Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-09-12T18:51:42Z No. of bitstreams: 1 DissBPS.pdf: 1727871 bytes, checksum: 9b93476d3effc98b9ff1ef9c08feeacf (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-13T20:20:17Z (GMT) No. of bitstreams: 1 DissBPS.pdf: 1727871 bytes, checksum: 9b93476d3effc98b9ff1ef9c08feeacf (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-13T20:20:26Z (GMT) No. of bitstreams: 1 DissBPS.pdf: 1727871 bytes, checksum: 9b93476d3effc98b9ff1ef9c08feeacf (MD5) / Made available in DSpace on 2016-09-13T20:20:34Z (GMT). No. of bitstreams: 1 DissBPS.pdf: 1727871 bytes, checksum: 9b93476d3effc98b9ff1ef9c08feeacf (MD5) Previous issue date: 2015-07-08 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / The decomposition of aquatic macrophytes is important for understanding the cycling of elements and organic matter in aquatic ecosystems. The decomposition rate is driven by biotic and abiotic factors. Thus, the aim of this study was to analyze the effects of trophic status and detritus quality on the humification and mineralization of aquatic plants. The study was conducted in two tropical reservoirs (RJ/Brazil) with different trophic statuse (Lajes Reservoir: oligo-mesotrophic; Vigário Reservoir: eutrophic). In each reservoir were incubated (litter bags), during the dry season, five species of aquatic plants (Eichhornia crassipes (Mart.) Solms., Pistia stratiotes (L.), Sagittaria montevidensis (Cham. & Schltdl.) Kuntze, Salvinia auriculata (Aubl.) and Urochloa arrecta (Hack. & Schinz) Morrone & Zuloaga). The remaining fractions were used for the extraction of humic acid (HA) and fulvic acids (FA), which were quantified on carbon basis (controlled combustion and infrared detection). FA and HA variations were adjusted to a 1st order kinetic model. Regardless of the kind of macrophyte and trophic status, the particulate detritus showed a reactive fraction (RPOC) related to the formation of humic substances (HS) and a fraction not involved with such formations, the humin (HU); FA predominated as the main constituent of HS and their mineralization rate constants were higher than those of HA, indicating greater contribution and rapid cycling of FA. HA represented the maintenance of carbon pool. The fraction HU indicated that, depending on the detritus quality, carbon is immobilized carbon (e.g. S. auriculata) and is not readily available to cycling in aquatic environments. The trophic status along with the quality of detritus influenced the mineralization rates, especially for floating species (P. stratiotes, E. crassipes and S. auriculata) and amphibious (U. arrecta); the effects were lower in decomposition of S. montevidensis. The eutrophic environment (Vigario Reservoir) improved the mineralization over humification. / A decomposição das macrófitas aquáticas é importante para o entendimento da ciclagem de elementos e da matéria orgânica nos ecossistemas aquáticos. A velocidade com que ocorre a decomposição é influenciada por fatores bióticos e abióticos. Desse modo, o objetivo desse trabalho foi analisar os efeitos do estado trófico e da qualidade do detrito sobre a humificação e mineralização de plantas aquáticas. O estudo foi realizado em dois reservatórios tropicais (RJ/Brasil) com diferentes estados tróficos (Lajes: oligo-mesotrófico; Vigário: eutrófico). Em cada reservatório foram incubadas (litte rbags), durante a estação seca, cinco espécies de macrófitas aquáticas (Eichhornia crassipes (Mart.) Solms., Pistia stratiotes (L.), Sagittaria montevidensis (Cham. & Schltdl.) Kuntze, Salvinia auriculata (Aubl.) e Urochloa arrecta (Hack. & Schinz) Morrone & Zuloaga). As frações remanescentes das incubações foram utilizadas para extração dos ácidos húmicos (AH) e ácidos fúlvicos (AF), que foram quantificados em base de carbono (combustão controlada e detecção no infravermelho). As variações de AF e AH foram ajustadas a um modelo cinético de 1ª ordem. Os resultados indicaram que independente da espécie de macrófita e da condição trófica, o detrito particulado apresentou uma fração reativa (RPOC) no que se refere à formação das substâncias húmicas (SH) e uma fração não envolvida com tais formações, a humina (HU); os AF predominaram como o principal constituinte das SH e seus coeficientes de mineralização foram maiores que os dos AH, indicando assim participação maior e ciclagem mais rápida dos AF na mineralização das SH. consequentemente, os AH representaram um composto de manutenção da reserva carbônica. A fração HU indicou que, dependendo da qualidade dos detritos, imobiliza o carbono (e.g. S. auriculata) não o disponibilizando prontamente para ciclagem nos ambientes aquáticos. O estado trófico juntamente com a qualidade do detrito exerceram alterações nos coeficientes de mineralização, principalmente para espécies flutuantes (P. stratiotes, E. crassipes e S. auriculata) e anfíbia (U. arrecta); os efeitos foram menores na decomposição de S. montevidensis. O meio eutrófico (reservatório de Vigário) beneficiou a mineralização das macrófitas em detrimento da humificação.

