Dissertations / Theses on the topic 'Macro-Ecology'
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Wahab, Md Abdul. "The ecology of benthic macro-invertebrates in earthen trout ponds at Howietoun, central Scotland." Thesis, University of Stirling, 1986. http://hdl.handle.net/1893/28840.
Full textMazel, Florent. "Comprendre et protéger la diversité des mammifères : une approche de biogéographie évolutive et fonctionnelle à l’échelle du globe." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAV063/document.
Full textMammals inhabit the Earth since at least the Cretaceous and have colonised all continents and oceans. My work aims at understanding the nature and importance of the different processes leading to current geographical distributions of mammals and in particular faunal similarities between regions of the globe. By describing the phylogenetic and functional facets of mammalian diversity, I adopt an integrative approach, at the interface between historical and functional biogeography.First, I review and synthesize most of the published multifaceted diversity metrics to propose a limited number of structural dimensions that parsimoniously describe the phylogenetic and functional structure of species assemblages. In particular, I point out how a multi-phylogenetic scale approach might improve our understanding of the mechanisms shaping diversity patterns.Second, I use this approach to understand the geographical distribution of mammals worldwide. I show that at large phylogenetic scales (e.g. families) distributions seem to be driven by geographic isolation of the regions over the course of the Cenozoic Era, while at small phylogenetic scales (e.g. species), distributions are related to climatic affinities. In addition, I show that those regions having developed independent mammalian faunas show exceptional functional similarities due to evolutionary convergences.Understanding the historical and ecological drivers of mammal biodiversity only represents the first step toward their conservation in the face of anthropic threats. The last part of my thesis shows the importance of an integrative approach using phylogenetic, functional and taxonomic facets to protect all dimensions of mammal diversity
Washko, Susan. "The Macroinvertebrate and Fish Communities of In-Stream Beaver Ponds in Northeastern Utah." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7395.
Full textPhilippe, Martin. "Perspectives multi-échelles de l'impact du chat domestique Felis catus sur la faune native." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASB025.
Full textThe impact of predation by the domestic cat, Felis catus, on biodiversity is increasingly recognized in ecological research as well as in public debate. Feral populations of domestic cats have had devastating effects on island ecosystems and in Australia, causing local and global extinctions of endemic species and raising major conservation concerns. As obligate carnivores with a diverse diet, these cat populations are responsible for the extinction of numerous species across various taxa, highlighting the urgency of appropriate conservation measures. However, the impact of Felis catus on biodiversity in continental contexts outside of Australia remains underexplored, requiring further studies to understand their ecological role and effectively mitigate their impacts if necessary. This thesis explores on a macro-ecological scale the patterns of Felis catus predation on endemic mammals and birds and examines the intensity of this predation considering different types of cat populations. Relying on open databases that include traits, phylogeny, distribution, and evidence of predation, and enhanced by artificial intelligence, the goal is to identify the species for which predation by cats could lead to local extinctions. Furthermore, this study also examines the factors influencing the mobility of domestic cats to better understand their impact on local wildlife. This work aims to redefine our understanding of the interactions between our domestic companions and the surrounding biodiversity, highlighting the challenges and opportunities for conservation in the Anthropocene era. In this research, the domestic cat is analyzed not as an invasive species but through a dual continuum of its independence from humans and its novelty as a predator, to deepen these phenomena on solid ecological grounds
Kriaučeliūnaitė, Kristina. "Makrofaunos (Lumbricidae) paplitimas agrofitocenozėse intensyvaus ūkininkavimo sąlygomis." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2006. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2006~D_20060607_164556-55484.
Full textChavy, Agathe Corinne. "Influence de l'environnement sur le cycle de transmission de la leishmaniose cutanée en Guyane, à multi-échelle spatiale Ecological niche modelling for predicting the risk of cutaneous leishmaniasis in the Neotropical moist forest biome Identification of French Guiana sand flies using MALDI-TOF mass spectrometry with a new mass spectra library « Regional scale ecological drivers of sandfly communities in French Guiana." Thesis, Guyane, 2019. http://www.theses.fr/2019YANE0013.
Full textFor many zoonotic diseases, transmission cycles remain difficult to determine, especially when they are due to generalist pathogens that can rely on several host and vector species to be transmitted. In addition, anthropogenic disturbances and climate change have strong impacts on ecosystems and can alter pathogen transmission cycles. Characterization and quantification of the relative importance of factors influencing host-pathogen-vector systems is then central for a global approach aiming to understand pathogen dynamics at different spatial scales. This approach has been used to study the ecology of the transmission cycle of cutaneous leishmaniasis (CL) in French Guiana. This vector-born disease, mainly sylvatic and including multiple hosts and vectors, is influenced by strong anthropic pressures that modified the dynamics of the cycle and led to an increase in the risk of transmission to human populations. In this work, we first explored the influence of environmental, climatic and anthropic factors on the distribution of human cases of CL at the global scale of the Amazonian biome and at the regional scale of French Guiana, using ecological niche modelling, allowing building risk maps. Then we observed the responses of communities of sandflies and known vectors at the regional scale in forest sites facing different disturbance levels. This work was made possible using a metabarcoding approach with high throughput sequencing. Last, we contributed to the improvement of the range of tools available for the identification of sandflies using the MALDI-TOF MS. This thesis contributed to the improvement of the general knowledge of the CL cycle in French Guiana
Schroeder, Gina. "Diversity investigations from the micro- to the macro-scale." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27918.
