Ciências da Vida | Artigos em revistas internacionais / Papers in international journals
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- Population dynamics of Acartia clausi from a temperate estuary (Mondego estuary, Western Portugal)Publication . Vieira, Luís; Morgado, Fernando; Ré, Pedro; Pereira, M.; Nicolau, Paula Bacelar; Marques, João C.; Azeiteiro, UlissesThe main purpose of this study was to estimate the distribution, production and production/biomass ratio values of Acartia clausi, one of the most representative taxa of the Copepoda community in the Mondego estuary. The following biomass/length relationship was estimated for specimens of Acartia clausi: AFDW = 2.27 BL 2.41. Length-weight relationships were used to estimate production taking into account cohort growth and mortality. The annual production was calculated at 63.44 mgC m−3y−1 and the production/biomass (P/[Bbar]) ratio was estimated at 25.50. These results indicate that Acartia clausi may play a significant role in transferring energy to higher trophic levels in the Mondego estuarine system.
- Distribution, production histology and histochemistry in Acartia tonsa (Copepoda: Calanoida) as means for life history and determination in a temperate estuaryPublication . Pastorinho, Ramiro; Vieira, Luís; Ré, Pedro; Pereira, Mário; Nicolau, Paula Bacelar; Morgado, Fernando; Marques, João C.; Azeiteiro, UlissesAcartia tonsa is a key species in the Mondego estuary and a widespread species in all temperate estuarine zooplankton communities; a fact that bestows high relevance upon the outcome of this study. One of the purposes of this study was to estimate the distribution, production and production/biomass ratio values of A. tonsa. Biomass/length relationship was estimated as follows: Y = 0.15e3.04x. Length-weight relationships were used to estimate production taking into account cohort growth and mortality. The annual production was calculated to be 43.12 mg Cm–3 year–1 and the production/biomass (P/B) ratio was estimated to be 10.56. The other purpose of this study was to use histology, histochemistry and biometry to determine as to whether fecundity is a limiting factor in itself or are zooplankters constrained to respond to an ever changing environment. Analyses of the maturation stage of oocytes in adult ovigerous females performed in two different periods of opposed abundance (February— high abundance, representing maximum fertility—and September—low abundance, representing “sterility”) demonstrated the presence of all three considered oocytical development stages: immature, vitellogenic and mature; with emphasis on the latter since it indicates a permanent capability for reproduction despite the registered population abundances. Taking into account the relevance of the species, this fact demonstrates the modulating influence of ecological parameters on general zooplankton reproductive traits.
- Bacterioplankton dynamics in the Mondego estuary (Portugal)Publication . Nicolau, Paula Bacelar; Nicolau, Leonor Bacelar; Marques, J. C.; Morgado, Fernando; Azeiteiro, UlissesIn this work, the density of bacterioplankton and environmental parameters were monitored over a 11 month period (July 1999-June 2000), and also during one tidal cycle (15 June 2000), at two sampling stations, in the estuary of River Mondego. These data were treated by multivariate analyses methods in order to identify the key factors that control the dynamics of the bacterioplankton in the estuary. Bacterial dynamics were dominated by temporal gradients (annual seasons and tide-related) and less by the spatial structure of the estuary. Three main metabolic groups of bacterioplankton—aerobic heterotrophic bacteria, sulphate-reducing bacteria (SRB) and nitrate-reducing bacteria (NRB)—involved in the cycling of organic matter, were present in the water column of the estuary.Their relative abundance depended on the particular physical, chemical and biological environment. The abundance of aerobic heterotrophic bacteria, during the 11 month study, was modelled as a function of nitrate (the most important variable, with a negative effect), temperature, salinity and pH (with positive effects). SRB appeared to be limited to the water-sediment interface, where concentrations of sulphate and POM were greater.A competition between SRB and NRB for carbon has also been suggested.