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

A serapilheira à essencial para a ciclagem de nutrientes e matÃria orgÃnica em ecossistemas florestais. Esses detritos vegetais sÃo fonte de alimento para diversos grupos de animais (os quais contribuem diretamente para a sua decomposiÃÃo) e parecem favorecer a formaÃÃo de microhabitats. Dessa forma, a presenÃa desse material sobre o solo pode servir como refÃgio para diversos organismos nos manguezais. O gastrÃpode Melampus coffeus (Linnaeus 1758) (Ellobiidae) à uma espÃcie comum em manguezais do AtlÃntico e se alimenta de folhas de mangue. Esses moluscos podem ser importantes componentes nas teias alimentares com base em detritos por, possivelmente, serem capazes de acelerar os processos de decomposiÃÃo de tecidos vegetais senescentes de mangue e facilitarem seu consumo por outros organismos. Foi assumida a hipÃtese de que M. coffeus utiliza a serapilheira como fonte de alimento, e assim acelera sua decomposiÃÃo, e como refÃgio, de modo que sua distribuiÃÃo espacial à afetada diretamente pela biomassa desses detritos vegetais. O objetivo geral do trabalho foi avaliar a distribuiÃÃo espacial de M. coffeus em relaÃÃo à biomassa de diferentes fraÃÃes de serapilheira, alÃm de avaliar o comportamento alimentar desses animais diante dessas estruturas vegetais. Para isso, foram realizadas coletas mensais, de janeiro a dezembro de 2010, de M. coffeus e de serapilheira em um bosque de franja dominado por R. mangle, localizado no mÃdio estuÃrio do rio Pacoti, CearÃ. A distribuiÃÃo espacial dos animais, quanto à densidade populacional e à altura da concha, foi avaliada em relaÃÃo à biomassa de diferentes estruturas de R. mangle amostradas na serapilheira. AlÃm disso, foram realizados experimentos em laboratÃrio, para avaliar a preferÃncia alimentar desses gastrÃpodes em relaÃÃo a galhos, flores e folhas de R. mangle, e em campo, para verificar a importÃncia desses invertebrados na decomposiÃÃo das folhas de mangue presentes sobre o solo do bosque estudado. Os resultados indicaram que a presenÃa de galhos na serapilheira favorece a ocupaÃÃo por indivÃduos de M. coffeus de menor tamanho, possivelmente por fornecer abrigo contra predadores e contra a dessecaÃÃo, jà que indivÃduos menores tendem a ser mais suscetÃveis a esses fatores. Contudo, esses animais parecem evitar tais estruturas como fonte de alimento e dÃo preferÃncia a estruturas provavelmente mais palatÃveis, como folhas e flores. Os resultados encontrados no experimento de campo indicaram que esses moluscos consomem tecidos foliares, sobretudo quando esses tecidos chegam a estÃgios mais avanÃados de decomposiÃÃo. Assim, em virtude de sua abundÃncia em Ãreas de mangue e de suas relaÃÃes ecolÃgicas com a serapilheira, essa espÃcie pode ser uma ferramenta de grande importÃncia nos estudos de conservaÃÃo, jà que sua presenÃa pode ser influenciada pela produÃÃo de serapilheira e, conseqÃentemente pela estrutura do mangue, alÃm de sua distribuiÃÃo espacial ser potencialmente capaz de afetar outros grupos de organismos que possivelmente se relacionam na teia alimentar dos manguezais. / The litter is essential for the nutrients and organic matter cycles in forests ecosystems. These vegetal detritus are a food source to many groups of animals that act directly on the litter decomposition. Litter also seems to provide microhabitats and works as a shelter for many individuals of the mangrove fauna. The gastropod Melampus coffeus (Linnaeus, 1758) (Ellobiidae) is a common snail in mangroves from the Atlantic and feed on mangrove leaves. These animals must be important components in detritus based food webs and may accelerate the detritus decompositions processes and also facilitate the mangrove litter consume by other organisms. It was hypothesized that these gastropods use mangrove litter as a food source, thus accelerating its decomposition, and as a refuge. So its spatial distribution may be directly affected by litter biomass accumulation. Therefore this research aimed to evaluate the M. coffeus spatial distribution related to biomasses of different mangrove litter fractions biomasses besides evaluate the feeding behavior of this specie when submitted to a diet based on different mangrove tissues. To test such hypothesis samples of M. coffeus and litter were procedure monthly through a year in a fringe mangrove forest in the middle estuary of Pacoti river, CearÃ, northeast of Brazil. The population density and shell length of M. coffeus were recorded and compared to the biomasses of different Rhizophora mangle structures that were sampled during this research. In addition of it laboratory and field experiments were carried out to test, respectively, the feeding preference of M. coffeus to different R. mangle tissues (leaves, twigs and flowers) and to evaluate the importance of these snails on R. mangle leaves decomposition in the study area. The results indicated that the presence of twigs in the mangrove litter may favor the occupation by smaller individuals of these snails, probably because these structures may provide a shelter against predators attack and dissection. However M. coffeus seemed to avoid such vegetal tissues as source of food and prefers some more palatable tissues like leaves and flowers. Field experiment confirmed that these gastropods feed on leaves of R. mangle, especially when these tissues get into advanced decomposition stages. So, because of the abundance in mangrove areas and because its ecological relations with mangrove litter, M. coffeus might be an important tool to environmental conservation researches, as its presence may be influenced by the mangrove litter production and, for consequence, by mangrove forest structure. Moreover, M. coffeus spatial distribution is potentially capable to affect the distribution of others organisms that are probably elements of the mangrove detritus food web.

