Karenia brevis is a toxic marine dinoflagellate species that blooms almost every year in the Gulf of Mexico. These blooms have had devastating effects on local economies, as well as on the fauna of the area. The ECOHAB:Florida project was founded to study the population dynamics and trophic impacts of K. brevis. The project included a series of monthly hydrographic offshore research cruises, as well as monthly surveys of a transect along the 10-meter isobath of the West Florida Shelf. This study focused on data from the alongshore transect over a three-year period (1999-2001). Physical parameters (temperature, salinity, and density) and chemical parameters (particulate carbon, nitrogen, and phosphorus; dissolved inorganic nitrogen and phosphorus) of the West Florida Shelf were analyzed. The amount of chlorophll a and the location and amount of K. brevis cells present were also examined. Clear spatial, seasonal, and interannual patterns in the hydrographic parameters, particulate matter (C, N, P), dissolved inorganic nutrient (nitrite, nitrate, and phosphate), and chlorophyll a concentrations were found. At various times throughout the study, the location of K. brevis blooms was influenced by all of these factors except for the amount of dissolved inorganic nutrients. There were differences in particulate matter ratios present in bloom and non-bloom periods. No clear-cut differences in dissolved inorganic nutrients between bloom and non-bloom periods were found. Finally, relationships between the biological indicators of blooms (i.e., chlorophyll a) and the aforementioned physical and chemical parameters were found.

Orientadores: Denis Miguel Roston, Jose Teixeira Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-04T08:27:27Z (GMT). No. of bitstreams: 1 Mansor_MariaTeresaCastilho_D.pdf: 2529546 bytes, checksum: 5e7bcdd25d9104de1649f7fade2168ac (MD5) Previous issue date: 2005 / Resumo: Em áreas rurais onde há intensa atividade agrícola, a eutrofização de corpos de água pode ser acelerada pelo influxo de nutrientes, provenientes de fertilizantes, transportados por escoamento superficial. A eutrofização pode provocar mudanças indesejáveis na estrutura e funções do ecossistema, bem como na qualidade da água destinada ao abastecimento. O controle dos níveis de P nas águas superficiais é tido como a melhor maneira de minimizar a eutrofização, uma vez que o P é identificado como um nutriente limitante para o crescimento de algas. As águas da bacia do rio Piracicaba recebem grande aporte de efluentes domésticos e industriais pontuais, bem como grande aporte de efluentes agrícolas difusos, tendo sido documentado aí um elevado grau de eutrofização. Uma avaliação preliminar das contribuições difusas de nutrientes às águas superficiais da bacia hidrográfica do rio Jaguari - formador do rio Piracicaba - feita a partir de dados oficiais em uma área de estudo de 3394 Km2, mostrou que 68,2% da carga total anual de Ntotal e 77,3% da carga total anual de Ptotal foram transportados nos meses de chuva. Ao se estimar a razão entre a carga média anual de origem rural (difusa) e urbana (pontual), obteve-se o valor de 1,3 para o Ntotal e 2,6 para o Ptotal; os coeficientes de exportação a partir da área rural foram estimados em 2,3 Kg Ntotal.ha-I.ano-l e 0,4 Kg Ptotal.ha-l.ano-l. A área de drenagem da bacia do ribeirão do Pinhal - afluente do rio Jaguari e manancial de abastecimento de Limeira, SP - foi o foco principal deste estudo, ocorrido entre fevereiro de 2003 e fevereiro de 2004. Estimou-se, para uma área de 301,4 Km2 de ocupação majoritariamente agrícola, a quantidade de P aplicada ao solo como fertilizante, obtendo-se um total de 820 ton.anoo1, dos quais inferiu-se que 23% foram exportados pela biomassa. Monitorou-se, no mesmo período, as concentrações de Ptotal e SStotais em cinco pontos da bacia do ribeirão do Pinhal, objetivando a estimativa de fluxos. As cargas anuais de Ptotal e SStotais obtidas na entrada do reservatório do Tatu foram iguais a 5,7 e 2160 ton.ano-I, respectivamente, sendo que 67,5% do Ptotal e 84,5% dos SStotais foram transportados no período chuvoso. Os coeficientes de exportação obtidos na entrada do reservatório foram iguais a 0,2 KgPtotal.haol.anool e 7,4 tonSStotaiS.Km-2.ano-l. Ao se inferir sobre as cargas difusas de Ptotal transportadas por escoamento superficial pelo ribeirão do Pinhal, obteve-se uma razão de 0,6 entre a carga anual de origem difusa e aquela pontual, apontando a importância desta última na bacia. Por fim, fez-se um levantamento limnológico do reservatório do Tatu, e observou-se