Browsing by Author "Vale, C."
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- Biomarkers: a strategic tool in the assessment of environmental quality of coastal watersPublication . Picado, Ana; Bebianno, Maria João; Costa, M. H.; Ferreira, A.; Vale, C.Ecosystems are under the pressure of complex mixtures of contaminants whose effects are not always simple to assess. Biomarkers, acting as early warning signals of the presence of potentially toxic xenobiotics, are useful tools for assessing either exposure to, or the effects of these compounds providing information about the toxicant bioavailability. In fact, it has been argued that a full understanding of ecotoxicological processes must consider an integrated multi-level approach, in which molecular impact is related with higher-order biological consequences at the individual, population and community levels. Monitoring programs should make use of this tool to link contaminants and ecological responses fulfilling strategies like those launched by OSPAR (Commissions of Oslo and Paris) Convention on the protection of the marine environment of the North-East Atlantic and the International Council for the Exploration of the Sea (ICES). An overview of the work done in the past few years using biomarkers as in situ tools for pollution assessment in Portuguese coastal waters is presented as a contribution to the set up of a biomonitoring program for the Portuguese coastal zone. Considering the data set available the biomonitoring proposal should include the analysis of biomarkers and effects at individual levels. The aim of the program will include a spatial and temporal characterization of the biomarkers acetyl-cholinesterase, metallothioneins, DNA damage, adenylate energy charge and scope-for-growth levels. The investigation of the spatial variation of biomarkers is crucial to define sites for long term monitoring, which will be integrated with a chemical monitoring program. This framework will be a major contribution to the implementation of a national database for the use of biomarkers along the Portuguese coast.
- Distribution of Fe, Mn, Cu and Cd in upper sediments and sediment-trap material of Ria Formosa (Portugal)Publication . Caetano, M.; Vale, C.; Bebianno, Maria JoãoIn shallow highly productive coastal environments intense biogeochemical activity is concentrated in the upper sediment layers. However, pore water composition of permeable inter-tidal sediments change as water flows over the areas during ebb and flood tides. In order to examine metal post-mobilisation, inter-tidal sediment cores of 4 cm length and particles settled in sediment-traps over several periods during 10 months were collected in Ria Formosa (SW Iberian Peninsula). Concentrations of Al, Fe, Mn, Cu and Cd, loss on ignition and the proportion of fine fraction were determined in sediment layers of 0.5 cm thickness and in sediment-trap material. Levels of Mn in sediments were similar to those in sediment-trap material, although enrichment in the topmost sediment layer (0.1 mm) was observed as MnO2 is formed. Although Fe in sediments and sediment-trap material ranged within similar intervals, two relationships with Al were found showing that sediment-trap material are impoverished in Fe in comparison to sediments. This suggests that Fe is mainly cycled inside the sediment. Copper and Cd exhibited different patterns. Levels in sediment-trap material were not correlated to Al or LOI, probably due to local contamination or uptake by plankton. These values were lower than levels in the topmost sediment layer, suggesting that Cu and Cd that reach the sediment surface are rapidly released to the water column. Concentrations in sediments, including the topmost layer, exhibited two relationships to Al, for both Cu and Cd. One corresponding to background values and the other found in stations closer to the anthropogenic sources. In these cases Cu and Cd are incorporated into the sediments that is facilitated by AVS values close to the sediment surface.
- Evaluation of eutrophication in the Ria Formosa coastal lagoon, PortugalPublication . Newton, Alice; Icely, John; Falcão, Manuela; Nobre, A.; Nunes, J.; Ferreira, J.; Vale, C.The Ria Formosa is a shallow mesotidal lagoon on the south coast of Portugal, with natural biogeochemical cycles essentially regulated by tidal exchanges at the seawater boundaries and at the sediment interface. Existing data on nutrients in the water column and the sediment, together with chlorophyll a and oxygen saturation in the water column,compared using different models for assessing eutrophication. The European Environmental Agency criteria are based on the comparison of nutrient concentrations which indicate that the situation in the Ria Formosa is ‘‘poor’’ to ‘‘bad’’. In contrast, the United States Estuarine Eutrophication Assessment is based on symptoms, including high chlorophyll a and low oxygen saturation, which indicate that the Ria Formosa is near pristine. Despite these contradictions, a preliminary assessment by Driving forces, Pressures, State, Impact, Reponses(DPSIR) of eutrophication demonstrate the potential for episodic eutrophic conditions from treated and untreated domestic effluent as well as from non-point source agricultural run off. Sediments are also an important source of nutrients in the lagoon, but their contribution to potential eutrophic conditions is unknown.
