EPT Taxa Research Articles

Development of Macroinvertebrate Multimetric Index for Assessment of Large Rivers in Thailand.

Human activities are a significant threat to the health of river ecosystems, especially in developing countries. In Thailand, benthic macroinvertebrates have been widely used for bioassessment for aquatic ecosystem evaluation. However, most of them focuses on streams, which may not be applicable to large rivers. This study aimed to fill this gap by developing a macroinvertebrate multimetric index for Thailand's large rivers. Sampling was conducted in 15 rivers, and 41 sites across Thailand. Physico-chemical parameters, habitat characteristics, and macroinvertebrates were analyzed. Macroinvertebrate data were analyzed and metrics calculated. The seven selected core metrics, including Plecoptera taxa, EPT taxa, insect individuals %, Crustaceans and Mollusca individuals %, collector-gatherers taxa, intolerant taxa in BMWPThai, and Hilsenhoff Biotic Index, showed a strong response to anthropogenic disturbance. The final Thailand Large River Multimetric Index (TLMI) classified river health from "Excellent" to "Very Poor" condition. The validation of TLMI confirmed its ability to distinguish river health conditions. Overall, the TLMI can used as an assessing and monitoring ecological health tool for Thailand's large rivers, that can be applied for river management and conservation.

Benthic Macroinvertebrate Communities in Wadeable Rivers and Streams of Lao PDR as a Useful Tool for Biomonitoring Water Quality: A Multimetric Index Approach

Lao PDR, a landlocked country in the lower Mekong River basin of Southeast Asia, has been considered a global biodiversity hotspot with a high level of biological endemism. In recent years, urban development and industrialization have affected the water quality of freshwater ecosystems in Lao PDR. However, the assessment of water quality in the country is primarily focused on a physicochemical method, while the application of a multimetric index (MMI) approach using benthic macroinvertebrates for biomonitoring in rivers and streams has not been established. MMI, based on benthic macroinvertebrates, is a biomonitoring tool that considers the effects of multiple anthropogenic impacts on benthic macroinvertebrate metrics associated with their biological attributes (e.g., taxa richness, composition, pollution tolerance, habits, and functional feeding) and aggregates individual metrics into a single value for assessing the water quality and health conditions of aquatic ecosystems. Here, we developed an MMI based on macroinvertebrate communities collected during 2016–2018 from 10 localities of streams and wadeable rivers in Lao PDR. Of the 54 potential metrics tested, 35 candidate macroinvertebrate metrics representing richness, composition, trophic structure, habit, and tolerance to pollution were selected, while 19 metrics were excluded. Of the 35-candidate metrics, a total of 11 core metrics (Total taxa, EPT taxa, Ephemeroptera taxa, %Diptera, %Plecoptera, %Tolerant, Beck’s biotic index, %Intolerant, Filterers taxa, %Sprawlers, and %Burrowers) were finally selected for the development of MMI based on their sensitivity, redundancy, and easy-to-apply tool for the biomonitoring program. These metrics can be used to distinguish the reference (seven sites) from stressed conditions (seven sites). In addition, the final MMI scores classified 40 sampling sites into four classes of water quality, including excellent (25%), good (10%), fair (60%), and poor (5%), which the conventional physicochemical method could not clearly distinguish. The Lao MMI developed in this study is an effective tool for evaluating the water conditions of sites affected by human activities, particularly agricultural areas, and, thus, is appropriate for use in future studies for assessing the ecological conditions of rivers and streams in the Mekong region.