Full textCoulibaly, Sekou Fanta Mady. "Effets des changements de pratiques agronomiques sur la diversité des vers de terre et collemboles- conséquences sur leurs fonctions associées." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR005/document.
Full textSoil is one of the essential components supporting the functioning of the ecosystem. It is the support of primary production; an habitat for biodiversity, and it fulfills many ecological processes. Human activities, including intensive agricultural practices, have led to impaired the soil causing a sharp decline in their biodiversity. In response to these effects, new agricultural practices have been developed to preserve the soils and the ecosystem services they provide. These so-called innovative practices rely mainly on the reduction of tillage, integrated management of crop residues, the installation of permanent plant cover or the introduction of legumes into crop rotations. It is in this context of changes in agricultural practices that this thesis topic lays. This thesis aims to better understand the effects of the adoption of these innovative management practices on (i) the diversity of the macro and mesofauna communities soil and (ii) soil functioning in terms of organic carbon storage (basic food source), soil structure and pore size distribution (living environment). During the different chapters of this work, we highlighted three actions related to innovative agricultural practices combining in situ and ex situ experimental approaches. The aim of the first action was to study the combined effect of the introduction of legume (faba bean) and the reduction of tillage on the endogenous compartment. To answer this question, we developed an empirical experimental design made with the combination of situations encountered on farms. Our results showed that theinteraction between the two innovative practices did not result in a significant increase in the diversity of soil fauna. Microbial functions and the dynamics of carbon (C) and nitrogen (N) also do not seem to be affected by these practices. It turns out that the beneficial effects of these innovative practices cannot be considered without taking into account how they are implemented at the scale of crop rotations and technical itineraries. This allowed us to promote a second action whose objective was to follow, under the same pedoclimatic conditions and the same technical itineraries, the long-term effect (four years) of five different management regimes on the communities of soil fauna. Treatments included combinations of different crops, different rates of nitrogen fertilization, incorporation or removal of crop residues and different plowing intensities. The results showed that the reduction of tillage intensity favored the diversity of Collembola and its functional groups by improving habitatconditions through the increase of microbial carbon biomass (trophic source). In addition, the other components of management, namely the "reduction of nitrogen inputs" and the "restitution / export of crop residues", had no effect on springtails (abundance and wealth), in particular on those living in the soil, whether hemi or euedaphic. However, this study demonstrates that the dissimilarity in the composition of Collembola assemblages increases with the temporal differentiation of agricultural practices, and tillage was the main factor responsible for this trajectory
Yguel, Benjamin. "Sortir de sa niche ancestrale : conséquences pour les interactions trophiques, le cas du chêne pédonculé et sessile." Phd thesis, Université Rennes 1, 2012. http://tel.archives-ouvertes.fr/tel-00793651.
Full textBigsby, Ewan. "The interactions between the macro-invertebrates, fish and diving ducks of Lough Neagh, Northern Ireland." Thesis, University of Ulster, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.232855.
Full textCowley, C. "The influence of road runoff on the benthic macro-invertebrates of an unpolluted chalk stream." Thesis, University of Westminster, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354965.
Full textPettersson, Siri. "Makrofossilanalys som ekologiskt verktyg : En metodutvärdering." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-321511.
Full textVanden, Bossche Jean-Pierre. "Typologie et qualité biologique du réseau hydrographique de Wallonie basées sur les assemblages des macroinvertébrés." Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210955.
Full textTypologie des cours d’eau en Wallonie et caractérisation par la faune invertébrée
Vingt-cinq types de cours d’eau ont été définis en Wallonie d’après les termes de la Directive Cadre pour l’Eau en tenant compte des facteurs obligatoires et optionnels rassemblés sous trois critères :la taille (du « ruisseau » à la « très grande rivière »), la pente (faible, moyenne et forte), et cinq régions naturelles (la région limoneuse, le Condroz, la Famenne, l’Ardenne et la Lorraine belge, résumant les facteurs obligatoires altitude, latitude, longitude et géologie). Une approche par analyses multivariées appliquées à un grand nombre d’échantillons (listes taxonomiques) a permis de définir de façon plus précise certains types de rivières et de distinguer sept groupes typologiques montrant des assemblages faunistiques similaires.
Conditions de référence types et définition de l’état écologique des rivières en Wallonie à l’aide de métriques biocénotiques basées sur les invertébrés
Les listes faunistiques et les valeurs métriques de l’IBGN (Indice biologique global normalisé) issues du réseau d’évaluation de la qualité biologique en Wallonie ont été utilisées pour discriminer les types de rivières et pour définir les sites de référence, les conditions de référence et les limites des classes des états écologiques. Au sud du sillon Sambre et Meuse, impliquant quatre groupes typologiques de rivières, les valeurs de référence et la définition des états écologiques ont été basées et calculées sur un réseau de référence de sites de très bon état. Les « valeurs de conditions de référence » ont été définies par les médianes des métriques des sites de « très bon état ». Lorsque aucun site de très bon état n’était disponible, c’est-à-dire pour les groupes typologiques au nord du sillon Sambre et Meuse et pour la Meuse et la Sambre, les conditions de référence (ou le « potentiel écologique maximal ») et les limites de classes ont été basées sur des coefficients appliqués aux sites de « bon état » et sur jugement d’expert.
