Temporal distribution of Ephemeroptera, Plecoptera and Trichoptera (EPT) adults at a tropical forest stream: response to seasonal variations

Temporal changes in Ephemeroptera, Plecoptera and Trichoptera (EPT) abundance were investigated monthly from January to December 2008 at a tropical forest stream of Tupah River (TR) at Gunung Jerai Forest Reserve, Malaysia. A total of 1,689 adult individuals belong to 16 families of EPT were collected from TR. EPT populations peaked in May, June and December. Mean EPT abundance was significantly different among months (Kruskal–Wallis test, P < 0.05). Among the three orders, Trichoptera had the most diverse community with eight families reported, followed by Ephemeroptera (six families) and Plecoptera (two families). The family Baetidae was the most abundant ephemeropteran. Meanwhile, caddisfly families Hydropsychidae, Leptoceridae and Lepidostomatidae were abundant at TR. However, plecopterans were mainly represented by Perlidae. There was significant difference in abundance (t = 4.863, P < 0.05) and diversity (t = 7.857, P < 0.05) of EPT adults between dry and wet seasons. Interestingly, abundance of EPT adults was higher in the dry season compared to the wet season. Consequently, seasonality impact on abundance of EPT adults at TR was obvious. The adult population of Trichoptera was dominant during the dry season. However, adults of Ephemeroptera were abundant during the wet season.     

Stream Condition in Piedmont Streams with Restored Riparian Buffers in the Chesapeake Bay Watershed1

Orzetti, Leslie L., R. Christian Jones, and Robert F. Murphy, 2010. Stream Condition in Piedmont Streams with Restored Riparian Buffers in the Chesapeake Bay Watershed. Journal of the American Water Resources Association (JAWRA) 46(3):473-485. DOI: 10.1111/j.1752-1688.2009.00414.x Abstract: This study tested the efficacy of restored forest riparian buffers along streams in the Chesapeake Bay watershed by examining habitat, selected water quality variables, and benthic macroinvertebrate community metrics in 30 streams with buffers ranging from zero to greater than 50 years of age. To assess water quality we measured in situ parameters (temperature, dissolved oxygen, and conductivity) and laboratory-analyzed grab samples (soluble reactive phosphorus, total phosphorus, nitrate, ammonium, and total suspended solids). Habitat conditions were scored using the Environmental Protection Agency Rapid Bioassessment Protocols for high gradient streams. Benthic macroinvertebrates were quantified using pooled riffle/run kick samples. Results showed that habitat, water quality, and benthic macroinvertebrate metrics generally improved with age of restored buffer. Habitat scores appeared to stabilize between 10 and 15 years of age and were driven mostly by epifaunal substrate availability, sinuosity, embeddedness, and velocity depth regime. Benthic invertebrate taxa richness, percent Ephemeroptera, Plecoptera, Trichoptera minus hydropsychids (%EPT minus H), % Ephemeroptera, and the Family Biotic Index were among the metrics which improved with age of buffer zone. Results are consistent with the hypothesis that forest riparian buffers enhance instream habitat, water quality, and resulting benthic macroinvertebrate communities with noticeable improvements occurring within 5-10 years postrestoration, leading to conditions approaching those of long established buffers within 10-15 years of restoration.     

Macroinvertebrate Responses to Constructed Riffles in the Cache River,Illinois, USA

Stream restoration practices are becoming increasingly common, but biological assessments of these improvements are still limited. Rock weirs, a type of constructed riffle, were implemented in the upper Cache River in southern Illinois, USA, in 2001 and 2003–2004 to control channel incision and protect high quality riparian wetlands as part of an extensive watershed-level restoration. Construction of the rock weirs provided an opportunity to examine biological responses to a common in-stream restoration technique. We compared macroinvertebrate assemblages on previously constructed rock weirs and newly constructed weirs to those on snags and scoured clay streambed, the two dominant substrates in the unrestored reaches of the river. We quantitatively sampled macroinvertebrates on these substrates on seven occasions during 2003 and 2004. Ephemeroptera, Plecoptera, and Trichoptera (EPT) biomass and aquatic insect biomass were significantly higher on rock weirs than the streambed for most sample periods. Snags supported intermediate EPT and aquatic insect biomass compared to rock weirs and the streambed. Nonmetric multidimensional scaling (NMDS) ordinations for 2003 and 2004 revealed distinct assemblage groups for rock weirs, snags, and the streambed. Analysis of similarity supported visual interpretation of NMDS plots. All pair-wise substrate comparisons differed significantly, except recently constructed weirs versus older weirs. Results indicate positive responses by macroinvertebrate assemblages to in-stream restoration in the Cache River. Moreover, these responses were not evident with more common measures of total density, biomass, and diversity.     

