La lutte contre l'eutrophisation des grands lacs péri-alpins a permis une réduction des concentrations internes en phosphore, pour des réponses écologiques parfois mitigées. Dans le Léman, les concentrations en P ont été divisées par dix en trente ans pourtant la biomasse algale et la production primaire restent aussi élevées qu'au maximum de l'eutrophisation, malgré une augmentation de la transparence des eaux. Donc, bien que la concentration en phosphore soit une variable de forçage majeure des communautés planctoniques, il apparait nécessaire de considérer le rôle d'autres variables de forçage qui interagissent avec la concentration interne en nutriments pour comprendre les réponses écologiques des lacs aux mesures de reoligotrophisation. Les communautés planctoniques peuvent être impactées par les pratiques de la gestion appliquées d'autres compartiments du réseau trophique tels que les populations piscicoles. A l'effet de ces facteurs locaux s'ajoutent à l'impact du réchauffement climatique, un phénomène planétaire participant au changement global qui se manifeste à partir du début des années 1980, et dont l'impact est de mieux en mieux mis en évidence dans les lacs.Peu de lacs ayant fait ou font l'objet de suivis de routine, l'observation des effets de ces divers forçages anthropiques et la compréhension de leurs interactions se heurtent au faible nombre de base de données disponibles. En outre les données collectées ne permettent pas de remonter assez loin dans le temps pour couvrir entièrement la période au cours de laquelle les perturbations anthropiques se sont accrues. Elles ne permettent pas non plus d'étudier les conditions environnementales précédant cette période. La paléolimnologie à haute résolution (échelle annuelle et saisonnière) appliqué aux périodes récentes (dernier siècle) est une démarche alternative proposée pour palier cette absence de données instrumentales.Ce travail de thèse vise à comprendre comment les modifications des concentrations en nutriments, la gestion piscicole d'une espèce zooplantonophage, le corégone, et le changement climatique contribuent à modifier la structure et la diversité des communautés planctoniques de diatomées et de rotifères des grands lacs péri-alpins français depuis la fin du XIXe siècle.Les communautés planctoniques choisies ont chacune un fort potentiel bio-indicateur et une très grande importance dans la structure et le fonctionnement des écosystèmes lacustres. Les trois perturbations majeures et simultanées survenant lors de la période d'étude se présentent avec des intensités différentes dans les trois lacs. L'évolution temporelle de certains paramètres physico-chimiques au sein de ces lacs est déjà en partie connue grâce à un suivi de limnologie mis en place depuis plusieurs dizaines d'années.Les acquis de la thèse sont de divers natures. (i) développement méthodologique concernant la reconstruction paléolimnologique des communautés de rotifères à partir des banques d'œufs archivées dans les sédiments, (ii) reconstruction des les réponses écologiques des compartiments diatomiques et rotifèriens au cours du dernier siècle, (iii) de comparer ces trajectoires entre lacs afin de discriminer les réponses à des perturbations locales, de celles à des perturbations plus globales et (iv) d'améliorer notre compréhension des interactions entres toutes ces perturbations. / During the XXth century, lacustrine ecosystems have undergone deep changes due to increased human activities on lakes and their watershed. Although significant restoration efforts have been undertaken since the 1980's, their efficiency can be limited. For instance, although phosphorous concentrations of Lake Geneva have been cut by 10 in the last 30 years (for a total cost of four billlions euros), the algal biomass and the primary production remain as high as during the eutrophication maximum, even if water transparency increased. So, the counter-intuitive response of lakes to restoration measures emphasizes that although phosphorous concentration is a major driver of phytoplankton, there is a need to consider the interaction with other environmental drivers, such as climate or top-down controls. Another fence however to the understanding of lake recent response to restoration measures is the lack of long-term monitoring data.The objective of this Ph-D work is to investigate how three human perturbations, i.e. changes in nutrient concentrations, fisheries management practices and climate change, can explain the response of the planktonic communities of three peri-alpine lakes (Lakes Geneva, Annecy and Bourget), using a high-resolution paleolimnological approach conducted on recent time periods. More specifically, the objectives of this PhD are three-fold:(i) To perform the methodological development of the use of rotifer egg banks archived in sediment for paleolimnological reconstructions(ii) To perform methodological development of paleolimnolgical reconstruction of diatom sesaon variability(iii) To delineate ecological responses of diatom and rotifer communities facing anthropogenic perturbations over the last century(iv) To scale the impact of local versus global perturbations over these ecological trajectories

