Macroinvertebrate Bioassessment Research Articles

Quantitative macroinvertebrate bioassessment in seasonally astatic aquatic habitats, Part II. Applying the method.

Seasonally astatic aquatic habitats are important ecologically, municipally, and agriculturally. Regulatory agencies and conservation organizations have developed various plans for protecting or constructing temporary wetlands, resulting in habitat monitoring requirements, particularly as relates to restoration and constructed habitats. Unfortunately, there has been no effort to develop a unified, consistent method for wetland biological monitoring. In Part I, we presented a quantifiable, replicable method for assessing seasonally astatic wetlands, which would allow for direct comparison between individual wetlands, wetland sites, and wetland types. Here in Part II, we apply the method and present the results from more than a decade of a data on two disparate sites that support California vernal pool habitats. These habitats include natural, restored, and constructed vernal pools. Our results demonstrate that the method we present yields reliable, statistically useful, and actionable data and provides a better method for assessing astatic wetland ecological health and the persistence of federally listed vernal pool crustaceans than other methods so far employed.

The Urgent Need for River Health Biomonitoring Tools for Large Tropical Rivers in Developing Countries: Preliminary Development of a River Health Monitoring Tool for Myanmar Rivers

Anthropogenic pressures such as river infrastructure, agriculture and power generation are rapidly increasing in Southeast Asia, aimed at providing food security within the region. However, this will lead to unintended river health consequences, and, currently, most Southeast Asian countries have no country-specific tools for monitoring river health. In Myanmar, one of Southeast Asia’s poorest and most rapidly developing countries, no country-specific tools exist, and there is an urgent need to provide tools that can inform better management and trade-off decision making. This research evaluated three rapid macroinvertebrate bioassessment methods under Myanmar conditions. The objective of the research was to assess the applicability of existing internationally accepted indexing methods for use in Myanmar. Through taxa identification in the laboratory and statistical analysis, it was concluded that the method with the best fit for Myanmar taxa is The Asia Foundation index method, although differences were small. This Asia Foundation method is comparable to the Australian Waterwatch method but includes a family present in our samples that is not included in the Waterwatch method. We then modified this method to include Myanmar taxa not recorded in The Asia Foundation method. The modified index method could be further developed into a Myanmar specific tool for widespread use potentially in combination with the also tested miniSASS, a much easier order-based method better suitable for non-professionals. We recommend additional testing using sites on other rivers across the country to establish a professional indexing method for Myanmar.

Bioassessment of benthic macroinvertebrates in wetlands: a paired comparison of two standardized sampling protocols

We compared a rapid bioassessment protocol (Traveling Sweep Approach [TSA]) with a more conventional time intensive protocol (Composite Transect Approach [CTA]) to describe macroinvertebrates in wetlands in Alberta, Canada. We collected one macroinvertebrate sample using each protocol from 16 wetlands and compared abundance, catch per unit effort, and relative abundance between sample protocols. We also quantified and compared the logistics required to implement each protocol. The macroinvertebrate communities differed statistically between protocols for all three response variables; however, the differences were generally small and communities similar. The CTA protocol tended to yield higher variability in the samples, likely driven by the way these samples are collected and composited, which may introduce an unwanted source of variation when the primary monitoring objective is to assess effects of human activities over time and between sites. The CTA protocol also required significantly greater investment of time (ca. 50% greater processing time), money (ca. 1.9 times sample processing cost), and resources to execute (e.g., requirement for watercraft). Both protocols provided adequate characterization of macroinvertebrate communities in wetlands, but differences in variability and resources for deployment and processing are important considerations when choosing a sampling protocol. The rapid time-limited sweep protocol (TSA) appears to be a viable monitoring approach given that macroinvertebrate communities identified by each protocol were relatively similar but were collected using the TSA protocol at a lower cost.