que o IET referente ao Ptotal e à clorofila a indicou estado eutrófico na cabeceira e barragem; entretanto, é provável que a alta taxa de descarga esteja limitando a proliferação de algas no reservatório. De modo geral, verificou-se preliminarmente a importância da poluição difusa de Ptotab de origem rural, na degradação das águas superficiais da bacia do rio Jaguari. Por outro lado, focando na bacia do ribeirão do Pinhal, concluiu-se que as altas concentrações de Ptotal aí obtidas foram influenciadas pela atividade industrial e ocupação humana, influência esta que se sobrepôs àquela do arraste de partículas causado pelo escoamento superficial decorrente das precipitações / Abstract: Intensive agricultural activities are known to cause anthropogenic inputs ofnutrients to surface waters in rural areas. The nutrient enrichment of water bodies, or eutrophication, can lead to highly undesirable changes in ecosystem structure and function, as well as in water quality for human consumption. It is known that nutrient loading restriction - specially the limiting nutrient phosphorus - is the essential comerstone of aquatic eutrophication controI. In a preliminary study, official water quality and flow data from Jaguari River were used to assess the diffuse loads of nutrients from rural areas into surface waters. Results showed that, in average, 68.2% of the TN annualloads and 77.3% of the TP annualloads were transported through a 3394 Km2 area during the raining season. The annual diffuse loads obtained coming primarily from rural sources - were equivalent to 55.1% and 69.4% ofthe total annual loads of TN and TP transported through the sub-basin, respectively. The mean export coefficients from diffuse loads were equal to 2.3 Kg TN.ha-1.year-1 and 0.4 Kg TP.ha-'.year-1. The main part of this study was realized at the Ribeirão do Pinhal - a Jaguari River affluent from February 2003 to February 2004. The annual phosphorus load applied as fertilizer to an area of301.4 Km2 ofthe ribeirão do Pinhal watershed was estimated to be 820 ton.year-', and 23% of it was calculated to be exported by the biomass of the agricultural fields. These results were based on the soil use and occupation of the area, mainly rural, producing basically sugarcane and citrus. The field sampling of Ribeirão do Pinhal superficial waters was done twice a month, in five locations at the watershed. Samples were analyzed for TP and TSS; the totalloads obtained were equal to 5.7 e 2160 ton.year-', respectively, at the entrance ofTatu reservoir; 67.5% of TP and 84.5% of TSS were transported during the raining season (October-March). The export coefficients obtained were equal to 7.4 ton TSS.Km-2.year-1 and 0.2 Kg TP.ha-1.year"'. A limnological profile of the Tatu reservoir was determined through field sampling in three locations on both dry and wet periods; results showed a eutrophic state at the entrance of the reservoir as well as at the damo Yet, the flushing rate is the possible limiting factor for the occurrence of eutrophication at the reservoir. In general, the importance of diffuse pollution, originally from rural areas, was verified at the Jaguari River watershed. On the other hand, at the Ribeirão do Pinhal watershed, the high TP concentrations observed were most1y influenced by the industrial and human activities occurring in the area / Doutorado / Agua e Solo / Doutor em Engenharia Agrícola

Ce travail de thèse s'inscrit dans l'effort actuel de construction d'une écologie intégrative. J'y étudie les mécanismes d'interaction entre ressources abiotiques, réseaux trophiques et propriétés des écosystèmes, au moyen d'une expérience d'évolution, d'un modèle de méta-écosystème et d'un modèle bioénergétique d'assemblage d'écosystèmes. Les organismes modifient la disponibilité des ressources en les prélevant pour leur croissance. Inversement, la disponibilité des ressources influence la diversité et la composition en espèces du réseau trophique, en agissant comme force de sélection sur les traits d'acquisition des ressources (chap. 1, 5). Les propriétés de l'écosystème, telles que stabilité et productivité, dérivent des interactions entre la dynamique des ressources et celle du réseau trophique (chap. 2). Enfin, le fonctionnement de l'écosystème rétroagit sur les ressources abiotiques via le recyclage de la biomasse (chap. 2, 5). Ces processus interviennent lors de l'assemblage des réseaux trophiques et structurent le développement des écosystèmes (chap. 3-5). Dans cette thèse j'analyse ces mécanismes de rétroaction biotique-abiotique sur plusieurs