Mercury poses significant challenges to human health and fisheries management. Historical industrial practices in Waynesboro, Virginia left portions of the Shenandoah River basin contaminated with mercury and stringent health advisories for fish consumption. I investigated processes affecting the bioaccumulation of mercury in Catostomus commersoni, Ictalurus punctatus, Lepomis auritus, and Micropterus dolomieu by studying food habits, total mercury and methylmercury in common prey items, and bioaccumulation dynamics of methylmercury in the mercury contaminated South River and South Fork of the Shenandoah River and uncontaminated North River. Additionally, I evaluated sexual and seasonal variations of total mercury in M. dolomieu in the South Fork of the Shenandoah River. Algae, aquatic insects, crayfish, detritus, and fish accounted for 75-97% of the diet. Total mercury in aquatic invertebrates and forage fish in contaminated rivers ranged from 66.7-398.3 and 198.0-594.9 ng/g wet weight, while total mercury in aquatic invertebrates and forage fish in the reference river were 4.4 and 29.3 ng/g. Model simulations indicated that dietary pathways accounted for 87% of methylmercury uptake by fish in contaminated rivers, but only 57% in the reference river. Total mercury in M. dolomieu was 19-20% higher in females than males and 14-21% higher during spring than summer and fall. Results of this study indicate that bioenergetics-based bioaccumulation models are valuable tools for evaluating field data, identifying processes critical to contaminant accumulation, and comparing outcomes of alternative management options associated with pollution control, ecosystem management, and/or restoration activities for management guidance prior to costly expenditures. / Master of Science

This study conducted the first high-resolution investigation of the ichthyofaunal assemblages on a high-latitude coral reef in the Western Indian Ocean (WIO). Two-Mile reef, in South Africa, is a large, accessible patch-reef, and was selected as a candidate study area. Although the effect of season in structuring coral reef fish communities is most-often overlooked, the relationship between these fish communities and their habitat structure has been investigated. In South Africa, however, neither of these potential community-level drivers has been explored. As coral reefs worldwide are faced with high levels of usage pressure, nondestructive underwater visual census (UVC) techniques were identified as the most appropriate survey methods. This study had two primary aims that were; (1) to identify the most suitable technique for the UVC of coral reef fishes, and to test variations of the selected technique for appropriateness to implementation in long-term monitoring programs, and (2) to determine if possible changes to ichthyofaunal community structure could be related to trends in season and/or habitat characteristics. A review of the literature indicated that the most appropriate UVC method for surveying epibenthic coral reef fishes is underwater transecting. To compare the traditional slate-based transects to variations that implement digital image technology, slate transects were compared to a first-attempt digital photographic transect technique, and digital videographic transects. Videographic transects produced the most favourable species richness, abundance, and standard deviations of the three techniques. Diversity was not significantly different between transect techniques. The minimum required sample size was lowest for videographic transects (17 replicates), intermediate for photographic transects (27 replicates) and highest for slate transects (37 replicates). Videographic and photographic transects required greater analysis time to generate counts, but required lower observer training time. While videographic transects produced the lowest proportion of species considered unidentifiable, all three transect techniques showed similar functionality to surveying epibenthic coral reef fishes. Videographic transects were therefore identified as the most appropriate UVC technique for this study. Videographic transects at shallow (6 – 14 m), intermediate (14 – 22 m) and deep (22 – 30 m) depths in mid-winter and mid-summer, sampled a total of 41 families consisting of 209 species and 18172 individuals, dominated by pomacentrids in abundance and labrids in richness. The fish assemblages on Two-Mile Reef were found to be similar in composition to lower-latitude WIO reefs. Overall ichthyofaunal abundance and richness was significantly higher in summer than in winter, and was higher at shallow sites than at intermediate and deep sites. A multivariate approach confirmed differences between seasons at shallow depths but not between seasons at intermediate and deep depths. The fish assemblages on Two-Mile Reef can therefore be described as being comprised of four relatively distinct communities: a shallow, winter community; a shallow, summer community; a year-round intermediate community; and a year-round deep community. The distributions of discriminating species indicated that high abundances of the algal-feeding pomacentrids are observed only at shallow and intermediate sites while high abundances of the zooplanktivorous serranid subfamily, the Anthiinae, are observed predominantly at deep sites. Assessment of all measured supplementary variables indicated that of all factor combinations, observed patterns could be ascribed most strongly to depth. Quantification of reef characteristics indicated that as depth increases, habitat complexity decreases, benthic communities shift from dense coral domination to sparse sponge domination, and algal biomass and cover decreases. The ability of the videographic transect technique to detect changes in community structure with season and depth indicates that season and depth should be accounted for in future high-latitude ichtyofaunal surveys, and that the videographic transect technique is suitable for implementation in long-term monitoring programs on coral reefs. The similarity in fish assemblages between Two-Mile Reef and lower latitude regions suggests that the protocol for surveying epibenthic coral reef fishes, resulting from this study, is relevant throughout the continental WIO.