Comparison of a wood sampler for macroinvertebrate bioassessment of non-wadeable streams in the southeastern coastal plain

Aquatic macroinvertebrates are often the subject of biomonitoring efforts because they are ubiquitous in most systems and are known to be suitable indicators of water quality. The vast majority of biomonitoring efforts that use macroinvertebrates are tailored towards small, wadeable streams, whereas methods for sampling macroinvertebrates in non-wadeable streams (i.e., large rivers) are often less available. We compared the use of a wood sampler to collect aquatic macroinvertebrates with two more commonly used samplers (Hester-Dendy and leaf packs) to assess its suitability for sampling non-wadeable systems in the Georgia Coastal Plain. All three types of samplers were deployed at three sites on each of the Savannah and Ogeechee River for approximately 30 days during the fall of 2014. Mean, standard deviation, and variance components were examined from 53 common bioassessment metrics and 2 multi-metric indices to assess for potential differences in colonizing macroinvertebrates between the samplers. Only 9 of the metrics examined scored significantly different between sampling devices, however, assemblages colonizing the three sampling devices differed (PERMANOVA; F14,37 =1.6078, P = 0.001). Results suggest assemblage differences were primarily driven by the proportions of taxa collected by each device, rather than by different taxa colonizing devices altogether. Estimates of variance components attributed a large percentage (i.e., >20%) of the variability encountered to differences between sites, rather than devices. Our study shows that wood samplers are comparable to other devices commonly used for collecting macroinvertebrates from non-wadeable streams in the Georgia Coastal Plain. Furthermore, wood samplers can provide a suitable alternative for bioassessment, although some differences in the proportions of taxa collected with alternative devices should be expected. Determining the precision and overall efficiency of alternative sampling devices is an important step towards developing standard operating procedures for the bioassessment of large coastal plain rivers.

The first statewide stream macroinvertebrate bioassessment in Washington State with a relative risk and attributable risk analysis for multiple stressors

We report results from the first statewide assessment of biological health in perennial streams in Washington State. Using a probabilistic sampling survey design, we were able to make unbiased estimates of biological condition of macroinvertebrate communities throughout the state based on 346 sites sampled from 2009 to 2012. Results from randomly sampled sites were classified as either good, fair, poor in comparison with 75 regional reference sites that were sampled concurrently. We determined that approximately 34 percent of stream kilometers assessed were in poor biological condition as measured with a multi-metric index, the Benthic Index of Biotic Integrity. Additionally, we evaluated a variety of chemical and physical habitat stressors known to negatively influence macroinvertebrate communities and determined that poor substrate conditions were the most prevalent and important stressors impacting stream macroinvertebrates, with relative bed stability and percent sand/fines being the most prevalent. A relative risk/attributable risk analysis suggests that improving physical habitat conditions in streams, most notably a reduction in percent sand/fines, will have the greatest impact for improving biological condition for macroinvertebrate communities. It is estimated that approximately 60% of stream kilometers now classified as in poor biological condition in Washington could be improved by reducing the amount of percent sand/fines in the substrate. These results are consistent with those obtained from EPA’s national stream surveys and suggest that poor habitat conditions are the most prevalent stressors impacting stream macroinvertebrates in Washington State.

Invertebrate-Based Water Quality Impairments and Associated Stressors Identified through the US Clean Water Act.

Macroinvertebrate community assessment is used in most US states to evaluate stream health under the Clean Water Act. While water quality assessment and impairment determinations are reported to the US Environmental Protection Agency, there is no national summary of biological assessment findings. The objective of this work was to determine the national extent of invertebrate-based impairments and to identify pollutants primarily responsible for those impairments. Evaluation of state data in the US Environmental Protection Agency's Assessment and Total Maximum Daily Load Tracking and Implementation System database revealed considerable differences in reporting approaches and terminologies including differences in if and how states report specific biological assessment findings. Only 15% of waters impaired for aquatic life could be identified as having impairments determined by biological assessments (e.g., invertebrates, fish, periphyton); approximately one-third of these were associated with macroinvertebrate bioassessment. Nearly 650 invertebrate-impaired waters were identified nationwide, and sediment was the most common pollutant in bedded (63%) and suspended (9%) forms. This finding is not unexpected, given previous work on the negative impacts of sediment on aquatic life, and highlights the need to more specifically identify the mechanisms driving sediment impairments in order to design effective remediation plans. It also reinforces the importance of efforts to derive sediment-specific biological indices and numerical sediment quality guidelines. Standardization of state reporting approaches and terminology would significantly increase the potential application of water quality assessment data, reveal national trends, and encourage sharing of best practices to facilitate the attainment of water quality goals.