échelles d'organisation, d'espace et de temps. Notamment, les modèles développés ici fournissent des outils novateurs pour étudier les mécanismes de construction des écosystèmes, en mettant en évidence les liens entre métabolisme des espèces, structure du réseau trophique et fonctionnement de l'écosystème, et leur variation au cours du temps. Ce travail ouvre de vastes perspectives de recherche en combinant les derniers progrès d'une écologie intégrative dans une conception mécaniste du développement des écosystèmes. / This thesis participates to the current effort towards the construction of an integrative ecology. I study the feedback mechanisms between abiotic resources, food webs and ecosystem properties, through an evolution experiment, a model of metaecosystem, and a bioenergetic ecosystem assembly model. Organisms modify resource availability by consuming them for their growth. Conversely, resource availability influences the species diversity and composition of the food web, by acting as a selection pressure on traits for resource acquisition (chap. 1, 5). Ecosystem properties, such as stability and productivity, derive from the interactions between resource and food web dynamics (chap. 2). Finally, ecosystem functioning feeds back on abiotic resources through the recycling of biomass (chap. 2 and 5). These processes occur during the food web assembly and drive the development of ecosystems (chap. 3-5). In this thesis I analyze these biotic-abiotic feedback mechanisms on several scales of organization, space and time. The models developed here provide innovative tools to study the mechanisms of ecosystem construction by pointing out the links between species metabolism, food web structure and ecosystem functioning, and their variation through time. This work opens wide research perspectives, as it combines the most recent progress of an integrative ecology into a mechanistic framework of ecosystem development.

No intuito de identificar as relações entre as variações espaciais e temporais da biomassa e produção primária fitoplanctônica frente às variáveis físicas e químicas da coluna de água, foram realizadas coletas mensais de parâmetros físicos, químicos (nutrientes inorgânicos), séston e biomassa fitoplanctônica em 4 estações oceanográficas localizadas na baía e 3 no canal de Santos no período entre novembro de 2004 a dezembro de 2005. O transporte de propriedades entre os canais estuarinos e a baía foi estimado através de medidas realizadas em estações fixas, nas entradas dos canais de Santos e São Vicente, durante um ciclo completo de maré (13h). Os principais fatores limitantes ao desenvolvimento da biomassa fitoplanctônica e da produtividade primária foram: a disponibilidade de luz, a estratificação da coluna de água e a temperatura. Os canais de Santos e São Vicente atuaram como importadores de sal, nutrientes e biomassa fitoplanctônica na maioria das ocasiões estudadas. Os elevados teores de nutrientes inorgânicos dissolvidos, associados à ausência de correlação entre nutrientes e biomassa, indicam que não há limitação nutricional, apesar das condições distróficas observadas. Os altos teores de Cl-a (média de 10,1 mg m-3) indicam que o ambiente continua apresentando características eutróficas, já reportadas em trabalhos realizados na área há mais de 30 anos. / The relationship between time-space variations of phytoplankton biomass and primary productivity and the variability in physical and chemical characteristics of the water column was investigated by monthly samplings of temperature, salinity, inorganic nutrients, seston and phytoplankton biomass in 4 oceanographic stations in Santos Bay and 3 stations in Santos Channel, during the period from November 2004 to December 2005. The transport of properties between estuarine channels and the bay was estimated by measurements conducted in fixed stations located at Santos and São Vicente Channels inlets throughout a complete tidal cycle (13h). The main limiting factors to phytoplankton biomass development were: light availability, water column stratification and temperature. Santos and São Vicente channels imported salt, nutrients and phytoplankton biomass in the majority of the studied cases. High levels of dissolved inorganic nutrients and biomass indicate no nutritional limitation, despite the dystrophic conditions observed. High chlorophyll-a concentrations (mean value 9.82 mg m-3) indicate the environment still displays the eutrophic characteristics already reported in former studies conducted in this area by more than 30 years ago.