Seasonally, in 1998 and 1999, I examined spatial and temporal variation in fish assemblages of agricultural, forested, and acid mine drainage tributaries within the Wayne National Forest (WNF) in southern Ohio. Land use and natural disturbance explained patterns in stream fish assemblages. Creek chub and green sunfish were present in all land use types. Generally, with the exception of creek chub and green sunfish, species most abundant in one land use type occurred infrequently in the other land use types sampled. For example, redbelly dace and blacknose dace dominated forested assemblages but rarely occurred in mining or agricultural assemblages. Agricultural sites consisted of higher order streams, located at lower elevations with reduced canopy cover. Forested sites included intermittent streams associated with higher elevation, low stream order, and high canopy cover. Acidic conditions characterized mining sites, which otherwise remained physically similar to forested sites. Stream order, elevation, and canopy cover explained the majority of the variance in assemblage structure within 1998, and pH was also important. In 1999, water quality, specifically dissolved oxygen, and seasonal variation became important. Assemblages changed following drought in 1999. Forested assemblages remained most similar following drought, while agricultural assemblages exhibited less similarity (i.e., greater variability). These results suggest that large-scale reach characteristics and chemical signals related to land use are important to fish assemblage structure, but in times of environmental fluctuation, water chemistry of other site-specific variables may be of even greater importance due to physiological tolerances and limitations of fishes. / Graduation date: 2002

Agricultural practices may influence stream biological communities by removing riparian vegetation and modifying stream channel morphology, both which may reduce water retention time. I collected benthic invertebrates and fishes in seven headwater agriculturally-influenced streams in central Indiana, to quantify controls on invertebrate and fish community assemblage variation. Invertebrates were collected at 14 sites and fish were collected at 12 sites in Buck Creek watershed. The abundances of invertebrates and fishes were analyzed in Detrended Correspondence Analyses (DCA) in PC-ORD software and correlated with abiotic and biotic factors. The sites located in close proximity to Buck Creek have increased stability of biotic (fish assemblages) and abiotic (flow and water depth) factors. Abundances of invertebrates of headwater streams in east-central Indiana agricultural landscapes are influenced by distance between sites, distance to Buck Creek, and presence of fish species. Abundances of fishes were correlated with water quality and distance to Buck Creek. / Department of Biology

Yellow perch, alewife, spottail shiner and round goby trawl catch per unit effort (CPUE) was evaluated in the Indiana waters of Lake Michigan from 1984-2006 to determine whether spatial or temporal variation in CPUE for these species occurred. Differences in CPUE among sites or periods were not clearly distinguished within a single sampling year. However, when compared over a 23 year time frame, spatial and temporal differences became evident. To determine the minimum number of samples needed to detect differences among sites and periods, we ran a Monte Carlo simulation using 23 years of empirical data. This compared favorably to results obtained from a power analysis that identified the minimum number of samples required to identify statistical differences. Sampling effort needed to distinguish differences in CPUE varied both spatially and temporally among the four species. Differences in sampling only became evident when multi-year efforts were employed. In addition, spatial and temporal differences in male and female (mature and immature) yellow perch proportions was also evaluated among our sample sites and periods from 1993-2006. / Department of Biology

