Article

Sediment integrative assessment of the Bay of Cadiz (Spain): An ecotoxicological and chemical approach

Instituto de Ciencias Marinas de Andalucía, Campus Universitario Río San Pedro s/n, 11510, Puerto Real, Cádiz, Spain.
Environment international (Impact Factor: 5.56). 04/2009; 35(6):831-41. DOI: 10.1016/j.envint.2009.02.003
Source: PubMed

ABSTRACT

This study consisted of the sediment toxicity assessment of the Bay of Cádiz based on two endpoints: growth inhibition for Cylindrotheca closterium (benthic microalgae) and fecundity inhibition for Tisbe battagliai (harpacticoid copepod). A new methodology to eliminate (but not as storage technique) the autochthonous biota present in the sediment samples by immersing them in liquid nitrogen (-196 degrees C) was also assessed. Sediment toxicity data showed different toxicity levels for both organisms. In general, T. battagliai was more sensitive; however a good correlation (r=0.75; p<0.05) between sediment toxicity results for both species was found. Data in pore water (pH, redox potential, and toxicity for microalgae and copepod) and sediment (pH, redox potential, organic carbon, and metal concentrations) demonstrated that ultra-freezing did not alter sample characteristics; thus, this technique can be adopted as a pre-treatment in whole-sediment toxicity tests in order to avoid misleading results due to presence of autochthonous biota. Multivariate statistical analysis such as cluster and principal component analysis using chemical and ecotoxicological data were employed. Silt and organic matter percentage and lead concentration were found to be the factors that explain about 77% of sediment toxicity in the Bay of Cádiz. Assay methodology determined in this study for both assayed species is considered adequate to be used in sediment toxicity monitoring programs. Results obtained using both species show that the Bay of Cádiz can be considered a moderately polluted zone.

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Available from: Cristiano V M Araújo
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    • "06º12'32.7''W), a location considered to be an area of low pollution (Araújo et al. 2009). Mimes were positioned in lines parallel to the shore of the Rio San Pedro at 36º33'03.37''N; "
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    ABSTRACT: Marine epibionts are organisms that grow on submerged surfaces. Those found on seagrass leaves are especially important because of their interactions with the plants, their contribution to primary production in these ecosystems, and their role as food source for heterotrophic fauna. Given the relative lack of ecotoxicological studies on epibionts, the aim of this study is to evaluate the effect of environmental pollution on epiphytes experimentally attached to artificial devices (mimes) consisting of thermally-sealed silicone tubes supported on bamboo sticks that mimic the morphology of seagrasses and serve as an anchor surface for marine epibionts. Mimes were installed on the sea floor in subtidal waters of the Rio San Pedro (Cádiz), collected after 28 days, and incubated in the laboratory with environmental concentrations of atrazine (herbicide), Irgarol (anti-fouling substance), and copper. Tube-dwelling diatoms formed the major component of the epiphyte community. Average surface covering, chlorophyll, and biomass content did not show significant differences between controls and treatments. The glutathione peroxidase activity increased significantly with 4 μg L(-1) of atrazine and 5 μg L(-1) of copper. This enzymatic activity increase seems to be sufficient to prevent oxidative cellular damage by removing reactive oxygen substances produced by oxidative stress; in addition to this enzyme, there might be other antioxidant enzymes which have not been measured in this study, that have also protected the organism from oxidative damage. Thus, the measurement of antioxidant enzymatic activity in epiphytes may be a useful toxicity indicator for coastal biomonitoring.
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    • "For the 12-h drift assay, six salinity treatments (9,12,15,19,24,30) plus a control treatment, quadruplicated in time, were assayed. The minimum salinity level chosen was 9 because represented the salinity at which growth was inhibited by 95% (IGS95); at lower salinities the displacement ability of the cells could be damaged [15] and cells starting to die (inhibition growth higher than 100%). "
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    ABSTRACT: Avoidance response is a well-known mechanism for escaping environmental stress. For organisms with reduced active movement, such as benthic microalgae, drifting could be a specifically selected mean of avoiding less favorable environments. To test this hypothesis, a system was developed to assess if hypo-saline stress triggers drift in the estuarine benthic diatom Cylindrotheca closterium. Concurrently, the effects of salinity on growth inhibition were also investigated in order to compare the sensitivity of this endpoint with the drift response, and to estimate the immediate population decline caused by both drift and population growth responses. It was verified that the salinity value that inhibited the algal population growth by 50% (IGS50) was 19, while the salinity value that triggered the drift response by 50% of the population (TDS50) was 15. These results indicate that drift is an identifiable response triggered to escape stressful environments. The combination of the two responses (population growth and drift) showed that population decline based exclusively on the inhibition of population growth may result in an underestimation of the risk, compared with the decline when drifting to avoid stress is also taken into account.
    Full-text · Article · Nov 2013 · PLoS ONE
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    • "This location is considered low-polluted (Araújo et al. 2009). After 56 days in situ, mimes covered by epiphytes were collected, immediately transferred to laboratory conditions, and then exposed to selected and "
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    ABSTRACT: Toxic effects of copper, atrazine and irgarol were evaluated on epiphytes attached to mimes (artificial devices that mimic the morphology of seagrasses) in order to check sensitivity of this biological group. Tube-dwelling diatoms were the major component of the epiphyte community. Superoxide dismutase activity was enhanced by exposure to 25 and 50 μg L(-1) of atrazine; the organism generates this antioxidant response to prevent cellular damage by removing reactive oxygen substances produced by oxidative stress. The measurement of antioxidant enzymatic activity in epiphytes could be a useful technique for ecotoxicology monitoring in marine coastal environments.
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Questions & Answers about this publication

