abstract: Humans have dramatically increased phosphorus (P) availability in terrestrial and aquatic ecosystems. As P is often a limiting nutrient of primary production, changes in its availability can have dramatic effects on ecosystem processes. I examined the effects of calcium carbonate (CaCO3) deposition, which can lower P concentrations via coprecipitation of phosphate, on P availability in two systems: streams in the Huachuca Mountains, Arizona, and a stream, Río Mesquites, in Cuatro Ciénegas, México. Calcium carbonate forms as travertine in the former and within the microbialites of the latter. Despite these differences, CaCO3 deposition led to lowered P availability in both systems. By analyzing a three-year dataset of water chemistry from the Huachuca Mountain streams, I determined that P concentrations were negatively related to CaCO3 deposition rates. I also discovered that CaCO3 was positively correlated with nitrogen concentrations, suggesting that the stoichiometric effect of CaCO3 deposition on nutrient availability is due not only to coprecipitation of phosphate, but also to P-related constraints on biotic nitrogen uptake. Building from these observations, bioassays of nutrient limitation of periphyton growth suggest that P limitation is more prevalent in streams with active CaCO3 deposition than those without. Furthermore, when I experimentally reduced rates of CaCO3 deposition within one of the streams by partial light-exclusion, areal P uptake lengths decreased, periphyton P content and growth increased, and periphyton nutrient limitation by P decreased. In Río Mesquites, CaCO3 deposition was also associated with P limitation of microbial growth. There, I investigated the consequences of reductions in CaCO3 deposition with several methods. Calcium removal led to increased concentrations of P in the microbial biomass while light reductions decreased microbial biomass and chemical inhibition had no effect. These results suggest that CaCO3 deposition in microbialites does limit biological uptake of P, that photoautotrophs play an important role in nutrient acquisition, and, combined with other experimental observations, that sulfate reduction may support CaCO3 deposition in the microbialite communities of Río Mesquites. Overall, my results suggest that the effects of CaCO3 deposition on P availability are general and this process should be considered when managing nutrient flows across aquatic ecosystems. / Dissertation/Thesis / Doctoral Dissertation Biology 2015

Orientador: Vidal Haddad Júnior / Banca: Fábio Lang da Silveira / Banca: Rafael Augusto Gregati / Resumo: O presente trabalho relata a composição, abundância e distribuição dos cnidários nas diferentes estações do ano, caracterizando as espécies dominantes da comunidade nas regiões amostradas, da costa do litoral norte do Estado de São Paulo (Ubatuba 23º26' 15''S e 45º03'45''W; Caraguatatuba 23º61'39"S e 45º32'56''W; São Sebastião 23º84' 94''S e 45º24'81''W), no período compreendido entre fevereiro de 2001 a dezembro de 2002. Foram encontradas 6 espécies de cnidários potencialmente causadores de acidentes, sendo 2 cubozoários: Tamoya haplonema (Müeller, 1859) e Chiropsalmus quadrumanus (Müeller, 1859); 2 hidrozoários: Nemalecium lighti (Hargitt, 1924) e Olindias sambaquiensis (F. Müller, 1861) e 2 cifozoários: Chrysaora lactea Eschscholtz, 1829 e Lychnorhiza lucerna Haeckel, 1880. As espécies de maior abundância e freqüência na comunidade foram C. lactea e O. sambaquiensis. Estas espécies também tiveram mais representatividade em análises de abundância além de sua distribuição espacial e temporal. T. haplonema foi uma espécie de ocorrência exclusiva apenas em outono e inverno e C. lactea foi uma espécie abundante de ocorrência no ano todo, com mais representantes nas estações de outono e inverno. Outro objetivo do estudo foi o registro de acidentes causados por algumas espécies de cnidários em banhistas da região de Ubatuba, além da identificação da espécie e associação às lesões dermatológicas e à provável etiologia dos acidentes, além da correlação da quantidade dos animais com a ocorrência de acidentes registrados em meses de veraneio. Foram registrados cento e vinte e oito pacientes, e desta forma, analisados sinais e sintomas, manifestações sistêmicas e extensões das lesões no corpo da vítima, comprovou-se uma associação entre as marcas cutâneas e a provável etiologia e gravidade dos acidentes. Além disso .... / Not available / Mestre