Corrigendum: Validation and Development of COI Metabarcoding Primers for Freshwater Macroinvertebrate Bioassessment

Corrigendum: Validation and Development of COI Metabarcoding Primers for Freshwater Macroinvertebrate Bioassessment

Validation and Development of COI Metabarcoding Primers for Freshwater Macroinvertebrate Bioassessment

A central challenge in the present era of biodiversity loss is to assess and manage human impacts on freshwater ecosystems. Macroinvertebrates are an important group for bioassessment as many taxa show specific responses to environmental conditions. However, generating accurate macroinvertebrate inventories based on larval morphology is difficult and error-prone. Here, DNA metabarcoding provides new opportunities. Its potential to accurately identify invertebrates in bulk samples to the species level, has been demonstrated in several case studies. However, DNA based identification is often limited by primer bias, potentially leading to taxa in the sample remaining undetected. Thus, the success of DNA metabarcoding as an emerging technique for bioassessment critically relies on carefully evaluating primers. We used the R package PrimerMiner to obtain and process cytochrome c oxidase I (COI) sequence data for the 15 most globally relevant freshwater invertebrate groups for stream assessment. Using these sequence alignments, we developed four primer combinations optimized for freshwater macrozoobenthos. All primers were evaluated by sequencing ten mock community samples, each consisting of 52 freshwater invertebrate taxa. Additionally, popular metabarcoding primers from the literature and the developed primers were tested in silico against the 15 relevant invertebrate groups. The developed primers varied in amplification efficiency and the number of detected taxa, yet all detected more taxa than standard ‘Folmer’ barcoding primers. Two new primer combinations showed more consistent amplification than a previously tested ribosomal marker (16S) and detected all 42 insect taxa present in the mock community samples. In silico evaluation revealed critical design flaws in some commonly used primers from the literature. We demonstrate a reliable strategy to develop optimized primers using the tool PrimerMiner. The developed primers detected almost all taxa present in the mock samples, and we argue that high base degeneracy is necessary to decrease primer bias as confirmed by experimental results and in silico primer evaluation. We further demonstrate that some primers currently used in metabarcoding studies may not be suitable for amplification of freshwater macroinvertebrates. Therefore, careful primer evaluation and more region / ecosystem specific primers are needed before DNA metabarcoding can be used for routine bioassessment of freshwater ecosystems.

Different surrogacy approaches for stream macroinvertebrates in discriminating human disturbances in Central China

Due to the difficulty of identifying many taxa of freshwater invertebrates to species, many researchers have assessed the utility of surrogates for species-level identifications (e.g. higher taxa) in bioassessment programs. Here, we examined the efficiency of two different approaches to species surrogacy, one using coarser taxonomic resolution and a second approach based on random aggregation (“Best practicable aggregation of species”, BestAgg), in portraying patterns of stream macroinvertebrates in Central China. The main objectives were: (1) to compare the discriminatory power of biodiversity indices and assemblage structure for different levels of human disturbances based on different taxonomic resolution and on BestAgg; (2) to identify the congruence of assemblage-environment and biodiversity-indices-environment relationships for datasets at the species level versus those at surrogate levels. We found that genus-level and BestAgg datasets accurately reproduced the pattern of species-level communities, whereas family- and order-level datasets did not. Specifically, both genus-level and BestAgg approaches performed almost as well as species-level data in distinguishing sites subjected to different disturbance levels. Most of the environmental variables that were important for species-level assemblages, also emerged as significant when analyzing genera and BestAgg surrogates, as shown by both analyses of indices and assemblage composition according to distance-based ordination models. Our results suggest that genus-level taxonomy, which resulted in the least loss of ecological information relative to species-level identification, is sufficient in studies of community ecology and bioassessment of stream macroinvertebrates in Central China. In addition, the BestAgg approach, which required identification of fewer taxa than genus-level analysis, has a similar ability to depict multivariate patterns of macroinvertebrate assemblages and differentiate different disturbance levels. Applying our results could enhance speed and cost-effectiveness of freshwater biomonitoring and bioassessment programs; however, independent determination of best taxonomic level and BestAgg will be required whenever a new geographic area or habitat type is assessed.