Exercice pilote d’inter-étalonnage
Cinquante échantillons ont été sélectionnés parmi les rivières du type d’inter-étalonnage européen R-C3 (petite taille, altitude moyenne, substrat siliceux) en Wallonie (correspondant aux « ruisseaux ardennais ») dans toute la gamme de qualités écologiques, du « très bon » au « mauvais » état. Chaque métrique de l’indice « Intercalibration Common Metrics » (ICM) a été comparée (par régression linéaire et polynomiale) aux valeurs de l’IBGN. La plus forte corrélation a été établie avec l’indice synthétique de l’ICM dont le R² très élevé (0,95) permet un inter-étalonnage précis et fiable. A un EQR (Equivalent Quality Ratio) de l’IBGN = 1 correspond un indice ICM très proche (= 1,004). En conséquence, la métrique « cote de l’IBGN » est proposée comme métrique pour l’évaluation de l’état écologique de la faune invertébrée en Wallonie.
Espèces exotiques et invasives
L’ouverture récente du canal à grand gabarit Main – Danube en 1992 et la navigation qui en résulte a permis à plusieurs espèces de macroinvertébrés ponto-caspiennes d’envahir successivement les bassins du Rhin et de la Meuse. De 1998 à 2000, le réseau de mesure a enregistré quatre nouvelles espèces exotiques dans la Meuse en Belgique :une polychète (Hypania invalida) et trois crustacés (Hemimysis anomala, Dikerogammarus villosus, D. haemobaphes). Peu avant, en 1995, le bivalve asiatique Corbicula fluminea et l’amphipode nord-américain Crangonyx pseudogracilis ont également été enregistrés pour la première fois. La dynamique des invasions a été étudiée et discutée.
L’état biologique actuel (2000-2002) des masses d’eaux de surface en Wallonie et l’évolution des états biologiques sur une décennie (1990-2002) figurent dans l’étude et sont discutés. Une amélioration globale de la qualité de 6 % est enregistrée pour cette période. L’amélioration de la qualité se manifeste principalement pour les états « mauvais » et « médiocre » s’élevant à l’état « moyen ».
Abstract
River typology in Wallonia and invertebrate fauna characterization
Twenty-five river-types in Wallonia were defined according to the Water Framework Directive taking into account obligatory and optional factors gathered in three criteria: the size (from “brook” to “very large river”), the slope (gentle, medium and strong) and five natural regions (Loess, Condroz, Famenne, Arden and Jurassic summarising the obligatory altitude, latitude, longitude and geology factors). A multivariate approach applied to a large amount of samples (i.e. taxa lists) led to give a more accurate definition of some river-types and to discriminate seven river-type groups exhibiting similar faunal assemblages.
Type-specific reference conditions and ecological status definition of rivers in Wallonia using invertebrate biocenotic metrics
Faunal lists and IBGN (i.e. "Standardized Global Biological Index IBGN") metric values, evolving from the biological quality assessment network in Wallonia, were used to discriminate the river types and to define the reference sites, the reference conditions and the status class limits. South of the axis made by the Sambre & Meuse Rivers, involving four river-type groups, reference values and ecological status definition were based and calculated on a reference network of sites of high status. The "reference condition values” were defined as the median values of the metrics in all “high status” sites. Where no site of high status was available, i.e. in the others river-type groups north of the same axis and in the Rivers Sambre and Meuse themselves, reference conditions (or maximum ecological potential) and class limits were based on coefficients applied to “good status” sites and on expert judgement.
Intercalibration pilot exercise
Fifty samples were selected from R-C3 rivers (i.e. small, mid-altitude, siliceous) in Wallonia (corresponding to the “Arden’s brooks”) showing the widest range of ecological quality from high to bad status. Each Intercalibration Common Metric (ICM) was compared (linear and polynomial regression) to IBGN scores. The highest correlation was found with the synthetic ICM index, whose high R² (0.95) allows accurate and reliable intercalibration. To IBGN EQR (i.e. Equivalent Quality Ratio) = 1 corresponds a very close ICM index value (= 1.004). Consequently, the metric IBGN score is being proposed to act as the metric for the assessment of the invertebrate fauna ecological status in Wallonia, Belgium.
Exotic and invasive species
The recent opening of the canal Danube – Main in 1992 and the subsequent navigation allowed several Ponto-Caspian macroinvertebrate species to invade successively the Rhine and the River Meuse basins. From 1998 to 2000, the monitoring network recorded four new alien species in the River Meuse in Belgium: one Polychaeta (Hypania invalida) and three Crustacea (Hemimysis anomala, Dikerogammarus villosus, D. haemobaphes). Earlier, in 1995, the Asian Bivalvia Corbicula fluminea and the North American Amphipod Crangonyx pseudogracilis were also recorded for the first time. The invasions’ dynamics were studied and discussed.
Present biological status (2000-2002) of surface water-bodies in Wallonia and biological status evolution over a one-decade period (1990-2002) is included and discussed in the study. A global quality improvement of 6 % is recorded for the period. Quality improvement concerns mainly the “bad” and “poor” status raising up to “moderate” status.
Doctorat en sciences, Spécialisation biologie animale
info:eu-repo/semantics/nonPublished
Fisher, Ruth-Mary Corne. "The impacts of channelisation on the geomorphology and ecology of the Kuils River, Western Cape, South Africa." University of Western Cape, 2003. http://hdl.handle.net/11394/7484.