Made available in DSpace on 2014-06-11T19:30:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-25Bitstream added on 2014-06-13T21:00:29Z : No. of bitstreams: 1 mendes_pr_me_botib.pdf: 1465265 bytes, checksum: bbb67eb612b94d3451a49d78c65fbdd4 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O presente trabalho relata a composição, abundância e distribuição dos cnidários nas diferentes estações do ano, caracterizando as espécies dominantes da comunidade nas regiões amostradas, da costa do litoral norte do Estado de São Paulo (Ubatuba 23º26’ 15’’S e 45º03’45’’W; Caraguatatuba 23º61’39”S e 45º32’56’’W; São Sebastião 23º84’ 94’’S e 45º24’81’’W), no período compreendido entre fevereiro de 2001 a dezembro de 2002. Foram encontradas 6 espécies de cnidários potencialmente causadores de acidentes, sendo 2 cubozoários: Tamoya haplonema (Müeller, 1859) e Chiropsalmus quadrumanus (Müeller, 1859); 2 hidrozoários: Nemalecium lighti (Hargitt, 1924) e Olindias sambaquiensis (F. Müller, 1861) e 2 cifozoários: Chrysaora lactea Eschscholtz, 1829 e Lychnorhiza lucerna Haeckel, 1880. As espécies de maior abundância e freqüência na comunidade foram C. lactea e O. sambaquiensis. Estas espécies também tiveram mais representatividade em análises de abundância além de sua distribuição espacial e temporal. T. haplonema foi uma espécie de ocorrência exclusiva apenas em outono e inverno e C. lactea foi uma espécie abundante de ocorrência no ano todo, com mais representantes nas estações de outono e inverno. Outro objetivo do estudo foi o registro de acidentes causados por algumas espécies de cnidários em banhistas da região de Ubatuba, além da identificação da espécie e associação às lesões dermatológicas e à provável etiologia dos acidentes, além da correlação da quantidade dos animais com a ocorrência de acidentes registrados em meses de veraneio. Foram registrados cento e vinte e oito pacientes, e desta forma, analisados sinais e sintomas, manifestações sistêmicas e extensões das lesões no corpo da vítima, comprovou-se uma associação entre as marcas cutâneas e a provável etiologia e gravidade dos acidentes. Além disso.... / Not available

Photoautotrophic microorganisms, i.e. cyanobacteria and microalgae, are ubiquitous in the glacial ecosystem of the high Arctic archipelago of Svalbard. Their communities play significant roles in the ecosystem, including organic carbon production on the glacier surface and its supply to downstream environments, initiating microbial colonisation after glacier retreat and preparing proglacial substrata for further succession.