In a Degraded Stream, Increased Salt Concentration is Correlated with Decreased EPT Diversity

Many streams in the Northern Panhandle of West Virginia are biologically impaired due to historical and concurrent anthropogenic activities, including mining, agriculture, and urbanization. These activities alter water chemistry which affects the benthic macroinvertebrate communities. While taxa like Ephemeroptera, Plecoptera, and Trichoptera (EPT taxa) are sensitive to water pollution, other taxa like tipulids, beetles, and chironomid midges are more pollution tolerant. However, responses to specific chemical pollutants are taxa specific and even some EPT are relatively pollution tolerant. We investigated how increases in chloride (Cl) and specific conductance (SPC) affected the macroinvertebrate community in a stream already heavily impacted by mining, urbanization and agriculture. Five upstream sampling sites were placed in a degraded stream above the outfall of an active coal mine, while five additional sites were placed downstream of the discharge. Water chemistry was measured in each site, and macroinvertebrates were collected with kick nets, leaf packs and a visual collection of unique habitats following the Stream Monitoring Information Exchange (SMIE) protocol. We found that temperature, SPC, and Cl were significantly higher downstream of the mine outfall with SPC and Cl more than doubling. SMIE water quality scores and whole community Shannon-Wiener Diversity Index scores were not significantly different between upstream and downstream sites but EPT diversity was significantly higher upstream of the mine. This data helps determine taxa specific responses to changes in water chemistry, specifically SPC and Cl, and highlights how streams already afflicted with poor water quality can lose additional taxa when the concentrations of salts increases.

Quantifiable Water Chemistry Trends in Streams Degraded by Acid Mine Drainage

Surface coal mining has been a major economic force in the Appalachian region for hundreds of years. Surface coal mining leads to runoff known as acid mine drainage (AMD) which infiltrates and severely degrades freshwater streams. Acid mine drainage impacted streams often see a marked decrease in biodiversity especially Ephemeroptera, Plecoptera, and Trichoptera (EPT taxa) which are intolerant to pollution. We researched the water quality in four streams. Two downstream mines were impacted by AMD while the other two served as control or unimpaired sites. Water chemistry of all four streams was measured including sulfate, iron, and magnesium using a YSI 9500 photometer. The pH of each stream was measured using a YSI Quatro meter. We found elevated levels of sulfate and iron in the impaired streams while magnesium levels varied across sites. The pH tended to be lower in the impaired streams but remained fairly alkaline ( pH > 5). These data are useful for understanding the chemistry of impaired streams and how freshwater macroinvertebrates may respond to these chemical parameters. Additionally these data aid in remediation efforts which may be dependent on specific water chemistry.

Response of macroinvertebrates to industrial warm discharges: the River Shannon case study (Ireland)

ABSTRACT Warm discharges from industrial processes have the potential to impact benthic invertebrate communities and undermine river functioning as well as inform climate change impacts. We evaluated the effects of heated cooling waters from 2 power plants across 2 River Shannon locations (Ireland) in summer and in winter. The overall multivariate community composition differed significantly between heated and unheated river sections in both seasons. In summer, overall invertebrate taxon richness and diversity were significantly lower in heated than in unheated sections. This finding was coupled with a striking decrease in Ephemeroptera, Plecoptera, and Trichoptera (EPT) abundance, taxon richness, and diversity in heated sections. Furthermore, aerial taxon richness and diversity were significantly lower in the heated sections. We also observed that the abundance of grazers was lower in heated sections. Winter patterns were similar to summer, but with lower invertebrate community abundance and decreased functional representation of shredders, gatherers, and predators in heated sections. Such impacts likely have strong implications for river functioning, including depressed connectivity with riparian habitats, and may impair the performance of eutrophication biomonitoring tools that rely on EPT taxa. Our results highlight the impact of warming of thermal plumes and other ubiquitous triggers of heating and may indicate climate change-driven trajectories.

A tale of two habitats: whole-watershed comparison of disturbed and undisturbed river systems in northern Michigan (USA), based on adult Ephemeroptera, Plecoptera, and Trichoptera assemblages and functional feeding group biomass

To test the differences in aquatic insect assemblages between otherwise similar habitats, adult genera of Ephemeroptera, Plecoptera, and Trichoptera (EPT) were sampled using ultraviolet lights during summer and early autumn at 15 sites each throughout the undisturbed Pine River watershed and the agricultural Charlotte River watershed, both of the Upper Peninsula of Michigan (USA). The percentage of intact watershed-scale terrestrial habitat upstream of each sampling site was the best of 32 candidate variables at predicting differences in both EPT taxonomic assemblages and functional feeding group (FFG) biomass. Relative to the Pine, streams of the Charlotte had lower intact habitat, lower genus richness, lower biomass of nearly all individual genera, and lower biomass of all FFGs, with scrapers and shredders decreasing more than filtering collectors. Both watersheds followed general trends of river continuity, although the Pine contained double the relative abundance of shredders than is typically reported. This study demonstrates that watershed-scale habitat disturbance decreases nearly all EPT taxa, regardless of FFG. It also demonstrates the importance of biomass values rather than simple specimen counts when calculating metrics, and the utility of sampling EPT adults with ultraviolet lights relative to sampling benthic specimens.

