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Platinum mining activities contribute substantially to South Africa's economy since it exceeded gold as economical contributor in 2001. Mining activities contribute to large amounts of waste production in the form of tailings and rock waste, deposited in the surrounding environment of the mine premises. Mining companies are held responsible for damages caused to the surrounding environment. These companies are required to introduce the cost of ecological rehabilitation in their operation costs as well as compile an environmental management plan. Numerous attempts to rehabilitate mine waste have proven unsuccessful. New and improved rehabilitation techniques are required to facilitate in the rehabilitation of these mine spoils. Woodchip-vermicompost produced from platinum mining wastes (woodchips and sewage sludge) was used as an alternative amendment to inorganic fertilisers during the rehabilitation of platinum mine tailings. The effectiveness of the woodchip-vermicompost as an alternative amendment during the platinum mine tailings rehabilitation were monitored using different ecosystem components. A natural veldt in the vicinity of the mine area was randomly selected to serve as a reference site. These ecosystem components selected have previously been shown to be effective as indicators of ecosystem quality. The components selected for this study includes the use of microbial enzymatic activity, microbial community structure, nematode trophic structures, and other mesofaunal groups such as micro-arthropods. The physical and chemical properties of the platinum mine tailings and reference area as well as the vegetation cover of the platinum mine tailings were determined. Statistical and multivariate analyses were use to determine the correlation between the dependent microbial components and dominate independent chemical properties. Nematode trophic structure, Maturity Index, and Plant-Parasitic nematode Index were used to compare the two rehabilitation techniques in terms of nematodes as indicators. Microarthropods family structures were used to compare the two amendments in terms of diversity and abundance. Enzymatic activity was positively affected by the addition of woodchip-vermicompost, than in the sites treated with inorganic fertilisers. The microbial community structure showed no statistically significant (p < 0.05) differences between the two amendments. A higher abundance of nematodes especially plant-parasitic nematodes and bacterivorous nematodes were observed in the woodchip-vermicompost sites than in the inorganic fertilised sites. According to the Maturity Index, both amendments became more enriched during the study period, while the Plant-Parasitic nematode Index showed that the carrying capacity for plantparasitic nematodes on the woodchip-vermicompost sites increased while it decreased in the inorganic fertilised sites, which can be related to the decrease in vegetation cover on the inorganic fertilised sites. Both coloniser (Prostigmata) and persister (Cryptostigmata and Mesostigmata) groups of the micro-arthropods, as well as a higher diversity of micro-arthropods, were present on the woodchip-vermicompost sites whereas the inorganic fertilised sites showed only the presence of colonisers, with a decrease in diversity and abundance of micro-arthropods over the study. The colonisation of micro-arthropods may have been affected by the addition of woodchip-vermicompost and vegetation cover, which contribute to the establishment of suitable microhabitats for these soil biota. By intercorrelating the results, it may be concluded that the addition of woodchip-vermicompost may be an essential part of the rehabilitation process, by contributing to soil organic material to the ecosystem system, which may improve the recolonisation of soil biota and ecosystem processes. However further studies need to be conducted in order to determine the long-term sustainability of the woodchip-vermicompost in providing organic material and sustaining the ecosystem processes. The study also showed the necessity to integrate various ecosystem components when evaluating ecosystem development due to the unique role each component plays and the impact it may have on other components. / Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2006.