Graduation date: 1999

Capes / Dado o cenário de degradação dos ecossistemas aquáticos - de modo particular os de menor ordem e mais susceptíveis aos agentes estressores, como os riachos - especialmente em decorrência de processos associados à urbanização e à agropecuária, o presente trabalho tem por objetivos comparar as respostas das assembleias de peixes de três bacias expostas a diferentes pressões oriundas do uso e ocupação do solo (urbana, periurbana e rural), especificamente em relação a: (i) estrutura trófica; (ii) estrutura das redes tróficas (conectância, densidade de ligações, aninhamento, modularidade) e robustez das redes; (iii) padrões de ocupação do espaço Ecomorfológico; e (iv) relações entre os parâmetros listados anteriormente e a estrutura da paisagem. A hipótese de trabalho sustenta que as redes tróficas de riachos urbanos e rurais respondem diferentemente aos impactos que estão expostos. Os peixes foram coletados com pesca manual e elétrica trimestralmente no ano de 2013, em nove pontos amostrais pertencentes a 3 bacias: Ribeirão Cambé (essencialmente urbano), Ribeirão Cafezal (inserido em um contexto periurbano) e Ribeirão Taquara (essencialmente rural). Foram analisados 815 indivíduos, distribuídos em 19 espécies. A partir dessas espécies foram estimados 37 caracteres morfológicos, transformados em 22 índices ecomorfológicos, para posterior cálculo do grau de empacotamento do espaço ecomorfológico das assembleias, através das métricas: distância para o vizinho mais próximo, distância média para o centróide, e desvio-padrão da distância para o vizinho mais próximo. Posteriormente foram identificados os itens alimentares presentes no trato gastrointestinal dos indivíduos, e calculadas as seguintes propriedades topológicas das redes (conectância, densidade de ligações, aninhamento, modularidade) e a robustez. Foram identificados um total de 46 itens alimentares, sendo o P2 Taquara o mais rico, e o P3 Cambé o menos rico. Os riachos urbanos apresentaram tendência de simplificação e empobrecimento. Os pontos rurais apresentaram tendência de maior aninhamento e robustez, sugerindo maior complexidade e estabilidade, em comparação aos urbanos. Também nos riachos rurais foi possível detectar maior proximidade ecomorfológica entre as espécies da assembleia, sugerindo uma tendência de especialização, ao contrário dos urbanos, onde as espécies se encontravam mais distantes. Dessa forma, pode-se concluir que as redes de interação trófica, associadas às análises de ocupação do espaço ecomorfológico revelaram-se ferramentas interessantes para a análise ambiental em riachos, apresentando resultados que sugerem que os impactos urbanos tendem a ser mais severos para as assembleias do que os rurais. / Given the scenario of degradation of aquatic ecosystems - particularly those of lower order and more susceptible to stressors, such as streams - especially due to processes associated with urbanization and agriculture, the present study aims to compare the responses of the assemblies of fish from three basins exposed to different pressures arising from the use and occupation of the soil (urban, periurban and rural), specifically in relation to: (i) trophic structure; (ii) structure of the trophic networks (connectivity, link density, nestedness, modularity) and robustness; (iii) patterns of occupation of the ecomorphological space; and (iv) relationships between the parameters listed above and the landscape structure. The working hypothesis holds that the trophic networks of urban and rural streams respond differently to the impacts they are exposed to. The fish were collected with manual and electric fishing quarterly in the year 2013, in nine sampling points belonging to three basins: Ribeirão Cambé (essentially urban), Ribeirão Cafezal (inserted in a periurban context) and Ribeirão Taquara (essentially rural). A total of 815 individuals were analyzed, distributed among 19 species. From these species, 37 morphological characters were estimated, transformed into 22 ecomorphological indexes, for later calculation of the degree of packing of the ecomorphological space of the assemblies, through the metrics: distance to the nearest neighbor, mean distance to the centroid, and standard deviation from the distance to the nearest neighbor. Subsequently, the food items present in the gastrointestinal tract of the individuals were identified and the following topological properties of the networks (connectivity, bond density, nesting, modularity) and robustness were calculated. A total of 46 food items were identified, with P2 Taquara the richest, and P3 Cambé the least rich. The urban streams showed a trend of simplification and impoverishment. The rural points presented a tendency of greater nesting and robustness, suggesting greater complexity and stability, in comparison to the urban ones. Also in the rural streams it was possible to detect greater ecomorphological proximity between the species of the assembly, suggesting a tendency of specialization, unlike the urban ones, where the species were more distant. Thus, it can be concluded that the networks of trophic interaction, associated to the analyzes of occupation of the ecomorphological space, have proved to be interesting tools for the environmental analysis in streams, presenting results that suggest that the urban impacts tend to be more severe for the assemblies than rural ones.