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-10-04T14:03:38Z No. of bitstreams: 1 samuelcamposgomides.pdf: 3181352 bytes, checksum: 99bb80becc865b5059c43181281f0a24 (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2016-10-04T15:17:37Z (GMT) No. of bitstreams: 1 samuelcamposgomides.pdf: 3181352 bytes, checksum: 99bb80becc865b5059c43181281f0a24 (MD5) / Made available in DSpace on 2016-10-04T15:17:37Z (GMT). No. of bitstreams: 1 samuelcamposgomides.pdf: 3181352 bytes, checksum: 99bb80becc865b5059c43181281f0a24 (MD5) Previous issue date: 2010-02-23 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A maior parte dos remanescentes florestais, na região sudeste do Brasil, se encontra em forma de fragmentos florestais, e por isso o interesse da comunidade científica em estudá-los e analisar as conseqüências sobre a biodiversidade. Pretendeu-se, portanto, avaliar a diversidade da herpetofauna em fragmentos urbanos de Mata Atlântica em Juiz de Fora, no sudeste do Brasil e avaliar se certas características do ambiente podem influenciar estas diversidades. A amostragem de répteis em campo ocorreu entre setembro de 2008 e abril de 2009 por procura ativa limitada por tempo, e coletas através de armadilhas de queda com cerca direcionadora e armadilhas de funil. A área com maior riqueza de espécies foi a Fazenda Floresta, seguida pela ReBio Poço D’Anta, e em seguida o PM da Lajinha e a ReBio Santa Cândida. A equitabilidade da Fazenda Floresta foi superior a das demais áreas. A diversidade variou significativamente para quase todas as áreas, com exceção entre o PM da Lajinha e a ReBio Santa Cândida. A diversidade também variou significativamente entre as áreas de borda, intermediária e central, sendo que a área intermediária foi a que obteve a maior diversidade. Isso se deu, sobretudo pela sobreposição das espécies florestais e as de áreas abertas. A umidade e a temperatura não variaram entre as áreas dos fragmentos. A intensidade de luz e a intensidade de ventos também não variaram entre as áreas dos fragmentos, mas variaram entre as áreas do fragmento em relação à matriz. As variáveis bióticas provavelmente predizem melhor a riqueza que as variáveis abióticas. Há uma tendência em que a riqueza, a abundância e a equitabilidade de espécies diminuam conforme aumenta o grau de perturbação do ambiente. Áreas pequenas, como os fragmentos urbanos de Juiz de Fora, podem abrigar representantes de Squamata, mas áreas conservadas ainda são fundamentais para preservação, pois são menos suscetíveis a perturbações constantes. A herpetofauna pode ser considerada um indicador ecológico de alterações em larga escala da integridade de um hábitat. / The most amount of the remaining forest in southeastern Brazil is in forest fragments, so the interest of the scientific community to study and analyze the consequences on the biodiversity. The purpose of this study was, wherefore, to assess the diversity of herpetofauna in urban fragments of Atlantic Forest in Juiz de Fora, in southeastern Brazil and if certain characteristics of the environment might influence this diversity. A sampling of reptiles in the field occurred between September 2008 and April 2009 by time constrained search and collected through pitfall traps with drift fence and funnel traps. The area with highest species richness was the Fazenda Floresta, followed by ReBio Poço D'Anta, and then the PM Lajinha and the ReBio Santa Cândida. The evenness of Fazenda Floresta was higher than other areas. The diversity varied significantly among all areas, except between the PM Lajinha and the ReBio Santa Cândida. Diversity also varied significantly among the border, intermediate and central areas, and the intermediate area was that got the highest diversity, this is mainly due the overlap of species of forest and open areas. The humidity and temperature did not vary among areas of the fragments. The intensity of light and intensity of winds also did not vary among areas of the fragments, but varied among areas of the fragment compared to the matrix. Biotic variables probably better predict the richness that the abiotic variables. There is a trend in which richness, abundance and evenness of species decrease with increasing the degree of disturbance of the environment. Small areas, such as urban fragments in Juiz de Fora, can to shelter representatives of Squamata, but conserved areas still are critical to conservation because they are less susceptible to disruption constant. The herpetofauna can be considered an indicator of environmental change on a large scale of the integrity of a habitat.

