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- Metal concentrations in the shell of Bathymodiolus azoricus from contrasting hydrothermal vent fields on the mid-Atlantic ridgePublication . Cravo, Alexandra; Foster, P.; Catarina Almeida, Ana; Bebianno, Maria João; Company, RuiSpecimens of Bathymodiolus azoricus were sampled along the Mid-Atlantic Ridge at the Menez Gwen, Lucky Strike and Rainbow hydrothermal fields. Individual shells (n = 51), through the weight range 0.62 to 15.70 g, were analyzed for their magnesium, strontium, iron, manganese, copper, zinc and cadmium concentrations. Amongst the marine molluscs the shell of B. azoricus is confirmed as being particularly impoverished in strontium (mean 943 microg g(-1)). Trace metal concentrations in the shells decreased in the order Fe> Mn> Zn> Cu> Cd. Despite originating from trace metal rich environments mean concentrations were low (37.9, 13.2, 10.7, 1.1 and 0.7 microg g(-1), respectively). Irrespective of geographical origin magnesium, strontium and copper concentrations were primarily dictated by shell weight. In contrast cadmium concentrations were elevated in shells from the Rainbow field and ambient seawater chemistry imparted site specific chemical fingerprints to the shells with respect to the iron to manganese ratio.
- Metals in the shell of Bathymodiolus azoricus from a hydrothermal vent site on the Mid-Atlantic RidgePublication . Cravo, Alexandra; Foster, P.; Catarina Almeida, Ana; Company, Rui; Cosson, R.P.; Bebianno, Maria JoãoSpecimens of the mussel Bathymodiolus azoricus were collected from Menez Gwen, a relatively shallow (850 m) hydrothermal vent field on the Mid-Atlantic Ridge. Each bivalve shell (n = 21) was individually cleaned by selective chemical. The residual crystal matrix of each shell was individually analysed for the concentrations of the minor elements magnesium and strontium and the trace elements iron, manganese, copper and zinc. The chemical composition of the crystal matrix is unusual. B. azoricus is identified as a species having one of the most strontium impoverished shells amongst the marine molluscs. For a bimineral species the magnesium concentration is also extraordinary low. Despite originating from a trace metal rich environment; the metal concentrations in the shells were exceptionally low. Mean concentrations of iron, manganese, copper and zinc were 20.6, 3.7, 0.6 and 9.4 microg g(-1) respectively. Minor and trace element concentrations exhibited a marked intra-population variability. Copper concentrations increased and iron and zinc concentrations decreased with increasing shell weight. Due to its insensitivity to the high environmental levels of trace elements and the variability in intra-population concentrations induced by shell weight the crystal matrix of the shell of B. azoricus has little potential for use in environmental trace metal monitoring in areas contiguous to deep-sea hydrothermal vents.
- DNA damage in two bivalve species: Mytilus galloprovincialis and Ruditapes decussatus from the South coast of PortugalPublication . Catarina Almeida, Ana; Cravo, AlexandraIn the last years, several studies have been carried out to assess the environmental “health” of the South Coast of Portugal. The aim of the present thesis was to evaluate DNA damage as a biomarker of genotoxic contamination in two bivalve species from the south coast of Portugal, mussels Mytilus galloprovincialis and clams Ruditapes decussatus. Mussels were sampled at nine sites along the coast, and clams were collected at four shellfish beds in the Ria Formosa Lagoon. The alkaline version of the Comet assay was used to estimate the DNA damage present in the haemolymph of bivalves. An image analysis system (Komet 5.5, Kinetic Imaging Ltd) was applied and 3 parameters were calculated, Tail DNA (%), Olive Tail Moment (OTM; arbitrary units) and Tail length (μm). Data obtained for both species were low, in the same order of magnitude for sites considered as reference. These values can be used as baseline/reference levels of the genotoxic contamination for future studies made in the South coast of Portugal. The nature and magnitude of contaminants in this coast were not particularly genotoxic. DNA damage present in mussel and clams haemolymph revealed to be a sensitive biomarker of genotoxic contamination. DNA damage in both specimens responded to the existing differences between sites and seasons, with highest values during summer. This damage biomarker was also sensitive to gender differences concerning both species and the overall data indicates that females have higher DNA damage than males. Moreover, this study demonstrated that information about the condition index (and Abstract - iii - reproductive cycle) and the local abiotic conditions are essential for the appropriate explanation of data. When comparing the DNA damage between the two analysed species, collected from close sites, DNA damage was relatively similar for both bivalve species. However, while mussels had highest DNA damage in August, clams showed maximum values in February/March, suggesting some interspecific differences possibly associated with dissimilar trophic strategies and/or habitats. Lipid peroxidation (LPO) was also analysed, to verify if the environmental conditions (contaminants and abiotic factors) can induce injuries in both cellular membranes and DNA. For mussels, the compounds/factors affecting LPO can also promote (low) genotoxicity. For clams, this relationship was only verified during July. Concluding, the present thesis demonstrates that the DNA damage present in M. galloprovincialis and R. decussatus is a sensitive biomarker to discriminate spatial, temporal and genders differences, revealing to be an appropriate tool for the evaluation of genotoxic contamination along the South coast of Portugal.