Predicting reference conditions for river bioassessment by incorporating boosted trees in the environmental filters method

Contemporary bioassessment methods for water bodies require the description of “reference conditions” representing an absence or only “very minor” presence of human impacts on hydromorphological, physical and chemical properties. However, minimally disturbed reference sites are lacking in many European regions and other parts of the world because of pervasive anthropogenic influences. Here we describe the use of environmental filters modelling, incorporating boosted trees (BT), to derive reference data for abiotic variables and biological communities (diatoms and macroinvertebrates) for rivers in a highly disturbed region (Portuguese central-western lowland area), where minimally disturbed reference sites are non-existent. We also revise quality class boundaries for diatom and macroinvertebrate bioassessment in this region, and develop a new multimetric diatoms index (MDI). The new index includes not only the ‘Indice de Polluosensibilité Spécifique’ (IPS) based on species’ sensitivity to organic pollution and nutrients, but also the numbers of total and sensitive taxa. Our approach predicted significantly different communities under reference conditions from those observed, with a higher median reference number of taxa per site than the observed number (69 against 27 for diatoms; 53 against 22 for macroinvertebrates). In addition, the predicted communities for both biological groups were more similar among sites than the observed communities. Adjustment of index calculation and quality class boundaries to incorporate the new reference data resulted in more stringent site assessments that were better correlated with human pressures than assessments with previous methods. This study brings new insight to solve the problem of an absence of minimally disturbed reference sites.

Evaluation of WET Testing as an Indicator of Aquatic Health

This project evaluated the quality of data needed to determine relationships between chronic Whole Effluent Toxicity (WET) test results and instream biological condition. A data quality objectives approach was used, which included several proposed measurement quality objectives (MQOs) that specified desired precision, bias, and sensitivity of methods used. Six facilities (four eastern and two western U.S.) participated in this study, all having design effluent concentrations > 60% of the stream flow. In accordance with a Quality Assurance Project Plan most of the facilities completed four quarters of chronic Ceriodaphnia dubia, and Pimephales promelas (fathead minnow) WET tests, and three quarters of Selenastrum capricornutum (green algae) WET testing following the most recent USEPA methods. Several other WET tests were conducted to address MQOs including splits, duplicates, and blind positive and negative controls. Macroinvertebrate, fish, and periphyton bioassessments were conducted at multiple locations up and downstream of each facility following the most recent USEPA Office of Water bioassessment protocols. Test acceptance criteria were met for most WET tests, however, this study demonstrated the need to incorporate other MQOs in a full study (such as minimum and maximum percent significant differences and performance on blind samples) to ensure accurate interpretation of effluent toxicity. More false positives, lower test endpoint (i.e., higher toxicity), and more “failed” (non-compliant) tests were observed using No Observed Effect Concentrations (NOEC) as compared to IC25s (concentration causing = 25% decrease in organism response compared to controls). Algae tests often yielded the most effluent toxicity in this study, however, this test was most susceptible to false positives and high inter-laboratory variability. WET test results exhibited few relationships with bioassessment results, even when incorporating actual effluent dilution. Neither frequency of WET non-compliance nor magnitude of WET were clearly related to differences in biological condition up and downstream of a discharge for the most part. Macroinvertebrate assessments were most able to discriminate small changes downstream of the effluent, followed by periphyton and then fish. The sampling methods used were robust but a full study should collect more field replicates up and downstream of each discharge to increase detection power. Macroinvertebrate and periphyton assessments together appeared to be sufficient to address project objectives. Fish assessments could be useful as well but would entail more effort and cost per site than expended in this project to be useful. This title belongs to WERF Research Report Series ISBN: 9781843397687 (Print) ISBN: 9781780403793 (eBook)

