1,720,985 research outputs found
Heavy metal bioaccumulation in Mytilus galloprovincialis: A transplantation experiment in Venice Lagoon
No full textMussels were transplanted from a marine reference site to a polluted area of the Venice Lagoon to study heavy metal bioaccumulation responses in soft tissues and shells. Soft tissue levels of Mn, Cu, Fe and Cr were initially lower in reference than in lagoon resident mussels, while no differences were observed for Pb and Zn. After one month, the Mn, Cu, Fe and Cr levels in the transplanted mussels increased and overtook both values recorded in resident and marine organisms. Two months after transplantation, metal levels dropped off. At the time of the last sampling, the metal levels seemed to stabilize at lagoon values, except for Cu. Shell levels of Cu, Zn and Pb were lower in mussels from the reference site than in those resident in the lagoon. After three month from transplantation, the bioaccumulation shell data indicated a sharp increase in Mn, Fe and Zn overtaking the levels of lagoon resident bivalves. The results show the usefulness of field transplantation experiments in studying bioaccumulation responses in polluted coastal environments
Short-term effects of enhanced zinc concentrations on population parameters of Dinophilus gyrociliatus (polychaeta)
No full textSurvival and fecundity data, recorded in experimental populations of the archiannelid polychaete Dinophilus gyrociliatus were used to investigate the life-table response to enhanced zinc concentrations. Results evidencing a decrease of net reproductive rate (Ro), stable rate of population increase (r) and reduction of generation time (T), highlight a complex effect of zinc, in which reduction of fecundity is compensated by the concomitant decrease of generation time
Heavy metal in sediments and bioaccumulation in the bivalve Corbula gibba in a drilling discharge area
No full textThe longterm bioavailability of heavy metals in sediments of a Northern Adriatic Sea shelf area affected by drilling mud and Cutting discharges was discussed. Levels of Mn, Cu, Cr, Zn and Pb in different geochemical phases of the sediment and in soft tissues of the bivalve Corbula gibba were recorded and the relationships between biological and geochemical metal investigated. Total metal content, acetic acid extractable-, exchangeable-, carbonate-, easily reducible-, moderately reducible-, oxidable- and residual-fractions were determined oil sediment samples. Corbula gibba was collected from wet sediments at the same times and sites, and the soft-tissue metal contents were determined. Correlations show that the fractions with greatest bioavailability are the exchangeable and carbonate for Cr and the exchangeable, carbonate, easily and moderately reducible fractions for Zn. Data also show a possible bioavailability of Pb only from the residual fraction, consisting of very resistant matter of more recent anthropogenic origin. Near the platform, total Mn content in sediments and in C. gibba tissues show a strong correlation suggesting that this organism is sensitive to variations of the Mn-oxi-hydroxides superficial film. No relationships were found between biological and sediment-bound Cu, however the discharged muds did not cause Cu enrichment. The metal fraction determined by weak acetic acid extraction at no point seems related to metal levels in Corbula gibba
Effetti di zinco su più generazioni di Dinophilus gyrociliatus: un approccio demografico.
No full textThe effects of zinc on life history and populations of Dinophilus gyrociliatus (Polychaeta) were studied. The life tables of three successive generations (P, F1, F2) were derived from a control cohort and a threated cohort kept in artificial seawater enriched with 1.0 ppm zinc. Zinc affected survival and fecundity of the three successive generations with different modality and intensity, determining a geralized reduction of all demographic indices and different demographic responses among generations
Effects of zinc on the polychaete Dinophilus gyrociliatus: a life table response experiment
No full textA life-table response experiment (LTRE) was performed in order to study the effects of enhanced zinc on the survival, fecundity and demographic indices of Dinophilus gyrociliatus (Polychaeta). A control group and three treated cohorts kept in artificial seawater enriched with nominal concentrations of zinc at 0.25, 0.50 and 1.00 g Zn/ml, respectively, were considered. Zinc marginally affected survival but had a strong impact on the reproduction of D. gyrociliatus. Zinc enrichment had no effect on age at maturity, whereas it induced a slight increase in fecundity during the early reproductive phases at 0.50 and 1.00 g Zn/ml, and a sharp decrease in fecundity from the twentieth day of life at all levels of metal enrichment tested. Treated groups were characterized by a marked reduction of the net growth rate (R0) and a decrease in generation time (T) with respect to the control groups, but no effect on life expectancy (e0) or on population growth rates () was observed. R0 and , which are the most commonly used indices of fitness, were not equally susceptible to zinc. appears less sensitive to stress induced by metal enrichment with respect to R0 and other life history traits like age-specific fecundity. D. gyrociliatus appears to be an appropriate bioindicator species in LTRE to assess the consequences of environmental heavy metals on individual life-history and population dynamics