Submitted by Maria de Lourdes Mariano (lmariano@ufscar.br) on 2017-01-12T12:18:43Z No. of bitstreams: 1 MELLO_Bruno Gomes_2014.pdf: 2169418 bytes, checksum: 157bccc008d9bb3bac70c082f1d983c3 (MD5) / Approved for entry into archive by Maria de Lourdes Mariano (lmariano@ufscar.br) on 2017-01-12T12:18:51Z (GMT) No. of bitstreams: 1 MELLO_Bruno Gomes_2014.pdf: 2169418 bytes, checksum: 157bccc008d9bb3bac70c082f1d983c3 (MD5) / Approved for entry into archive by Maria de Lourdes Mariano (lmariano@ufscar.br) on 2017-01-12T12:19:00Z (GMT) No. of bitstreams: 1 MELLO_Bruno Gomes_2014.pdf: 2169418 bytes, checksum: 157bccc008d9bb3bac70c082f1d983c3 (MD5) / Made available in DSpace on 2017-01-12T12:19:08Z (GMT). No. of bitstreams: 1 MELLO_Bruno Gomes_2014.pdf: 2169418 bytes, checksum: 157bccc008d9bb3bac70c082f1d983c3 (MD5) Previous issue date: 2014-05-22 / Não recebi financiamento / The growing interest in studies of functional diversity allows to address the relationship between the functional characteristics of species with variations in the environment attempt to understand the organization of biological communities. We examined the relationship between physical and structural characteristics of 19 stretches of headwater streams in the Atlantic Forest and morphological characteristics related to swimming ability of fish species. The environment was described by altitude, distance from species pool, substrate composition and depth of the channel. The functional characteristics were described by 11 morphological measurements. The RLQ analysis was used and the first two axes explained 97.8% of the total variation. The first axis was interpreted as the action of the altitudinal/longitudinal gradient in the structuring of assemblies of fish which varied with morphological measurements of length of caudal fin and caudal peduncle. We can say that there are two distinct assemblies positioned at the extremes of the environmental gradient separated by capacity of swimming of the species. Within these groups we can say that on a local scale the physical structure of the channel generates subgroups related to the use of the niche, suggesting the action of environmental filters. Thus, we present evidence that environmental attributes of headwaters of the Atlantic Forest are related to the structure of the assemblies of fishes that inhabit these environments. / O crescente interesse por estudos de diversidade funcional permite abordar a relação entre as características funcionais das espécies com variações no ambiente buscando entender a organização das comunidades biológicas. Nós examinamos a relação entre as características físicas e estruturais de 19 trechos de riachos de cabeceira na Mata Atlântica e as características morfológicas relacionadas com a capacidade de natação das espécies de peixes. O ambiente foi descrito quanto à altitude, distância da fonte de espécies, composição do substrato e profundidade do canal; enquanto que as características funcionais foram descritas por 11 medidas morfológicas. Utilizamos uma análise RLQ e os dois primeiros eixos explicaram 97,8% do total da variação. O primeiro eixo foi interpretado como a ação do gradiente altitudinal/longitudinal na estruturação das assembleias de peixes que variou com as medidas morfológicas de comprimento da nadadeira e pedúnculo caudal. Podemos afirmar que existem duas assembleias distintas posicionadas nos extremos do gradiente ambiental separadas pela capacidade de deslocamento das espécies. Dentro destes grupos podemos dizer que em escala local a estrutura física do canal gera subgrupos relacionados ao uso do nicho, sugerindo a ação de filtros ambientais. Desta forma, apresentamos evidências de que a estrutura das assembleias de peixes está relacionada com atributos ambientais de riachos de cabeceira da Mata Atlântica.