Full textUrbanisation and storm water input in the Kuils River catchment changed the flow of the river from ephemeral to perennial. This led to flooding problems in the Kuilsrivier central business district. The river was channelised in 2000 to increase the carrying capacity of the channel and thus to reduce the flood risk. This study aims to monitor the impacts of channelisation on the geomorphology and ecology of the Kuils River. This was done by selecting representative study sites upstream, within and downstream of the channelised reach. The geomorphological and ecological characteristics of the river were recorded in detail with changes tracked over a year period incorporating channelisation activities and winter floods.
Abolaffio, Milo. "How Turbulence affects living systems? From micro to macro-scales." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3422795.
Full textIn questa tesi studiamo da un punto di vista fisico, tre problemi collegati agli effetti della turbolenza (marina e atmosferica)sui sistemi viventi. Il primo problema è una quantificazione del cambio del flusso di nutrienti da parte di un micro-organismo in turbolenza usando metodi sia numerici che analitici. Il secondo problema è un indagine quantitativa della relazione presente tra i punti di foraggiamento di uccelli pelagici (in particolare le Berte) e la turbolenza marina misurata attraverso la profondità del mixed layer depth. Infine il terzo è invece una verifica dell'ipotesi di navigazione olfattiva da parte delle Berte mettendo in relazione la distribuzione delle lunghezze dei segmenti di volo lineare delle stesse con il livello della turbolenza atmosferica determinato attraverso l'intensità del vento medio. In questi ultimi due argomenti abbiamo usato calcoli derivanti dalla teoria della turbolenza e un analisi statistica delle traiettorie GPS delle Berte.
Marzin, Anahita. "Indicateurs biologiques de la qualité écologique des cours d'eau : variabilités et incertitudes associées." Phd thesis, AgroParisTech, 2013. http://pastel.archives-ouvertes.fr/pastel-00879788.
Full textAndrews, Claire Elizabeth. "The measurement of the erosion of the chalk shore platform of East Sussex, the effect of coastal defence structures and the efficacy of macro scale bioerosive agents, in particular the common." Thesis, University of Sussex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340824.
Full textAYO-BALI, ABIODUN Emmauel. "Geochemical Analysis of the Environmental Phases of La Barra de Santiago Estuary, El Salvador." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1556804693894507.
Full textBredenhand, Emile. "Evaluation of macro-invertebrates as bio-indicators of water quality and the assessment of the impact of the Klein Plaas dam on the Eerste River." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/2630.
Full textA semi-arid country, like South Africa, with unpredictable seasonal rainfall, is subject to great scarcity in water and an ever-increasing demand from the rising human population. Therefore, efficient reservoirs as well as monitoring methods are needed to manage the South African water supply. This study was undertaken on the Eerste River in the Western Cape, South Africa, focusing on the impact of the Klein Plaas dam system on the benthic macroinvertebrates. The study also examined the use of benthic macroinvertebrates as bioindicators of water quality with special reference to the South African Scoring System Version 5(SASS5) that is currently being used nationally. The impoundment of the water, as well as the inter-basin transfer programme and the experimental cage-culture trout farm, all play a significant role in the disturbance impact of the dam on the Eerste River system. The disturbance is manifested as a drop in water quality that can be seen in the distribution of keystone species, changes in the riparian vegetation, as well as in physical-, chemical-, and biomonitoring evaluations. The study also indicated that the SASS5 is effective, but needs some adjustments, such as inclusion of a prediction phase, finer spatial-scale methodologies and greater consideration of the rarity of species.
Suriani, Ana Lucia. "A estrutura da comunidade de macro-invertebrados bentônicos em três represas do médio rio Tietê (SP), com ênfase nas espécies exóticas Melanoides tuberculata (Gastropoda, Thiaridae) e Corbicula fluminea (Bivalvia, Corbiculidae)." Universidade Federal de São Carlos, 2006. https://repositorio.ufscar.br/handle/ufscar/1897.
Full textUniversidade Federal de Sao Carlos
The reservoirs are artificial ecosystems constructed by the man and attend to the multiple uses. The reservoir provokes alterations in the aquatic ecosystem, causing modifications in the chemical and physical composition of the sediment and of the water and consequently in the circulation and the organization of the biological communities. The purpose of this study was to characterize the taxonomic composition and the benthic community density in 3 reservoirs of the Middle Tietê River (Barra Bonita, Bariri and Ibitinga), to analyze the physical and chemical characteristics of the water and of the sediment and to verify the possible relation of these with the structure of the benthic community, considering the populations of the native species and the invading species Melanoides tuberculata and Corbicula fluminea. The samplings were carried out in two climatic periods, the rainy season (November 2002) and the dry season (August 2003), showing three portions in each reservoir (upper, middle and lower) and following a sweeping with 6 sampling points in each transect. In each point, the samples of sediment were collected in duplicate with one drag of the type van Veen. Based on the limnological data the reservoirs of Barra Bonita and Bariri were classified as whereas Ibitinga Reservoir was characterized as mesotrophic for the periods evaluated. In November 2002, 21, 29 and 25 taxa of macroinvertebrates were registered in Barra Bonita, Bariri and Ibitinga reservoirs, respectively, while in August 2003, there were 23, 31 and 27 taxa, respectively, in each reservoir. A greater similarity between the benthic macroinvertebrates was found for the associations sampled in both periods in the same reservoir than between the different reservoirs, evidencing that each environment have a particular composition of taxa, although some taxa are common among them. The invading species M. tuberculata e C. fluminea were current in all the reservoirs, in both periods of sampling, except in the Barra Bonita reservoir. The generalized occupation of M. tuberculata and the high densities of this specie in the studied reservoirs reveal the high invading potential of same and the probable competition with the native species.
