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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An Ecological Survey of the Reptiles and Amphibians of Wise county, Texas

Welch, Donald A. 01 1900 (has links)
The purpose of this study was to record the relationships between the reptiles and amphibians of Wise County and the ecological subdivisions of the area. Wise County was chosen because of the heterogenity of the area and because of its proximity to other counties which have been previously and similarly studied.
2

Levantamento populacional de fungos micorrízicos arbusculares e de fitonematoides em áreas produtoras de algodão no estado de Goiás / Survey of arbuscular mycorrhizal fungi and nematode population in cotton producing areas in The state of Goiás

Ferreira, Bruno da Silva 28 August 2015 (has links)
Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-10-17T20:25:43Z No. of bitstreams: 2 Dissertação - Bruno da Silva Ferreira - 2015.pdf: 2213963 bytes, checksum: 9d6325fb6aaf93b0f49154c30b557bc0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-10-18T16:21:22Z (GMT) No. of bitstreams: 2 Dissertação - Bruno da Silva Ferreira - 2015.pdf: 2213963 bytes, checksum: 9d6325fb6aaf93b0f49154c30b557bc0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-10-18T16:21:22Z (GMT). No. of bitstreams: 2 Dissertação - Bruno da Silva Ferreira - 2015.pdf: 2213963 bytes, checksum: 9d6325fb6aaf93b0f49154c30b557bc0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-08-28 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Different management strategies are necessary for the control of plant nematodes. The arbuscular mycorrhizal fungi (AMF) have been an option as potential microorganisms for biological control. There is a demand of ways to manage plant parasitic nematode with less environmental impact and lower cost. Thus, the aim of this study was to survey nematodes and AMF in cotton producing areas in the state of Goiás and evaluate the interaction between AMF and nematodes, and relate their populations to the physical and chemical soil traits. The survey was conducted during two crop seasons (June/2013 and February/2014) in ten cotton producing areas. Three samples composed of ten subsamples were collected in each area. Soil and roots were collected in the depth of 0 to 20 cm. For quantification and identification of AMF and nematodes soil and root analysis were carried out in the laboratory. There was also the analysis of physical and chemical soil properties. For data analysis we used the Pearson correlation coefficient, principal component analysis (PCA) and the diversity indexes of Shannon-Wiener, Simpson and Margalef. In all sampled areas was observed occurrence of nematodes, the main genera being Meloidogyne, Pratylenchus, Helicotylenchus, Rotylenchus, Rotylenchulus, Aphelenchus and Criconemoide. The Helicotylenchus and Pratylenchus genres presented higher abundance in the two years of study, followed by Meloidogyne. The major cause of cotton damage, Rotylenchulus sp. was not observed in 80% of the sampled areas, with presence only in two areas in the first crop season (2013). Different AMF species were found, being the main genre Glomus, with most species. AMF were distributed evenly among the evaluated areas and in the two crop seasons. The correlation between Aphelenchus species and AMF Cetraspora pellucida was positive, as well as between Meloidogyne and Glomus sp. On the contrary, the correlation between G. macrocarpum and Pratylenchus was negative. The largest quantity of organic matter negatively affected Helicotylenchus sp. and positively the AMF R. intraradices. The higher phosphorus content influenced positively the population of Glomus sp. Areas cultivated with cotton in the state of Goiás with greater presence of AMF have a lower number of nematodes in the soil and roots. / Para o controle dos fitonematoides é necessário que se utilize diferentes estratégias de manejo. Os fungos micorrízicos arbusculares (FMAs) são empregados como uma opção de microrganismos com potencial controle de patógenos. Existe uma demanda por formas de manejo de fitonematoides com menor impacto ambiental e de menor custo. Com isso, o objetivo deste estudo foi realizar o levantamento de fitonematoides e de FMAs em áreas produtoras de algodão no estado de Goiás e avaliar a interação entre FMAs e fitonematoides, além de relacionar com os atributos físico-químicos do solo de Cerrado. Foi realizado o levantamento de espécies de FMAs e fitonematoides associados à cultura do algodoeiro em dois anos de cultivo agrícola (junho/2013 e fevereiro/2014) em dez áreas no estado de Goiás. Em cada área foram coletadas três amostras compostas por dez pontos (subamostras). Em cada ponto retirou-se solo e raiz na profundidade de 0 a 20 cm. Para quantificação e identificação de FMAs e fitonematoides em solo e raiz realizou-se análises em laboratório. Também realizou-se a análise dos atributos físicos e químicos do solo. Para análise dos dados foi utilizado o coeficiente de correlação de Pearson, análise de componentes principais (PCA) e os índices de diversidade de Shannon-Wiener, Simpson e Margalef. Em todas as áreas amostradas foi observada ocorrência de fitonematoides, sendo os principais gêneros Meloidogyne, Pratylenchus, Helicotylenchus, Rotylenchus, Rotylenchulus, Aphelenchus e Criconemoide. Os gêneros Helicotylenchus e Pratylenchus apresentaram maior abundância nos dois anos de estudo, seguido de Meloidogyne. Um dos principais causadores de danos em algodoeiro, o gênero Rotylenchulus não foi observado em 80% das áreas amostradas, com presença apenas em duas áreas na primeira amostragem (2013). Foram encontradas diferentes espécies de FMAs, sendo o principal gênero Glomus, com maior número de espécies. Os FMAs distribuíram- se uniformemente entre as áreas avaliadas e entre os anos avaliados. A correlação entre Aphelenchus e a espécie de FMA Cetraspora pellucida foi positiva, bem como, entre Meloidogyne e Glomus sp. Ao contrário disso a correlação entre G. macrocarpum e Pratylenchus foi negativa. A maior quantidade de matéria orgânica afetou de forma negativa Helicotylenchus sp. e positiva o FMA R. intraradices. O maior teor de fósforo influenciou de maneira positiva a população de Glomus sp. Áreas cultivadas com algodão no estado de Goiás com maior presença de FMAs apresentam menor número de nematoides no solo e nas raízes.
3