Comparison of Macroinvertebrate‐Derived Stream Quality Metrics Between Snag and Riffle Habitats1

Abstract: We compared benthic macroinvertebrate assemblage structure at snag and riffle habitats in 43 Wisconsin streams across a range of watershed urbanization using a variety of stream quality metrics. Discriminant analysis indicated that dominant taxa at riffles and snags differed; Hydropsychid caddisflies (Hydropsyche betteni and Cheumatopsyche spp.) and elmid beetles (Optioservus spp. and Stenemlis spp.) typified riffles, whereas isopods (Asellus intermedius) and amphipods (Hyalella azteca and Gammarus pseudolimnaeus) predominated in snags. Analysis of covariance indicated that samples from snag and riffle habitats differed significantly in their response to the urbanization gradient for the Hilsenhoff biotic index (BI), Shannon’s diversity index, and percent of filterers, shredders, and pollution intolerant Ephemeroptera, Plecoptera, and Trichoptera (EPT) at each stream site (p ≤ 0.10). These differences suggest that although macroinvertebrate assemblages present in either habitat type are sensitive to detecting the effects of urbanization, metrics derived from different habitats should not be intermixed when assessing stream quality through biomonitoring. This can be a limitation to resource managers who wish to compare water quality among streams where the same habitat type is not available at all stream locations, or where a specific habitat type (i.e., a riffle) is required to determine a metric value (i.e., BI). To account for differences in stream quality at sites lacking riffle habitat, snag‐derived metric values can be adjusted based on those obtained from riffles that have been exposed to the same level of urbanization. Comparison of nonlinear regression equations that related stream quality metric values from the two habitat types to percent watershed urbanization indicated that snag habitats had on average 30.2 fewer percent EPT individuals, a lower diversity index value than riffles, and a BI value of 0.29 greater than riffles.     

Evaluation of Deposited Sediment and Macroinvertebrate Metrics Used to Quantify Biological Response to Excessive Sedimentation in Agricultural Streams

The objective of this study was to evaluate which macroinvertebrate and deposited sediment metrics are best for determining effects of excessive sedimentation on stream integrity. Fifteen instream sediment metrics, with the strongest relationship to land cover, were compared to riffle macroinvertebrate metrics in streams ranging across a gradient of land disturbance. Six deposited sediment metrics were strongly related to the relative abundance of Ephemeroptera, Plecoptera and Trichoptera and six were strongly related to the modified family biotic index (MFBI). Few functional feeding groups and habit groups were significantly related to deposited sediment, and this may be related to the focus on riffle, rather than reach-wide macroinvertebrates, as reach-wide sediment metrics were more closely related to human land use. Our results suggest that the coarse-level deposited sediment metric, visual estimate of fines, and the coarse-level biological index, MFBI, may be useful in biomonitoring efforts aimed at determining the impact of anthropogenic sedimentation on stream biotic integrity.     

Evaluating the Eco‐Geomorphological Condition of Restored Streams Using Visual Assessment and Macroinvertebrate Metrics

The Stream Performance Assessment (SPA), a new rapid assessment method, was applied to 93 restored, 21 impaired, 29 reference, and 13 reference streams with some incision throughout North Carolina. Principal component analysis (PCA) indicated restored streams align more closely with reference streams rather than impaired streams. Further, PCA‐based factor analysis revealed restored streams were similar to reference streams in terms of morphologic condition, but exhibited a greater range of scores relative to aquatic habitat and bedform. Macroinvertebrate sampling and GIS watershed analyses were conducted on 84 restored streams. SPA and watershed data were compared to Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa to determine which factors indicate stream health. SPA and watershed factors were used in least squares, ridge, and principal component regression (PCR) to develop a prediction model for EPT taxa. All three methods produced reasonable predictions for EPT taxa. Cross‐validation indicated ridge regression resulted in the lowest prediction error. The ridge model was then used to predict EPT taxa numbers for 21 impaired and 25 reference streams in addition to the 84 restored streams. Statistical comparisons of the predicted scores indicated urban streams (>10% impervious watershed cover) have lower expected numbers of EPT taxa. Rural restored streams have macroinvertebrate metric scores similar to those predicted for rural reference streams.     

