Bioassessment is the concept of evaluating the ecological condition of habitats by surveying the resident assemblages of living organisms. Conducting bioassessment with benthic macroinvertebrates is still evolving and continues to be refined. There are strongly divided opinions about study design, sampling methods, laboratory analyses, and data analysis. Two issues that are currently being debated about study design for bioassessment in streams were examined here: 1) what habitats within streams should be sampled; 2) and is it necessary to identify organisms to the species level? The influence of habitat sampling design and level of taxonomic identification on the interpretation of ecological conditions of ten small streams in western Virginia was examined. Cattle watering and grazing heavily affected five of these streams (impaired sites). The other five streams, with no recent cattle activity or other impact by man, were considered to be reference sites because they were minimally impaired and represented best attainable conditions. Inferential and non-inferential statistical analyses concluded that multiple habitat sampling design was more effective than a single habitat design (riffle only) at distinguishing impaired conditions, regardless of taxonomic level. It appeared that sampling design (riffle habitat versus multiple habitats) is more important than taxonomic identification level for distinguishing reference and impaired ecological conditions in this bioassessment study. All levels of taxonomic resolution, which were studied, showed that the macroinvertebrate assemblages at the reference and impaired sites were very different and the assemblages at the impaired sites were adversely affected by perturbation. This study supported the sampling of multiple habitats and identification to the family level as a design for best determining the ecological condition of streams in bioassessment. / Master of Science

Devido à importância do uso de bioindicadores para avaliação da qualidade ambiental e às vantagens do emprego de macroinvertebrados bentônicos para este fim, estes organismos foram utilizados para avaliar a qualidade da água da bacia do alto Atibaia (SP) em oito pontos de amostragem: 3 no rio Atibainha, 3 no rio Cachoeira e 2 no rio Atibaia. Foram amostrados o canal, a margem deposicional e a margem erosional, sendo coletadas três unidades amostrais em cada ambiente de cada ponto, com auxílio do amostrador Hess (rede de 500 μm e área de 678,9 cm2) ou pegador Petersen modificado (área de pegada de 325 cm2). Foram coletadas amostras de sedimento com pegador Petersen modificado em aço inox para análise de granulometria, resíduos totais, voláteis e fixos e umidade. Este trabalho está dividido em três capítulos. No primeiro, a análise da fauna evidenciou que os pontos de cabeceira e à jusante dos reservatórios dos rios Atibainha e Cachoeira tenderam a apresentar riqueza e diversidade menores que os pontos de localização intermediária. Já nos pontos situados no rio Atibaia, a fauna respondeu à deterioração da qualidade da água, refletindo um gradiente ambiental. No segundo capítulo, visando à utilização de técnicas de avaliação rápida para facilitar a análise e interpretação de dados, foram aplicadas vinte e uma métricas biológicas. Dentre todas as métricas testadas, as que evidenciaram o gradiente ambiental presente na bacia estudada, com restrito coeficiente de variação no ponto referência foram riqueza e diversidade de famílias, densidade total, riqueza de EPT e ETO, porcentagem de Táxons de Diptera (exceto Tanytarsini) e não insetos, BMWP “JUNQ” e IBBJ. No terceiro capítulo, com a finalidade de contribuir para a elaboração de um plano de monitoramento de avaliação rápida para a bacia do Alto Atibaia (SP), concluiu-se que, com a metodologia empregada, a margem erosional seria o habitat que melhor corresponderia à media ou somatória para o ponto, pelo menos durante o período de estiagem. / Due to importance of the use of bioindicators to assess environmental quality and the advantages of employing benthic macroinvertebrates for this purpose, these organisms were used to assess the water quality of the Atibaia river basin (SP) in eight sites: 3 in the Atibainha river, 3 in the Cachoeira river, and 2 in the Atibaia river. Channel, depositional margin and erosional margin were sampled. Three replicates were collected in each habitat using a Hess sampler (678.9 cm2, 500μm mesh) or modified Petersen grab (325 cm2). Sediment samples were collected with a stainless steel modified Petersen grab for analysis of granulometry, humidity and total, volatile and fixed residues. This study is divided in three chapters. In the first, the fauna showed that headwater and downstream reservoir sites of Cachoeira and Atibainha rivers presented lower richness and diversity than intermediate sites. In the sampling sites of the Atibaia river, the fauna responded to the water quality decline, reflecting an environmental gradient. In the second chapter, aiming the utilization of rapid assessment techniques to facility data analysis and interpretation, twenty one biological metrics were applied. Metrics that evidence the environmental gradient of the basin, with restricted variation coefficient, were richness and diversity of families, total density, richness of EPT and ETO, percent of Diptera taxa and noninsects, BMWP “JUNQ” and IBBJ. In the third chapter, aiming to contribute to the development of a rapid assessment monitoring plan for the Atibaia river basin, according to the methodology employed, it was concluded that the erosional margin was the habitat that showed the best correspondence with the average or sum of the sites, at least during the dry season.