No intuito de identificar as relações entre as variações espaciais e temporais da biomassa e produção primária fitoplanctônica frente às variáveis físicas e químicas da coluna de água, foram realizadas coletas mensais de parâmetros físicos, químicos (nutrientes inorgânicos), séston e biomassa fitoplanctônica em 4 estações oceanográficas localizadas na baía e 3 no canal de Santos no período entre novembro de 2004 a dezembro de 2005. O transporte de propriedades entre os canais estuarinos e a baía foi estimado através de medidas realizadas em estações fixas, nas entradas dos canais de Santos e São Vicente, durante um ciclo completo de maré (13h). Os principais fatores limitantes ao desenvolvimento da biomassa fitoplanctônica e da produtividade primária foram: a disponibilidade de luz, a estratificação da coluna de água e a temperatura. Os canais de Santos e São Vicente atuaram como importadores de sal, nutrientes e biomassa fitoplanctônica na maioria das ocasiões estudadas. Os elevados teores de nutrientes inorgânicos dissolvidos, associados à ausência de correlação entre nutrientes e biomassa, indicam que não há limitação nutricional, apesar das condições distróficas observadas. Os altos teores de Cl-a (média de 10,1 mg m-3) indicam que o ambiente continua apresentando características eutróficas, já reportadas em trabalhos realizados na área há mais de 30 anos. / The relationship between time-space variations of phytoplankton biomass and primary productivity and the variability in physical and chemical characteristics of the water column was investigated by monthly samplings of temperature, salinity, inorganic nutrients, seston and phytoplankton biomass in 4 oceanographic stations in Santos Bay and 3 stations in Santos Channel, during the period from November 2004 to December 2005. The transport of properties between estuarine channels and the bay was estimated by measurements conducted in fixed stations located at Santos and São Vicente Channels inlets throughout a complete tidal cycle (13h). The main limiting factors to phytoplankton biomass development were: light availability, water column stratification and temperature. Santos and São Vicente channels imported salt, nutrients and phytoplankton biomass in the majority of the studied cases. High levels of dissolved inorganic nutrients and biomass indicate no nutritional limitation, despite the dystrophic conditions observed. High chlorophyll-a concentrations (mean value 9.82 mg m-3) indicate the environment still displays the eutrophic characteristics already reported in former studies conducted in this area by more than 30 years ago.