Evaluation of alternative macroinvertebrate sampling techniques for use in a new tropical freshwater bioassessment scheme

Aim: The study aimed to determine the effectiveness of benthic macroinvertebrate dredge net sampling procedures as an alternative method to kick net sampling in tropical freshwater systems, specifically as an evaluation of sampling methods used in the Zambian Invertebrate Scoring System (ZISS) river bioassessment scheme. Tropical freshwater ecosystems are sometimes dangerous or inaccessible to sampling teams using traditional kick-sampling methods, so identifying an alternative procedure that produces similar results is necessary in order to collect data from a wide variety of habitats.MethodsBoth kick and dredge nets were used to collect macroinvertebrate samples at 16 riverine sites in Zambia, ranging from backwaters and floodplain lagoons to fast flowing streams and rivers. The data were used to calculate ZISS, diversity (S: number of taxa present), and Average Score Per Taxon (ASPT) scores per site, using the two sampling methods to compare their sampling effectiveness. Environmental parameters, namely pH, conductivity, underwater photosynthetically active radiation (PAR), temperature, alkalinity, flow, and altitude, were also recorded and used in statistical analysis. Invertebrate communities present at the sample sites were determined using multivariate procedures.ResultsAnalysis of the invertebrate community and environmental data suggested that the testing exercise was undertaken in four distinct macroinvertebrate community types, supporting at least two quite different macroinvertebrate assemblages, and showing significant differences in habitat conditions. Significant correlations were found for all three bioassessment score variables between results acquired using the two methods, with dredge-sampling normally producing lower scores than did the kick net procedures. Linear regression models were produced in order to correct each biological variable score collected by a dredge net to a score similar to that of one collected by kick net sampling.ConclusionsThe use of a dredge net in macroinvertebrate bioassessment schemes is an effective, alternative method in certain environments when site conditions prohibit the use of the preferred kick net sampling method. The results of this study can be used to aid in the development of other tropical freshwater bioassessment schemes around the world, including Brazil.

Does Supplementing Dipnet Samples with Activity Traps Improve the Ability to Assess the Biological Integrity of Macroinvertebrate Communities in Depressional Wetlands?

Dipnet (DN) sampling is routinely employed for macroinvertebrate bioassessments in wetlands, but it has been demonstrated that some taxa are more effectively collected with activity traps (AT). The Minnesota Pollution Control Agency (MPCA) used both DN and AT methods to evaluate the biological condition of depressional wetlands in the Mixed Wood Plains (MWP) and Temperate Prairies (TP) ecoregions. Two indices of biotic integrity (IBIs) were developed for each ecoregion using: 1) DN data alone and 2) composite samples consisting of both DN and AT data. ATs collected more active taxa such as diving beetles and swimming Hemiptera. DNs collected more taxa and collected more skating taxa and those associated with sediment or vegetation. A comparison of the effectiveness of the IBIs to evaluate biological condition indicated that the composite data had a slightly better relationship with anthropogenic disturbance and was marginally more precise. A comparison of sampling and processing costs revealed that sampling using composite samples was 130 % greater and processing was 50 % greater compared to DN-only samples. Based on the cost and limited benefit of adding AT samples, a DN-only sampling protocol is recommended to assess biological condition in depressional wetlands.