Effects of Management Legacies on Stream Fish and Aquatic Benthic Macroinvertebrate Assemblages

Fish and benthic macroinvertebrate assemblages often provide insight on ecological conditions for guiding management actions. Unfortunately, land use and management legacies can constrain the structure of biotic communities such that they fail to reflect habitat quality. The purpose of this study was to describe patterns in fish and benthic macroinvertebrate assemblage structure, and evaluate relationships between biota and habitat characteristics in the Chariton River system of south-central Iowa, a system likely influenced by various potential management legacies (e.g., dams, chemical removal of fishes). We sampled fishes, benthic macroinvertebrates, and physical habitat from a total of 38 stream reaches in the Chariton River watershed during 2002–2005. Fish and benthic macroinvertebrate assemblages were dominated by generalist species tolerant of poor habitat quality; assemblages failed to show any apparent patterns with regard to stream size or longitudinal location within the watershed. Metrics used to summarize fish assemblages and populations [e.g., presence–absence, relative abundance, Index of Biotic Integrity for fish (IBI_F)] were not related to habitat characteristics, except that catch rates of piscivores were positively related to the depth and the amount of large wood. In contrast, family richness of benthic macroinvertebrates, richness of Ephemeroptera, Trichoptera, and Plecoptera taxa, and IBI values for benthic macroinvertebrates (IBI_BM) were positively correlated with the amount of overhanging vegetation and inversely related to the percentage of fine substrate. A long history of habitat alteration by row-crop agriculture and management legacies associated with reservoir construction has likely resulted in a fish assemblage dominated by tolerant species. Intolerant and sensitive fish species have not recolonized streams due to downstream movement barriers (i.e., dams). In contrast, aquatic insect assemblages reflected aquatic habitat, particularly the amount of overhanging vegetation and fine sediment. This research illustrates the importance of using multiple taxa for biological assessments and the need to consider management legacies when investigating responses to management and conservation actions.     

INFLUENCES OF WATERSHED URBANIZATION AND INSTREAM HABITAT ON MACROINVERTEBRATES IN COLD WATER STREAMS1

ABSTRACT: We analyzed data from riffle and snag habitats for 39 small cold water streams with different levels of watershed urbanization in Wisconsin and Minnesota to evaluate the influences of urban land use and instream habitat on macroinvertebrate communities. Multivariate analysis indicated that stream temperature and amount of urban land use in the watersheds were the most influential factors determining macroinvertebrate assemblages. The amount of watershed urbanization was nonlinearly and negatively correlated with percentages of Ephemeroptera‐Plecoptera‐Trichoptera (EPT) abundance, EPT taxa, filterers, and scrapers and positively correlated with Hilsenhoff biotic index. High quality macroinvertebrate index values were possible if effective imperviousness was less than 7 percent of the watershed area. Beyond this level of imperviousness, index values tended to be consistently poor. Land uses in the riparian area were equal or more influential relative to land use elsewhere in the watershed, although riparian area consisted of only a small portion of the entire watershed area. Our study implies that it is extremely important to restrict watershed impervious land use and protect stream riparian areas for reducing human degradation on stream quality in low level urbanizing watersheds. Stream temperature may be one of the major factors through which human activities degrade cold‐water streams, and management efforts that can maintain a natural thermal regime will help preserve stream quality.     

STREAM ASSESSMENTS USING BIOTIC INDICES: RESPONSES TO PHYSICOCHEMICAL VARIABLES1

ABSTRACT: Responses of the Wyoming Stream Integrity Index (WSII), a regionally calibrated multimetric index, were investigated in relation to background elevational changes in water quality and habitat conditions versus accelerated anthropogenic degradation at the watershed scale. Assessments were conducted for three rivers in southeast Wyoming: the Little Medicine Bow River, the Medicine Bow River, and Rock Creek. Pearson correlation coefficients and regression models related “core metrics” and index scores to elevational gradients of physicochemical variables. Velocity, substrate, and weighted habitat values were positively correlated to index scores, while suspended solids was negatively correlated. The exclusive dependence of index scores on physical variables specifies the type of environmental gradients the WSII is most robust in detecting. The individual “core metrics” Plecoptera taxa, Trichoptera taxa, percent Trichoptera without Hydropsychidae, and percent noninsects appeared most sensitive to physical changes and were thus driving associations between index scores and physical variables. Despite strong correlations with physical variables, anomalies existed where habitat conditions were good, unknown stressors existed, or gradients were naturally occurring despite “Poor” index scores (i.e., degraded stream conditions). Such findings illustrate the influence of regional variability on biotic indices and the importance of identifying sufficient reference and impaired stream reaches used to develop and calibrate multimetric indices relying on reference conditions.     