Arricchimento ambientale di metalli ed effetti sulla demografia del polichete Dinophilus gyrociliatus
No full text[online] URL:http://www.xiiicongresso.societaitalianaecologia.org/articles/Mauri-86.pd
Bioaccumulo ed effetti biologici di Pd sul collembolo Folsomia candida (Willem)
No full textL’aumento della concentrazione di metalli rari quali il palladio (Pd) nei suoli a seguito dell’introduzione delle marmitte catalitiche sta assumendo un crescente interesse nell’ambito della ricerca ambientale per il potenziale impatto sugli ecosistemi terrestri. Ai fini della validazione di un metodo per la valutazione dell’impatto della contaminazione di microinquinanti da traffico, è stato valutato l’effetto di Pd su esemplari del collembolo Folsomia candida, esposto per 28 giorni in terreno artificiale a dosi del metallo nel range 0-800 ng/g, in termini di bioaccumulo, sopravvivenza e riproduzione. Folsomia candida ha mostrato di accumulare Pd proporzionalmente alla frazione solubile del metallo presente nel terreno, senza alcuna efficace regolazione nel periodo considerato. Un effetto significativo sulla sopravvivenza dei collemboli è stato osservato a partire dalla concentrazione di 200 ng/g, mentre una dose di 50 ng/g si è mostrata sufficiente a produrre una inibizione della fecondità dell’ordine del 25% rispetto al controllo.La dimostrazione di effetti su parametri importanti a livello di popolazione a partire da concentrazioni che sono già rilevabili nei suoli urbani, evidenzia come la contaminazione da Pd sia da considerarsi seria minaccia e quanto siano necessari ulteriori studi sull’impatto dei contaminanti da traffico sulle comunità del suolo
Novel antifouling agent- Zinc pyrithione: Short- and long-term effects on survival and reproduction of the marine polychaete Dinophilus gyrociliatus
No full textThe recent ban on TBT in boat antifouling paints has resulted in a large employment of the biocide zinc pyrithione (ZnPT) as substitute. Despite concerns of environmental toxicity at ultra-trace concentrations, ZnPT has received little attention, as it was assumed to photo-degrade easily. On the contrary, recent evidence has suggested that ZnPT only partially degrades, and rather, persists in the marine environment, especially where the influence of light is limited, such as in harbours.Short-term acute toxicity tests and life table response experiments (LTREs) were performed to evaluate the effects of ZnPT on the polychaete Dinophilus gyrociliatus at both individual and population level. The 96h-LC50 values for ZnPT on D. gyrociliatus were 7.8 and 11.5 nM under dark and 12h light/12h dark conditions, respectively. In LTREs, laboratory cultured cohorts of D. gyrociliatus were exposed to sublethal concentrations of ZnPT (0.5 and 1 nM) and compared to a control cohort. The survival among individuals exposed to the highest concentration decreased already during the 2nd week of life with respect to the control. The effects of the biocide on fecundity were even more evident: ZnPT caused a considerable reduction in both the exposed groups. The demographic approach here applied succeeded in identifying ZnPT effects both on the biological cycle and on the growth potential of polychaete D. gyrociliatus. The net growth rate (R0) appeared the demographic parameter most sensitive to ZnPT, as the biocide determined a sharp decline of R0 in both the 0.5 and the 1 nM groups (-41% and -63% respectively) in comparison to the control cohort. The population growth rate l (often used as an index of population fitness) and the life expectancy e0 were also significantly reduced, while ZnPT exposure did not affect the generation time T.These results highlight the potential ecological threat posed by the biocide ZnPT, even at the very low tested concentrations, which are already detectable in some European marinas
HEAVY-METAL ACCUMULATION AND CALCIUM CONTENT IN THE BIVALVE DONACILLA-CORNEA
No full textAccumulation of heavy metals (Cu, Cd and Mn) and their effects on total Ca content were studied under laboratory conditions in sandy-bottom bivalves Donacilla cornea from an unpolluted shore in northern Sardinia. The bivalves were found to accumulate the 3 metals. Exposure at 2 different temperatures (18 and 25-degrees-C) showed significant differences only for Cu accumulation. Following decontamination in clean seawater, the body content of Cu and Mn decreased strongly, whereas that of Cd remained practically unchanged. Among organs, gills contained the highest metal concentrations. A net increase of total Ca concentration in the body was observed during metal accumulation, and the digestive gland seems the most suitable organ for studies on the effects of heavy metals on calcium homeostasis
Heavy metal bioaccumulation associated with drilling and production activities in middle Adriatic Sea
No full textThe results presented here constitute part of a wide-ranging research project carried out between 1992 and 1994, aiming to investigate the effects of offshore AGIP hydrocarbon production activities on the abiotic and biotic environments of the Adriatic Sea. The following data in particular allow us to carry out an assessment of the effects of the contamination - in relation to both the long term effects of past discharge of drilling muds and the release of metals from sacrificial anodes - on selected marine bivalves, located in the area influenced by a gas platform named Antares and sited off the coast of Ravenna
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