En esta tesis se presenta un estudio sobre la evolución de paisajes mediterráneos continentales a partir de varios registros polínicos procedentes de sectores meridionales de Guadalajara y del Llano Occidental Catalán. El término paisaje es entendido en este trabajo como el resultado de las interacciones entre sociedad humana y medio. Los cambios reflejados en el paisaje a partir del registro polínico ponen de manifiesto, por tanto, las prácticas humanas, la historia ambiental, los usos del suelo y la variabilidad climática. El uso de datos paleoambientales de dos sectores geográficos diferentes permite su intercomparación. Esta estrategia de investigación permite la identificación de tendencias comunes y divergencias, lo que permite determinar el papel humano en el cambio paisajístico a lo largo del tiempo. Tres registros polínicos fueron obtenidos en Guadalajara: Somolinos α (174 cm comprendiendo desde 1600 cal aC. hasta época actual), Somolinos PAS (380 cm cubriendo desde 800 cal aC hasta 700 cal dC) y Cañamares (250 cm depth cubriendo desde 450 cal aC hasta época actual). En el Llano Occidental Catalán se obtuvieron dos registros polínicos: Ivars (415 cm cubriendo desde 800 cal aC hasta 1500 cal dC) y Els Vilars d’Arbeca (yacimiento arqueológico con algunas muestras datadas en el s. IV cal aC). El análisis de los registros de Guadalajara ha permitido determinar que el Macizo de Pela estuvo forestado durante el I milenio aC. Este sector experimentó una transformación paisajística importante en el s. I cal aC, resultado de la administración romana del territorio y de la extensión de las actividades agropecuarias. Durante el período visigótico y andalusí (s. V a XI dC) las actividades antrópicas se desintensificaron, aunque el medio permaneció abierto. Posteriormente, durante la expansión cristiana, las actividades humanas y el bosque experimentaron un avance. Entre los s. XVI y XIX dC, el sector asiste a una extensión de los pastizales vinculados al desarrollo de una importante actividad transhumante. En el Llano Occidental Catalán los registros polínicos evidencian la existencia de un paisaje abierto y la presencia de vegetación adaptada a condiciones de semiaridez desde el s. IX cal aC. En este momento se constatan evidencias de actividades antrópicas, especialmente de ganadería. Episodios puntuales de aridez parecen incidir en el sector en torno a ca. 700 cal aC. No obstante, desde ca. 450 cal aC estos episodios podrían haberse acentuado, pudiendo haber ocasionado una desecación parcial de la laguna e impidiendo la conservación polínica. Este período seco pudo estar vinculado al abandono del asentamiento de Els Vilars d’Arbeca. No obstante, otros asentamientos ibéricos continuaron ocupados entre el s. V aC y el II aC, lo cual podría sugerir la existencia de diferentes estrategias adaptativas a la variabilidad ambiental por parte de estas comunidades de la Edad del Hierro. Las actividades antrópicas fueron escasas durante época romana bajoimperial. En este momento, el bosque experimentó un avance. No obstante, en s. V cal dC, durante el período visigótico, se detectan importantes deforestaciones. Bajo el desarrollo de la administración andalusí en el sector se constata la extensión de las actividades agrícolas. Posteriormente, el área se establece como una región fronteriza entre los condados cristianos septentrionales y los reinos musulmanes meridionales, ofreciendo escasas evidencias de explotación territorial. Posteriormente, el sector experimentó un desarrollo importante de la agricultura durante la Baja Edad Media. En este momento se constata, además, el desarrollo de la actividad ganadera, probablemente vinculada al desarrollo de rutas trashumantes establecidas entre las llanuras leridanas y las cordilleras montañosas septentrionales. Este trabajo ha permitido documentar diferentes respuestas al cambio ambiental en la Península Ibérica, vinculadas a los diferentes factores políticos, económicos y sociales que predominaron en los diferentes territorios. Por otra parte, los datos paleoambientales ponen de manifiesto la relevancia del papel humano en el cambio paisajístico de los sectores de media montaña peninsular durante época romana. / "Evolution of Mediterranean continental landscapes in Lleida and Guadalajara during the last 3000 years on the basis of Ivars, Somolinos and Cañamares pollen sequences." Abstract: The evolution of landscapes through time has been studied in this work by the analysis of several pollen records from two Mediterranean continental areas of the Iberian Peninsula: the Northern Guadalajara area and the Western Plain of Catalonia. Landscapes are understood in this work as a result of the relationship between human societies and the environment. Subsequently, the changes in landscape reported by pollen record reflect the evolution of the human practices, environmental history, land-use, climate variability. The use of palaenvironmental data from two areas enables a comparison between sites. !is approach has allowed to identify convergence/divergence trends and, in consequence, to assess the role of human agency in the evolution of landscape through time. Three pollen records were obtained in Guadalajara area: Somolinos α (174 cm depth covering from 1600 cal AD to present time), Somolinos PAS (380 cm depth covering from 9th century cal BC to 8th century cal AD) and Cañamares (250 cm depth covering from 5th century cal AD to present time). Two pollen records were obtained in the Western Plain of Catalonia: Ivars (415 cm depth covering from 9th cal century BC to 15th century cal AD) and Els Vilars d’Arbeca archaeological site, of which some sedimentary samples were dated at 4th century cal BC). The analysis of the Guadalajara records