Made available in DSpace on 2014-06-11T19:30:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-11Bitstream added on 2014-06-13T20:00:14Z : No. of bitstreams: 1 paula_fr_me_rcla.pdf: 4342789 bytes, checksum: 9634421fb04b3df8470ee1faea4a0d90 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os peixes apresentam uma grande diversidade de espécies, sendo na região Neotropical onde se encontra o maior número de espécies de água doce. Entretanto, esta grande diversidade encontra-se ameaçada devido à degradação dos ecossistemas lóticos, principalmente pela alteração do habitat devido à destruição das florestas e fragmentação da rede hidrográfica. As florestas, principalmente as florestas ripárias, possuem funções ecológicas importantes para a estruturação dos riachos e das comunidades aquáticas. Por muito tempo, as florestas têm sido extensamente destruídas, sendo substituídas principalmente pelos usos agrícolas, ocasionando a destruição dos ecossistemas e da biodiversidade aquática. Além das alterações nas florestas, a presença de represamentos e cruzamentos de estradas gera impactos adicionais para os peixes ao romper a conectividade existente na rede hidrográfica. Os peixes possuem ciclos de vida complexos que dependem da complexidade estrutural do riacho e da conectividade entre trechos montante e jusante da rede. Portanto, a conservação das florestas e a manutenção da conectividade hidrológica são fatores importantes para a conservação das comunidades de peixes. Neste trabalho, avaliou-se a diversidade das comunidades de peixes de riachos em função das alterações na estrutura da paisagem florestal (composição e configuração) e da conectividade da rede hidrográfica em paisagens agrícolas. O estudo foi realizado em microbacias de 1ª a 4ª ordem pertencentes à bacia do rio Corumbataí. Diferenças nos índices de diversidade das comunidades foram testadas a partir da Análise de Variância considerando a estrutura da paisagem florestal em diferentes escalas espaciais (microbacia, rede de drenagem e trecho de coleta) e a conectividade da rede hidrográfica. As relações entre as variáveis da paisagem (estrutura da paisagem... / Fish exhibit great species diversity, and the Neotropical region holds the largest number of freshwater fish species . However, this great diversity is threatened due to lotic ecosystems degradation, mainly through forest destruction and stream network fragmentation. Forests, mainly riparian forests, have important ecological functions for stream and aquatic communities structuring. For a long time, forests have been extensively destroyed and replaced mainly by agricultural uses, causing stream and aquatic biodiversity destruction. Besides the alterations in forests, the presence of dams and road crossings generates additional impacts to fish by disrupting existing connectivity to the stream network. Fish have complex life cycles that depend of the stream structural complexity and the connectivity between upstream and downstream sections of the stream network. Hence, forest conservation and maintenance of hydrological connectivity are important factors for the conservation of fish communities. In this study, we evaluated stream fish community diversity in relation to changes in forest landscape structure (composition and configuration) and the stream network connectivity in agricultural landscapes. The study was conducted in 1st and 4th order catchments belonging to the Corumbatai river basin. Differences in diversity indices were tested by Analyses of Variance considering forest landscape structure at different spatial scales (whole catchment, stream network and stream sampled reach) and stream network connectivity. The relationship between landscape variables (forest landscape structure, riparian forest landscape structure and physical and hydrological hierarchy variables) and aquatic environment variables (channel structure and limnology and fish diversity indices) were evaluated using Redundancy Analysis (RDA) and Multiple Regression Analysis. These relationships were also assessed... (Complete abstract click electronic access below)

The Mngazana and Mngazi estuaries are situated just south of Port St. Johns close to the biogeographical boundary between the warm temperate and subtropical zones along the east coast of Southern Africa. The Mngazana estuary is a permanently open estuary with three species of mangrove. The Mngazi estuary is a temporarily open/closed system. The ichthyofauna was sampled with seine nets and gillnets during June 2005, August 2005, November 2005, February 2006 and April 2006. The fish community structure was significantly different between the two estuaries with the differences being especially noticeable in the larger fish sampled with gillnets. There were significant differences in the fish community sampled with the seine net on both spatial and temporal scales in both of the estuaries. Certain warm temperate species were less abundant and certain subtropical species were more abundant at the Mngazana estuary than they were during a study conducted in 1975. Stomach content analysis revealed that most species had similar diets in the two estuaries with the only differences occurring among benthic feeding species. The diet of sub-adult piscivores comprised of a large proportion of penaeid prawns while the juveniles feed mainly on mysids. The zooplanktivorous fish feed mainly on copepods and mysids with the proportions varying between the species. Benthic feeding fishes showed the greatest variability in diet with plant material, detritus, crabs and copepods being the main food sources. Stable isotopes revealed that particulate organic matter and microphytobenthos were the most important carbon sources to fish in the Mngazi estuary. In the Mngazana estuary a combination of mangrove material, detritus, particulate organic matter and Zostera material were the most important carbon sources. The importance of each of these sources did, however, vary greatly between the different trophic guilds of the fish in the Mngazana estuary. The distribution of certain fish species was investigated in relation to physical parameters (temperature, salinity, turbidity and depth) and biological parameters (prey and predators) in the environment. It was found that most small fish (< 100 mm SL) were strongly correlated with turbidity where-as they showed weak correlations with their prey. Sub-adult piscivores fell into two groups, i.e. those that could tolerate turbid water and those that were only found in clear water. The group that also occurred in turbid water showed very strong correlations with their prey but the clear water group did not. It would appear that the small and thus vulnerable fish seemed to occur in areas that offered them protection rather than areas where their food supply is most abundant, where-as the piscivores were more influenced by prey distribution, as long as the physical conditions were tolerable to them.