Bioassessment II: Douglas Nieman Memorial
Presiding: M B Griffith, National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency; J Orr, Pennsylvania State
NB24A-01 15:30h
A RIVPACS Type Model for Wadeable Streams of Wyoming
RIVPACS models produce a community-level measure of biological condition known as O/E, which is derived from a comparison of the observed (O) biota with those expected (E) to occur in the absence of anthropogenic stress. Benthic macroinvertebrate and environmental data collected at 739 stream monitoring stations, from 1993 to 1999, were used to develop, validate, and apply a RIVPACS model to assess the biological condition of wadeable streams in Wyoming. We used multivariate analyses to group 157 reference sites based on similarities in macroinvertebrate community structure as well as examine which environmental variables best discriminated among reference groups. A suite of fifteen categorical and continuous environmental variables best discriminated among fifteen reference groups and explained >75% of the natural variability in biota within the reference dataset. Mean reference site O/E values were near unity. Mean test site values ranged from 0 to 1.60 (mean =0.79). Our model was accurate and reasonably precise (SD of O/E values for validation data = 0.17). O/E responded to anthropogenic stressors and was robust both temporally and spatially. These results show that RIVPACS models can produce effective assessments of biological condition over broad, ecologically diverse, geographic regions of the intermountain west such as Wyoming.
NB24A-02 15:45h
A Comparison of Trichoptera (Caddisfly) Species Diversity From Several Peninsular Florida Waterbodies Using Benthic and Terrestrial Sampling Methods
Typically, environmental agencies tasked with water quality bioassessment solely use benthic sampling methods to collect aquatic insects. Because most aquatic insects live in water only as immatures, benthic samples consist largely of larvae. In Trichoptera, and most insect groups, alpha taxonomy is chiefly based on adult reproductive structures, thus specimens from benthic samples in many cases cannot be assigned species names. Therefore, benthic sampling gives a limited picture of species diversity within aquatic insect communities and may result in monitoring programs not detecting biological impairment involving population losses or declines. In this study of several waterbodies on the Florida peninsula we compare caddisfly species diversity in samples collected using benthic protocols used by the Florida Department of Environmental Protection with that of samples of adult caddisflies collected using UV-blacklight. Light-trap samples yielded significantly higher numbers of both caddisfly individuals and taxa. Benthic samples because of smaller sample sizes and genus-level determinations gave relatively incomplete characterizations of caddisfly community structure. So that aquatic communities can be better understood and protected, we recommend that environmental agencies begin to incorporate additional sampling methods such as light trapping into their assessment and monitoring programs.
NB24A-03 16:00h
Macroinvertebrate Community Response to the Elimination of Concentrated Feedlot Runoff to a Headwater Stream
During rainfall and snow melt events, a first order, cold-water stream was receiving varying amounts of liquefied manure from a concentrated feed lot. Stream restoration efforts included the implementation of best management practices to prevent further discharge of the water/manure mixture to the stream. Physical, chemical and biological data were collected pre-construction and two years post-construction of the containment system at a fixed location downstream of the feedlot. Hilsenhoff Biotic Index scores improved significantly, from 6.79 or "Fairly Poor" before the installation of the manure containment system, to 5.28 or "Good" after the installation of the manure containment system. Taxa richness improved from 25 to 34 and the EPT score improved from 0 to 4. Key words: macroinvertebrate, community response, manure, feedlot runoff, stream restoration
NB24A-04 16:15h
Correlation of Fish and Benthic Macroinvertebrate Communities With Multi-scale Environmental Descriptors in Wadeable Streams of the Yukon River Basin
We sampled fish and benthic macroinvertebrates at thirty wadeable stream sites in the Yukon River basin in Yukon Territory, Canada during July, 2004, to establish reference conditions in Yukon River basin stream communities. We also measured water quality (eg. temperature, dissolved oxygen, conductivity, pH), stream flow, substrate characteristics and riparian vegetation at each site. Water samples from each site were subsequently analyzed for nutrients and metals. In addition, catchment area, catchment perimeter, catchment land cover, distance of each site to major water bodies and stream barriers were determined through Geographic Information System and satellite photography analysis. Fish and benthic macroinvertebrate community structures and their relationships with the multi-scale description of the stream environment were quantified with non-metric multidimensional scaling, principal component analysis, and correlation analysis.
NB24A-05 16:30h
Ecological Relevance of Abiotic Factors on Macroinvertebrate Communities and its Importance to Validate Portuguese River Typology
The objective of this study is to validate an abiotic river typology in Portugal in order to fulfil the requirements of the Water Framework Directive. Macroinvertebrate samples were taken at 155 potential reference sites covering a set of pre-established river types. At each collecting site 6 hand net kick samples (500 mm mesh size, multi-habitat approach) were taken.. In a PCA ordination of the sites the factors altitude, runoff, mean annual precipitation, annual precipitation variability and mean annual temperature (climatic and morphological features) were correlated with the first axis (p<0.01), while distance to source and drainage area (longitudinal dimension) were correlated with the second axis (p<0.01). Geology, expressed as mineralization classes, is correlated with the three first axis (p<0.01). ANOSIM was used to merge river types when none significant differences were detected (p>0.05). Nemouridae and Leptophlebidae tend to be associated to river types with less runoff, while Leuctridae and Heptagenidae usually are more abundant at river types with higher runoff. Sites with drainage area higher than 100 km2 tend to have lower diversities in EPT taxa. From the initial 27 abiotic river types only 17 proved to be ecological relevant.
NB24A-06 16:45h
Evaluation of the Representative Reach Sampling Methodology for Biomonitoring Using Benthic Macroinvertebrates
Bioassessments by resource management agencies to determine the condition of streams often rely on sampling benthic macroinvertebrate assemblages in "representative reaches". That information is used to represent assemblages in other reaches with similar characteristics. The goal of our study was to evaluate the effectiveness of using "representative reach" sampling to characterize assemblages at different scales (local-regional). During summer 1999, we sampled assemblages in a relatively undisturbed area in northwestern Pennsylvania using a nested design (n=81) to describe variation in assemblages at different scales. We found that assemblages changed gradually along the stream continuum rather than forming discrete groups based a priori on knowledge of environmental variables. Taxa richness in any sample averaged 12.5% of total taxa richness summed across all scales, requiring 4-30 1-m2 samples to be taken in any reach to capture the majority (>70%) of taxa. Due to the continuous nature of assemblages, and the inability to collect the majority of taxa in any sample, caution should be used in relying solely on representative sampling to characterize other assemblages. An iterative process of refinement using a posteriori knowledge to test validity of methods should be used in establishing biomonitoring programs to assure accuracy and precision in management decisions.