Multiple-Stressor Interactions in Tributaries Alter Downstream Ecosystems in Stream Mesocosm Networks

We studied how multiple-stresssors in tributaries affect function, diversity, and physical habitat of recipient downstream ecosystems. Using a mesocosm model of a stream network, we manipulated sediment and nutrients individually and in combination in tributaries of second-order channels, to test the effect of complex stressor interactions within tributaries on recipient channels. Sedimentation in second-order channels increased with the level of disturbance of the tributaries. Moreover, Ephemeroptera, Plecoptera, and Trichoptera (EPT) density and EPT richness were higher in second-order channels fed by tributaries where the stressors were applied separately, compared to those fed by tributaries where the stressors were applied simultaneously. Our observations suggest this result was due to the combination of the two stressors within the same tributary reducing EPT drift from the tributaries further than the addition of the stressors in separate tributaries. These results support the hypothesis that cumulative upstream disturbance can influence downstream recipient ecosystems in stream networks. However, contrary to our expectations, most observed effects were due to impacts on dispersal patterns of EPT taxa, rather than downstream accumulation of disturbances throughout the network. Our results underscore the importance of metacommunity frameworks to understand how tributary disturbance may influence population dynamics in downstream ecosystems.

Conservation Across Aquatic-Terrestrial Boundaries: Linking Continental-Scale Water Quality to Emergent Aquatic Insects and Declining Aerial Insectivorous Birds

Larval aquatic insects are used to assess water quality, but less attention is paid to their adult, terrestrial life stage, which is an important food resource for declining aerial insectivorous birds. We used open-access water-quality, aquatic-invertebrate, and bird-survey data to study how impaired water quality can emanate from streams and lakes through changes in aquatic insect communities across the contiguous United States. Emergent insect relative abundance was highest across the West, in northern New England, and the Carolinas in streams, and highest near the Great Lakes, parts of the Southwest, and northern New England for lakes. Emergent insects declined with sedimentation, roads, and elevated ammonium concentrations in streams, but not lakes. The odds that a given taxon would be non-emergent increased by up to 2.0× as a function of pollution tolerance, underscoring the sensitivity of emergent aquatic insects to water-quality impairment. However, relationships between bird populations and emergent insects were generally weak for both streams and lakes. For streams, we observed the strongest positive relationships for a mixture of upland and riparian aerial insectivorous birds such as Western Wood-Pewee, Olive-sided Flycatcher, and Acadian Flycatcher and the strongest negative association for Purple Martin. Different avian insectivores responded to emergent insect abundances in lakes (e.g., Barn Swallow, Chimney Swift, Eastern Wood-Pewee, Common Nighthawk). In both streams and lakes, we observed stronger, but opposing, relationships between several aerial insectivores and the relative abundance of sensitive insect orders (E)phemeroptera, (P)lecoptera, and (T)richoptera (positive), and pollution tolerant individuals (negative). Overall, our findings indicate that emergent insects are negatively correlated with pollution tolerance, suggesting a large-scale loss of this nutritional subsidy to terrestrial environments from impaired aquatic ecosystems. While some bird populations tracked scarcities of emergent aquatic insects, especially EPT taxa, responses varied among species, suggesting that unique habitat and foraging behaviors likely complicated these relationships. Strengthening spatial and temporal concordance between emergent-insect and bird-survey data will improve our ability to interpret species-level responses over time. Thus, our analysis highlights the need for developing conservation and biomonitoring strategies that consider the cross-ecosystem effects of water quality declines for threatened insectivorous avifauna and other terrestrial wildlife.

