Post-mining reservoirs as hotspots of diatom diversity
Progressive climate change, driven by the unsustainable exploitation of natural resources, results in more frequent droughts, reduced levels of groundwater and surface water, and increased average annual air temperatures. The activity of opencast mines exacerbates the negative water balance due to groundwater drainage, leading to disturbances in the ecological stability of aquatic ecosystems and a direct decline in biodiversity. The recently adopted conclusion by the Council of the European Union highlights the importance of restoring and protecting biodiversity for human life.
One effective approach to improving biodiversity in mining areas is the reclamation of sites where natural resource extraction is either ongoing or has been completed. Recultivation aims to restore the proper functioning of degraded areas, with one method focusing on water management. This involves creating water reservoirs in opencast locations, which can serve as potential substitute ecosystems for aquatic organisms, such as diatoms, and foster a high taxonomic diversity of these microorganisms. Examples of such post-mining reservoirs in Poland include the Łęczyca hydrological complex (iron ore), the Bogdałów reservoir (brown coal), and the Pełczyska hydrological complex (resulting from salt deposit exploration).
Fig. 1 Chamaepinnularia plinskii
In the studied ecosystems, nearly 200 diatom taxa have been observed, including many centric species. As a result of morphological variability analysis, three new species have been identified. In particular, the specific environmental conditions in the Pełczyska hydrological complex, characterized by increased chloride ion concentrations, shaped the taxonomic diversity of diatom communities. This allowed for the observation of morphological variability in Chamaepinnularia krookiformis sensu lato. Based on distinct morphological features and differences with specimens from the type material of Pinnularia krookiformis (≡Chamaepinnularia krookiformis), a new diatom species, Chamaepinnularia plinskii Fig. 1, has been formally described (Żelazna-Wieczorek et al., 2015; Żelazna-Wieczorek & Olszyński, 2016).
Figure 2. Aulacoseira pseudomuzzanensis
The hydrological complex in Łęczyca exhibited increased water pH, higher trophy conditions, and enhanced saprobic activity. These specific environmental factors influenced the species composition of diatoms, with Aulacoseira muzzanensis sensu lato appearing in large numbers. After a detailed analysis of the morphological structure of A. muzzanensis s.l. from the studied reservoirs compared to specimens from the type material of Melosira muzzanensis (≡A. muzzanensis), a new diatom species, Aulacoseira pseudomuzzanensis Fig. 2, has been distinguished(Olszyński & Żelazna-Wieczorek, 2018).
Light microscope photomicrographs of Nitzschia spp. A–L N. nandorii from natural population K type species (marked by an asterisk (*)) M–AE N. nandorii from culture AF–AW N. lacuum AX–BI N. alpinobacillum.
SEM of Nitzschia nandorii
In the Bogdałów reservoir, several similar taxa from the Nitzschia genus were identified, including N. lacuum and N. alpinobacillum. Through an analysis of morphological features along with molecular analysis of three markers—rbcL, psbC, and SSU 18S—a new species, Nitzschia nandorii Figs 3-4, was described (Olszyński et al., 2024). The unique environmental conditions in the Pełczyska hydrological complex, the Łęczyca reservoir complex, and the Bogdałów reservoir have led to the proposal of establishing new or revising current ecological indicator values for 16 characteristic species (Olszyński et al., 2019).
References
Olszyński, R. M., Szczepocka, E., & Żelazna-Wieczorek, J. (2019). Critical multi-stranded approach for determining the ecological values of diatoms in unique aquatic ecosystems of anthropogenic origin. PeerJ, 2019(12). https://doi.org/10.7717/PEERJ.8117/SUPP-5
Olszyński, R. M., Zakrzewski, P. K., Rimet, F., Sulkowska, J., Peszek, Ł., & Żelazna-Wieczorek, J. (2024). Morphology and phylogeny of Nitzschia nandorii sp. nov. (Bacillariophyceae), a new small-celled lanceolate species from a post-mining reservoir. PhytoKeys 241: 1-26, 241, 1–26. https://doi.org/10.3897/PHYTOKEYS.241.117406
Olszyński, R. M., & Żelazna-Wieczorek, J. (2018). Aulacoseira pseudomuzzanensis sp. nov. and other centric diatoms from post iron ore mining reservoirs in Poland. Diatom Research, 33(2), 155–185. https://doi.org/10.1080/0269249X.2018.1509886
Żelazna-Wieczorek, J., & Olszyński, R. M. (2016). Taxonomic revision of Chamaepinnularia krookiformis Lange–Bertalot et Krammer with a description of Chamaepinnularia plinskii sp. nov. Fottea, 16(1), 112–121. https://doi.org/10.5507/fot.2016.001
Żelazna-Wieczorek, J., Olszyński, R. M., & Nowicka-Krawczyk, P. (2015). Half a century of research on diatoms in athalassic habitats in central Poland. Oceanological and Hydrobiological Studies, 44(1), 51–67. https://doi.org/10.1515/OHS-2015-0006
I’m an assistant professor in the Department of Algology and Mycology at the University of Lodz. My research focuses on the taxonomy and ecology of benthic diatoms in post-mining reservoirs. I’m studying how the unique environmental conditions prevailing in these types of ecosystems affect diatom communities. Recently I’ve been working with the diatom culturing and phylogeny of some Bacillariaceae species.