  • Fernando R. Diz added an answer in Freeze Drying:
    How can one remove ethanol from rose bengal stained sediment samples? It would not freeze at -27C and creates a problem in freeze drying the samples?

    I am working on rose bengal stained sediment samples and when I tried to deep freeze the sample at -27C it wouldn't freeze because ethanol, which is used for rose bengal staining, doesn't freeze at -27C (Having freezing point -117C). So I have to remove it. If I directly decant it then some ethanol must be in sediment pore spaces and it causes problem to freeze dryer, and if I use distilled water to dilute it, it removes the salt content from sediment  which I don't want to lose.

    Fernando R. Diz

    Have you tried to evaporate it? I`m sure that ethanol evaporates propertly at room temperature. You just have to extend the samples to get the maximum surface of evaporation (for instance in opened petri plates) and just wait. Or you also can try to freeze your samples with liquid nitrogen and then keep at -27ºC. We had tried this technique and chemical composition is not affected by liquid nitrogen (See the publication attached).

    Good luck!

    • Source
      [Show abstract] [Hide abstract]
      ABSTRACT: This study consisted of the sediment toxicity assessment of the Bay of Cádiz based on two endpoints: growth inhibition for Cylindrotheca closterium (benthic microalgae) and fecundity inhibition for Tisbe battagliai (harpacticoid copepod). A new methodology to eliminate (but not as storage technique) the autochthonous biota present in the sediment samples by immersing them in liquid nitrogen (-196 degrees C) was also assessed. Sediment toxicity data showed different toxicity levels for both organisms. In general, T. battagliai was more sensitive; however a good correlation (r=0.75; p<0.05) between sediment toxicity results for both species was found. Data in pore water (pH, redox potential, and toxicity for microalgae and copepod) and sediment (pH, redox potential, organic carbon, and metal concentrations) demonstrated that ultra-freezing did not alter sample characteristics; thus, this technique can be adopted as a pre-treatment in whole-sediment toxicity tests in order to avoid misleading results due to presence of autochthonous biota. Multivariate statistical analysis such as cluster and principal component analysis using chemical and ecotoxicological data were employed. Silt and organic matter percentage and lead concentration were found to be the factors that explain about 77% of sediment toxicity in the Bay of Cádiz. Assay methodology determined in this study for both assayed species is considered adequate to be used in sediment toxicity monitoring programs. Results obtained using both species show that the Bay of Cádiz can be considered a moderately polluted zone.
      Full-text · Article · Apr 2009 · Environment international

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