow withdrawal

Tropical island streams worldwide are threatened by existing or proposed dams and diversions that remove freshwater for human use; yet, there have been few studies that address the effects on aquatic communities. The objective of this study was to quantify changes in tropical macroinvertebrate communities associated with stream flow withdrawal. Benthic macroinvertebrates were collected from riffle habitats located above and below a stream diversion on Maui, Hawaii, from June to August 2000. Native and introduced taxa were identified from both locations. The most dominant taxon was midges (Diptera: Chironomidae) followed by two introduced caddisflies, Cheumatopsyche analis (Banks) (Trichoptera: Hydropsychidae) and Hydroptila potosina (Buenoa‐Soria) (Trichoptera: Hydroptilidae). A native shrimp, Atyoida bisulcata, and beach fly, Procanace sp. (Diptera: Canacidae), were either eliminated from or significantly reduced below the diversion. Mean total macroinvertebrate densities were greater above (13 357 individuals/m²) the diversion compared to below (10 360 individuals/m²). Mean total macroinvertebrate biomass was significantly reduced by 60 per cent below the diversion, but specific taxa did not show this effect. These results suggest that diverted stream flow limited macroinvertebrate colonization and growth, expressed as reduced community density and biomass, which may alter the structure and function of other trophic levels within tropical stream food webs. Copyright © 2008 John Wiley & Sons, Ltd.     

Thermal variability and stream flow permanency in an alpine river system

Despite the importance of thermal conditions in influencing biodiversity of alpine river systems, knowledge of year round stream temperature variability is very limited. This paper advances understanding of alpine stream temperature dynamics using hourly resolution data collected over two consecutive years at five sites within a glacierized basin in the French Pyrénées. The potential utility of temperature for understanding river flow patterns at ungauged sites (most notably during winter) is explored. The results indicated marked heterogeneity in water column temperatures; groundwater streams were typically warmer and more thermally stable than those draining snow and ice. Based upon stream temperature patterns, it appears possible to differentiate between river flow conditions including: free‐flowing, surface freezing, dewatering and snow cover. Notably, groundwater‐fed streams appeared to exhibit greater flow permanency than meltwater‐fed streams, the latter freezing for extended periods. These new insights into long‐term alpine stream thermal conditions have major implications for understanding the strategies adopted by benthic macroinvertebrate taxa when overwintering, particularly where streams freeze. Copyright © 2006 John Wiley & Sons, Ltd.     

Associations of watershed vegetation and environmental variables with fish and crayfish assemblages in headwater streams of the Pedernales River,Texas

Intermittent headwater streams serve important functions for humans and wildlife in semi‐arid rangelands. Increases in ashe juniper coverage in central Texas over recent decades are believed to have negatively impacted stream flows. Few studies have examined relationships between aquatic species and environmental factors in these systems as well as the influence of juniper coverage on assemblage structure. During summer 2003 and spring 2004, we examined species–environment relationships to infer potential effects of juniper cover on aquatic ecology relative to local‐scale and watershed‐scale environmental variables. Fish and crayfish species assemblages and physicochemical variables were investigated in spring‐fed headwater tributaries of the Pedernales River, Texas. Fish abundance was much higher in summer 2003, whereas crayfish abundance was higher in spring 2004. Fish species richness was lower during spring 2004, possibly due to below average precipitation during spring 2004 that reduced deep‐water refugia. Higher abundance of crayfish in spring 2004 samples was probably due to their ability to survive low‐flow conditions, and a release from fish predation pressure. Fish assemblage structure was more strongly associated with local abiotic factors during spring 2004 when flow was reduced, whereas structure during summer 2003 samples suggested a relatively greater influence of predation. In general, juniper cover was weakly associated with fish and crayfish assemblages, although it tended to be positively associated with relatively high‐quality habitat for sensitive taxa (flowing runs with coarse substrate; deep, connected pools). We suggest that intermediate levels of juniper cover in the region provide indirect benefits to aquatic organisms. However, short‐term, local environmental factors appear to have a much greater influence than watershed vegetation on fish and crayfish assemblages in these intermittent streams. Copyright © 2007 John Wiley & Sons, Ltd.     

