Morphological abnormalities of diatom silica walls in relation to heavy metal contamination and artificial growth conditions

Falasco, Elisa; Bona, Francesca; Ginepro, Marco; Hlúbiková, Daša; Hoffmann, Lucien; Éctor, Luc

doi:10.4314/wsa.v35i5.49185

Cited by 68 publications

(52 citation statements)

References 26 publications

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“…Thus the dominance of these cosmopolitan diatom species throughout the cores suggests that this lake is an unstable environment probably attributable to fluvio-laccustrine behaviour of the lake and high silt loads. Despite the difficulties in interpreting environmental conditions associated with these diatoms, the presence of deformed forms of S. construens could imply some level of contamination (Falasco et al, 2009). This observation is also supported by the presence of eutrophication-tolerant species such as Gomphonema parvulum, Cyclotella meneghiniana and Achnanthes spp.…”

Section: Discussionmentioning

confidence: 99%

Palaeolimnological reconstruction of recent environmental change in Lake Malombe (S. Malawi) using multiple proxies

Dulanya¹,

Croudace²,

Reed³

et al. 2014

WSA

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Shallow inland water bodies in Malawi continue to be threatened by various environmental challenges despite their importance to the fisheries industry. Due to the complex interaction between natural and anthropogenic disturbances, disentangling the effect of the two may be a complicated process. The littoral zone of most water bodies is important in environmental reconstructions including pollution and lake level monitoring. This study used a littoral zone, transectbased approach employing multi-proxy palaeolimnological techniques to reconstruct recent environmental change (ca. 100 yrs.) in Lake Malombe in the Malawi Rift, East Africa. The results of the study could inform fisheries management in Lake Malombe, which experienced a catastrophic decline in fish stocks. Results support documentary evidence for the complete desiccation of the lake less than 100 years ago. Subsequently, there is evidence for accelerated eutrophication in the recent past. In light of these results, it is concluded that transect sampling approaches rather than relying on single core measurements, and the need for careful consideration of the types of proxy, are significant considerations in palaeoenvironmental reconstructions.

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Section: Discussionmentioning

confidence: 99%

Palaeolimnological reconstruction of recent environmental change in Lake Malombe (S. Malawi) using multiple proxies

Dulanya¹,

Croudace²,

Reed³

et al. 2014

WSA

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“…A minimum of 400 frustules were identified per sample using specialized literature (Lavoie et al 2008;Lange-Bertalot 1986-1991. Individual deformities were quantified in parallel and classified into the following 7 categories: 1: valve, 2: ornamentation, 3: central area, 4: raphe, 5: raphe canal system, 6: colony arrangement 7: multiple (Falasco et al 2009). Diatom species diversity was measured from taxonomic inventories with OMNIDIA software (Lecointe et al 1993) using the Shannon index (Shannon and Weaver 1949):…”

Section: Diatom Quantification and Identificationmentioning

confidence: 99%

Recovery potential of periphytic biofilms translocated in artificial streams after industrial contamination (Cd and Zn)

et al. 2012

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Metal wastes can significantly disturb aquatic communities, particularly photosynthetic organisms, the main primary producers in freshwater running ecosystems. In this study, biofilms and diatoms were used as bioindicators to characterize the kinetics of biofilm recovery. An experimental decontamination study was conducted under laboratory conditions, after biofilm colonisation at a site subject to discharge of industrial metals (Zn and Cd) and in parallel at an upstream site, metal-free, considered as a control. After 24 days of colonisation, biofilms were translocated and maintained in the laboratory for 56 days under clean conditions (control and decontamination) or metal contamination. Various tests were conducted from the community level--measures of metal bioaccumulation, cell densities and taxonomic investigations, to the individual level--measures of teratological forms. After 56 days of decontamination, Zn and Cd concentrations in decontaminated biofilms showed a sharp decline, respectively ranging from 6.7 ± 2 to 4 ± 2.5 mg Zn g⁻¹ DW and from 207.6 ± 24.5 to 45.4 ± 9.9 μg Cd g⁻¹ DW. However, at the end of the experiment bioaccumulations remained significantly higher than concentrations in control biofilms. Despite a diatom evolution in biofilm assemblages, taxonomic inventories did not demonstrate a complete restoration of diatom communities in biofilms under decontamination conditions compared with controls, since metal-resistant species initially present after colonisation at the contaminated site, such as Eolimna minima, persisted in high abundance in decontaminated biofilms. Biofilms kept under metal pressure showed very high bioaccumulation capacities and a sharp decline of species diversity which allowed identification of some resistant species. Regarding these first results on the behaviour of diatom biofilms under experimental decontamination conditions, improvement of the natural hydrosystem's chemical state appears quickly, but an eventual return to good ecological status appears delayed, with the persistence of metal-tolerant species even after 56 days.

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“…Only clear morphological deformities of the frustule outline were taken into account (Falasco et al, 2009) excluding irregular striation. The proportion of deformed valves of S. angusta was specifically estimated from a mean total count of 75¡ 39 (S.D.)…”

Section: Diatom Microscopic Examinationmentioning

confidence: 99%

“…The link between abnormal diatom forms and contamination by heavy metals has been well documented (Gold et al, 2003;Cattaneo et al, 2004;Morin et al, 2008;Falasco et al, 2009). However, the literature on the effect of herbicides on diatom morphology is scarce.…”

Section: Relevance Of Abnormal Forms As An Indication Of Toxicitymentioning

confidence: 99%

Impact of the herbicide metolachlor on river periphytic diatoms: Experimental comparison of descriptors at different biological organization levels

Roubeix

Mazzella

Méchin

et al. 2011

Ann. Limnol. - Int. J. Lim.

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-A microcosm experiment was carried out in order to test the effect of the herbicide metolachlor on river periphytic diatoms and to find potential diatom bioindicators of contamination. Effects were investigated at different biological organization levels (biofilm, diatom community, population and individual levels). The colonization of glass substrates by natural biofilm in artificial streams did not vary quantitatively between control and contaminated conditions (5 and 30 mg.L x1 ). However, non-parametric multivariate analysis of variance revealed a significant difference between contaminated and control diatom communities with regard to species composition. The difference was due to the greater development of probably tolerant species in the presence of the herbicide (e.g., Planothidium frequentissimum, Planothidium lanceolatum, Amphora montana, Surirella brebissonii and Nitzschia gracilis). An increase in the occurrence of abnormal forms was observed in relation to metolachlor concentration. In particular, up to 8% of the frustules of the species Surirella angusta exhibited prominent deformities. Monospecific acute toxicity tests were then performed on two species to estimate toxicity parameters based on growth inhibition. These tests also confirmed the teratogenic effect of the herbicide on S. angusta. This study shows that low concentrations of metolachlor in natural streams may significantly alter diatom community structure and that abnormal diatom forms should be taken into account in water contamination assessment.

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Morphological abnormalities of diatom silica walls in relation to heavy metal contamination and artificial growth conditions

Cited by 68 publications

References 26 publications

Palaeolimnological reconstruction of recent environmental change in Lake Malombe (S. Malawi) using multiple proxies

Palaeolimnological reconstruction of recent environmental change in Lake Malombe (S. Malawi) using multiple proxies

Recovery potential of periphytic biofilms translocated in artificial streams after industrial contamination (Cd and Zn)

Impact of the herbicide metolachlor on river periphytic diatoms: Experimental comparison of descriptors at different biological organization levels

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