9,885 research outputs found
Effects of elevated CO2 and nutrients on the community metabolism of a Cymodocea nodosa bed
We assessed the combined effects of elevated CO2 and nutrients on the metabolism of a benthic community dominated by the seagrass Cymodocea nodosa (Ucria) Ascherson in a mesocosm experiment. C. nodosa plants and their associated community were exposed to two CO2 levels simulating future (700 ppm, pH 7.84) and current (360 ppm, pH 8.12) conditions, and two nutrient levels (enriched and ambient concentration) in a total of four treatments (-C-N, -C+N, +C-N, +C+N). Net community production (NCP) was estimated from changes in the concentration of dissolved inorganic carbon in the seawater in light incubations using benthic chambers. The variation pattern of NCP with the ordinance was consistent for all treatments. Although differences among treatments were not statistically significant, average NCP values were lowest under CO2 enrichment conditions. NCP was lower at a high CO2 level and ambient nitrogen concentration compared to when nutrient availability was higher, suggesting that the low nutrient availability may modulate the community response to CO2 enrichment. The results obtained suggest that the stimulation of the net community production of C. nodosa by elevated CO2 concentrations may be curtailed by low nutrient availability
On the vulval morphology of some species of Bursaphelenchus (Nematoda: Parasitaphelenchinae)
The vulval pattern of six species of the genus Bursaphelenchus (B. abruptus, B. conicaudatus, B. fraudulentus,
B. luxuriosae, B. mucronatus and B. xylophilus) was studied using scanning electron microscopy. A terminology for the vulval region
structures observed is proposed herein and illustrated by micrographs and line drawings. It was shown that, of the studied species, only
B. mucronatus and B. xylophilus share an identical morphology of the vulval region, all other species differing significantly from each
other and from both B. mucronatus and B. xylophilus. This study indicates the diagnostic potential for variation in vulval morphology
within Bursaphelenchus and it is recommended that such features are recorded in all future descriptions
Nitrogen metabolism in the seagrass Zostera noltii
Tese de dout., Ciências do Mar (Ecologia Marinha), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011Nitrogen metabolism is a vital component in plant’s life. The main purpose of this thesis was to investigate the ecophysiology of nitrogen metabolism of the seagrass Zostera noltii in Ria Formosa lagoon. In the global change scenario, the effects of CO2 enrichment on photosynthesis, growth and nitrogen metabolism of Z. noltii were also investigated. Ammonium was identified as the preferential Ni source for Z. noltii, although nitrate uptake rates were considerable in the absence of ammonium. The ammonium uptake rates through the leaves were one order of magnitude higher than through the roots. Leaves were also identified as the main site for the reduction of ammonium and nitrate, as revealed by the much higher activity of the enzymes nitrate reductase and glutamine synthetase in the leaves than in the roots. The simultaneous supply of both Ni forms to Z. noltii enhanced the ammonium uptake rates and decreased the rates of nitrate uptake comparatively to the rates obtained when Ni forms were supplied separately. The uptake of ammonium or nitrate by one plant part (e.g. leaves) did not affect the uptake rate of the other plant part (e.g. roots), and no internal translocation of incorporated nitrogen was detected. The estimated whole-plant nitrogen budget of Z. noltii in the peak production season (spring) was slightly lower than the total nitrogen requirement for growth, which indicates that the growth of Z. noltii in the lagoon is only slightly limited by nitrogen. Z. noltii took up ammonium and nitrate at similar rates in the light and in the dark. In both light conditions, the nitrogen uptake displayed a temporal pattern of enhanced initial rates followed by lower but relatively constant rates. The uptake of nitrogen in the dark represented an additional use and mobilization of carbohydrate reserves. Z. noltii plants exposed to CO2-enriched conditions
enhanced the photosynthetic rates while growth and ammonium uptake rates were not affected, suggesting that Z. noltii may benefit from future increases in seawater CO2 concentrations.Fundação para a Ciência e Tecnologia (FCT
Demand for higher education programs: the impact of the Bologna process
The Bologna process aims at creating a European Higher Education Area where intercountry mobility of students and sta?, as well as workers holding a degree, is facilitated. While several aspects of the process deserve wide public support, the reduction of the length of the first cycle of studies to three years, in several continental European countries where it used to last for four or five years, is less consensual. The paper checks the extent of public confidence in the restructuring of higher education currently underway, by looking at its implications on the demand for academic programs. It exploits the fact that some programs have restructured under the Bologna process and others have not, in Portugal. Precise quantification of the demand for each academic program is facilitated by the rules of access to higher education, in a nation-wide competition, where candidates must list up to six preferences of institution and program. We use regression analysis applied to count data, estimating negative binomial models. Results indicate that the programs that restructured to follow the Bologna principles were subject to higher demand than comparable programs that did not restructure, as if Bologna were understood as a quality stamp. This positive impact was reinforced if the institution was a leader, i.e. the single one in the country that restructured the program. Still an additional increase in demand was experienced by large programs that restructured to offer an integrated master degree, thus conforming to Bologna principles while not reducing the program duration.education policy; European Higher Education Area; economic, social and cultural integration; count data.