Food web structure is of underlying importance to ecological functions and processes. Whilst it is understood that a range of biotic and abiotic factors affect structure, relatively little is known of the role of biodiversity per se in structuring food webs. In this thesis I utilise novel multi-dimensional estimates of food web structure based on stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) to quantify structural responses to changing community diversity. I additionally investigate methodological aspects of sample preparation and stable isotope quantifications of food chains. Using an arthropod prey-predator system, in chapter 2 I demonstrate that tissue selection and lipid extraction are important methodological procedures for deriving accurate δ15N and δ13C signatures. In chapter 3 I test the utility of δ15N to quantify food chain length, and δ13C to trace primary energy sources through to end consumers. Bayesian resampling of variance in sample means for plant and arthropod food chains produces robust isotopic estimates that match known food chain length well despite some error variance, and estimates of δ13C-range that trace trophic transfers. Chapter 4 represents a change in system from lab to field as I determine δ15N and δ13C signatures for plant and invertebrate species within three grassland communities representing a gradient of biodiversity. Quantifications of community bivariate isotopic space using isotopic metrics revealed that greater taxonomic richness increased both diversity of resource space exploited and overlap in resource space. These results therefore suggest that loss of diversity affected structure through altering relative patterns of niche partitioning in resource exploitation amongst community members. In chapter 5, I additionally find evidence that grassland management mediated changes in food web compartmental structure that were associated with differences in generalist invertebrate predator feeding habits. Taken together, these findings develop and demonstrate the utility of isotopic approaches to quantifying food web structure, and provide evidence of important mechanisms by which biodiversity affects food web structure. I conclude that the preservation of natural food web structure and trophic dynamics are further reasons for halting loss of biodiversity.

Estudaram-se a estruturas taxionômica e trófica e determinaram-se os índices de maturidade de comunidades de nematóides ocorrentes em áreas contíguas de mata natural preservada e de culturas perenes (bananeira, citros, pessegueiro) e anuais (milho x leguminosas) em rotação em Piracicaba (SP). Três amostras compostas de solo (volume aproximado de um litro) foram coletadas de cada área em duas épocas (\"seca\", agosto/2004 e \"chuvosa\", março/2005) e profundidades (0-15 e 15-30 cm). Para cada amostra, extraíram-se os nematóides de volume de 500 ml pela técnica de peneiramento combinado com flotação em centrífuga com solução de sacarose, sendo depois fixados em formalina, contados e infiltrados com glicerina. Para o cálculo das abundâncias, indicadores de diversidade e os índices de maturidade, 150 exemplares foram coletados ao acaso por amostra e identificados ao nível de gênero. Assinalaramse 61 gêneros, filiados a 32 famílias. As abundâncias totais foram maiores à menor profundidade, nas duas épocas de coleta. Os maiores valores de número e riqueza de gêneros, à menor profundidade, ocorreram na mata; à maior profundidade, tal se deu na área de anuais e de citros, nas primeira e segunda épocas de coleta, respectivamente. Os índices de diversidade de Shannon- Weaver e de Simpson e respectivos índices de eqüitatividade foram menos eficientes que o número e a riqueza de gêneros na discriminação dos sistemas estudados. Os parasitos de plantas constituíram o grupo trófico prevalente em todos os sistemas avaliados, nas duas épocas e profundidades de coleta, seguidos no geral pelos bacteriófagos. Todavia, não foi possível separar cultivos anuais de perenes com base nas abundâncias de parasitos de plantas. Os valores de T (diversidade trófica) não se prestaram à clara distinção entre os cinco sistemas, mas os de MI, mMI e PPI indicaram menor ocorrência de distúrbios na mata e no pomar cítrico em relação às demais áreas cultivadas. A herbivoria foi o canal prevalente de decomposição nos diferentes sistemas, exceto no pomar de citros. Dentre os microbiófagos (FF/BF), a predominância foi da via bacteriana. / The taxonomic structure, trophic structure and maturity index of nematode communities occurring in neighbouring areas of native forest and four different agroecosystems were studied in Piracicaba, São Paulo State, Brazil. Agroecosystems were three perennial (banana, citrus and peach orchards) and one annual (corn, rotating with leguminous plants or followed by fallow) crops. Three soil samples (one liter approximately) were collected per area at two different times (August/2004 and March/2005) and depths (0-15 and 15-30 cm). Nematodes were extracted from 500 cc of soil by a sieving and sugar flotation technique, fixed with formalin, counted and infiltrated with glycerin. Subsequently, 150 specimens randomly picked were identified to the genus level. A total number of 61 genera affiliated to 32 families was recorded. Total abundance was higher at lower depth irrespective of the sampling time. At depth 0-15 cm, higher values of genus number and genus richness were calculated for the forest in both sampling times; at 15-30 cm, the highest values were assigned to annual crop and citrus areas, respectively. Shannon- Weaver and Simpson indexes were less efficient than genus number and genus richness in discriminating the studied ecosystems. Plant-parasitic nematodes prevailed as a trophic group in all systems at both sampling times and depths, the bacterivorous usually ranking second position. However, the data of relative abundance of phytonematodes did not allow annual and perennial crop areas to be statistically differentiated. The studied systems also were not clearly distinguished with basis on the T values, but according to the MI, mMI and PPI data the forest and the citrus orchard were the less disturbed areas. Herbivory was the predominant decomposition channel in all systems, with exception of the citrus orchard. In terms of microbial decomposition (FF/BF), the process was usually dominated by bacteria.

Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2006.

Platinum mining activities contribute substantially to South Africa's economy since it exceeded gold as economical contributor in 2001. Mining activities contribute to large amounts of waste production in the form of tailings and rock waste, deposited in the surrounding environment of the mine premises. Mining companies are held responsible for damages caused to the surrounding environment. These companies are required to introduce the cost of ecological rehabilitation in their operation costs as well as compile an environmental management plan. Numerous attempts to rehabilitate mine waste have proven unsuccessful. New and improved rehabilitation techniques are required to facilitate in the rehabilitation of these mine spoils. Woodchip-vermicompost produced from platinum mining wastes (woodchips and sewage sludge) was used as an alternative amendment to inorganic fertilisers during the rehabilitation of platinum mine tailings. The effectiveness of the woodchip-vermicompost as an alternative amendment during the platinum mine tailings rehabilitation were monitored using different ecosystem components. A natural veldt in the vicinity of the mine area was randomly selected to serve as a reference site. These ecosystem components selected have previously been shown to be effective as indicators of ecosystem quality. The components selected for this study includes the use of microbial enzymatic activity, microbial community structure, nematode trophic structures, and other mesofaunal groups such as micro-arthropods. The physical and chemical properties of the platinum mine tailings and reference area as well as the vegetation cover of the platinum mine tailings were determined. Statistical and multivariate analyses were use to determine the correlation between the dependent microbial components and dominate independent chemical properties. Nematode trophic structure, Maturity Index, and Plant-Parasitic nematode Index were used to compare the two rehabilitation techniques in terms of nematodes as indicators. Microarthropods family structures were used to compare the two amendments in terms of diversity and abundance. Enzymatic activity was positively affected by the addition of woodchip-vermicompost, than in the sites treated with inorganic fertilisers. The microbial community structure showed no statistically significant (p < 0.05) differences between the two amendments. A higher abundance of nematodes especially plant-parasitic nematodes and bacterivorous nematodes were observed in the woodchip-vermicompost sites than in the inorganic fertilised sites. According to the Maturity Index, both amendments became more enriched during the study period, while the Plant-Parasitic nematode Index showed that the carrying capacity for plantparasitic nematodes on the woodchip-vermicompost sites increased while it decreased in the inorganic fertilised sites, which can be related to the decrease in vegetation cover on the inorganic fertilised sites. Both coloniser (Prostigmata) and persister (Cryptostigmata and Mesostigmata) groups of the micro-arthropods, as well as a higher diversity of micro-arthropods, were present on the woodchip-vermicompost sites whereas the inorganic fertilised sites showed only the presence of colonisers, with a decrease in diversity and abundance of micro-arthropods over the study. The colonisation of micro-arthropods may have been affected by the addition of woodchip-vermicompost and vegetation cover, which contribute to the establishment of suitable microhabitats for these soil biota. By intercorrelating the results, it may be concluded that the addition of woodchip-vermicompost may be an essential part of the rehabilitation process, by contributing to soil organic material to the ecosystem system, which may improve the recolonisation of soil biota and ecosystem processes. However further studies need to be conducted in order to determine the long-term sustainability of the woodchip-vermicompost in providing organic material and sustaining the ecosystem processes. The study also showed the necessity to integrate various ecosystem components when evaluating ecosystem development due to the unique role each component plays and the impact it may have on other components. / Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2006.