- Vanadium, rubidium and potassium in Octopus vulgaris (Mollusca: Cephalopoda)Publication . Seixas, Sónia; Pierce, GrahamThe levels of vanadium, rubidium and potassium were determined in Octopus vulgaris caught during commercial fishing activities at three locations (Cascais, Santa Luzia and Viana do Castelo) in Portugal in autumn and spring. We determined the concentration of these elements in digestive gland, branchial heart, gills, mantle and arms in males and females. At least five males and five females were assessed for each season/location combination. Elemental concentrations were determined by Particle Induced X-ray Emission (PIXE). Vanadium was detectable only in digestive gland and branchial heart samples. Its concentration was not correlated with total weight, total length or mantle length. There were no differences in concentrations of V, Rb and K between sexes. There were significant differences in vanadium concentrations in branchial hearts in autumn between samples from Viana do Castelo and those from the other two sites. We found a significant positive relationship between the concentration of vanadium and those of potassium and rubidium in branchial hearts. Branchial hearts appear to play an important role in decontamination of V.
- Clinical variables related to propofol effect-site concentrations at recovery of consciousness after neurosurgical proceduresPublication . Nunes, Catarina S.; Ferreira, David A.; Antunes, Luís; Amorim, PedroTarget controlled infusion (TCI) systems and computer data acquisition software are increasingly used in anesthesia. It was hypothesized that the use of such systems might allow retrieval of information useful to anticipate the effect-site concentrations of propofol at which patients would recover from anesthesia. The goal of the study was to identify variables related to propofol effect-site concentrations at recovery of consciousness (ROC). Sixteen patients with a Glasgow of 15, ASA 1 or 2, subjected to neurosurgical procedures, received TIVA with TCI propofol and remifentanil. Data were collected every 5 seconds from Datex AS3 and Aspect A200XP (BIS). Effect-site TCI was used for propofol (initial effect target 5.0 mg/ml) and for remifentanil (initial plasma target 2.5 ng/ml). All clinical events were noted. Variables possibly related to propofol effect-site concentration at ROC were selected. Data are expressed as mean 6 SD. Effect-site propofol concentration at ROC was 1.3 6 0.5 mg/ml. A positive correlation was found between propofol effectsite concentration at ROC and: age (49.3 6 17 years) (P = 0.003); mean remifentanil dose during surgery (0.11 6 0.05 mg/kg/min) (P = 0.003); mean propofol dose during surgery (0.12 6 0.03 mg/kg/min) (P = 0.046); and remifentanil effect-site concentration at ROC (2.85 6 2.06 ng/ml) (P = 0.002). Propofol effect-site concentrations were not correlated with: weight, height, LBM, duration of anesthesia, minimum BIS at induction (30.4 6 6.8), time till minimum BIS (4.7 6 2.2 min), mean and median BIS during surgery (38.2 6 4.5 and 37.8 6 5.3). BIS-related variables were not useful as ROC predictors. Only drug variables and age correlated with propofol effectsite concentrations at ROC.
- Accumulation of mercury in the tissues of the common octopus Octopus vulgaris (L.) in two localities on the Portuguese coastPublication . Seixas, Sónia; Bustamante, Paco; Pierce, GrahamMercury concentrations were measured in tissues of 12 individuals of Octopus vulgaris, captured by the commercial fishery at two points along the Portuguese coast, Viana do Castelo and Cascais, in spring 2002. Concentrations were determined in six tissues (digestive gland, branchial hearts, gills, mantle, arms, and gonads). Correlations between mercury concentrations in different tissues were examined as were correlations between mercury levels and total length, mantle length, weight, gonadosomatic index, digestive gland index, and state of maturation. Differences between sexes and localities were analysed. The concentration of mercury in the digestive gland (Viana, 0.58F0.08, and Cascais, 3.43F2.57 mg/kg dry weight) was higher than in the other tissues, and values were generally similar to those recorded in previous studies on octopods. Arm muscle contained most of the mercury with 56% of the total body burden followed by the digestive gland with 31%, mantle with 11%, gills with 0.8%, gonad with 0.5%, and branchial heart with 0.2%. In all tissues, mercury concentrations were slightly higher in samples from Cascais than in Viana do Castelo, which is consistent with higher concentrations recorded in seawater at Cascais. Levels of mercury determined in octopus were within the range of values legally defined as safe for human consumption.