- Hg and metallothionein-like proteins in the black scabbardfish Aphanopus carboPublication . Bebianno, Maria João; Santos, Carolina; Canário, J.; Gouveia, N.; Sena-Carvalho, D.; Vale, C.Aphanopus carbo fishery is economically relevant in Portugal (Madeira Archipelago) since the 19th century and an important diet component of its inhabitants. However, Hg levels in this species are a cause of concern due to the insufficient knowledge of Hg subcellular distribution, accumulation and detoxification mechanisms. Hg concentrations (total and subcellular) and metallothionein-like proteins (MTs) were measured in the gills, muscle and liver of A. carbo of different size (50-150 cm) to assess Hg subcellular distribution and the role of MT in Hg binding. Total Hg concentrations in A. carbo decrease from liver to gills and increase exponentially with fish length in all tissues. Hg subcellular distribution in muscle and liver decreased from insoluble > high molecular weight proteins and heat-treated cytosol where MT occurs highlighting the role of the insoluble fraction in Hg distribution. In the gills, Hg was mainly in the soluble fraction except for 75-100 cm specimens, whose Hg distribution was similar between soluble and insoluble factions. The variation of MT with size is different from that of Hg. MT levels in the gills decrease with size/age and is unrelated with Hg concentrations. In the muscle although decreasing with size/age, MT is inversely proportional to Hg. In the liver, however, MT is directly proportional with size/age and to the Hg accumulated (total and HTC subcellular fraction) highlighting an age related change in these two parameters and the importance of MT in detoxifying Hg in this tissue. Due to Hg concentrations present in the muscle (used for human consumption) and liver (consumed mainly by fisherman) consumption of A. carbo should be taken with caution in a population with such an important seafood weekly intake.
- Spatial and temporal assessment of sediment contamination in Sado estuary: a methodological approachPublication . Nunes, L.; Caeiro, S.; Costa, Maria H.; Caetano, M.; Martins, Flávio Augusto Bastos da Cruz; Castro, O.; Vale, C.For better management of estuarine ecosystems their contamination assessment should be easily communicated to local managers and decision makers. The problem is the lack of available data and the search of methodologies to enable that assessment using only few data. The Sado estuary in Portugal is as good example of a site where human pressures and ecological values collide with each other and where the degree of metal and organic contamination has not been subject to an overall assessment, either in terms of spatial or temporal variability, in a way that managers can understand.
- Tidal flushing of ammonium, iron and manganese from inter-tidal sediment pore watersPublication . Caetano, M.; Falcão, M.; Vale, C.; Bebianno, Maria JoãoConcentrations of ammonium, manganese and iron were examined in sediment pore water and near-bottom water of inter-tidal sediments of Ria Formosa, a coastal lagoon in the South of Portugal, during the short period of time that water flooded the area. Short-sediment cores and overlying water retained during the ebb tide were sampled at air-exposed area. Immediately after the inundation sediment cores and flooding water were repeatedly collected over short periods of time: 20 min for ammonium and 60 min for iron and manganese. The pore water composition of the upper 2-cm sediment changed dramatically in NH4+, Mn and Fe during the first minutes of the flood. This decrease was recorded together with an increase of ammonium and manganese in the flooding water. The inundation causes a mixing of freshly tidal water in the interstices of sediment surface, pore water being mixed with sea water and oxygen supplied to anoxic layers of the sediment. Consequently NH: in pore water and weakly bound to sediment is exported to the water column, Mn(II) also escapes from the sediment, but Fe(II) is oxidised rapidly and iron is recycled inside the sediment. These processes occur on a semi-diurnal time scale that implies a continuously re-adjustment of the chemical of inter-tidal sediment surface of Ria Formosa.