Stream Invertebrate Communities, Water Quality, and Land-Use Patterns in an Agricultural Drainage Basin of Northeastern Nebraska, USA

We used invertebrate bioassessment, habitat analysis, geographic information system analysis of land use, and water chemistry monitoring to evaluate tributaries of a degraded northeast Nebraska, USA, reservoir. Bimonthly invertebrate collections and monthly water chemistry samples were collected for two years on six stream reaches to identify sources contributing to reservoir degradation and test suitability of standard rapid bioassessment methods in this region. A composite biotic index composed of seven commonly used metrics was effective for distinguishing between differentially impacted sites and responded to a variety of disturbances. Individual metrics varied greatly in precision and ability to discriminate between relatively impacted and unimpacted stream reaches. A modified Hilsenhoff index showed the highest precision (reference site CV = 0.08) but was least effective at discriminating among sites. Percent dominance and the EPT (number of Ephemeroptera, Plecoptera, and Trichoptera taxa) metrics were most effective at discriminating between sites and exhibited intermediate precision. A trend of higher biotic integrity during summer was evident, indicating seasonal corrections should differ from other regions. Poor correlations were evident between water chemistry variables and bioassessment results. However, land-use factors, particularly within 18-m riparian zones, were correlated with bioassessment scores. For example, there was a strong negative correlation between percentage of rangeland in 18-m riparian zones and percentage of dominance in streams (r ² = 0.90, P < 0.01). Results demonstrate that standard rapid bioassessment methods, with some modifications, are effective for use in this agricultural region of the Great Plains and that riparian land use may be the best predictor of stream biotic integrity.     

Agriculture and stream water quality: A biological evaluation of erosion control practices

Agricultural runoff affects many streams in North Carolina. However, there is is little information about either its effect on stream biota or any potential mitigation by erosion control practices. In this study, benthic macroinvertebrates were sampled in three different geographic areas of North Carolina, comparing control watersheds with well-managed and poorly managed watersheds. Agricultural streams were characterized by lower taxa richness (especially for intolerant groups) and low stability. These effects were most evident at the poorly managed sites. Sedimentation was the apparent major problem, but some changes at agricultural sites implied water quality problems. The groups most intolerant of agricultural runoff were Ephemeroptera, Plecoptera and Trichoptera. Tolerant species were usually filter-feeders or algal grazers, suggesting a modification of the food web by addition of particulate organic matter and nutrients. This study clearly indicates that agricultural runoff can severely impact stream biota. However, this impact can be greatly mitigated by currently recommended erosion control practices.     

A Comparison of Single and Multiple Habitat Protocols for Collecting Macroinvertebrates in Wadeable Streams1

Abstract: In 2003, we compared two benthic macroinvertebrate sampling methods that are used for rapid biological assessment of wadeable streams. A single habitat method using kick sampling in riffles and runs was compared to a multiple habitat method that sampled all available habitats in proportion of occurrence. Both methods were performed side‐by‐side at 41 sites in lower gradient streams of the Piedmont and Northern Piedmont ecoregions of the United States, where riffle habitat is less abundant. Differences in sampling methods were examined using similarity indices, two multimetric indices [the family‐level Virginia Stream Condition Index (VSCI) and the species‐level Macroinvertebrate Biotic Integrity Index (MBII)], their component metrics, and bioassessment endpoints based on each index. Index scores were highly correlated between single and multiple habitat field methods, and sampling method comparability, based on comparison of similarities between and within sampling methods, was particularly high for species level data. The VSCI scores and values of most of its component metrics were not significantly higher for one particular method, but relationships between single and multiple habitat values were highly variable for percent Ephemeroptera, percent chironomids, and percent Plecoptera and Trichoptera (Hydropsychidae excluded). A similar level of variability in the relationship was observed for the MBII and most of its metrics, but Ephemeroptera richness, percent individuals in the dominant five taxa, and Hilsenhoff Biotic Index scores all exhibited differences in values between single and multiple habitat field methods. When applied to multiple habitat samples, the MBII exhibited greater precision, higher index scores, and higher assessment categories than when applied to single habitat samples at the same sites. In streams with limited or no riffle habitats, the multiple habitat method should provide an adequate sample for biological assessment, and at sites with abundant riffle habitat, little difference would be expected between the single and multiple habitat field methods. Thus, in geographic areas with a wide variety of stream types, the multiple habitat method may be more desirable. Even so, the variability in the relationship between single and multiple habitat methods indicates that the data are not interchangeable, and we suggest that any change in sampling method should be accompanied by a recalibration of any existing assessment tool (e.g., multimetric index) with data collected using the new method, regardless of taxonomic level.     