Water column methane measurements have been used to understand both the global distribution of methane in the oceans and the local flux of methane from geologic sources on the continental margins, including methane vents and gas-hydrate-bearing sites. We have measured methane concentrations in 1607 water samples collected along the central California continental margin. Methane supersaturation of the surface mixed layer (0-50 msbsl) is widespread and above a well-defined subsurface particle maximum (~50 mbsl) that generally corresponds with the pycnocline. Local production of methane appears to be occurring in the surface mixed layer above the particle maximum and may not be particle-associated. Methane concentrations in water column CTD cast profiles and ROV-collected bottom waters obtained in Partington, Hueneme, Santa Monica, and Redondo submarine canyons increase towards the seafloor and are distinctly higher (up to 186 nM) compared to open-slope and shelf waters at similar depths. These values are in excess of measured surface water methane concentrations and could not be generated by mixing with surface water. Elevated methane concentrations in these submarine canyons and persistent mid-water methane anomalies in Ascension and Ano Nuevo Canyons could result from restricted circulation and/or proximity to gas vents, seafloor exposure of methane gas hydrates, recently-eroded methane-rich sediment, submarine discharge of methane-rich groundwater, or particle-associated methane production. On the Santa Barbara shelf water column methane profiles near known gas vents also increase in concentration with increasing depth. Thus, elevated bottom water methane concentrations observed in submarine canyons may not be diagnostic of proximity to methane vents and may be caused by other processes.

Univ., Diss., 2009--Frankfurt (Main). / Engl. Übers. des Hauptsacht.: U-Pb geochronology, Hf isotopy and trace element geochemistry of detrital zircons from recent sediments of the Orange and Vaal river system in South Africa.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 151-169).

No description available.