Bioassessment of Benthic Macroinvertebrates of the Middle Penns Creek, Pennsylvania Watershed

ABSTRACT During October and November 2011, an assessment of the benthic macroinvertebrate assemblage was conducted in the middle Penns Creek (PA) watershed. The survey consisted of 10 tributary sites within a 40km portion of the watershed. The goals were to establish baseline conditions for headwater streams in this section of the watershed, determine their current biotic health, and suggest possible designated use upgrades. All sample sites were low-order (1–3) streams typically of higher gradient. We calculated the Pennsylvania Benthic Macroinvertebrate Index of Biotic Integrity at each site based on the following biotic indices: Beck's Index, Total Taxa Richness, EPT (Ephemeroptera + Plecoptera + Trichoptera) Taxa Richness (Pollution Tolerance Values 0–4), Shannon Diversity Index, Hilsenhoff Biotic Index, and Percent Sensitive Individuals (Pollution Tolerance Values 0–3) . All study streams are currently designated by Pennsylvania Department of Environmental Protection (PA DEP) as Cold Water Fish (1), High Quality (6), or Exceptional Value (3) streams. We found six streams to be of highest biotic quality (IBI score >80). Benthic macroinvertebrate IBI scores for Little Poe Creek (93.2) exceeded the current designated use of High Quality by PA DEP, and should be considered for a re-designated increase to Exceptional Value. In total, 10 pollution sensitive genera (Epeorus, Leuctra, Sweltsa, Tallaperla, Acroneuria, Pteronarcys, Agapetus, Dolophilodes, Wormaldia, and Diplectrona) were present across all study streams. Panther Run (51.9) received the lowest benthic macroinvertebrate IBI score, possibly due to low total organisms which may suggest it could be experiencing ecological stressors. Our overall results indicate these Penns Creek streams to currently be of good biotic health, however long-term monitoring may be necessary to further assess anthropogenic impacts within the watershed.

Refining a kick sampling strategy for the bioassessment of benthic macroinvertebrates in headwater streams

Small headwater streams constitute a large proportion of the river channel network in many parts of the world. In this study, two multihabitat kick sampling methods (60-second and 20-second) were compared across 10 small headwater streams in the southwest and east of Ireland in spring and summer 2009 to determine the influence of sampling on various benthic macroinvertebrates in headwater streams. The performance of each method, over time and replication, was examined using a range of benthic macroinvertebrate metrics, as well as the community composition and structure recorded by both methods. The ability to recruit taxa, as well as the field sampling and laboratory processing effort required for each method, was also assessed. Results indicated that both kick sampling methods generally recorded similar metric scores with the exception of taxonomic richness (t = 180 s and n = 9 replicates test) where the 20-second kicks consistently out preformed those calculated for the 60-second kicks. All other metrics compared generally performed equally as well regardless of the method used. Multivariate analysis of macroinvertebrate community assemblage, using SIMPROF, RELATE and CS-SMC analyses, further highlighted the high similarity in the macroinvertebrate assemblage recorded between both methods. Finally, the 20-second kicks recruited taxa as efficiently as 60-second kicks samples so long as replication was equal but required less sampling effort (NSE) and processing time. Therefore, the shorter 20-second kicks can be used to assess the ecological health of headwater streams, provided that adequate replication is adopted, resulting in significant effort, cost and time savings.

Within-year temporal variation and life-cycle seasonality affect stream macroinvertebrate community structure and biotic metrics