Large-scale prediction of tropical stream water quality using Rough Sets Theory

Assessing water quality in streams is usually measured at the local scale and often it is spatially restricted. To scale-up water-condition assessment, there is a need to use new tools that enable prediction of large-scale changes in water quality by expanding the analysis to landscape-levels and bioclimatic predictors. In addition, the traditional use of linear models in biomonitoring can be inappropriate in detecting complex relationships, such as changing patterns of aquatic community structure and complex environmental gradients. In this context, Artificial Intelligence (AI) techniques such as Rough Sets Theory (RST) can be particularly useful for dealing with vague, imprecise, inconsistent and uncertain knowledge involving biotic and abiotic data to enable the classification and prediction of changes in stream water. Here, we applied RST to estimate the water quality in streams of the Brazilian Atlantic Forest by analyzing connections between landscape and climate data with the inclusion of up to 15 families of aquatic insect groups from the orders Ephemeroptera, Plecoptera and Trichoptera (usually known as EPT taxa). First, we developed different decision sets which were the arrangements of the response variable (EPT index) and the predictor classifications. Then, we applied the best decision sets to monitor the condition of stream water in the Atlantic Forest on a large-scale. Our results showed the best decision rules were 61% accurate. Depending on the initial stream condition, this approach on a large-scale led to variable accuracy. By combining the development of different decision sets, the application of the best one on a large-scale, and the use of open-access data (landscape and climate predictors), our study approach demonstrated the potential applicability to evaluate streams in an objective with low-cost manner. This method can complement the environmental assessment of streams based only on local variables. Our framework also creates new perspectives in the analysis of water quality to generate scenarios of changes in streams based on landscape measurements to optimize monitoring networks.

Feeding Patterns and Strategies of Ephemeroptera, Plecoptera and Trichoptera in Relation to Seasonality, Landscape Elements and Mesohabitats

We inspected functional feeding groups in relationship with seasonality, stream order, Land Scape Elements (LSE), and mesohabitat of Ephemeroptera, Plecoptera, and Trichoptera (EPT) based on gut content analysis and mouthparts in 27 streams of the Western Ghats and the Eastern Ghats. From the study, a total of 14,168 specimens were collected and identified. The composition of trophic categories showed a slight variation among the different seasons with the dominance of collectors. The results of the abundance of functional feeding groups of EPT across stream orders additionally showed the predominance of collectors and predators in-stream orders 1 and 2. Collectors and filter feeders dominate in-stream orders 3 and 4. By examining the LSE elements, it is found that collectors were high in the streams flowing through areca nut and low in the streams flowing through natural vegetation. The distributions of functional feeding groups within the orders were also analyzed. Mesohabitat results showed scrapers were found to be predominant in riffles whereas collectors, predators, shredders, and filter feeders overwhelm in runs. ANOVA results showed that only mesohabitat was found to be significant. The results of the present study did not broadly concur with the predictions of the River Continuum Concept (RCC) because of the lack of thickly canopied headwater stream sites and the limitation of our study to only EPT taxa.

Community turnover provides insight into variable invertebrate recovery between restored streams with different integrated catchment management plans

ABSTRACT Understanding temporal patterns in restored environments is important for identifying potential barriers to recovery and improved management of degraded habitats. In this paper, we use temporal beta diversity analyses to compare invertebrate community recovery trajectories in three restored agricultural stream sites under different integrated catchment plans, a native forest reference site, and two unmodified pasture control stream sites over 24 years. The restored sites diverged from their initial community composition over time and became more similar to the reference site community, which was relatively stable over time. Variation partitioning showed that prior to restoration beta diversity was primarily associated with environmental and spatial drivers, whereas post-restoration beta diversity was more influenced by temporal and environmental drivers, including changes in substrate size, fine sediments, water clarity, and nutrients, as well as temperature and flow regime. Species’ contributions to beta diversity varied between sites and years, with sensitive EPT taxa contributing more in reference and control sites. However, contributions of some EPT species, particularly mayflies, increased in restored sites post-ICM. In summary, after nearly two decades of ICM, restored stream sites show recovery towards reference conditions, yet differences persist, indicating that rehabilitation may take longer, depending on the restoration goals.