Based on a field study and several mesocosm experiments, I evaluated the use of pigments as chemotaxonomical biomarkers for phytoplankton community composition in the Baltic Sea and I examined effects of inorganic nutrients on the dynamics of carotenoids and thiamine (vitamin B1) at the phytoplankton–copepod level in marine pelagic food webs. My results show that HPLC pigment analysis combined with CHEMTAX data processing was an accurate alternative to microscopic analysis of Baltic Sea phytoplankton. Experimental supply of N, P and Si affected copepod growth and biochemical status via changes in biomass and composition of their phytoplankton diet. Net population growth rates were generally higher when phytoflagellates dominated (low Si:N ratio) and lower when diatoms dominated (high Si:N ratio). Copepod body concentrations of astaxanthin decreased with fertilization. Correlations with reduced under-water irradiance were consistent with the photo-protective function of this antioxidant. Thiamine concentrations in phytoplankton also decreased with fertilization. In copepods, low Si:N ratios resulted in higher thiamine concentrations than high Si:N ratios. Thiamine concentration and degree of phosphorylation were useful as indicators of thiamine shortage both in phytoplankton and copepods. The concentrations of thiamine and astaxanthin in the copepod communities were positively correlated. As copepods constitute a major link between pelagic primary producers and higher trophic levels, fertilization effects may be responsible for astaxanthin and thiamine deficiencies in salmon suffering from the M74 syndrome, which appeared concurrently with large-scale eutrophication in the Baltic Sea. As both thiamine and astaxanthin are deficient in M74-affected salmon, there is a need for physiological and molecular investigations of possible interactions between the two compounds in living cells.

Dans les écosystèmes forestiers pauvres en nutriments, les minéraux du sol constituent la principale source de nutriments inorganiques nécessaires à leur bon fonctionnement. Néanmoins ces nutriments ne sont pas directement accessibles aux racines des arbres. C'est l'action conjointe de facteurs abiotiques, comme le pH ou la circulation de l'eau, et biotiques comme les racines ou les microorganismes du sol dont les bactéries, qui vont conduire à l'altération de ces minéraux. A ce jour, nos connaissances sur les communautés bactériennes impliquées dans le processus d'altération et leur distribution dans des sols forestiers restent limitées, notamment à des habitats tels que la rhizosphère et la mycorhizosphère. Les objectifs de cette thèse étaient de caractériser les communautés bactériennes colonisant les minéraux du sol et leur aptitude à altérer les minéraux et enfin d'identifier les gènes bactériens impliqués. La combinaison d'approches cultivable, non cultivable et de biogéochimie sur des minéraux enterrés pendant 4 ans dans un sol forestier, a démontré que leur surface était colonisée par des communautés bactériennes spécifiques, capables d'altérer les minéraux et présentant des capacités métaboliques limitées, suggérant que ce support pourrait être considéré comme un habitat : la minéralosphère. La relation minéral/bactéries a été testée in situ via un amendement minéral sur une plantation et a mis en évidence l'impact de la disponibilité en nutriments sur la structuration des communautés bactériennes capables d'altérer les minéraux. L'étude génétique réalisée sur la souche modèle PML1(12) a révélé l'implication de plusieurs mécanismes dans la fonction altération / In nutrient-poor forest ecosystems, minerals are the main source of inorganic nutrients for the long lasting functioning of the forests. However, these nutrients are not directly accessible to the tree roots. It is the joined action of abiotic factors, such as pH and water circulation, and biotic factors such as tree roots and soil microorganisms, and notably bacteria, which leads to the solubilisation of these minerals. To date, our knowledge of the bacterial communities involved in the mineral weathering process and their distribution in forest soils is very limited and remains restricted to habitats such as the rhizosphere and mycorrhizosphere. The goals of this PhD thesis were to characterise the mineral associated bacterial communities, their ability to weather minerals and finally to identify the bacterial genes involved in the mineral weathering process. The combination of geochemical, cultivation-dependent and -independent approaches applied on minerals grounded in a forest soil during 4 years, revealed that the mineral associated bacterial communities were specific, able to weather minerals and had restricted metabolic abilities. These results suggest that minerals could be considered as a true ecological habitat: the mineralosphere. The mineral/bacteria relationship was tested in situ through a mineral amendment applied on a small-scale plantation, which has highlighted that the nutrient availability impacted the functional structure of the mineral weathering bacterial communities. At least, random mutagenesis applied on a model mineral weathering bacterial strain revealed that its mineral weathering ability resulted from several molecular mechanisms