As represas são ecossistemas artificiais construídos pelo homem e destinadas a múltiplos usos. A condição de represa provoca alterações no ecossistema aquático, causando modificações na composição química e física do sedimento e da água, e conseqüentemente na circulação e na organização das comunidades biológicas. O objetivo deste trabalho foi caracterizar a composição taxonômica e a densidade da comunidade bentônica em três represas do sistema Tietê (Barra Bonita, Bariri e Ibitinga), analisar as características físicas e químicas da água e do sedimento e, verificar a possível relação dessas com a estrutura da comunidade bentônica, considerando as populações das espécies nativas e as espécies invasoras Melanoides tuberculata e Corbicula fluminea. As coletas foram realizadas em dois períodos climáticos, o chuvoso (novembro de 2002) e o seco (agosto de 2003), amostrando-se três porções em cada represa (superior, mediana e barragem) e seguindo uma varredura com 6 pontos amostrais em cada transecto. Em cada ponto as amostras de sedimento, foram coletadas em réplicas com uma draga do tipo van Veen. Os resultados obtidos para as variáveis limnológicas classificaram as represas de Barra Bonita e Bariri como eutróficas, enquanto a represa de Ibitinga apresentou características mesotróficas, durante os períodos avaliados. Nas represas de Barra Bonita, Bariri e Ibitinga, em novembro de 2002 foram registrados 21, 29 e 25 táxons e em agosto de 2003 ocorreram 23, 31 e 27 táxons, respectivamente. Foi registrada uma maior similaridade entre as associações amostradas nos dois períodos de cada represa do que entre as diferentes represas, sendo que cada ambiente possui uma comunidade de macro-invertebrados com composição taxonômica particular, embora compartilhem parte dos táxons. As espécies invasoras M. tuberculata e C. fluminea foram encontradas em todas as represas, em ambos os períodos de coleta, exceto na represa de Barra Bonita. A ocupação generalizada de M. tuberculata e C. fluminea e as elevadas densidades destas espécies nas represas estudadas revelam o alto potencial invasor das mesmas e a provável competição com as espécies nativas.
Hedde, Mickael. "Etude de la relation entre la diversité des macro-invertébrés et la dynamique de la matière organique des sols limoneux de Haute-Normandie." Phd thesis, Université de Rouen, 2006. http://tel.archives-ouvertes.fr/tel-00543169.
Full textMarzin, Anahita. "Indicateurs biologiques de la qualité écologique des cours d’eau : variabilités et incertitudes associées." Thesis, Paris, AgroParisTech, 2013. http://www.theses.fr/2013AGPT0002/document.
Full textSensitive biological measures of ecosystem quality are needed to assess, maintain or restore the ecological conditions of rivers. Since our understanding of these complex systems is imperfect, river management requires recognizing variability and uncertainty of bio-assessment for decision-making. Based on the analysis of national data sets (~ 1654 sites), the main goals of this work were (1) to test some of the assumptions that shape bio-indicators and (2) address the temporal variability and the uncertainty associated to prediction of reference conditions.(1) This thesis highlights (i) the predominant role of physiographic factors in shaping biological communities in comparison to human pressures (defined at catchment, riparian corridor and reach scales), (ii) the differences in the responses of biological indicators to the different types of human pressures (water quality, hydrological, morphological degradations) and (iii) more generally, the greatest biological impacts of water quality alterations and impoundments. (2) A Bayesian method was developed to estimate the uncertainty associated with reference condition predictions of a fish-based bio-indicator (IPR+). IPR+ predictive uncertainty was site-dependent but showed no clear trend related to the environmental gradient. By comparison, IPR+ temporal variability was lower and sensitive to an increase of human pressure intensity. This work confirmed the advantages of multi-metric indexes based on functional metrics in comparison to compositional metrics. The different sensitivities of macrophytes, fish, diatoms and macroinvertebrates to human pressures emphasize their complementarity in assessing river ecosystems. Nevertheless, future research is needed to better understand the effects of interactions between pressures and between pressures and the environment
Pérès, Guénola. "Identification et quantification in situ des interactions entre la diversité lombricienne et la macro-bioporosité dans le contexte polyculture breton. Influence sur le fonctionnement hydrique du sol." Phd thesis, Université Rennes 1, 2003. http://tel.archives-ouvertes.fr/tel-00007432.
Full textBurfeid, Castellanos Andrea Montserrat. "Ecological factors and diatom diversity at rivers of the iberian mediterranean river basins: macro-scale, meso-scale and micro-scale = Factores ecológicos y diversidad de diatomeas en los ríos de las cuencas hidrográficas del Mediterráneo ibérico: maro-escala, meso-escala y micro-escala." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/663475.