Seasonal changes in macroinvertebrate taxon abundances that are related to life history introduce temporal variation into macroinvertebrate community structure that can potentially confound bioassessments. In this study, macroinvertebrates from three rural and three urban streams were sampled monthly to assess temporal variability in community structure, determine how taxon life-cycle seasonality affects this variability, and determine if this temporal variability confounds biotic index interpretations. Temporal variation in taxon abundances was higher in the rural streams than in the urban streams, and 17 of 23 indicator taxa from rural streams exhibited, or are known to exhibit, either fast- or slow-seasonal life cycles. Conversely, five taxa were identified as indicators for urban streams, but only two of these taxa exhibited seasonal life cycles. Further, the life-cycle seasonality of many rural stream indicator taxa appeared to be linked to the seasonality of environmental conditions such as hydrologic permanence and benthic leaf detritus availability. Macroinvertebrate bioassessment index (MBI) scores were higher in the rural streams than in the urban streams during all months except June, July, and October when no difference was detected. We attribute the reduced discriminatory power of the MBI in the summer and early autumn to the life-cycle of a single taxon ( Stenelmis sp.), and its effects on % Clingers – a component metric of the MBI. Stenelmis sp. exhibited a non-seasonal life cycle with a larval development time of approximately 12 months with considerable overlapping of cohorts present during the summer and early autumn when an extended first instar recruitment period was evident. During this overlap period, urban stream MBI values increased resulting in no statistical difference in the MBI between urban and rural streams in June, July, and October. Analyses of temporal variability in taxon abundances and life-history characteristics, as completed in this study, can greatly contribute to the creation and/or validation of bioassessment protocols.

Effect of fixed-fraction subsampling on macroinvertebrate bioassessment of rivers

We investigated the effect of different subsample fractions on the variability of benthic invertebrate metrics. The results of six fractions 1/12, 1/6, 1/4, 1/3, 5/12 and 1/2 were compared to the results of the whole samples. Over 120 metrics were tested using five datasets: ecoregion Alps and four river types. In general, variability of metrics decreased with increasing subsample size, but variability varied greatly with the selected metric group and river type. Independent of river type, the highest variation was observed for the composition/abundance group metrics and the richness metrics, whereas it was low for the diversity indices and for the metrics of the sensitivity/tolerance group and intermediate for the functional metric group. For all metric groups independent of river type, the main decrease in variability occurs up to 1/4 subsample. We suggest that the effect of subsample size on variability of metrics should be tested prior to selecting potential assessment metrics.

The bioassessment of fish and macroinvertebrates in a Mediterranean–Atlantic climate: Habitat assessment and concordance between contrasting ecological samples

Abstract Human intervention and drought conditions in Mediterranean rivers may necessitate the collection of organisms from a different habitat type to that specified by the original bioassessment protocol; it is therefore critical to understand the consequences of adaptive sampling strategies in these lotic systems. In a survey of 31 streams (2nd–4th order) in northern Portugal we collected separate macroinvertebrate samples from running-water and standing-water habitats and fish samples from a delineated reach, inclusive of all habitat types. In addition to collecting habitat data specific to macroinvertebrates and fish we conducted a generalized River Habitat Survey (RHS) and derived scores designed to report habitat quality and habitat degradation. Ecological data were described in terms of taxonomic structure, functional organization and by biotic indices and interpreted in relation to habitat data, comparing samples within and between sites for concordance. Macroinvertebrates from respective habitats differed in their relationship with habitat variable with running-water samples more strongly related to substrate and water quality and standing-water samples more strongly reflecting habitat characteristics at the reach scale. Running- and standing-water samples from the same-site varied widely, indicating that substituting standing-water for running-water samples in macroinvertebrate-based bioassessment carries a high risk of misclassification. However, a consistent bias in index scores suggests that a habitat-adjusted interpretation of biotic indices could be employed to improve measurement precision. Variation in key parameters of the fish community corresponded to changes in water quality and habitat structure and to reach-scale features recorded by the RHS. Trends between macroinvertebrate and fish measurements indicated common patterns for oxygen/flow sensitive taxa and for trophic organization that were related to similar habitat preferences. Whilst macroinvertebrates demonstrated no relationship with derived scores of habitat quality, the fish-based Index of well-being (Iwb) was strongly related to the Habitat Modification Score. Overall these data indicate how different ecological samples can be used to focus on different aspects of habitat quality and are suggestive of strategies for both the collection and interpretation of ecological data that would improve assessment performance. This study emphasizes the need to adapt assessment methods not only to the species pool but also to the differences in the managed and natural habitat characteristics of these types of Mediterranean streams.