- Regular clinical use bispectral index monitoring may result in lighter depth of anesthesia as reflected in average higher bispectral index valuesPublication . Nunes, Catarina S.; Ferreira, David A.; Antunes, Luís M.; Amorim, Pedro
- Assessing heavy metal contamination in Sado EstuaryPublication . Caeiro, Sandra; Costa, Maria Helena; Ramos, Tomás B.; Fernandes, F.; Silveira, N.; Coimbra, Ana Paula; Medeiros, G.; Painho, MarcoThe Sado Estuary in Portugal is a good example of a site where human pressures and ecological values collide with each other. An overall contamination assessment has never been conducted in a way that is comprehensible to estuary managers. One of the aims of this work was to select different types of index to aggregate and assess heavy metal contamination in the Sado Estuary in an accessible manner. Another aim was to use interpolation surfaces per metal to compare and gauge the results of the indices and to assess the contamination separately per metal. Seventy-eight stations were sampled within the main bay of the estuary and a set of heavy metals and metalloids was established, Cd, Cu, Pb, Cr, Hg, Al, Zn and As. The sediment fine fraction content, organic matter and redox potential were also analysed. Various indices for contamination, background enrichment and ecological risk were used, tested, compared and performance-evaluated. All metals and metalloids were strongly correlated, and the indices appear to reflect heavy metal variability satisfactorily. Difficulties were found in some indices regarding boundary definition (minimum and maximum) and comparability with other estuaries, thus better methods of standardization should be a priority issue. According to the index that has the highest performance score within the group of ecological risk indices – the Sediment Quality Guideline Quotient – only 3% of the stations are highly contaminated and register a high potential for observing adverse biological effects, whereas 47% display moderate contamination. This index can be complemented with the contamination index, which allows more site-specific and accurate information on contaminant levels. If the aim of work on contamination evaluation is to assess the overall contamination of a study area, the indices are highly appropriate. For spatial and source evaluation per metal, interpolation surfaces should also be used.
- Bioaccumulation of lead, calcium and strontium and their relationships in the Octopus Octopus vulgarisPublication . Seixas, Sónia; Pierce, GrahamOctopuses (Octopus vulgaris) landed from commercial fishing were sampled and the concentrations of lead, calcium and strontium, in digestive gland, branchial heart, gills, mantle and arms, were determined using PIXE (particle-induced X-ray emission). Lead was detected in all tissues, although not in samples from all animals analysed. Female octopuses accumulated more lead in digestive gland than did males. The digestive gland index, an indicator of nutritional status, showed a negative correlation with lead concentration in both sexes. There were positive correlations between the concentration of lead and those of calcium and strontium in digestive gland and a negative correlation between lead and calcium in branchial heart tissue. Concentrations of calcium in arms were lower in autumn and spring than in winter and summer. Lead content increased with increasing body weight and mantle length so we can conclude that lead continues to accumulate during the animal’s life. Concentrations of lead in two samples were higher than the maximum legally permitted concentration of lead in food.
- Benthic biotope index for classifying habitats in the sado estuary: PortugalPublication . Caeiro, Sandra; Costa, Maria Helena; Goovaerts, Peter; Marco, Painho; Flavio, MartinsAn integration of sediment physical, chemical, biological, and toxicity data is necessary for a meaningful interpretation of the complex sediment conditions in the marine environment. Assessment of benthic community is a vital component for that interpretation, yet their evaluation is complex and requires a large expenditure of time and funds. Thus, there is a need for new tools that are less expensive and more understandable for managers. This paper presents a benthic biotope index to predict from physical and chemical variables the occurrence of macrobenthic habitats. Parameters such as sediment type, organic matter, depth, and hydrodynamic parameters were selected, through a discriminant analysis, to compute the index. Other authors have used multivariate methods to determine the benthic biotopes for Sado Estuary. The index proved to be a valid tool to classify and assess the spatial patterns of benthic habitat and to synthesize stress biotope gradients.