Made available in DSpace on 2015-09-25T12:19:47Z (GMT). No. of bitstreams: 1 Kalina Gioconda Matos de Souto.pdf: 1967648 bytes, checksum: 47de7afca793cf8c0b917b98b974f8bd (MD5) Previous issue date: 2012-05-31 / In semiarid Caatinga biome predominates with a heterogeneous vegetation, called caatinga, endowed with mechanisms associated with water deficit due to geomorphological and climatic characteristics of the region. Changes in the natural and anthropogenic, this region has been the loss of vegetation cover. Since the water is limiting, it is essential to preserve the forests for the preservation of rivers. In order to expand knowledge of the floristic and phytosociological component shrub - tree vegetation, this study aimed to diagnose the state of vegetation conservation of the Riacho of Bodocongó, consolidating a database that can support programs for their recovery. The study was conducted in areas found along the route of the Riacho Bodocongó, from where the Riacho Bodocongó borns, in the town of Puxinanã, traveling by Campina Grande, Caturité, Queimadas and near Barra de Santana. 16 transects were plotted in environments strategic geographically located in areas adjacent, perpendicular to the stream and in each transect was plotted six equidistant points with systematic distribution (10 mx 60 m). The first point of each transect started 10m from the edge of the fragment. The four individuals closest point in each quadrant was sampled using the criteria of inclusion of species and a diameter of the ground level (DNS) ≥ 3 cm and height ≥ 1m. Phytosociological parameters were calculated frequency, density, dominance, importance value, cover value. Were also calculated Shannon diversity indices-Wiener (H') and Pielou s equability (J'), and other parameters, Sorensen similarity index, Payandeh, and basal area. We recorded 110 individuals, 22 species, 19 genera and 10 families. The most representative families were Fabaceae (8), Anacardiaceae (3), Euphorbiaceae(2), Cactaceae (2) and Capparaceae (2) The similarity revealed heterogeneity of vegetation smallest species number. The species of greatest importance were Prosopis juliflora(Sw.) DC, Amburana cearensis (Allemão) ACSM, Croton sonderianus Muell. Arg, Mimosa spp, Mimosa caesalpiniifolia Benth Pithecellobium dulce (Rouxb.), Benth, Jatropha pohlianaMuell. Arg, L, Crateva tapia, Anacardium occidentale L. Ziziphus joazeiro Mart. Among the most important values of the prevailing species P. juliflora (37.29%) than the other species, resembling the results obtained by Trovão, et al., (2010). In the spatial distribution showed characteristic dominant species grouped. The total basal area was 4.543 ha-¹ infers that the vegetation is in early regeneration showing that undergoes disturbances significantly altering the ecosystem. / No Semiárido predomina o bioma Caatinga com uma vegetação heterogênea, chamada caatinga, dotada de mecanismos associados ao déficit hídrico devido às características geomorfológicas e climáticas da região. As alterações de ordem natural e antrópica nesta região, tem levado à perda da cobertura vegetal. Tendo a água como fator limitante, é fundamental a preservação das florestas para a preservação dos rios da região. Com o propósito de ampliar o conhecimento Florístico e Fitossociológico do componente arbustivo arbóreo da vegetação, esse trabalho teve o objetivo de diagnosticar o estado de conservação da vegetação do Riacho Bodocongó, consolidando um banco de dados que possa subsidiar ações para a sua recuperação. O estudo foi desenvolvido em áreas encontradas ao longo do percurso do riacho Bodocongó, desde o local onde o riacho Bodocongó nasce, no município de Puxinanã, percorrendo por Campina Grande, Caturité, Queimadas e próximo a Barra de Santana.Foram plotados 16 transectos em ambientes estratégicos localizados geograficamente em áreas adjacentes, perpendiculares ao curso d água e em cada transecto, foram plotados seis pontos com distribuição sistemática equidistante (10 m x 60 m). O primeiro ponto de cada transecto iniciou-se a partir de 10m da borda do fragmento. Os quatro indivíduos mais próximos do ponto em cada quadrante foram amostrados utilizando o critério de inclusão de espècies e diâmetro do caule ao nível do solo (DNS) ≥ 3 cm e a altura ≥ 1m. Foram calculados os parâmetros Fitossociológicos de frequência, densidade, dominância, valor de importância, valor de cobertura. Foram calculados também os índices de diversidade de Shannon Wiener (H ) e de equabilidade de Pielou (J ), e outros parâmetros, índice de similaridade Sorensen, Payandeh, e área basal. Foram registrados 110 indivíduos, 22 espécies, 19 gêneros e 10 famílias. As famílias mais representativas foram Fabaceae (8), Anacardiaceae (3), Euphorbiaceae (2), Cactaceae (2) e Capparaceae (2) A similaridade revelou heterogeneidade da vegetação com múmero ínfimo de espécies. As espécies de maior importância foram Prosopis juliflora (Sw.) DC, Amburana cearensis (Allemão) A.C.Sm, Croton sonderianusMuell. Arg, Mimosa spp, Mimosa caesalpiniifoliaBenth, Pithecellobium dulce(Rouxb.)Benth, Jatropha pohlianaMuell. Arg, Crateva tapia L, Anacardium occidentale L., Ziziphus joazeiro Mart. Entre os valores de maior importância prevaleceu a espécie P. juliflora (37,29%) em relação as demais espécies, assemelhando-se aos resultados obtidos por Trovão, et al.,(2010).Na distribuição espacial as espécies dominantes apresentaram característica de agrupada. A área basal total foi de 4,543 ha-¹ infere que a vegetação esteja em início de regeneração evidenciando que passa por perturbações alterando significativamente o ecossistema.

