Marine foundation species shifting ranges and genetic baselines

This thesis revealed the most importance factors shaping the distribution, abundance and genetic diversity of four marine foundation species. Environmental conditions, particularly sea temperatures, nutrient availability and ocean waves, played a primary role in shaping the spatial distribution and abundance of populations, acting on scales varying from tens of meters to hundreds of kilometres. Furthermore, the use of Species Distribution Models (SDMs) with biological records of occurrence and high-resolution oceanographic data, allowed predicting species distributions across time. This approach highlighted the role of climate change, particularly when extreme temperatures prevailed during glacial and interglacial periods. These results, when combined with mtDNA and microsatellite genetic variation of populations allowed inferring for the influence of past range dynamics in the genetic diversity and structure of populations. For instance, the Last Glacial Maximum produced important shifts in species ranges, leaving obvious signatures of higher genetic diversities in regions where populations persisted (i.e., refugia). However, it was found that a species’ genetic pool is shaped by regions of persistence, adjacent to others experiencing expansions and contractions. Contradicting expectations, refugia seem to play a minor role on the re(colonization) process of previously eroded populations. In addition, the available habitat area for expanding populations and the inherent mechanisms of species dispersal in occupying available habitats were also found to be fundamental in shaping the distributions of genetic diversity. However, results suggest that the high levels of genetic diversity in some populations do not rule out that they may have experienced strong genetic erosion in the past, a process here named shifting genetic baselines. Furthermore, this thesis predicted an ongoing retraction at the rear edges and extinctions of unique genetic lineages, which will impoverish the global gene pool, strongly shifting the genetic baselines in the future.

Effects of nutrient and light enrichment on phytoplankton growth

Alterations of freshwater flow regimes and increasing eutrophication lead to alterations in light availability and nutrient loading into adjacent estuaries and coastal areas. Phytoplankton community respond to these changes in many ways. Harmful phytoplankton blooms, for instance, may be a consequence of changes in nutrient supply, as well as the replacement of some phytoplankton species (like diatoms, that contribute for the development of large fish and shellfish populations) by ohers (like cyanobacteria, that may be toxic and represent an undesirable food source for higher trophic levels). Nutrient and light enrichment experiments allow us to understand and predict the effects of eutrophication on the growth of phytoplankton. This is a fundamental tool in water management issues, since it enables the prediction of changes in the phytoplankton community that may be harmful to the whole ecosystem, and the design of mitigation strategies (Zalewski 2000).

Primary production in systems subject to natural and anthropogenic eutrophication

Tese dout., Química, Universidade do Algarve, 2005

The role of papyrus plants (Cyperus papyrus) and internal waves in the nutrient balance of Lake Victoria, East Africa

Dissertação mest., Gestão da água e da costa, Universidade do Algarve, 2007

Bottom-up regulation of phytoplankton in the Guadiana estuary

Tese dout., Ciências do Mar (Ecologia Marinha), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2010

Temperature, pH, and conductivity control of the nutrient solution of an hydroponic greenhouse

One of the aspects of modern agriculture is characterised by a culture without soil (hydroponic cultures). These culture techniques are identified by possessing automatic control systems to control the nutrient solution. In first hydroponic cultures this control was accomplished by “on- off” analog controllers that applied a single control law implemented in hardware. Therefore, the changes of the control law resulted in the change of all interface electronics. In digital control implemented by micro-controllers the alteration of such control law is easily performed by changing only a computer program, leaving untouched all the interface hardware. In this way, the use and substitution of the control strategy is improved, as well, the use of advanced control strategies.

Interaction between water and nutrient deficiencies in helianthus annuus

The physiological response of plants to water deficits are known to vary according to the conditions of application of drought stress and the rate of development of leaf water deficits. At the whole plant level the effect of the water shess is usually perceived as a decrease in photosynthesis and growth, and is associated with alterations in C and N metabolism (McDonald and Davies, 1996). The decrease in water potential affects transpiration and hence xylem transport of nitrate or reduced N into growing regions. The response of the photo-synthetic apparatus either to water stress or rehydration seems to be dependent "on leaf age (O'Neill, 1983; Wolfe et al., 1988). Degradation of both thylakoid and stromal N-containing compounds can occur in response to water stress, recovery from which may pequire more than a week (Chaves, 1991).

A proteomic study of the effects of nutrient restriction in utero on postnatal metabolism

It is widely recognized that protein restriction in utero may cause metabolic and endocrine adaptations, which may be of benefit to the neonate on a short-term basis but may cause adverse long-term conditions such as obesity, Type 2 diabetes, metabolic syndrome, hypertension and cardiovascular diseases. Adequate foetal and early post natal nutrient and energy supply is therefore essential for adult animal health, performance and life span. In this project it was investigated the progressive adaptations of the hepatic proteome in male mink offspring exposed to either a low protein (FL) or an adequate protein (FA) diet in utero fed either on a low protein (LP) or on an adequate (AP) diet from weaning until sexual maturity. Specifically, the aim was to determine the metabolic adaptations at selected phases of the animal’s first annual cycle and establish the metabolic priorities occurring during those phases. The three different morphological stages studied during the first year of development included, end of bone growth at 4 months of age, maximal fat accretion at 6 months of age and sexual maturity at 12 months of age. A reference proteome of mink liver coming from these different animal groups were generated using 2D electrophoresis coupled to MALDI-TOF analysis and the way in which dietary treatment affect their proteome was established. Approximately 330 proteins were detected in the mink liver proteome. A total of 27 comparisons were carried out between all different animal groups which resulted in 20 differentially expressed proteins. An extensive survey was conducted towards the characterization of these proteins including their subcellular localization, the biological processes in which they are involved and their molecular functions. This characterization allowed the identification of proteins in various processes including the glycolysis and fatty acid metabolism. The detailed analysis of the different dietary treatment animal groups was indicative of differences in metabolism and also to changes associated with development in mink.