Article

Use of microbenthic algal communities in ecotoxicological tests for the assessment of water quality: the Ter river case study

Univ. de Barcelona
Journal of Applied Phycology (Impact Factor: 2.49). 01/2002; 14:41-48. DOI: 10.1023/A:1015242301451

ABSTRACT The tolerance of microbenthic algal communities to two model toxicants, atrazine and copper, was studied in the Ter river during spring and summer. Artificial substrata were colonised at 9 sites and used to perform short-term (1-4 h) toxicity tests in the laboratory and to obtain photon yield as the ecotoxicological endpoint. The tolerance was lower in spring than in summer for both toxic substances and varied according to the site studied. Copper toxicity was associated with physico-chemical conditions (total suspended solids and water pH) and, especially, with several biomass-related parameters, whereas atrazine toxicity was related to algal abundance and species composition. Temporal and spatial changes in nutrient concentration may alter the biomass and species composition of the communities and thus affect their tolerance to toxic substances. It has to be therefore considered that the environmental characteristics of the river system may determine relevant direct and indirect effects on the algal communities, then affecting their specific ecotoxicological responses. Once this is assumed, the empirical expressions obtained on calculating EC50 and EC10 can be used to predict the community-level transient effects of toxic exposures.

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Available from: Enrique Navarro, Jul 28, 2015
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    • "Most ecotoxicological tests are performed in the laboratory on small populations of certain species; and although providing useful information on toxicant effects, those assays are not fully reliable in forecasting eventual impacts within natural systems (Cairns and Niederlehner, 1995; Navarro et al., 2002). Tests on single species do not enable an understanding of the effects of toxicants at the community level (Sabater et al., 2007) and furthermore lack ecological realism (Adams et al., 2000; Lagadic et al., 1994; NRCC, 1985). "
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    ABSTRACT: Diatoms are an integral and often dominant component of the benthic microalgal assemblage in estuarine and shallow coastal environments. Different toxic substances discharged into these ecosystems persist in the water, sediments, and biota for long periods. Among these pernicious agents, the toxicity in diatoms by metal is linked to different steps in the transmembrane and internal movements of the toxicant, causing perturbations in the normal structural and functional cellular components. These changes constitute an early, nontaxonomic warning signal that could potentially serve as an indicator of this type of pollution. The aim of this work was to study the environment-reflecting short-term responses at different levels of organization of epipsammic diatoms from the Río de la Plata estuary, Argentina that had been exposed to hexavalent chromium within experimental microcosms. To this end we monitored: (i) changes in the proportion of the diatoms in relation to other algal groups at the biofilm community level; (ii) shifts in species composition at the diatom-assemblage level; (iii) projected changes in the densities of the most representative species at the population level through comparison of relative growth rates and generation times; and (iv) the cytological changes at the cellular and subcellular levels as indicated by the appearance of teratological effects on individuals and nuclear alterations. The epipsammic biofilms were exposed for 96h to chromium at a concentration similar to that measured in highly impacted sites along the coast (80μgL(-1)). Chromium pollution, at this concentration and short exposure time did not affect the algal biomass and density of these mature biofilms. The biofilm composition, however, did change, as reflected in a decline in cyanophytes and an increment in the proportions of diatoms and chlorophytes; with Hippodonta hungarica, Navicula novaesiberica, Nitzschia palea, and Sellaphora pupula being the most frequent and abundant species. The most notable shifts related to chromium exposure were a decrease in the relative abundance of H. hungarica and a significant increase in the proportion of N. palea. Moreover, the species analyzed in the treatment microcosms showed higher growth rates than in the controls - N. palea grew faster, while H. hungarica replicated more slowly. The total nuclear abnormalities - as recorded in Fallacia pygmaea and N. novaesiberica - were significantly higher in the treatment microcosms; whereas in N. palea, the dominant species in treatment microcosms, neither nuclear alterations nor abnormal frustules were observed.
    Aquatic toxicology (Amsterdam, Netherlands) 03/2013; 134-135C:82-91. DOI:10.1016/j.aquatox.2013.03.007 · 3.51 Impact Factor