Regional and local drivers of macroinvertebrate assemblages in boreal springs

AbstractAim To identify the most important environmental drivers of benthic macroinvertebrate assemblages in boreal springs at different spatial scales, and to assess how well benthic assemblages correspond to terrestrially derived ecoregions.Location Finland.Methods Benthic invertebrates were sampled from 153 springs across four boreal ecoregions of Finland, and these data were used to analyse patterns in assemblage variation in relation to environmental factors. Species data were classified using hierarchical divisive clustering (twinspan) and ordinated using non‐metric multidimensional scaling. The prediction success of the species and environmental data into a priori (ecoregions) and a posteriori (twinspan) groups was compared using discriminant function analysis. Indicator species analysis was used to identify indicator taxa for both a priori and a posteriori assemblage types.Results The main patterns in assemblage clusters were related to large‐scale geographical variation in temperature. A secondary gradient in species data reflected variation in local habitat structure, particularly abundance of minerogenic spring brooks. Water chemistry variables were only weakly related to assemblage variation. Several indicator species representing southern faunistic elements in boreal springs were identified. Discriminant function analysis showed poorer success in classifying sites into ecoregions based on environmental than on species data. Similarly, when classifying springs into the twinspan groups, classification based on species data vastly outperformed that based on environmental data.Main conclusions A latitudinal zonation pattern of spring assemblages driven by regional thermal conditions is documented, closely paralleling corresponding latitudinal patterns in both terrestrial and freshwater assemblages in Fennoscandia. The importance of local‐scale environmental variables increased with decreasing spatial extent. Ecoregions provide an initial stratification scheme for the bioassessment of benthic macroinvertebrates of North European springs. Our results imply that climate warming, landscape disturbance and degradation of spring habitat pose serious threats to spring biodiversity in northern Europe, especially to its already threatened southern faunistic elements.

Downstream effects of mountaintop coal mining: comparing biological conditions using family- and genus-level macroinvertebrate bioassessment tools

Surface coal mining with valley fills has impaired the aquatic life in numerous streams in the Central Appalachian Mountains. We characterized macroinvertebrate communities from riffles in 37 small West Virginia streams (10 unmined and 27 mined sites with valley fills) sampled in the spring index period (March-May) and compared the assessment results using family- and genus-level taxonomic data. Specific conductance was used to categorize levels of mining disturbance in mined watersheds as low (,500 lS/cm), medium (500-1000 lS/cm), or high (.1000 lS/cm). Four lines of evidence indicate that mining activities impair biological condition of streams: shift in species assemblages, loss of Ephemeroptera taxa, changes in individual metrics and indices, and differences in water chemistry. Results were consistent whether family- or genus-level data were used. In both family- and genus-level nonmetric multidimensional scaling (NMS) ordinations, mined sites were significantly separated from unmined sites, indicating that shifts in community structure were caused by mining. Several Ephemeroptera genera (e.g., Ephemerella, Epeorus, Drunella) and their families (Ephemerellidae, Heptageniidae) were correlated most strongly with the primary NMS axis (r . 0.59 for these genera; r . 0.78 for these families). These same Ephemeroptera were absent and, thus, eliminated from most of the mined sites. Total Ephemeroptera richness and relative abundance both declined with increasing mining disturbance. Several other metrics, such as richness, composition, tolerance, and diversity, clearly discriminated unmined vs mined sites. Most family-level metrics performed well and approximated the strength of genus-based metrics. A genus-based multimetric index (MMI) rated more mined sites as impaired than did the family-based MMI. Water-quality variables related to mining were more strongly correlated to NMS axis-1 scores, metrics, and MMIs than were sedimentation and riparian habitat scores. Generally, the correlations between the genus-level MMI and water-quality variables were stronger than the correlations between the family-level MMI and those variables. Our results show that mining activity has had subtle to severe impacts on benthic macroinvertebrate communities and that the biological condition most strongly correlates with a gradient of ionic strength.