The effect of stress on egg quality in farmed Atlantic Cod (Gadus morhua L.)

Dissertação de mestrado, Aquacultura, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2011

Alterações à fisiologia e infeção por Plasmodium berghei do mosquito Anopheles gambiae mediadas pela ativação de recetores GPCR

Dissertação de Mestrado, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2015

Spatial patterns of genetic diversity in Mediterranean eagle owl Bubo bubo populations

Little information is available on the patterns of genetic connectivity in owls. We studied the genetic structure of the eagle owl Bubo bubo (Linnaeus, 1758) in southeastern Spain at two different spatial scales. Seven microsatellites previously described for this species were used, although only six loci amplified correctly. The observed low genetic variation could be explained by the short dispersal distance, high mortality rate and high degree of monogamy shown by this large nocturnal predator. As expected, the highest genetic isolation was detected in the geographically most isolated population. Significant genetic differentiation was found among study units separated by less than 50 km. The territorial analysis showed interesting connectivity patterns related with the gene flow and turnover rate of the breeding individuals. The lowest genetic diversity was found in the region with the largest population, which could imply incipient inbreeding.

In two waters: contemporary evolution of lagoonal and marine white seabream (Diplodus sargus) populations

Brackish water ecosystems are often exposed to wide variations in environmental variables, including temperature and salinity, which may cause strong selective pressures on organisms modifying the genetic patterns of species. The aim of this work was to test whether there is a ‘divergence-with-gene flow’ in coastal lagoon populations of white seabream (Diplodus sargus) (Ria Formosa, S Portugal and Mar Menor, SE Spain) respect to four marine populations, by using partial sequences of cyt b mitochondrial gene and information from nine microsatellite loci. Genetic diversity was highest in both coastal lagoons (Mar Menor and Ria Formosa) considering mitochondrial and nuclear markers. Although some of FST population pairwise comparisons were not significant, analyses of molecular variance (AMOVAs) detected differences between groups (coastal lagoon and marine) close to significance. Also, only two haplotypes (Cytb-17 and Cytb-18) were detected in both coastal lagoon sampling sites and these localities (Mar Menor and Ria Formosa) showed the highest number of singletons, some of them with a high number of mutations, as has been already described for other Mar Menor populations (Pomatochistus marmoratus and Holothuria polii). Also, several tests detected significant positive and balancing selection considering mtDNA and microsatellite data. These data support the hypothesis of selection as one of the drivers of the genetic differences found between coastal lagoon and marine populations. The life strategy adopted by Diplodus sargus in coastal lagoons allows it to decrease its mortality rate and improve the heritability of its genes. Also, the increase time spent in coastal lagoons with different temperatures and salinities favours the fitness selection and the maintenance of exclusive haplotypes and genotypes in coastal lagoon inhabitants favouring the ‘divergence-with-gene-flow’.

The efficacy of releasing caught Nephrops as a management measure

The objective of this work was to examine if a policy of releasing caught lobsters, Nephrops, could be used to protect the Nephrops population off the south coast of Portugal. Such a measure, as an alternative to closing the fishery completely, would allow the continued operation of the fleet in targeting other species, resulting in a reduced economic and social impact compared with a complete closure. For such a proposal to be considered, information on survival rates of released lobsters is required. Nephrops were sampled randomly from the catch of commercial trawlers and put in cages, in an area with similar conditions to the area where they were caught, in order to evaluate survival rates. The cages were immersed for periods of 5–9 days. Several factors were considered to potentially affect survival, including duration of the tow and season, and biological characteristics of the individuals (e.g. size, sex and ovigerous condition). Survival was only affected by season (increased mortality inwarm months).Aglobal estimate of survival of released lobsters, taking into consideration survival and proportion of the catches for each season, was 35%. Simulation models were used to investigate the potential effect of a release measure on the population. Assuming the number of recaptured individuals is negligible, Z (instantaneous total mortality rate)would be considerably reduced if a release policy was implemented. This is particularly important if the levels of exploitation are high, which seems to be the case in this stock. It is our belief that the implementation of amanagement measure of returning all caught lobsters to the sea is worth considering as a means of aiding recovery of the resource. This measure would have the side effect of discouraging the choice of Nephrops as a target species, potentially reducing the fishing mortality even more significantly.