Ecology of Binwa a Western Himalayan Hill Stream in relation to Water Quality

Binwa is a perennial hill stream of the Western Himalayan region of Himachal Pradesh. During the present investigation, four observation sites based on altitudinal differences were selected, i.e., Kharli(S1), Baijnath (S2), near Chobin (S3), and Triveni (S4) and water samples were analyzed for physico-chemical and biological parameters for one year (Mar.2011-Feb.2012). Water temperature, water current, dissolved oxygen, turbidity, T.D.S., electric conductivity, total Hardness, phosphate, and nitrate had played an essential role in determining the variations in planktonic and macroinvertebrate fauna of the stream.Species diversity indices such as Simpson, Shannon and Wiener, and Margalef’s diversity index of macroinvertebrates were worked out for all the observation sites. Based on the comparison of physico-chemical parameters of water samples with different standards prescribed for drinking water, water quality index for four stations calculated. Similarly, EPT taxa (Ephemeroptera, Plecoptera, Trichoptera) measured, and EPT index computed. The water quality of the stream deteriorates downstream from head to mouth due to different types of anthropogenic interferences. The findings revealed that stream has no pollution at S1, while it is oligotrophic from S2 to S3 and meso-oligotrophic at S4.

The use of macroinvertebrate based biotic indices and diversity indices to evaluate the water quality of Lepenci river basin in Kosovo

Benthic macroinvertebrates are used to evaluate water quality in 8 sampling stations in Lepenci river basin in Kosovo. Sampling was performed in spring, summer and fall 2017. Following biotic indices are used: EPT taxa richness, Biological Monitoring Working Party (BMWP), Average Score per Taxon (ASPT), Stroud Water Research Center index (SWRC), Family biotic index (FBI), as well as diversity indices: Shannon-Weaver index (H), Simpsons index (D), Hill’s index (Hi), Mergalef index (DMe) and Menhicnik’s index (DMa). Our results show the presence of 34 macroinvertebrate taxa in Lepenci river which belong to Insecta, Crustaceans and Annelidae. The water quality along the river show variation from high and good class upstream, to moderate, poor and bad, downstream. The Pearson’s bivariate correlation used to analyze the relationship between physicochemical parameters with biotic and diversity indices showed a significant correlation (p < 0.01) of EC, TSS, O2, COD, BOD, NH4, and PO43- with biotic indices EPT, BMWP, ASPT, SWRC, FBI. We can conclude that the values of biotic and diversity indices have shown differences in water quality between polluted and unpolluted sites and reflect the ecological status of the river, therefore we can consider them as valuable tools for water quality assessment in rivers in Kosovo.

In‐stream habitat and macroinvertebrate responses to riparian corridor length in rangeland streams

Conservation and restoration of riparian vegetation in agricultural landscapes has had mixed success at protecting in‐stream habitat, potentially due to the mismatch between watershed‐scale impacts and reach‐scale restoration. Prioritizing contiguous placement of small‐scale restoration interventions may effectively create larger‐scale restoration projects and improve ecological outcomes. We performed a multi‐site field study to evaluate whether greater linear length of narrow riparian tree corridors resulted in measurable benefits to in‐stream condition. We collected data at 41 sites with varying upstream tree cover nested within 13 groups in rangeland streams in coastal northern California, United States. We evaluated the effect of riparian tree corridor length on benthic macroinvertebrate communities, as well as food resources, water temperature, and substrate size. Sites with longer riparian corridors had higher percentages of invertebrates sensitive to disturbance (including clingers and EPT taxa) as well as lower water temperatures and less fine sediment, two of the most important aquatic stressors. Despite marked improvement, we found no evidence that macroinvertebrate communities fully recovered, suggesting that land use continued to constrain conditions. The restoration of long riparian corridors may be an economically viable and rapidly implementable technique to improve habitat, control sediment, and counter increasing water temperatures expected with climate change within the context of ongoing land use.