Full textLas diatomeas bentónicas son organismos fotoautotróficos unicelulares, acuáticos y colonizadores de sustratos, que se han usado en bioindicación por ser buenas indicadoras del estado ecológico del agua. En esta tesis hemos estudiado cómo las diatomeas de ríos ibéricos mediterráneos se ven afectadas por la ecología del medio donde habitan, a diversas escalas. Estos organismos se estudiaron a nivel taxonómico e indicativo, funcional y morfométrico. La estructura de esta tesis sigue una aproximación a la reducción de escala de trabajo. El capítulo de macro-escala se basó en una investigación de las comunidades bentónicas epilíticas de las diatomeas del río Ebro, en base a muestreos realizados a lo largo de 10 años. Este estudio se ha demostrado que la división en ecotipos fluviales establecida para el seguimiento de la Directiva Marco del Agua (DMA) no coincide con la diversificación delascomunidades deestosorganismos. Nuestrosresultados apuntanqueunaaproximacióndoble (composición físico-química y estructura de la comunidad) puede reflejar mejor la realidad para las diatomeas. En el capítulo de meso-escala se investigó el río Segre con la finalidad de establecer las relaciones entre los usos del suelo y las comunidades de diatomeas y valores de los índices de diatomeas. Los usos del suelo afectan directamente a la composición del agua fluvial. Por ello, se esperaba una correlación entre el uso del suelo aguas arriba de las comunidadesde diatomeas estudiadas. Los resultados muestranque únicamentelos usos mayoritarios afectan la composición las comunidades de diatomeas y los valores de los índices diatómicos. En el capítulo de microescala se estudió la reacción de las diatomeas en cada punto. Para ello el capítulo se dividió en tres secciones. Un experimento observó el efecto de puntos intrínsecamente diferenciales sobre las formas de vida, y cambios de estas tras su translocación. La otra sección comparó la composición funcional de la comunidad de diatomeas en ríos temporales, que sufren pérdida parcial o total del agua superficial. Finalmente, aún en microescala, se fotografiaron automáticamente muestras de diatomeas del río Ebro para calcular sus características morfométricas. Estas se relacionaron con los parámetros fisicoquímicos de cada punto y con su variabilidad temporal. El resultado fue una clara afectación de tamaños valvares según la composición del agua. La relación superficie-volumen estaba altamente correlacionada y la anchura valvar, obviada hasta ahora, se vio afectada por los parámetros fisicoquímicos.
Les diatomees bentòniques, organismes fotoautotròfics unicel·lulars, aquàtics i colonitzadors de substrats, que s’han utilitzat a la bioindicació per ser bones indicadores del estat ecològic de l’aigua. En aquesta tesi hem estudiat com les diatomees de rius ibèrics mediterranis es veuen afectades per l’ecologia del medi al que habiten a diverses escales. Aquests organismes es varen observar a nivell taxonòmic-indicatiu, funcional i morfomètric. L’estructura d’aquesta tesi segueix una aproximació a la reducció d’escala de treball. El capítol de macro-escala es basà en una investigació taxonòmica de les comunitats bentòniques epilítiques de diatomees del riu Ebre, basat en mostrejos realitzats al llarg de 10 anys. Aquest estudi ha mostrat que la divisió d’ecotips fluvials establerta per a el seguiment de la Directiva Marc de l’Aigua (DMA) no coincideix amb la diversificació de les comunitats d’aquests organismes. Els resultats assenyalen que una aproximació doble (composició fisicoquímica i estructura comunitària) podria reflectir millor la realitat per a les diatomees. Al capítol de meso-escala s’estudià el Segre per tal d’establir les relacions entre els usos del sòl, les comunitats de diatomees i els seus valors indicadors. Els usos del sòl afecten directament a la composició de l’aigua fluvial. Per això, s’esperava una correlació entre els usos del sòl aigües amunt de les comunitats de diatomees estudiades. Els resultats mostren que únicament els usos majoritaris afecten els la composició de les comunitats de diatomees els i valors dels índexs diatòmics. El capítol de micro-escala investigà la reacció de les diatomees a cada punt. Per això, el capítol es dividí en tres seccions. Un experiment observà l’efecte de punts intrínsecament diferencials sobre les formes de vida i canvis d’aquests després de la translocació. L’altra secció comparà la composició funcional de la comunitat de diatomees a rius temporals, que pateixen la pèrdua total o parcial de l’aigua superficial. Finalment, seguint a la micro-escala, es fotografiaren les mostres del riu Ebre automàticament per calcular les seves característiques morfomètriques. Aquestes es relacionaren amb els paràmetres fisicoquímics de cada punt i la seva variabilitat temporal. El resultat fou una clara afectació de mides valvars segons la composició de l’aigua. La relació superfície-volum estava altament correlacionada amb les variacions fisicoquímiques i l’amplada valvar, obviada fins ara, era afectada pels paràmetres fisicoquímics.
Ruby, Margaret E. "Forest macro-arthropods as potential indicators of ecosystem conditions in Western Idaho : an analysis of community composition, biological diversity, and community structure /." 2001. http://hdl.handle.net/1957/11060.
Full text"An assessment of the effects of small-scale farming on macro-invertebrate and diatom community structure in the Vhembe District, Limpopo." Thesis, 2015. http://hdl.handle.net/10210/13838.
Full textThe Limpopo Province covers an area of 12.46 million hectares and these accounts for 10.2 per cent of the total land area of the Republic of South Africa. The province is endowed with abundant agricultural resources and it is one of the country’s prime agricultural regions noted for the production of fruits and vegetables, cereals, tea, and sugar. A key feature of the agricultural industry of Limpopo Province is its dualism. There are two distinct types of agricultural production systems. The large scale commercial farming system occupies approximately 70% of the total land area. The smallholder farms are located mostly in the former homeland areas and they cover approximately 30% of the provincial land surface area. The town of Thohoyandou, with its surrounding villages, is the area of greatest human concentration in the Luvuvhu Catchment and subsistence farming is about a third of the total agricultural component. It is important to study the effects of agricultural inputs (e.g. fertilizers and sediment loads) on aquatic ecosystems in order to fully understand the processes involved of these stresses on aquatic ecosystems. Knowledge of these impacts toward the environment and human health is often limited due to lack of capacity building, especially among small scale farmers. Ten bio-monitoring sites were studied on five systems in the Vhembe district. The sites were sampled during the low flow period of November 2011 and the high flow period of April 2012. Sampling sites were selected to present conditions in the Mutale, Mutshindudi and Tshinane Rivers upstream and downstream of the potential influence of small scale agricultural activities...