Development and evaluation of a Macroinvertebrate Biotic Integrity Index (MBII) for regionally assessing Mid-Atlantic Highlands Streams

The Macroinvertebrate Biotic Integrity Index (MBII) was developed from data collected at 574 wadeable stream reaches in the Mid-Atlantic Highlands region (MAHR) by the U.S. Environmental Protection Agency's (USEPA) Environmental Monitoring and Assessment Program (EMAP). Over 100 candidate metrics were evaluated for range, precision, responsiveness to various disturbances, relationship to catchment area, and redundancy. Seven metrics were selected, representing taxa richness (Ephemeroptera richness, Plecoptera richness, Trichoptera richness), assemblage composition (percent non-insect individuals, percent 5 dominant taxa), pollution tolerance [Macroinvertebrate Tolerance Index (MTI)], and one functional feeding group (collector-filterer richness). We scored metrics and summed them, then ranked the resulting index through use of independently evaluated reference stream reaches. Although sites were classified into lowland and upland ecoregional groups, we did not need to develop separate scoring criteria for each ecoregional group. We were able to use the same metrics for pool and riffle composite samples, but we had to score them differently. Using the EMAP probability design, we inferred the results, with known confidence bounds, to the 167,797 kilometers of wadeable streams in the Mid-Atlantic Highlands. We classified 17% of the target stream length in the MAHR as good, 57% as fair, and 26% as poor. Pool-dominated reaches were relatively rare in the MAHR, and the usefulness of the MBII was more difficult to assess in these reaches. The process used for developing the MBII is widely applicable and resulted in an index effective in evaluating region-wide conditions and distinguishing good and impaired reaches among both upland and lowland streams dominated by riffle habitat.     

Understanding Stream Geomorphic State in Relation to Ecological Integrity: Evidence Using Habitat Assessments and Macroinvertebrates

Scientists have long assumed that the physical structure and condition of stream and river channels have pervasive effects on biological communities and processes, but specific tests are few. To investigate the influence of the stream-reach geomorphic state on in-stream habitat and aquatic macroinvertebrate communities, we compared measures of habitat conditions and macroinvertebrate community composition between stable and unstable stream reaches in a paired-study design. We also explored potential associations between these ecological measures and individual geomorphic characteristics and channel adjustment processes (degradation, aggradation, overwidening, and change in planform). We found that habitat quality and heterogeneity were closely tied to stream stability, with geomorphically stable reaches supporting better habitat than unstable reaches. Geomorphic and habitat assessment scores were highly correlated (r = 0.624, P < 0.006, n = 18). Stable reaches did not support significantly greater macroinvertebrate densities than unstable reaches (t = −0.415, P > 0.689, df = 8). However, the percent of the macroinvertebrate community in the Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa was significantly correlated with the overall habitat assessment scores as well as with individual measures of geomorphic condition and habitat quality. While there is a clear need for more work in classifying and quantifying the responses of aquatic and aquatic-dependent biota to various geomorphic states and processes, this study provides solid preliminary evidence that macroinvertebrate communities are affected by the geomorphic condition of the stream reaches they inhabit and that geomorphic assessment approaches can be used as a tool for evaluating ecological integrity.     

IMPACTS OF URBAN LANDUSE ON MACROINVERTEBRATE COMMUNITIES IN SOUTHEASTERN WISCONSIN STREAMS1

ABSTRACT: Macroinvertebrates were used to assess the impact of urbanization on stream quality across a gradient of watershed imperviousness in 43 southeastern Wisconsin streams. The percentage of watershed connected imperviousness was chosen as the urbanization indicator to examine impact of urban land uses on macroinvertebrate communities. Most urban land uses were negatively correlated with the Shannon diversity index, percent of pollution intolerant Ephemeroptera, Plecoptera, and Trichoptera individuals, and generic richness. Nonurban land uses were positively correlated with these same metrics. The Hilsenhoff biotic index indicated that stream quality declined with increased urbanization. Functional feeding group metrics varied across a gradient of urbanization, suggesting changes in stream quality. Proportions of collectors and gatherers increased, while proportions of filterers, scrapers, and shredders decreased with increased watershed imperviousness. This study demonstrated that urbanization severely degraded stream macroinvertebrate communities, hence stream quality. Good stream quality existed where imperviousness was less than 8 percent, but less favorable assessments were inevitable where imperviousness exceeded 12 to 20 percent. Levels of imperviousness between 8 and 12 percent represented a threshold where minor increases in urbanization were associated with sharp declines in stream quality.     