has allowed to clarify that the Pela Massif was formerly forested during the 1st millennium BC. !is sector experienced a major landscape transformation in the 1st century cal BC, as a result of the onset of Roman administration at Tiermes and the widespread of extensive farming and grazing through the land. During the Visigothic and Andalusian periods (5th to 11th century AD) human activities reduced, but the area still remained as an open landscape. Later on, after the expansion of the northern Christian kingdoms towards the South, both the forest and the human activities recovered in this area. Between the 16th and 19th centuries the area transformed into pastures linked to the development of transhumance activities. In the Western Plain of Catalonia the pollen records has evidenced an open landscape and the presence of semi-arid vegetation since 9th century cal BC. At this time, evidences of human activities, specially of grazing, are reported. Episodes of droughts seemed to be recurrent in ca. 700 cal BC, however, a major dry period started in ca. 450 cal BC and involved the interruption of the pollen preservation, resulting from a possible dissecation of the Ivars lake. !is dry period could be linked to the abandonment of Els Vilars archaeological site. However, other Iberian villages still remained occupied between 5th and 2nd century BC, which may suggest different adaptative strategies to environmental variability of these Iron Age societies. Human activities were reduced in late roman times, the period when the pollen record is resumed. At this point, the forest had recovered, however, major deforestations occurred during the Visigothic times in 5th century cal AD. With the development of Andalusian administration, a slight development of agriculture is witnessed. Later on, the area remained as a boundary between northern Christian and southern Muslim kingdoms, with no evidences of land exploitation. Nevertheless, in late medieval times the area experienced a major spread of farming and also grazing, which was probably linked to the establishment of transhumace routes between the Lleida Plains and the high mountain ranges in the North. This work has documented diverse responses to climate change in the Iberian Peninsula, which are linked to the different economic, social and political factors prevailing in several territories. At this respect, alaeoenvironmental data highlights the strong capacitiy to modify the landscape by Roman people in entral areas of Iberia.

Cette thèse a pour objectif d’identifier les trajectoires plurimillénaires des écosystèmes de Corse à basse et moyenne altitude sous la triple influence des forçages climatiques, eustatiques et anthropiques à travers l’étude des assemblages d’insectes fossiles et des données paléobotaniques disponibles ou nouvellement acquises. Cette approche multidisciplinaire a été appliquée sur trois séquences sédimentaires prélevées à l’étang du Greco sur l’île Cavallo, au marais de Cannuta et à la tourbière de Bagliettu.Les résultats obtenus révèlent des changements majeurs dans la structuration du couvert végétal. Des signes d’ouverture du paysage apparaissent sur Cavallo et à Cannuta dès 5500-5000 cal. BP. Ils coïncident avec des indices d’activités des sociétés insulaires, lesquelles s’intensifient après 3000 cal. BP et plus particulièrement depuis 1000 ans à Bagliettu. Notre étude suggère que la sensibilité et la réponse des zones humides littorales face à la remontée relative du niveau marin dépend du contexte géomorphologique. Sur l’île Cavallo où le relief est faible, la transgression marine induit une augmentation de la salinité dans l’étang du Greco vers 3700 cal. BP, qui provoque une chute irréversible de la diversité des coléoptères aquatiques et hygrophiles. Au marais de Cannuta, où l’érosion des versants a favorisé la progradation de la plaine alluviale, notre étude montre une diminution de l’influence marine après 5000 cal. BP et une diversification de cette même entomofaune à partir de 1200 cal. BP. À Bagliettu, nous avons démontré l’importance des changements hydro-morphologiques des rivières dans la dynamique des écosystèmes tourbeux attenants et de leur entomofaune. / This thesis aims to define the multi-millennial trajectories of Corsican ecosystems under the climatic, eustatic and anthropic factors via the study of fossil insect assemblages and previous or new palaeobotanical data. This multidisciplinary approach was carried out at low and middle elevation on three sedimentary archives from the Greco pond on Cavallo Island, the Cannuta marsh and the Bagliettu peat-bog. The results reveal major changes in the structure of the vegetation cover over the last 7000 years. Signs of more open landscapes occurred on Cavallo and in Cannuta from 5500-5000 cal. BP. They coincide with bio-markers of insular societies activities, which increased from 3000 cal. BP onward and more particularly during the last 1000 years at Bagliettu.This study also suggests that the sensitivity and the response of coastal wetlands to the relative sea-level rise depend on the geomorphological context. On the low-lying Cavallo Island, marine transgression induced an increase of salt conditions in the Greco pond from 3700 cal. BP, which in turn, caused an irreversible loss of aquatic and hygrophilous beetle diversity. In Cannuta marsh, erosion on catchment slopes favoured the progradation of the coastal floodplain and the results reveal a progressive decrease of the marine influence from 5000 cal. BP as well as a diversification of this entomofauna over the last 1200 years. In Bagliettu, the results show how hydro-morphological changes of the rivers impact the dynamics of adjacent peaty ecosystems and beetle diversity.