Demand for Higher Education Programs: The Impact of the Bologna Process
The Bologna process aims at creating a European Higher Education Area where inter-country mobility of students and staff, as well as workers holding a degree, is facilitated. While several aspects of the process deserve wide public support, the reduction of the length of the first cycle of studies to three years, in several continental European countries where it used to last for four or five years, is less consensual. The paper checks the extent of public confidence in the restructuring of higher education currently underway, by looking at its implications on the demand for academic programs in Portugal. Precise quantification of the demand for each academic program is facilitated by the rules of access to higher education, in a nation-wide competition, where candidates must list up to six preferences of institution and program. We use regression analysis applied to count data, estimating negative binomial models. Results indicate that the programs that restructured to follow the Bologna principles were subject to higher demand than comparable programs that did not restructure, as if Bologna were understood as a quality stamp. This positive impact was reinforced if the institution was a leader, i.e. the single one in the country that restructured that program. Still an additional increase in demand was experienced by large programs that restructured to offer an integrated master degree, thus conforming to Bologna principles while not reducing the program duration.education policy, European Higher Education Area, economic, social and cultural integration, count data
First description of seagrass distribution and abundance in Sao Tome and Principe
Seagrass meadows in Sao Tome and Principe, eastern Atlantic Ocean, are described here for the first time. Specifically, we quantified the biomass and density of seagrasses, characterized the plant morphology and measure their nutrient content as a proxy of the nutrient environmental conditions where the meadows develop. The seagrass Halodule wrightii was found in two locations of the northeastern coast of the island of Sao Tome: 1) developing throughout an estimated area of 1500 ha surrounding Cabras islet, at a depth range of 4-10 m, on sandy bottom; and 2) at Santana bay with an area of 1500 m(2) at 5-10 m depth, on sandy bottom. A highly morphologically different population of Halodule wrightii was found on the northeastern coast of the island of Principe, off Abade beach, covering an area of 135 m2 at 4 m depth. Further research is needed to assess if this is a different species. Shoot biomass and density was 10 and 4-fold higher in Sao Tome than in Principe, respectively. CN ratios of above and belowground tissues of plants collected in Sao Tome were also significantly higher than in Principe. The carbon content of Halodule leaves from Sao Tome and Principe (41%) was much higher than that reported for other Halodule species, suggesting that meadows may have an important ecological role for carbon fixation. The presence of H. wrightii in Sao Tome and Principe raises ecological and evolutionary questions that warrant further research.PADI Foundation [21670
Greenwashing na publicidade associada ao consumo de energia e às alterações climáticas
Na "publicidade verde" as empresas alegam qualidades ecológicas dos produtos, embora muitas vezes estas não possam ser realmente comprovadas ou a informação fornecida seja insuficiente para o efectivo esclarecimento do consumidor. É o caso de menções como "produto amigo do ambiente", "protege a natureza", "100% natural" ou "não poluente". O criticismo gerado pelos abusos praticados conduziu a que diversos autores apelidassem o fenómeno de greenwashing (Westerveld, 1986), sugerindo uma camuflagem de produtos convencionais com uma errónea imagem de impactos ambientais reduzidos. O cepticismo desenvolvido relativamente a este tipo de marketing poderá explicar o decréscimo na «publicidade verde» a partir de meados dos anos 90 (Corbett, 2002; Hansen, 2002). Mas nos últimos anos a atenção pública internacionalmente dada aos problemas relacionados com as alterações climáticas e à crise energética parece ter motivado um recrudescimento deste género de publicidade, sobretudo com recurso a argumentos relativos ao consumo de energia e à redução de emissões de gases com efeito de estufa (Alexandre e Horta, 2011). Neste trabalho analisam-se os argumentos veiculados nos anúncios publicitários considerados «verdes», identificando as estratégias de greenwashing centradas na eficiência energética e na redução de emissões com impacto nas alterações climáticas. A análise realizada incidiu numa amostra representativa de todos os anúncios com aqueles argumentos inseridos na revista de informação geral semanal Visão, de 2007 a 2011
- …