Assessment Tools for Urban Catchments: Developing Biological Indicators Based on Benthic Macroinvertebrates1

Abstract: Biological indicators, particularly benthic macroinvertebrates, are widely used and effective measures of the impact of urbanization on stream ecosystems. A multimetric biological index of urbanization was developed using a large benthic macroinvertebrate dataset (n = 1,835) from the Baltimore, Maryland, metropolitan area and then validated with datasets from Cleveland, Ohio (n = 79); San Jose, California (n = 85); and a different subset of the Baltimore data (n = 85). The biological metrics used to develop the multimetric index were selected using several criteria and were required to represent ecological attributes of macroinvertebrate assemblages including taxonomic composition and richness (number of taxa in the insect orders of Ephemeroptera, Plecoptera, and Trichoptera), functional feeding group (number of taxa designated as filterers), and habit (percent of individuals which cling to the substrate). Quantile regression was used to select metrics and characterize the relationship between the final biological index and an urban gradient (composed of population density, road density, and urban land use). Although more complex biological indices exist, this simplified multimetric index showed a consistent relationship between biological indicators and urban conditions (as measured by quantile regression) in three climatic regions of the United States and can serve as an assessment tool for environmental managers to prioritize urban stream sites for restoration and protection.     

Hydrogeomorphic Reference Condition and Its Relationship with Macroinvertebrate Assemblages in Southeastern U.S. Sand Hills Streams

Defining stream reference conditions is integral to providing benchmarks to ecological perturbation. We quantified channel geometry, hydrologic and environmental variables, and macroinvertebrates in 62 low‐gradient, SE United States (U.S.) Sand Hills (Level IV ecoregion) sand‐bed streams. To identify hydrogeomorphic reference condition (HGM), we clustered channel geometry deviation from expectations given watershed area (Aws), resulting in two HGM groups discriminated by area at the top of bank (Atob) residuals <0.6 m² and >0.6 m² predicted to be HGM reference/nonreference streams, respectively. Two independent partial least squares discriminate analyses used (1) hydrologic/environmental variables and (2) macroinvertebrate mean trait values (mT) on 10 reference/nonreference stream pairs of similar Aws for classification validation. Nonreference streams had flashier hydrographs and altered flow magnitudes, lower organic matter, coarser substrate, higher pH/specific conductivity compared with reference streams. Macroinvertebrate assemblages corresponded to HGM groupings, with mT indicative of multivoltinism, collector‐gatherer functional feeding groups, fast current‐preference taxa, and lower Ephemeroptera, Plecoptera, and Trichoptera richness and biotic integrity in nonreference streams. HGM classifications in Sand Hills, sand‐bed streams were determined from channel geometry. This easily implemented classification is indicative of contemporary hydrologic disturbance resulting in contrasting macroinvertebrate assemblages.     

River Habitat Quality from River Velocities Measured Using Acoustic Doppler Current Profiler

Prior research has demonstrated the utility of metrics based on spatial velocity gradients to characterize and describe stream habitat, with higher gradients generally indicative of higher levels of physical heterogeneity and thus habitat quality. However, detailed velocity data needed to compute these metrics are difficult to obtain. Acoustic Doppler current profilers (ADCP) may be used to rapidly collect detailed representations of river velocity fields. Herein we demonstrate use of ADCP to obtain ecologically relevant data and compute associated metrics. Data were collected from four reaches of the Little Tallahatchie River in northern Mississippi. Sampled reaches were selected to observe velocity regimes associated with three distinctly different conditions: downstream from a major flow obstruction (a low weir), downstream from the apices of each of two bends, and within an extremely long, straight reach created by channelization. Three-dimensional velocity data sets from each site were used to compute metrics of habitat quality proposed by others. A habitat metric based on the presence of rotational flow in the vertical plane proved to be the best discriminator among conditions within the sampled reaches. Two of four habitat quality metrics computed from these measured velocities were greatest for the sharpest meander bend. ADCP hold great potential for study of riverine physical aquatic habitats, particularly at the reach scale. Additional work is needed to develop generally applicable field protocols and data reduction tools. Specifically, guidelines for ADCP settings and configuration appropriate for a range of riverine site conditions must be developed. Advances in instrumentation are needed to allow collection of information in closer proximity to the free surface and solid boundaries.