Foster, Lee-Ann Sade. "The effect of water and sediment quality on macro-invertebrate communities from selected endorheic pans." Thesis, 2014. http://hdl.handle.net/10210/11326.
Full textWetlands play a significant role in our environment as they provide a variety of goods, services and benefits to living species ranging from humans, animals and plants to microorganisms. Despite their importance, wetlands have somewhat been neglected over the past few years which has led to a rapid deterioration of wetland conditions and functions. Wetlands provide unique functions that cannot be provided by any other ecosystem; their value was recognised in the 1960s. Prior to this realisation the value of wetlands had been seriously underestimated to the extent where they were even previously labelled as “wastelands”. The reality is that to date minimal measures have been put in place to assist in the rehabilitation and future conservation of wetlands. The lack of wetland management and monitoring can be attributed to the fact that very little is known about the functioning of some of the wetland systems. Endorheic wetlands have recently been emerging as ecosystems of importance. Very little is known about endorheic wetlands and their ecological functioning. To date a fair amount of studies have been conducted on the pans in Mpumalanga and in the Free State but minimal information exists on the pans in the North West Province. The objectives of this study were therefore to compare the abiotic and biotic composition of pans in Mpumalanga and North West Provinces, in order to contribute to the knowledge which will eventually assist in devising rehabilitation measures and future conservation of pans in the area. Three different water ecosystem components were studied; these included aquatic invertebrate communities, water quality and sediment characteristics. The collected water samples were taken to an accredited laboratory to be analysed. When compared between the two provinces, the water-quality results indicated differences between provinces as well as among individual pans. However, most of the pans in both provinces show characteristics of being dystrophic alkaline systems. The invertebrates were collected using sweep nets and stored in jars containing 5% neutrally buffered formalin and a staining agent (Rose Bengal). The sediment characteristics were determined by using standard techniques and results showed that there were no obvious similarities between the different pans in the different provinces. Water-quality analyses were performed on samples taken during both winter- and summer-sampling surveys and these samples were analysed by a reputable laboratory. Based on the analyses of the invertebrate community samples, 25 taxa were identified; results show similarities in the structure of communities in both provinces with the exception of one or two different species. Sampling was conducted over a period of two seasons at all sampling points and several species were found belonging to different families. Invertebrates sampled in Mpumalanga pans were similar to those reported in previous studies done in the area and most of the invertebrates sampled in Mpumalanga and the North West are known to be commonly found in temporary habitats. Spatial and temporal variations in invertebrate assemblages were determined; this analysis displayed differences in the different variables (biotic, physical and chemical) tested over the two seasons. The pans in Mpumalanga were dominated by coarse sand. Large amounts of coarse sand accompanied by poor water quality were observed in MP Pan A in Mpumalanga Province; this could be an indication of somewhat poor catchment management. The results of the abiotic and biotic comparison show that there are minor similarities and differences among the selected pans studied in each province. The knowledge acquired can now be utilised to enhance the available literature on these pans. Long-term studies have to be done to better understand the ecological functioning of the pans in the North West Province in order to devise mitigation measures as well as appropriate rehabilitation strategies and conservation measures.
Reynard, Jerome Peter. "Macro-faunal exploitation in the Cape Floral Region (Fynbos Biome) of the southern Cape, South Africa c. 75-60 ka: case studies from Blombos Cave and Klipdrift Shelter." Thesis, 2016. http://hdl.handle.net/10539/21640.
Full textThe analysis of faunal remains from archaeological sites can reveal much about past behaviour, palaeoenvironments and bone technology. This is especially pertinent for the Middle Stone Age (MSA): a period that corresponds to both the behavioural and anatomical development of Homo sapiens. In this thesis, I examine the faunal remains from Blombos Cave (BBC) and Klipdrift Shelter (KDS), two significant MSA sites about 45 km apart along the present-day southern Cape coast. The focus of the analyses is on the Still Bay (SB) layers (c. 75 – 68 thousand years ago [ka]) at BBC and the Howiesons Poort (HP) layers (c. 65 – 59 ka) at KDS. The aim of this thesis is to explore subsistence behaviour and environmental conditions during the SB and HP in the fynbos region of the southern Cape. I also investigate the effects of trampling on bone and whether trampling and other types of taphonomic modification can be used to infer occupational intensity in cave and rock shelter sites. Taphonomic data indicate that significant differences exist between the SB and HP faunal assemblages at BBC and KDS, respectively. Carnivores and scavengers had a greater effect on the SB than on the KDS assemblage. Furthermore, subsistence activities at KDS focused on marrow extraction while filleting was probably an important strategy at BBC. Taxonomic analyses indicate that the representative fauna from both sites is generally consistent with what is expected in the fynbos biome but with some noticeable differences. Grazers, for example, are significantly more prevalent at KDS than BBC while seal is more common at BBC. Other zooarchaeological data also show differences in prey selection strategies. Diet breadth is more extensive at KDS than at BBC, although bovid mortality profiles at BBC are more juvenile-dominated. I propose that many of these contrasting patterns imply that subsistence intensification is more evident in the HP layers at KDS than in the SB at BBC. Moreover, the taphonomic data suggest that the SB at BBC was a low-intensity, sporadically occupied period in contrast to the high-intensity occupations, particularly during the middle layers of the HP at KDS. The results of the KDS analysis also indicate a shift in environmental conditions during the HP and show links between prey selection, the environment and occupational intensity during this period. Trampling experiments indicate that trampling can generally be distinguished from butcherymarks, although bioturbation in shelly deposits can sometimes result in marks that mimic cutiii marks. More importantly, experiments show that pitting and abrasion are a more significant indicator of trampling than lines that resemble cut-marks. Based on these experiments, I argue that trampling modification can be used to infer occupational intensity at archaeological sites. Trampling marks in the KDS assemblage, for example, correspond well with the high occupational periods as indicated by other taphonomic data. Trampling and taphonomic data support the notion that BBC was a low-intensity, sporadically occupied site during the SB. By incorporating taxonomic, taphonomic and novel methods of skeletal-part analyses, this study contributes to our knowledge of human subsistence and palaeoenvironments during the SB and HP in the southern Cape. This thesis strengthens and adds to other research that has demonstrated variability in subsistence behaviour during the MSA.