?rea de concentra??o: Conserva??o e Restaura??o de Ecossistemas Florestais. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2018-03-07T19:22:48Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) lelis_vaz_leite_oliveira.pdf: 2388952 bytes, checksum: 4d43bd58c8b2ec58bf2ad86b22291639 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2018-03-09T19:57:08Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) lelis_vaz_leite_oliveira.pdf: 2388952 bytes, checksum: 4d43bd58c8b2ec58bf2ad86b22291639 (MD5) / Made available in DSpace on 2018-03-09T19:57:08Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) lelis_vaz_leite_oliveira.pdf: 2388952 bytes, checksum: 4d43bd58c8b2ec58bf2ad86b22291639 (MD5) Previous issue date: 2013 / Impactos ambientais comprometem direta ou indiretamente a riqueza e estrutura tr?fica da avifauna local e regional e informa??es sobre esta tem?tica s?o escassas para as forma??es do Cerrado, em especial para a o Espinha?o Meridional. Assim, este estudo busca fornecer informa??es sobre a conserva??o, endemismo e estrutura tr?fica da avifauna em forma??es sav?nicas (cerrado t?pico e cerrado rupestre), de tr?s ?reas que se encontram em diferentes est?dios de conserva??o na Serra do Espinha?o Meridional. Em cada ?rea foi pr?-estabelecido um transecto de 5 km, os quais foram visitados mensalmente. Cada uma dessas visitas teve dura??o de oito horas, totalizando 120 horas/ ?rea. Ao percorrer tais transectos, foram registradas todas as aves vistas e/ou ouvidas. Foi avaliado o status de degrada??o de cada ?rea estudada, por meio de uma matriz de impactos e a quantifica??o estrutural da paisagem foi feita por meio de ?ndices de composi??o e configura??o espacial. No Parque Estadual do Biribiri e antigo dep?sito de lixos de Diamantina (BL) foram registradas 123 esp?cies de aves distribu?das em 34 fam?lias. Para o RP foram registradas 88 esp?cies e 28 fam?lias e para a ?rea de Prote??o Ambiental Pau-de-Fruta (PF) foram registradas 76 esp?cies e 23 fam?lias. Considerando que o pior cen?rio de impactos poss?vel, no qual todos os crit?rios est?o com a maior pontua??o alcan??vel some 132, o RP atingiu 25% (33 pontos), o PF 26,5% (35 pontos) e o BL 60,6% (80 pontos). Em rela??o ? estrutura tr?fica n?o houve diferen?as significativas entre as ?reas estudadas tanto para todo o per?odo analisado (H = 5,670; p = 0,127), como para as duas esta??es seca (H = 5,436; p= 0,145) e chuvosa (H = 4,744; p = 0,191) e demonstrou um predom?nio de esp?cies inset?voras, seguidas por frug?voras e on?voras. A insetivoria foi a guilda mais predominante durante as duas esta??es em todos os ambientes estudados. Houve uma consider?vel similaridade da avifauna entre as ?reas. Os padr?es encontrados por este estudo refor?am a necessidade melhor compreens?o de ambientes antropizados, principalmente aqueles em ?reas de forma??es sav?nicas, onde a avifauna indica uma tend?ncia a apresentar maior plasticidade e amplitude ambiental. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Ci?ncia Florestal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2013. / Environmental impacts directly or indirectly compromise the richness and trophic structure of local and regional avifauna and information on this subject are scarce for the formations of the Cerrado, especially to the southern Espinha?o. Thus, this study aims to provide information about conservation, endemism and trophic structure of the avifauna in savanna formations (typical cerrado and grasslands) of three areas that are at different stages of conservation in the southern Espinha?o. In each area was pre-established a transect of 5 km, which were visited monthly. Each of these visits lasted eight hours, totaling 120 hours/area. In such transects were recorded all birds seen and / or heard. The deterioration status of each studied by means of an array of structural impacts and quantification of the landscape area was made by compounding rates and spatial configuration was evaluated. In the Biribiri State Park and ancient deposit of waste from Diamantina (BL) 123 species of birds distributed in 34 families were recorded. RP for 88 species and 28 families were recorded and the Environmental Protection Area Pau-de-fruit (PF) 76 species and 23 families were recorded. . In the Biribiri State Park and ancient deposit of waste from Diamantina (BL) 123 species of birds distributed in 34 families were recorded. In the Rio Preto State Park (RP) 88 species and 28 families were recorded and at the Environmental Protection Area Pau-de-Fruta (PF) 76 species and 23 families were recorded. Whereas the worst possible impacts, where all criteria are reached with the highest score some 132, RP reached 25% (33 points), PF 26.5% (35 points) and 60.6% BL (80 points). Regarding the trophic