Life history, food habits, energetics, and production by nymphs of Pteronarcys proteus were measured. The life cycle lasted four years in an Appalachian mountain stream in southwestern Virginia. Adults emerged late May to early June, and eggs deposited did not hatch until the following spring. Nymphs grew at least 3 years with 12 male instars and 13 female instars. The nymphal diet was primarily leaf detritus, with a small percentage of moss and animal matter. Total crude lipid content of nymphs varied from 6% to 29% of dry insect weight and was dependent on age, season, and developmental state. Lipid content of nymphs in the two youngest cohorts generally declined during late summer, but increased after leaf-fall in November. A similar pattern was observed in the oldest cohort, but a significant decline in the spring prior to emergence of adults was also observed. The data indicate that P. proteus relied on lipid stores during periods of low food availability and for reproductive maturation. The energetic parameters of growth (G), respiration (R), ingestion (I), and egestion (E) for nymphs in each of the three cohorts were measured in the laboratory. Growth rates ranged from 0.031 to 0.0037 mg/mg/day, with small nymphs growing fastest. Ingestion ranged from 5 to 40% of dry body weight per day. Respiration ranged from 330 to 980 µl O₂/g/hr. Mean AD was 13.5%, mean gross growth efficiency was 5.2%, and mean net growth efficiency was 38.7%. Total assimilation by a population was estimated at 119 kcal m⁻², accounted for primarily by the two oldest cohorts. Annual energetics of the nymphal population were: I= 906, G= 41, R= 78, and E= 828 kcal m⁻². Annual production was 0.438 g m⁻², 3.158 g m⁻², and 4.182 g m⁻², with the youngest cohort contributing the smallest. Mean cohort densities ranged from 23.8 to 9.3 nymphs m⁻², and mean standing stock biomass ranged from 0.143 to 1.790 gm⁻². Mean relative growth rates (RGR) in the stream were greatest for smallest nymphs and ranged from 0.939 to 0.182 percent increase per day. The data indicate that growth rates of small nymphs were influenced by temperature and larger nymphs by food supply. It was estimated that P. proteus consumed 41-61% of the litterfall in the study stream. / Ph. D.

In this thesis I explore the effect of parameter uncertainty in ocean biogeochemical models on the calculation of carbon uptake by the ocean. The ocean currently absorbs around a quarter of the annual anthropogenic CO2 emissions to the atmosphere [Scholes et al., 2009], slowing the increase in radiative forcing associated with the increasing atmospheric CO2 concentration. Ocean biogeochemical models have been developed to study the role of the ocean ecosystem in this process. Such models consist of a greatly simplified representation of the hugely complex ocean ecosystem. This simplification requires extensive parameterisation of the biological processes that convert inorganic carbon to and from organic carbon in the ocean. The HadOCC ocean biogeochemical model is a Nutrient-Phytoplankton-Zooplankton-Detritus (NPZD) model that is used to represent the role of the ocean ecosystem in the global carbon cycle in the HadCM3 and FAMOUS GCMs. HadOCC uses twenty parameters to control the processes of biological growth, mortality, grazing and detrital sinking that control the uptake and cycling of carbon in the ocean ecosystem. These parameters represent highly complex and in some cases incompletely understood biological processes, and as a result are uncertain in value. A sensitivity analysis is performed to identify the HadOCC parameters that due to uncertainty in value have the greatest possible effect on the exchange of CO2 between the atmosphere and the ocean—the air-sea CO2 flux. These are found to be the parameters that control phytoplankton growth in the well lit surface ocean, the formation of carbonate by marine organisms and the sinking of biological detritus. The uncertainty in these parameters is found to cause changes to the air-sea CO2 flux calculated by the FAMOUS GCM. The initial effect of these changes is equivalent to the order of the error of current estimates of the net annual carbon uptake by the ocean (2.2 ± 0.3 Pg C y−1 [Gruber et al., 2009], 2.2 ± 0.5 Pg C y−1 [Denman et al., 2007]). This indicates that while the effect of ocean biogeochemical parameter uncertainty is non-negligible, it is within the bounds of the uncertainty of the total (inorganic and organic) ocean carbon system, and is considerably less than the uncertainty in the carbon uptake of the terrestrial biosphere [Houghton, 2007]. However, as the ocean plays a crucial role in the global carbon cycle and the regulation of the Earth’s climate, further understanding and better modelling of the role of the ocean ecosystem in the global carbon cycle and its reaction to anthropogenic climate forcing remains important.

This study examines the relative contribution of algae and vascular plant litter to the food chains of freshwater marshes. Twelve enclosures (5 m diam.) were deployed in a nutrient-poor marsh of the Interlake region of Manitoba. Algae levels in six of the enclosures were increased by fertilizing the water column. In addition, the hardstem bulrush (Scirpus lacustris glaucus (Sm.) Hartm) litter present was replaced with a non-nutritive artificial substrate in half of the fertilized and unfertilized enclosures. Fertilization did not affect the dry weight loss of bulrush litter, but N and P concentrations were higher in the decomposing litter of the fertilized treatments. Dominant taxa of nektonic herbivores-detritivores responded to fertilization but were not affected by the replacement of plant litter by a non-nutritive substrate. Epiphytic herbivores-detritivores responded to changes in both detritus and algal food sources. Fertilization resulted in early peaks of emergence for the Chironominae, Tanypodinae and Orthocladiinae. Emergence data late in the study period suggest that the importance of litter as a food source may increase as decomposition progresses.