Riparian Forest Harvesting Effects on Maximum Water Temperatures in Wetland-sourced Headwater Streams from the Nicola River Watershed, British Columbia, Canada

Water temperature was continuously recorded during the ice-free season between June/July and October/November at 90 sites with lentic and lotic stream sources distributed throughout the Nicola River watershed (British Columbia, Canada) in 1999, 2000, and 2001. The eight lentic-sourced stream temperature monitoring sites were located in two adjacent watersheds. The headwaters and riparian areas around the wetland outlet of the treatment watershed were harvested during the overwinter period between 1999 and 2000. Areas around and downstream of the headwater wetland outlet in the control watershed were not harvested. Reducing riparian shade by harvesting activities increased maximum stream temperatures in the treatment watershed by up to 1–2°C relative to the control watershed. Because of the general downstream cooling trends in lentic-sourced headwater streams, riparian harvesting activities in these regions have a reduced thermal impact relative to similar harvesting alongside lotic-sourced headwater streams, whose maximum stream temperatures may warm by up to 8°C following harvesting. The downstream influence of elevated maximum stream temperatures from riparian harvesting of lentic-sourced headwater streams appears to be localized, but persists for at least 2 years following harvesting. Both lentic-sourced treatment and control streams in the current study relaxed towards baseline equilibrium temperature estimated by the lotic-sourced watershed trend within several hundred meters of downstream travel distance, with cooling rates proportional to the distance from expected thermal equilibrium. Due to the heating in wetland-sourced stream reaches adjacent to riparian harvesting, the regions downstream of treatment areas cool more rapidly than similar regions in control watersheds as the stream attempts to achieve thermal equilibrium.     

LONG‐TERM TAXON‐SPECIFIC RESPONSES OF MACROINVERTEBRATES TO DAM REMOVAL IN A MID‐SIZED SWEDISH STREAM

Dam removal to restore ecologically impaired rivers is becoming increasingly common. Although the target often is to facilitate fish migration, dam removal has also been assumed to benefit other types of organisms. Because few studies thus far deal with effects of dam removal on stream macroinvertebrates and because results have been equivocal, we investigated both short‐ and longer‐term dam‐removal effects on downstream macroinvertebrate communities. We did this in a before‐and‐after study of the removal of a dam located in a south Swedish stream. We sampled the benthic fauna 6 months before dam removal and both 6 months and 3.5 years after the dam was removed. We compared species composition, taxonomic richness, total densities and densities of macroinvertebrate groups before and after dam removal and between downstream and reference sites. We found that dam removal reduced some macroinvertebrate taxa at the downstream site, but we found no effect on community composition. Although this corroborates results from previous short‐term studies, we also found a reduction of taxonomic richness and that some dam‐removal effects persisted or even increased over time. The most likely explanation for the suppression of benthic macroinvertebrate richness following dam removal is a significantly increased sediment transport from the former reservoir and a subsequent loss of preferred substrates. Our results indicate that adverse dam‐removal effects may be long lasting but taxon specific. We therefore call for longer‐term studies on a variety of organisms to better understand how dam removal may influence downstream macroinvertebrate communities. Copyright © 2012 John Wiley & Sons, Ltd.     