The phenology of plants in northern ecosystems is currently changing. Roots have a key role in these ecosystems, though the phenology of roots is still poorly understood. The aim of this report was to investigate if above- and belowground phenology of the circumpolar sedge Eriophorum vaginatum was synchronized in a subarctic peatland underlain by permafrost, and to investigate which abiotic factors are limiting root growth. Additionally, the length of the belowground growing season was examined. The study was performed with a non-destructive in situ method (minirhizotrons and NDVI measurements) in the northernmost part of Sweden. Both above- and belowground phenology was measured biweekly during the whole growing season in 2016. The depth of the active layer, air temperature, soil temperature and soil moisture were measured to investigate the determinants of root growth. Root growth and aboveground activity was asynchronous, as peak in root growth occurred on average 21 days before maximum NDVI was reached. Soil temperature and thaw depth seem to be important factors regulating root growth in this peatland. The result highlight that solely studying the aboveground parts of plants can give a misleading interpretation about the phenology of the entire plant and thus during which time periods important ecosystem processes take place. Hence, to more accurate forecast ecosystem responses to global warming, both aboveground and belowground phenology should be considered.

Marine ecosystems contain both highly abundant and diverse communities of vertebrates and invertebrates; however anthropogenic activity has drastically altered the species composition and diversity of these ecosystems. Specifically, human activity has targeted high trophic level species and degraded much of the biogenic habitat that faunal communities rely upon. These alterations have resulted in the loss of many marine predators and overall declines of marine biodiversity. To investigate the consequences of marine predator loss and community level species decline, I use a combination of large-scale data synthesis and in situ field observations of marine fish communities. I first use a meta-analysis approach to synthesize the consequences of marine predator loss in benthic marine ecosystems worldwide. From this synthesis, I was able to determine some of the biotic and abiotic factors that regulate the response of marine herbivores and primary producers to predator loss. Specifically, I show that marine predators have the strongest effect on populations of marine herbivores when predators and herbivores were similar in size and when larger herbivores were involved. Conversely the factors that best explained the response of the primary producer populations were related to the abiotic environment. The results show that primary producers respond the most positively to the presence of predators in high nutrient environments. While I found no link between the magnitude of change in the herbivore population and the magnitude of change in the producer population, I was able to demonstrate that primary producers are under the strongest top-down controls when nutrient concentrations are high, sea surface temperatures are low, and when the predator is larger in size than the herbivore. Finally, I use the data related to marine reserves to show that reserves are an effective tool to help reverse the trophic consequences of marine predator loss and that they are most effective when they are older in age. The third chapter examines the links between community diversity and community biomass within fish communities in eelgrass ecosystems in Northern British Columbia. After controlling for environmental variation, I found that it was the dominance of certain species within a community that resulted in the highest ecosystem function. This finding was demonstrated by both the taxonomic and functional metrics of diversity used. While previous work on this topic has shown that richness is positively correlated to function, my results are to the contrary, and suggest that further investigation into which aspects of community diversity drive ecosystem function is required. In conclusion, my results provide a new synthesis of the consequences of marine predator loss across the world and show how species diversity is linked to ecosystem function in local eelgrass fish communities. / Graduate / 2018-12-17

