1,720,976 research outputs found
Variability in the structure of epiphytic assemblages of the Mediterranean seagrass Posidonia oceanica in relation to depth
No full textEffects of enhanced loads of nutrients on epiphytes on leaves and rhizomes of Posidonia oceanica
No full textThe increase of anthropogenic activities has severely altered both terrestrial and aquatic systems. Urbanisation, excessive use of agricultural fertilisers, organic runoff and climate change have caused an increase of nutrients in coastal waters, altering the diversity and food-web structure of benthic assemblages. The aims of the present paper were to text if an experimentally increased availability of nutrients, primarily nitrogen and phosphorous, in an oligotrophic basin, would affect epiphytic assemblages on leaves and rhizomes of P. oceanica and whether this could change rates of consumption of the plant by herbivores. In particular, we tested the hypothesis i) that changes to species composition and abundance of epiphytic assemblages generated by nutrients enrichment would vary between leaves and rhizomes and that ii) alterations to epiphytic assemblages on leaves might, in turn, modify feeding rates of herbivorous fish. After two years, the structure of both leaf and rhizome epiphytic assemblages responded to changes in nutrient concentrations before the occurrence of drastic alterations to the host plant, but only the former showed significant changes in terms of species composition. Moreover, a larger intensity of grazing on P. oceanica leaves was documented in experimentally enriched areas than in controls. The present findings and conclusions are applicable to other systems where patterns of biodiversity depend on changes in the availability of nutrients due to natural or anthropogenic events, likely interacting with biological processes, such as competition and grazing
Supercritical fluid extraction of oil from schizochytrium sp.
No full textMicroalgae are recognised as an important renewable source of lipids with a high proportion of polyunsatured fatty acids, which have been shown to be effective in preventing or treating several diseases. For the extraction of oil from microalgae, supercritical CO2 (ScCO2) is regarded with interest. In such a contest a mathematical model, able to describe the kinetics of a ScCO2 extraction process, was applied to the recovery of oil from the microalga Schizochytrium sp., characterised by a particularly high content in docosahexaenoic acid. The mathematical model, which allows the optimisation of working parameters and the determination of process yields, is reported together with the effect of operating conditions on extraction kinetics and fatty acid composition of extracts
Kinetics of supercritical CO2 extraction of bioactive oil from microalga Spirulina platensis
No full text
- …