structure there were no significant differences among the studied areas for the entire period analyzed both (H = 5.670, p = 0.127) and for the two dry seasons (H = 5.436, p = 0.145) and wet (H = 4,744 p = 0.191) and demonstrated a predominance of insectivores, followed by frugivorous and omnivorous species. The insectivorous guild was most prevalent during the two seasons in all environments studied. There was considerable similarity between the avifauna in the study areas. The patterns found in this study reinforce the need for better understanding of anthropogenic environments, especially those in areas of savanna formations where birdlife indicates a tendency to have higher plasticity and environmental amplitude.

Estudaram-se a estruturas taxionômica e trófica e determinaram-se os índices de maturidade de comunidades de nematóides ocorrentes em áreas contíguas de mata natural preservada e de culturas perenes (bananeira, citros, pessegueiro) e anuais (milho x leguminosas) em rotação em Piracicaba (SP). Três amostras compostas de solo (volume aproximado de um litro) foram coletadas de cada área em duas épocas (\"seca\", agosto/2004 e \"chuvosa\", março/2005) e profundidades (0-15 e 15-30 cm). Para cada amostra, extraíram-se os nematóides de volume de 500 ml pela técnica de peneiramento combinado com flotação em centrífuga com solução de sacarose, sendo depois fixados em formalina, contados e infiltrados com glicerina. Para o cálculo das abundâncias, indicadores de diversidade e os índices de maturidade, 150 exemplares foram coletados ao acaso por amostra e identificados ao nível de gênero. Assinalaramse 61 gêneros, filiados a 32 famílias. As abundâncias totais foram maiores à menor profundidade, nas duas épocas de coleta. Os maiores valores de número e riqueza de gêneros, à menor profundidade, ocorreram na mata; à maior profundidade, tal se deu na área de anuais e de citros, nas primeira e segunda épocas de coleta, respectivamente. Os índices de diversidade de Shannon- Weaver e de Simpson e respectivos índices de eqüitatividade foram menos eficientes que o número e a riqueza de gêneros na discriminação dos sistemas estudados. Os parasitos de plantas constituíram o grupo trófico prevalente em todos os sistemas avaliados, nas duas épocas e profundidades de coleta, seguidos no geral pelos bacteriófagos. Todavia, não foi possível separar cultivos anuais de perenes com base nas abundâncias de parasitos de plantas. Os valores de T (diversidade trófica) não se prestaram à clara distinção entre os cinco sistemas, mas os de MI, mMI e PPI indicaram menor ocorrência de distúrbios na mata e no pomar cítrico em relação às demais áreas cultivadas. A herbivoria foi o canal prevalente de decomposição nos diferentes sistemas, exceto no pomar de citros. Dentre os microbiófagos (FF/BF), a predominância foi da via bacteriana. / The taxonomic structure, trophic structure and maturity index of nematode communities occurring in neighbouring areas of native forest and four different agroecosystems were studied in Piracicaba, São Paulo State, Brazil. Agroecosystems were three perennial (banana, citrus and peach orchards) and one annual (corn, rotating with leguminous plants or followed by fallow) crops. Three soil samples (one liter approximately) were collected per area at two different times (August/2004 and March/2005) and depths (0-15 and 15-30 cm). Nematodes were extracted from 500 cc of soil by a sieving and sugar flotation technique, fixed with formalin, counted and infiltrated with glycerin. Subsequently, 150 specimens randomly picked were identified to the genus level. A total number of 61 genera affiliated to 32 families was recorded. Total abundance was higher at lower depth irrespective of the sampling time. At depth 0-15 cm, higher values of genus number and genus richness were calculated for the forest in both sampling times; at 15-30 cm, the highest values were assigned to annual crop and citrus areas, respectively. Shannon- Weaver and Simpson indexes were less efficient than genus number and genus richness in discriminating the studied ecosystems. Plant-parasitic nematodes prevailed as a trophic group in all systems at both sampling times and depths, the bacterivorous usually ranking second position. However, the data of relative abundance of phytonematodes did not allow annual and perennial crop areas to be statistically differentiated. The studied systems also were not clearly distinguished with basis on the T values, but according to the MI, mMI and PPI data the forest and the citrus orchard were the less disturbed areas. Herbivory was the predominant decomposition channel in all systems, with exception of the citrus orchard. In terms of microbial decomposition (FF/BF), the process was usually dominated by bacteria.