LG2017
Diedericks, Gerhardus Johannes. "The influence of run-off from road networks on aquatic macro-invertebrates in Mamatole commercial tree plantation (Komatiland Forests), Upper Letsitele Catchment, Limpopo Province, South Africa." Thesis, 2012. http://hdl.handle.net/10210/6305.
Full textThe purpose of this study was to determine whether unpaved roads in commercial forests have a detrimental impact on aquatic macro-invertebrates in the receiving rivers associated with these roads. The upper section of the headwaters of the Motlhaka-Semeetse River was chosen as the Study Area because a portion is situated in the Wolkberg Wilderness area (natural area with no roads) and a portion in a commercial forestry plantation (high road network density). Stream conditions based on a rapid bio-assessment of aquatic macro-invertebrates using SASS5 were then compared between the two catchments amid 2002 and 2010. In order to support the SASS5 results, daily rainfall data from December 1959 to October 2010 was collated and compared to daily stream flow data from January 1960 to October 2010. In addition, geomorphological and instream habitat changes in the river between the two catchment areas were recorded, as well as the condition of stream crossings and their linkage to stream networks in the afforested catchment. The SASS5 results revealed that stream conditions at the upper unimpaired site were significantly better, visibly and statistically (p < 0.05) than conditions at the lower site within the forestry plantation. In addition, there were noteworthy changes in the catchment hydrology, the geomorphology and instream habitat between the natural and afforested catchments. Road network densities in commercial forests are mostly considerably higher than suggested in literature and exceed stream network densities. Roads increase the surface area for interception of rainfall and the runoff from this high density of roads results in modification of the catchment hydrology, geomorphology and instream habitat of receiving streams. This physical change to the receiving streams is one of the main reasons for the deterioration in SASS5 results, disproving the hypothesis that road networks in forestry areas have no impact on receiving aquatic ecosystems. Commercial forestry in South Africa needs to improve their road planning, layout, management and maintenance to reduce these environmental impacts. In doing so, the road network density will be reduced with considerable environmental and economic benefits.
Nel, Jacoba Elizabeth. "Ontwikkeling van 'n reflekterende span met 'n ekosistemiese benadering tot gesinsterapie." Diss., 1999. http://hdl.handle.net/10500/15600.
Full textBesorgdheid het in die gemeenskap bestaan oar die toenemende getalle kinders wat binne die stedelike konteks van Pretoria op straat leef en werk. Hierdie navorsing is onderneem om die behoeftes van die kinders aan te spreek en om alternatiewe wyses te vind om met hulle te werk. 'n Konteks is geskep sodat na hulle stemme geluister kon word. nag 'n alternatief tot "tradisionele" vorme van gesinsterapie bruikbaar is, op sekere voorwaardes, soos aangedui in hoofstuk vier. Sleutelwoorde: reflekterende span; "straatkinders"; ekosistemiese benadering; ekologie; epistemologie; konstruktivisme; objektivisme; kubernetika; sisteemteorie; mikro-, meso- en makrosisteme; sirkulere en liniere punktuasie Ekosistemiese beginsels is aanvanklik benut, maar was nie vir die span wat saamgewerk het, betekenisvol nie. 'n Gevallestudie-ontwerp was nuttig om die ontwikkeling en "opleiding" van die span wat sou saamwerk, te beskryf, asook die benutting van ekosistemiese beginsels tydens dienste aan die "straatkinders" en hulle gesinne by ltumeleng. Die navorsing het aangedui dat 'n ekosistemiese benadering tot gesinsterapie as
The community showed concern about the increasing number of children living and working on the streets within the urban context of Pretoria. This researchwas undertaken to address the needs of these children and to find alternative ways of working with them. A context was created so that their voices could be heard. Ecosystemic principles were initially used, but were not meaningful to the team who worked together. A case study design proved useful in developing and "training" of the team who would be working together, as well as applying ecosystemic principles while making services available to the "street children" and their families in ltumeleng. The research indicated that an ecosystemic approach to family therapy could be used as an alternative to "traditional" forms of family therapy, subject to certain conditions, as stipulated in Chapter Four.
Social Work
M.A. (Sosiale Wetenskappe (Geestesgesondheid))