Méthodes d’analyse fonctionnelle et multivariée appliquées à l’étude du fonctionnement écologique des assemblages phytoplanctoniques de l’étang de Berre

Malkassian, Anthony 03 December 2012 (has links)
L'étude de la relation entre les variations d'abondance du phytoplancton et les facteurs environnementaux (naturels ou anthropiques) dans les zones saumâtres peu profondes est essentielle à la compréhension et à la gestion de cet écosystème complexe. Les relations existant entre les variables physico-chimiques (température, salinité et les nutriments) et les assemblages de phytoplancton de l'étang de Berre ont été analysées à partir d'un suivi écologique mensuel de 16 années (1994-2010). A l'aide des données recueillies par cette étude à long terme, des questions en relation avec la gestion de ce milieu ont été abordées grâce à l'application d'analyses statistiques et à la représentation originale des données. Depuis 2004, la nouvelle politique de relargage d'eau douce a provoqué de forts changements dans la salinité globale de la lagune : une diminution de la stratification et une raréfaction des phénomènes d'anoxie dans sa partie la plus profonde. Un changement dans la structure de la communauté phytoplanctonique a également été observé en association avec l'évolution des conditions environnementales. Une augmentation de la richesse spécifique phytoplanctonique, et plus précisément, l'émergence d'espèces à affinité marine a permis de mettre en évidence la première étape d'une marinisation de la lagune. Ces résultats soulignent l'impact significatif d'un nouvelle politique de gestion de cette zone côtière particulière. Nous nous sommes ensuite intéressés à la dynamique du phytoplancton à l'échelle de la journée reflet des variations rapides de l'environnement. / The study of the relationship between variations in phytoplankton abundance and environmental forces (natural or anthropogenic) in shallow brackish areas is essential to both understanding and managing this complex ecosystem. Over a 16 year (1994-2011) monthly monitoring program the relationships between physicochemical variables (temperature, salinity and nutrients) and phytoplankton assemblages of the Berre Lagoon were analyzed. Using data collected from this long-term study, we have addressed environmental management issues through the application of advanced statistical analyses and original data displays. These analyses and data displays can readily be applied to other data sets related to the environment, with the aim of informing both researcher and practitioner. Since 2004, a new policy for freshwater discharge has induced strong changes in the global salinity of the lagoon : a weakened stratification and a rarefaction of anoxia phenomena in its deepest part. A shift in the structure of the phytoplankton community has been observed in association with changes in environmental conditions. An increase of phytoplanktonic species richness, and more precisely, the emergence of species with marine affinity highlights the first step of a marinization of the lagoon. The results underline the significant impact of a new management policy in this specific coastal zone. We then focused on the response of phytoplankton to quick environmental variations. An original approach for automated high frequency analysis of phytoplankton was adopted with the use of an autonomous flow cytometer (CytoSense).
4

FOUR DIFFERENT ENVIRONMENTAL CONSULTING PROJECTS IN OHIO:THE SIMILARITY OF STREAM AND WETLAND ASSESSMENTS AND DIFFERENCES IN REGULATIONS

Wells, Marion Elizabeth 13 August 2013 (has links)
No description available.

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