Devido à importância do uso de bioindicadores para avaliação da qualidade ambiental e às vantagens do emprego de macroinvertebrados bentônicos para este fim, estes organismos foram utilizados para avaliar a qualidade da água da bacia do alto Atibaia (SP) em oito pontos de amostragem: 3 no rio Atibainha, 3 no rio Cachoeira e 2 no rio Atibaia. Foram amostrados o canal, a margem deposicional e a margem erosional, sendo coletadas três unidades amostrais em cada ambiente de cada ponto, com auxílio do amostrador Hess (rede de 500 μm e área de 678,9 cm2) ou pegador Petersen modificado (área de pegada de 325 cm2). Foram coletadas amostras de sedimento com pegador Petersen modificado em aço inox para análise de granulometria, resíduos totais, voláteis e fixos e umidade. Este trabalho está dividido em três capítulos. No primeiro, a análise da fauna evidenciou que os pontos de cabeceira e à jusante dos reservatórios dos rios Atibainha e Cachoeira tenderam a apresentar riqueza e diversidade menores que os pontos de localização intermediária. Já nos pontos situados no rio Atibaia, a fauna respondeu à deterioração da qualidade da água, refletindo um gradiente ambiental. No segundo capítulo, visando à utilização de técnicas de avaliação rápida para facilitar a análise e interpretação de dados, foram aplicadas vinte e uma métricas biológicas. Dentre todas as métricas testadas, as que evidenciaram o gradiente ambiental presente na bacia estudada, com restrito coeficiente de variação no ponto referência foram riqueza e diversidade de famílias, densidade total, riqueza de EPT e ETO, porcentagem de Táxons de Diptera (exceto Tanytarsini) e não insetos, BMWP “JUNQ" e IBBJ. No terceiro capítulo, com a finalidade de contribuir para a elaboração de um plano de monitoramento de avaliação rápida para a bacia do Alto Atibaia (SP), concluiu-se que, com a metodologia empregada, a margem erosional seria o habitat que melhor corresponderia à media ou somatória para o ponto, pelo menos durante o período de estiagem. / Due to importance of the use of bioindicators to assess environmental quality and the advantages of employing benthic macroinvertebrates for this purpose, these organisms were used to assess the water quality of the Atibaia river basin (SP) in eight sites: 3 in the Atibainha river, 3 in the Cachoeira river, and 2 in the Atibaia river. Channel, depositional margin and erosional margin were sampled. Three replicates were collected in each habitat using a Hess sampler (678.9 cm2, 500μm mesh) or modified Petersen grab (325 cm2). Sediment samples were collected with a stainless steel modified Petersen grab for analysis of granulometry, humidity and total, volatile and fixed residues. This study is divided in three chapters. In the first, the fauna showed that headwater and downstream reservoir sites of Cachoeira and Atibainha rivers presented lower richness and diversity than intermediate sites. In the sampling sites of the Atibaia river, the fauna responded to the water quality decline, reflecting an environmental gradient. In the second chapter, aiming the utilization of rapid assessment techniques to facility data analysis and interpretation, twenty one biological metrics were applied. Metrics that evidence the environmental gradient of the basin, with restricted variation coefficient, were richness and diversity of families, total density, richness of EPT and ETO, percent of Diptera taxa and noninsects, BMWP “JUNQ" and IBBJ. In the third chapter, aiming to contribute to the development of a rapid assessment monitoring plan for the Atibaia river basin, according to the methodology employed, it was concluded that the erosional margin was the habitat that showed the best correspondence with the average or sum of the sites, at least during the dry season.

The diversity of fish species found in warmwater stream systems provides a perplexing challenge when selecting species for Instream Flow Incremental Methodology (IFIM) studies. An often-suggested approach has been to use habitat guilds to incorporate the diversity found in these systems. My goal is to determine the feasibility of developing habitat suitability criteria (HSC) for the entire fish assemblage in the North and South Fork Shenandoah River, Virginia, using habitat guilds. I examined the strengths and weaknesses of direct underwater observation via snorkeling and throwable anode electrofishing to sample fish habitat use (e.g., depth, velocity, distance to cover, dominant and subdominant substrate, cover, and embeddedness) indicates that using the data collected from both techniques may produce better criteria than using just one of the two sampling techniques. To develop habitat suitability criteria using habitat guilds I placed each species a priori into a guild based on a hypothesized guild structure. Transitional life stages with significantly different habitat use were placed separately into the guild structure. The four guilds (riffle, fast generalist, pool-run, and pool-cover) were found to be significantly different from each other using the data collected for the species assigned to the guilds. Criteria were then developed for representative species from each guild and the entire guilds. Criteria developed for depth, velocity, Froude number, cover, distance to cover, substrate, and embeddedness were used to estimate a habitat response function (i.e., the relations between usable habitat and stream flow) for a representative species from each guild, the guild itself, and for a second species from each guild for comparisons. Both the representative species and guild criteria showed similar habitat response functions for the riffle guild, fast generalist guild, and pool-run guild. However, neither set of criteria performed well for the pool-cover guild. For guilds, other than pool-cover, either the guild or the representative species approach may be a viable option to developing habitat suitability criteria. The transferability tests were performed to determine if criteria developed in the North Fork Shenandoah River, Virginia would transfer to the South Fork Shenandoah River, Virginia. Only criteria for the margined madtom (Noturus insignis) and the juvenile smallmouth bass (Micropterus dolomieu) transferred for both suitable and optimal habitat. Criteria for mottled sculpin (Cottus bairdi), Cyprinella sp. (spotfin and satinfin shiners), river chub (Nocomis micropogon), adult and juvenile redbreast sunfish (Lepomis auritus), and adult smallmouth bass did not transfer. Only the pool-cover guild criteria transferred for both suitable and optimal habitat, while riffle guild, fast generalist guild, and pool-run guild criteria did not transfer. I recommend the use of site-specific criteria for the South Fork Shenandoah or different variable combinations. / Master of Science