Cascade macroinvertebrate assemblages for in‐stream flow criteria and biomonitoring of tropical mountain streams

Few comprehensive studies on stream assessment and biomonitoring have been conducted in tropical, freshwater watersheds. Currently under threat from climate change, urbanization and increasing freshwater demands, there is a need for innovative approaches to tropical watershed assessment and management. This study investigated cascade habitat macroinvertebrate communities among four tropical mountain streams with the goal of enhancing future efforts to identify flow biocriteria for watersheds of Polynesia. Cascade macroinvertebrate communities were compared between streams of differing size and magnitude of flow removal to evaluate the biological effects of water withdrawal on benthic communities. Two cascade microhabitats, identified as torrenticolous and amphibious, were evaluated for macroinvertebrate community differences and presence of native taxa among watersheds. Cascade habitat in general was reduced, by as much as 98%, in downstream reaches, having a significant impact on the stream ecosystem physical template important for native stream communities. In addition, two‐way ANOVA results revealed no main effects, but significant interactions of watershed size and flow removal on mean macroinvertebrate density for torrenticolous microhabitats; however, the opposite was true for the amphibious microhabitat. Diversity was significantly higher under undiverted flow conditions (t = 4.21, df = 272, p = 0.0004) and in torrenticolous microhabitats (t = 3.86, df = 272, p < 0.0001) over the entire study period. The amphibious microhabitat was composed of 39% native taxa, while the torrenticolous microhabitat contained <7%. This study provides new options for biomonitoring of native populations in Polynesian watersheds. Further studies that support the development of in‐stream flow criteria to preserve cascades are important to understanding the role of this habitat in tropical stream ecosystem function. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of extreme floods on macroinvertebrate assemblages in tributaries to the Mohawk River,New York,USA

Climate change is forecast to bring more frequent and intense precipitation to New York which has motivated research into the effects of floods on stream ecosystems. Macroinvertebrate assemblages were sampled at 13 sites in the Mohawk River basin during August 2011, and again in October 2011, following historic floods caused by remnants of Hurricane Irene and Tropical Storm Lee. The annual exceedance probabilities of floods at regional flow‐monitoring sites ranged from 0.5 to 0.001. Data from the first 2 surveys, and from additional surveys done during July and October 2014, were assessed to characterize the severity of flood impacts, effect of seasonality, and recovery. Indices of total taxa richness; Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness; Hilsenhoff's biotic index; per cent model affinity; and nutrient biotic index‐phosphorus were combined to calculate New York State Biological Assessment Profile scores. Analysis of variance tests were used to determine if the Biological Assessment Profile, its component metrics, relative abundance, and diversity differed significantly (p ≤ .05) among the four surveys. Only total taxa richness and Shannon–Wiener diversity increased significantly, and abundance decreased significantly, following the floods. No metrics differed significantly between the July and August 2014 surveys which indicates that the differences denoted between the August and October 2011 surveys were caused by the floods. Changes in taxa richness, EPT richness, and diversity were significantly correlated with flood annual exceedance probabilities. This study increased our understanding of the resistance and resilience of benthic macroinvertebrate communities by showing that their assemblages were relatively impervious to extreme floods across the region.     

The effect of damming on biological quality according to macroinvertebrates in some Estonian streams,Central—Baltic Europe: A pilot study

The effect of damming on the structure of the macroinvertebrate community and biological quality was studied in nine (the 3–6th order) lowland streams of Estonia, Central—Baltic ecoregion of Europe. Four habitats—reservoirs with accumulated fine sediments, reservoirs with hard bottom, and two corresponding below‐dam areas (both fast‐flowing)—were compared to study whether and how significantly the bottom substrata in dammed areas affected macroinvertebrates and biological quality downstream of dams. The standard kick‐net samples (1.25 m², complemented with qualitative sample) were collected in autumn 2005—spring 2006. The multimetric biological quality, based on five macroinvertebrate indices (total taxa richness, EPT taxa richness, Average Score Per Taxon, Danish Stream Fauna Index, Shannon diversity) was estimated and compared with reference values. Biological quality in reservoirs with hard bottom and their downstream reaches corresponded to good, or even high quality. Conversely, damming affected biological quality significantly and negatively, above the dam if fine sediments were accumulated. The effect was the strongest within muddy reservoirs themselves (revealing moderate quality only). However, some harmful consequences of mud were observed also downstream of dams. The results also demonstrated that the indices of estimation of organic pollution and/or general quality were able to reflect significant changes in stream flow. Copyright © 2010 John Wiley & Sons, Ltd.