Orientador: Wagner André Pedro / Banca: Paulo de Marco Junior / Banca: Luiz Dino Vizotto / Resumo: A região Noroeste do estado de São Paulo, bem como microregiões adjacentes, carece de informações concisas sobre a composição floristica e faunística, em especial à avifauna. Esta condição aliada ao alto grau de degradação ambiental apresentado favorece a perda incontestável de biodiversidade. A grande maioria dos remanescentes florestais do interior paulista são representados por pequenos trechos de mata, isolados na maior parte daz vezes por matrizes inóspitas como cultivo de cana-de-açúcar e pastagens. As formações florestais representadas pela Floresta Estacional tipo Semidecidual cobrem a maior parte do interior do estado de São Paulo e, portanto refletem um quadro sazonal relativamente acentuado com dois períodos bastante distintos de seca e chuva. Esta condição sazonal interfere em vários aspectos da historia de vida da fauna inserida na região, especialmente das aves e artrópodes. Neste sentido, procuro-se aqui descrever a estrutura da comunidade de aves em um remanescente florestal de pouco mais de 2.400 ha, com inferências ao grau de endemismo de algumas espécies, grau de conservação e ameaça, habitats e dependência florestal. Ainda, em segundo momento, teve-se por objetivo analisar e avaliar os efeitos da sazonalidade e disponibilidade de presas invertebradas para a comunidade como um todo, mas em especial aos insetívoros. Ao todo foram xi registradas 171 espécies na área de estudo, sendo 95 no remanescente florestal e 76 em áreas de entorno que englobaram ambientes antropizados e aquáticos. Sete espécies foram consideradas endêmicas da Mata Atlântica ou Cerrado, 22 apresentando algum grau de ameaça e 28 espécies dependentes da floresta. Os resultados para as relações sazonais demostraram-se diferentes para as diferentes guildas, sendo que frugívoros tiveram suas populações oscilando mais do que insetívoros e onívoros entre... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Northwest region of São Paulo, as well as adjacent microregions, lacks concise information on the floristic composition and wildlife, especially the avifauna. This condition coupled with the high degree of environmental degradation presented incostestável favors the loss of biodiversity. Most of the interior of forest remnants are represented by small patches of forest, mostly isolated daz times inhospitable matrix as the cultivation of sugar cane and pasture. The forest types represented by seasonal forest type Semidecidual cover most of the state of Sao Paulo, and thus reflect a relatively strong seasonal table with two very distinct periods of drought and rain. This seasonal condition interferes with many aspects of life history fauna inserted into the region, especially birds and arthropods. In this sense, I try here to describe the community structure of birds in a forest remnant of just over 2,400 ha, with inferences to the degree of endemism of some species, conservation status and threat, and dependence on forest habitats. Still, in the second time it was taken to analyze and evaluate the effects of seasonality and availability of invertebrate prey for the community as a whole, but especially the insectivores. Altogether 171 species were recorded in the study area, 95 and 76 in the remaining forest in the surrounding areas have included aquatic and anthropogenic environments. Seven species are endemic to the Atlantic Forest and Cerrado, 22 showing some degree of threat and 28 species of forest-dependent. The xiii results demonstrated for seasonal relationships are different for different guilds, and their populations ranging frugivores had more than insectivores and omnivores between the dry and rainy seasons. The species richness was significantly correlated with invertebrate abundance of foliage. The breeding season of birds recorded in the remaining forest... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-12-17T14:02:04Z (GMT). No. of bitstreams: 1 MichelleMR.pdf: 448282 bytes, checksum: a72147e483ab07cc3c64242fa0a8d888 (MD5) Previous issue date: 2007-03-21 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Artificial lakes must differ from natural lakes in important structural and functional aspects that need to be understood so that these ecosystems can be properly managed. The aim of this work was to test the hypothesis that the artificial lakes (impoundments) in the semi-arid region of the Rio Grande do Norte State are more eutrophic and turbid and have different trophic structure when compared to the natural coastal lakes that occur in the humid eastern coast of the State. To test this hypothesis, 10 natural lakes and 8 artificial lakes with about 100 ha were sampled between September and November 2005 for the determination of some limnological variables and the abundance of the main fish species, which were grouped in three trophic guilds: facultative piscivores, facultative planktivores and omnivores. The results show that the artificial lakes had significantly higher concentrations of total nitrogen, total phosphorus, chlorophyll a , total and volatile suspended solids than the natural lakes. Results also show that the values of pH, total alkalinity, electric conductivity, turbidity as well as the coefficient of vertical attenuation of light were significantly higher in the artificial lakes than in the natural lakes. In the artificial lakes, the abundance of facultative planktivores was significantly higher, while the abundance of facultative piscivores significantly lower than in the natural lakes. There was no significant difference in the abundance of omnivorous fish between the two types of lakes. These results suggest that the increase in turbidity together with the other changes in the water quality of the artificial lakes, modifies the trophic structure of the fish communities reducing the importance of piscivores and the length of the food chains / Lagos artificiais devem diferir de lagos naturais em importantes aspectos estruturais e funcionais que precisam ser compreendidos para que possamos manejar adequadamente esses ecossistemas. Este trabalho foi realizado com o objetivo de testar a hip?tese de que os lagos artificiais (a?udes) na regi?o semi-?rida s?o ambientes mais eutrofizados e t?rbidos que possuem uma estrutura tr?fica distinta dos lagos costeiros naturais que ocorrem no litoral leste ?mido do Estado do Rio Grande do Norte. Para testar esta hip?tese, 10 lagos naturais e 8 lagos artificiais com cerca de 100 ha foram amostrados entre setembro e novembro de 2005 para determina??o de algumas vari?veis limnol?gicas e da abund?ncia das principais esp?cies de peixes, as quais foram agrupadas em tr?s guildas tr?ficas: pisc?voros facultativos, planct?voros facultativos e on?voros. Os resultados mostram que os lagos artificiais apresentaram concentra??es significativamente maiores de nitrog?nio e f?sforo total, clorofila a e s?lidos totais e vol?teis em suspens?o do que os lagos naturais. Os resultados tamb?m mostram que o pH, a alcalinidade total, a condutividade el?trica, a turbidez da ?gua e coeficiente de atenua??o vertical da luz nos lagos artificiais foram significativamente maiores do que nos lagos naturais. Nos lagos artificiais, a abund?ncia de peixes planct?voros facultativos tamb?m foi significativamente maior, enquanto que a abund?ncia de peixes pisc?voros facultativos foi significativamente menor do que nos lagos naturais. N?o houve diferen?as significativas na abund?ncia de peixes on?voros entre os dois tipos de lagos estudados. Esses resultados sugerem que a maior turbidez da ?gua aliada a outras mudan?as na qualidade da ?gua dos lagos artificiais eutrofizados afetam a estrutura tr?fica das comunidades de peixes reduzindo a import?ncia dos peixes pisc?voros e conseq?entemente o comprimento das cadeias alimentares