Ranking the importance of benthic metrics and environmental stressors from over a decade of bioassessment multiple stressor studies in five California waterbodies

Comprehensive bioassessment multiple stressor field studies were conducted in five waterbodies in the Central Valley, San Francisco and Central Coast areas of California between 2006 and 2017. Samples were collected over multiple years in Pleasant Grove Creek (PGC – 8 years), Kirker Creek (KC – 2 years), Arcade Creek (ARC – 3 years), Salinas streams (SAL – 3 years) and the lower Santa Maria River watershed (SM – 3 years). In each watershed, metrics indicative of physical habitat quality and the relative health of benthic communities were collected, along with measurements of various potential toxicants in sediment (metals and pyrethroids), total organic carbon (TOC) and sediment grain size characteristics. For all waterbodies, pyrethroids have been reported at concentrations suspected to be toxic based on single-species laboratory toxicity tests. The data from all of these studies were assembled into a single data base which was analyzed by a series of univariate and multivariate statistical analyses. These analyses were designed to examine overall relationships between benthic community health and environmental quality conditions across the watersheds, as well as to address the following two key questions: (1) Which benthic metrics (response indicators) were the most important to relationships with environmental quality conditions and how do these metrics rank from most to least important? and (2) Which environmental variables (stressors) were the most important in terms of relationships to benthic metrics indicative of community health and how do the stressors rank from most to least important? Consensus ranking of 14 benthic metrics showed that stress tolerant (% Tolerant taxa, Tolerance value and Collectors/gatherers) and stress sensitive (EPT taxa and taxa richness) were the most important. The consensus ranking of 38 environmental variables from most to least important showed that habitat metrics, metals and grain size characteristics were most important for shaping benthic communities while pyrethroids were not reported to be an important stressor across the geographic scope of the watersheds.

Aquatic Ecosystem Degradation of High Conservation Value Upland Swamps, Blue Mountains Australia

Temperate highland peat swamps on sandstone (THPSS) are unique state and federally protected ecological communities. THPSS is a higher level classification which is comprised of multiple swamp communities which include Blue Mountains Swamps and Newnes Plateau Shrub Swamps. The Blue Mountains has a string of urban settlements surrounded by large expanses of undisturbed natural vegetation which have varied degrees of protection ranging from state forests to World Heritage national parks. This study investigated aquatic invertebrates from seven THPSS within the Greater Blue Mountains area. Four swamps drain catchments with varying degrees of urban development and associated impervious surfaces, and three swamps have non-urban, naturally vegetated catchments. Water chemistry of non-urban swamps was acidic (mean pH 4.70) and dilute (mean EC 26.7 uS/cm) and dominated by sodium and chloride ions with most other major ions at low concentrations often below detection limits (Belmer et al. 2015). In contrast, urban swamps had higher pH (mean 6.60) and salinity (mean 153.9 uS/cm) and were dominated by calcium and bicarbonate ions (Belmer et al. 2015). Aquatic macroinvertebrate abundance, family richness and % EPT taxa were all found to be lower within urban swamps when compared to non-urban swamps. These results support the hypothesis of Belmer et al. (2015) that urban runoff within THPSS catchments is affecting the condition of their aquatic ecosystems.

Impacts of rapid urbanization on the water quality and macroinvertebrate communities of streams: A case study in Liangjiang New Area, China

