Diatom Deformities and Tolerance to Cadmium Contamination in Four Species

Abstract

The relative tolerance of four diatoms (Nitzschia palea, Pinnularia mesolepta, Mayamaea atomus, and Gomphonema truncatum) to Cd was evaluated, including their proneness to deformities, and the severity of the abnormalities in relation to Cd concentration. The indirect effect of Cd on photosynthetic capacities was assessed during a short time exposure experiment using a dose-response approach to evaluate the relative tolerance of the four diatom species. The EC25 were 9 (3, 23), 606 (348, 926), 1179 (1015, 1349) and 2394 (1890, 2896) µg/L for P. mesolepta, G. truncatum, N. palea, and M. atomus respectively. P. mesolepta was by far the most Cd sensitive species while M. atomus was the most tolerant. In addition, diatoms were exposed to a single concentration of Cd comparable to a heavily contaminated environment for a longer duration to evaluate the effect of Cd on growth kinetics and the deformities induced. N. palea, P. mesolepta, and M. atomus were able to grow when cultivated with Cd while G. truncatum was not. Cadmium strongly affected the effective quantum yield in G. truncatum (4.8 ± 5.9% of the control) and P. mesolepta cultures (29.2 ± 6.9% of the control). The effects were moderate for N. palea (88.3 ± 0.7% of the control) and no impact was observed for M. atomus. The results from the two approaches were in accordance since they identified N. palea and M. atomus as the two most tolerant species to Cd, while P. mesolepta and G. truncatum were the most sensitive. The microscopy analyses revealed that P. mesolepta was more impacted by Cd than N. palea and M. atomus considering both the quantity of abnormal cells and the severity of the deformities. Overall, this research shows that not all deformities can be considered equal for a water quality bio-assessment. The work highlights a need to take into account metal-tolerance/sensitivity of the species and the severity of the deformities.

Looking back, looking forward: a review of the new literature on diatom teratological forms (2010–2020)

“…teratological forms. In our previous review (Falasco et al, 2009a), we already cited several studies which highlighted the existing relationship between trace metal contamination and the presence of teratological forms, and these results have been strengthened in the following years up to date (Tapia, 2008;Ferreira da Silva et al, 2009;Sierra & Gómez, 2010;Ciszewski et al, 2011;Corcoll et al, 2012;Lavoie et al, 2012Lavoie et al, , 2018Lavoie et al, , 2019Pandey et al, 2014Pandey et al, , 2015Pandey et al, , 2018bRenzi et al, 2014;Laird et al, 2015;Salusso & Moraña, 2015;Cichoń, 2016;Pandey & Bergey, 2016Sienkiewicz & Gąsiorowski, 2016;Gautam et al, 2017;Mu et al, 2017;León et al, 2018;Simić et al, 2018;Kim Tiam et al, 2019). However, in many of the above-cited studies, the relationship between metal concentrations and teratology frequencies or abundances was not statistically corroborated, even when trace metal contamination appeared as the only potential cause of valve deformation.…”

“…Different metal stress-mediated mechanisms are activated to mitigate cell damages induced by trace metals. Diatoms can internally trap trace metals through glutathione and phytochelatins (Branco et al, 2010;Figueira et al, 2014) or excrete them in the external environment, with different efficiency degrees depending on species (Kim Tiam et al, 2019). In our previous review, basing on studies up to 2009, we proposed the production of extracellular polymeric substances (EPS) as one of these defence tools.…”

“…At a community scale, trace metal contamination selects for tolerant species which are generally represented by pioneer adherent taxa (Morin et al, 2012a), in particular by Achnanthidium minutissimum (Kützing) Czarnecki (Tapia, 2008;Luís et al, 2011;Olenici et al, 2017;Lavoie et al, 2019;Sivarajah et al, 2019;Pandey, 2020) (Pandey, 2020). However, many studies recognized as tolerant taxa also motile species such as nitzschioid diatoms (Pandey & Bergey, 2018), Navicula cincta (Ehrenberg) Ralfs (Guasch et al, 2012), Nitzschia palea (Kützing) W. Smith or Mayamaea atomus (Kützing) Lange-Bertalot (Kim Tiam et al, 2019), high-profile species such as G. pseudoaugur (Gautam et al, 2017) or Hygropetra balfouriana (Grunow ex Cleve) Krammer & Lange-Bertalot in Krammer (Lavoie et al, 2019). Generally, teratological forms in these kinds of resistant communities are rare (Cattaneo et al, 2004;Ferreira da Silva et al, 2009;Lavoie et al, 2012), even if exceptions sometimes occurred (Cantonati et al, 2014;Olenici et al, 2017).…”

“…laevis Hustedt (Stachura-Suchoples et al, 2016) strains. The appearance of teratological individuals under artificial growth conditions represents an important limit to the laboratory ecotoxicological tests, since it represents a significant background noise masking the species response to a certain contaminant (Kim Tiam et al, 2019). For this reason, further research is needed to improve and optimize the conditions for long-term diatom cultivations.…”

“…In both laboratory and field studies, Pandey et al (2015) and Pandey & Bergey (2016) observed a dominance of type 4 teratology (affecting raphe slit) in periphytic communities exposed to Cu and Zn, while Pandey et al (2014Pandey et al ( , 2015 reported prevalence of abnormal striations and mixed deformities under Zn stress. Recently, Kim Tiam et al (2019) observed that raphe related deformities (which they classified as ''early morphogenesis deformities'') generally affected Cd tolerant species, such as N. palea and M. atomus, that appeared more resistant to valve outline deformation or striae alterations.…”