Biodiversity is a complex concept incorporating genes, species, ecosystems, composition, structure and function. The global scientific and political community has recognized the importance of biodiversity for human well-being, and has set goals and targets for its conservation, sustainable use, and benefit sharing. Monitoring biodiversity will help meet conservation goals and targets, yet observations collected in-situ are limited in space and time, which may bias interpretations and hinder conservation. Remote sensing can provide complementary datasets for monitoring biodiversity that are spatially comprehensive and repeatable. However, further research is needed to demonstrate, for various spatial scales and regions, how remotely sensed datasets represent different aspects of biodiversity. The overall goal of this dissertation is to advance the mapping and monitoring of biodiversity indicators, globally and within Canada, through the use of remote sensing. This research produced maps that were rich with spatially explicit, spatially continuous data, filling gaps in the availability and spatial resolution or scalability of information regarding ecosystem function (primary productivity) at global scales, tree species composition at regional scales (Saskatchewan, Canada), and ecosystem structure at local scales (coastal British Columbia, Canada). Further, the remotely sensed indicator datasets proposed and tested in each of the research chapters are repeatable, ecologically meaningful, translate to specific biodiversity targets globally and within Canada, and are calculable at multiple spatial scales. Challenges and opportunities for fully implementing these or similar remotely sensed biodiversity indicators and indicator datasets at a national level in Canada are discussed, contributing to the advancement of biodiversity monitoring science. / Graduate

These days, it is hard to discuss innovation and the creative economy without mentioning platforms, which have become core strategy for dominating the market. An accurate understanding of platform business is a key factor in being a successful platform provider, so discussions of platform strategies need to be invigorated, value chains need to be analysed, and theoretical factors need to be seriously considered. Corporations are yearning for new innovations and worry about the absence of an efficient and sustainable growth model. First, this thesis analyses how the value chain and value stream are changed in the platform business model in order to explore value chains and value streams in the two-sided market, which has a distinct group of users on both sides. It proposes three types of platform business strategy which will serve as a frame of reference for analysing the impact of the different value chains on platform businesses. Second, this thesis indicates how a step-by-step business strategy based on the perspective of dynamic approach could be constructed. This research identifies four major stages of platform business (entry stage, growth stage, expansion stage, and maturity stage), and different core elements and strategies exist for each stage. These serve as the conceptual frameworks with which to build a platform business model. The key contributions of this research are as follows. Firstly, the main differences and features of the literature reviewed were suggested with collective action and strategic choice perspectives from different academic approaches. Secondly, this study extends the understanding of the value chain that was the critical strategic element of a corporation in the platform business. Thirdly, this research presents the core elements and strategies for each of the four major growth stages of platform business with the dynamic approach, depending on the distinctive features of the contents and platforms.

Magister Scientiae (Biodiversity and Conservation Biology) / Two species of Chrysaora are described from the northern Benguela ecosystem: C. fulgida and C. africana. These species can be diagnosed by a combination of morphological features including lappet and tentacle number, shape of lappets, colouration patterns (alive), shape of the proximal portion of radial septa, gastrovascular pouch shape, point of attachment of gonads and the presence or absence of small raised nematocyst warts on the exumbrellar surface. Objective, quantitative statistical analyses coupled with molecular sequence data support the qualitative morphological dissimilarity observed, as these analyses unambiguously diagnose C. fulgida and C. africana as two distinct species. There is a strong superficial resemblance between the C. fulgida material described here and the preserved specimens of C. hysoscella examined at the Natural History Museum, London. Thorough investigation does however allow the separation of these two species. Morphological features found to be dissimilar were the proximal portion of the manubrium, gastrovascular pouch shape and the presence or absence of sperm sacs. Objective, quantitative statistical analyses support these findings. Nuclear sequence variation suggests considerable divergence between the two species but additional molecular work is needed. / South Africa