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    • "Changes in the composition of photosynthetic pigments have also been used as indicators of changes in the structure of the photosynthetic apparatus of biofilms as response mechanisms to avoid environmental stress (Barranguet et al., 2003; Laviale et al., 2010). Diatom community often represents the major autotrophic proportion of biofilms (Navarro et al., 2002; McClellan et al., 2008; Morin et al., 2010). It has been widely reported that diatoms respond to chemical stress not only at the community level through shifts in dominant taxa and diversity patterns (structural endpoints), but also at the individual level with increasing occurrence of frustule deformities or decrease in cell size of the community or within specific taxa (morphological endpoints) (Morin et al., 2007; Falasco et al., 2009; Luís et al., 2011). "
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    ABSTRACT: With the aim of evaluating cause-effect relationships between metal pollution and biofilm structure and function, a translocation study was performed in a metal-polluted stream (the Osor stream "la riera d'Osor", NE Spain). Biofilm responses were measured as temporal changes in chl-a fluorescence parameters, pigment composition and diatom species composition. Biofilms from a non-polluted site were translocated to four downstream sites presenting a gradient of metal pollution, corresponding to scenarios of low and moderate metal pollution. Metal effects (Zn bioaccumulation, Fe bioaccumulation and Zn in water) were distinguished from other stressors (phosphate concentration in water). Based on the results obtained, a fast bioaccumulation of Zn (after few hours of exposure) was linked to a decrease in photosynthetic efficiency and an enhancement of mechanisms of protection through the xanthophyll cycle. After longer exposure, differences in Zn and Fe bioaccumulation and Zn water concentration between sites were linked to diatom community changes: decrease in diatom cell biovolume, along with a decrease in the IPS index of diatoms. Based on our results, we recommend including Zn in the list of priority pollutant substances of the European Water Framework Directive (2000/60/EC), due to its occurrence and toxicity. In addition, our study supports the use of chl-a fluorescence parameters together with the analysis of photosynthetic pigments of biofilms as suitable functional endpoints of early toxicity. Furthermore, diatom community studies are recommended for their clear response after chronic exposure. However, new diatom indices beyond the use of the IPS are required to increase their sensitivity to metal pollution, e.g. to identify the damage caused by moderate to low metal pollution. (C) 2012 Elsevier Ltd. All rights reserved.
    Ecological Indicators 07/2012; 18:620-631. DOI:10.1016/j.ecolind.2012.01.026 · 3.23 Impact Factor
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    • "Changes in the composition of photosynthetic pigments have also been used as indicators of changes in the structure of the photosynthetic apparatus of biofilms as response mechanisms to avoid environmental stress (Barranguet et al., 2003; Laviale et al., 2010). Diatom community often represents the major autotrophic proportion of biofilms (Navarro et al., 2002; McClellan et al., 2008; Morin et al., 2010). It has been widely reported that diatoms respond to chemical stress not only at the community level through shifts in dominant taxa and diversity patterns (structural endpoints), but also at the individual level with increasing occurrence of frustule deformities or decrease in cell size of the community or within specific taxa (morphological endpoints) (Morin et al., 2007; Falasco et al., 2009; Luís et al., 2011). "
    [Show abstract] [Hide abstract]
    ABSTRACT: With the aim of evaluating cause-effect relationships between metal pollution and biofilm structure and function, a translocation study was performed in a metal-polluted stream (the Osor stream “la riera d’Osor”, NE Spain). Biofilm responses were measured as temporal changes in chl-a fluorescence parameters, pigment composition and diatom species composition. Biofilms from a non-polluted site were translocated to four downstream sites presenting a gradient of metal pollution, corresponding to scenarios of low and moderate metal pollution. Metal effects (Zn bioaccumulation, Fe bioaccumulation and Zn in water) were distinguished from other stressors (phosphate concentration in water). Based on the results obtained, a fast bioaccumulation of Zn (after few hours of exposure) was linked to a decrease in photosynthetic efficiency and an enhancement of mechanisms of protection through the xanthophyll cycle. After longer exposure, differences in Zn and Fe bioaccumulation and Zn water concentration between sites were linked to diatom community changes; decrease in diatom cell biovolume, along with a decrease in the IPS index of diatoms. Based on our results, we recommend including Zn in the list of priority pollutant substances of the European Water Framework Directive (2000/60/EC), due to its occurrence and toxicity. In addition, our study supports the use of chl-a fluorescence parameters together with the analysis of photosynthetic pigments of biofilms as suitable functional endpoints of early toxicity. Furthermore, diatom community studies are recommended for their clear response after chronic exposure. However, new diatom indices beyond the use of the IPS are required to increase their sensitivity to metal pollution, e.g. to identify the damage caused by moderate to low metal pollution.
    Ecological Indicators 01/2012; · 3.23 Impact Factor
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