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

Abstract

Over the last years, issues concerning diatom teratological forms and environmental stress have received growing interest within the scientific community. Publications on this topic dated back to 1890 and were summarized in a review published in 2009 by the journal Hydrobiologia, accounting for high citation rates (i.e. 117 citations Scopus and 232 citations Google Scholar, October 2020). This wide interest stimulates the authors to further unravel teratological forms significance in the light of the most recent publications (2010–2020). Diatom teratological forms are one of the best individual-level biomarkers since they provide a rapid response to several environmental stressors, including new emerging pollutants. The mechanisms involved in teratological valve likely involve both cytoskeleton and silicon metabolic pathway impairments. However, teratologies do not seem to weaken the reproduction capacity and viability of the affected individuals. We recognized eight types of teratologies as involving different parts of the valve, depending on genus. In order to summarize the information obtained by several years of research, we suggest a four-step procedure aimed at providing a theoretical pathway that researchers should follow to better explain results obtained in next-future studies and representing a starting point for the development of an environmental index based on teratological forms.

Geometric Morphometrics of Bilateral Asymmetry in Eunotia bilunaris (Eunotiales, Bacillariophyceae) as a Tool for the Quantitative Assessment of Teratogenic Deviations in Frustule Shapes

“…Several previous studies and reviews have stressed that assessing the severity of frustule teratology is an important step for further advancing research on the relationship between these morphogenetic deformities and their causative environmental factors [4,5,58,59]. We suggest that the presented geometric morphometric framework for the analysis of bilateral asymmetry across the transapical axis of eunotioid diatoms represents one such approach for quantifying shape teratogeny in this diatom group.…”

“…In addition, teratogenic shape asymmetry in genera with heteropolar valves, such as Gomphonema, Licmophora, and Didymosphenia [61], needs to be quantified based on the reflection of configurations across the apical axis. However, in all cases, the Procrustes-based decomposition of the shape asymmetry could represent a well-applicable framework for scoring the severity of diatom frustule teratology in relation to different types of environmental stress, such as the metal contamination, acidification, eutrophication, or increased radioactivity [5].…”

“…Diatoms are generally sensitive to the environmental conditions of their habitats, which is reflected in the changes of their species composition in natural communities and in the patterns of morphological variation of frustules [4,5]. Teratogenic changes in frustule morphology have been well documented in scientific literature, especially in relation to various stress factors, such as increased sublethal concentrations of heavy metals [6][7][8], acidification [9,10], increased radiocativity [11], and organic pollution [12].…”

“…The incidence of such morphological deformations in the sedimentary record has frequently been used as proxy data for the identification of historical changes in the anthropogenic loading of various aquatic ecosystems [3,5,6,13]. In these studies, the stress rate is usually quantified as the proportion of deformed frustules relative to the "standard" shapes.…”

Diatom microalgae as smart nanocontainers for biosensing wastewater pollutants: recent trends and innovations

“…On the other hand [ 106 ], they observed no increase in LB in diatoms treated with Pb. [ 107 ]. They did a detailed study of teratological forms of diatoms under different environmental stresses making them a highly sensitive biosensor for all types of environmental pollutants [ 108 ].…”