Rapid urbanization in China has dramatically deteriorated the water quality of streams and threatening aquatic ecosystem health. This study aims to 1) assess the impacts of urbanization on water quality and macroinvertebrate composition and 2) address the question of how urbanization affects macroinvertebrate distribution patterns. Environmental variables over multispatial scales and macroinvertebrate community data were collected on April (dry season) and September (wet season) of 2014 and 2015 at 19 sampling sites, of which nine had a high urbanization level (HUL), six had moderate urbanization level (MUL) and four had low urbanization level (LUL), in the Liangjiang New Area. The results of this study showed that macroinvertebrate assemblages significantly varied across the three urbanization levels. The sensitive species (e.g., EPT taxa) were mainly centralized at LUL sites, whereas tolerant species, such as Tubificidae (17.3%), Chironomidae (12.1%), and Physidae (4.61%), reached highest relative abundance at LUL sites. The values of family biotic index (FBI) and biological monitoring working party (BMWP) indicated the deterioration of water quality along urbanization gradient. Seasonal and inter – annual changes in macroinvertebrate communities were not observed. The results of variation partitioning analyses (CCAs) showed that habitat scale variables explained the major variation in macroinvertebrate community composition. Specifically, the increased nutrient concentrations favored tolerant species, whereas high water flow and substrate coarseness benefitted community taxa richness, diversity and EPT richness. Considering the interactions between scale-related processes, the results of this study suggested that urbanization resulted in less diverse and more tolerant stream macroinvertebrate assemblages mainly via increased nutrient concentrations and reduced substrate coarseness.

Temporal effects of enhanced fine sediment loading on macroinvertebrate community structure and functional traits

Deposition of fine sediment that fills interstitial spaces in streambed substrates is widely acknowledged to have significant negative effects on macroinvertebrate communities, but the temporal consistency of clogging effects is less well known. In this study the effects of experimentally enhanced fine sediment content on aquatic invertebrates were examined over 126days in two lowland UK streams. Taxonomic approaches indicated significant differences in macroinvertebrate community structure associated with sediment treatment (clean or sedimented substrates), although the effects were variable on some occasions. The degree of separation between clean and sedimented communities was strong within seven of the nine sampling periods with significant differences in community composition being evident. EPT taxa and taxon characterised as sensitive to fine sediment demonstrated strong responses to enhanced fine sediment loading. Faunal traits also detected the effects of enhanced fine sediment loading but the results were not as consistent or marked. More widely, the study highlights the temporal dynamics of sedimentation effects upon macroinvertebrate communities and the need to consider faunal life histories when examining the effects of fine sediment loading pressures on lotic ecosystems.

Benthic and hyporheic macroinvertebrate distribution within the heads and tails of riffles during baseflow conditions

The distribution of lotic fauna is widely acknowledged to be patchy reflecting the interaction between biotic and abiotic factors. In an in situ field study, the distribution of benthic and hyporheic invertebrates in the heads (downwelling) and tails (upwelling) of riffles were examined during stable baseflow conditions. Riffle heads were found to contain a greater proportion of interstitial fine sediment than riffle tails. Significant differences in the composition of benthic communities were associated with the amount of fine sediment. Riffle tail habitats supported a greater abundance and diversity of invertebrates sensitive to fine sediment such as EPT taxa. Shredder feeding taxa were more abundant in riffle heads suggesting greater availability of organic matter. In contrast, no significant differences in the hyporheic community were recorded between riffle heads and tails. We hypothesise that clogging of hyporheic interstices with fine sediments may have resulted in the homogenisation of the invertebrate community by limiting faunal movement into the hyporheic zone at both the riffle heads and tails. The results suggest that vertical hydrological exchange significantly influences the distribution of fine sediment and macroinvertebrate communities at the riffle scale.

Molecular analysis of nestling diet in a long-distance Neotropical migrant, the Louisiana Waterthrush (Parkesia motacilla)

ABSTRACT Elucidating the diet of Neotropical migratory birds is essential to our understanding of their ecology and to their long-term conservation. Reductions in prey availability negatively impact Neotropical migrants by affecting their survival as both nestlings and adults. Beyond broad taxonomic or morphological categories, however, the diet of Neotropical migrants is poorly documented. Using the molecular techniques of DNA barcoding and next-generation sequencing, we elucidated the diet of Louisiana Waterthrush (Parkesia motacilla) nestlings in Arkansas and Pennsylvania, USA. Waterthrush have been shown to respond negatively to the reduced availability of aquatic insects in the orders Ephemeroptera, Plecoptera, and Trichoptera (EPT taxa). We hypothesized that Louisiana Waterthrush nestling diet would be primarily composed of these pollution-sensitive aquatic taxa, and that changes in the riparian insect community would be reflected in their diet. Unexpectedly, the orders Lepidoptera (92%) and Diptera...