Springs ecosystems as refuge areas of diatom biodiversity

by Julia Sulkowska |

Springs are ecotonal environments that form when groundwater crosses the earth’s surface. This unique habitat plays an important role in the conservation of freshwater biodiversity. The physical and chemical parameters of water in springs are strongly influenced by the geological characteristics of the substratum, climate, and land use. These ecosystems are perceived as physicochemical stable habitats with mosaic structures of microhabitats. Thanks to the uniqueness of spring habitats, they are treated as hotspots of biological diversity (Cantonati et al., 2012, 2020).

Springs are certainly considered to be globally threatened ecosystems, mainly because of direct and indirect anthropogenic pressure manifested by for example: habitat destruction, hydrological systems modifications, intensification of agriculture and climate change. Human activity is the greatest threat to natural or near-natural oligotrophic ecosystems. Most studies of algal flora in springs have been focused on diatoms. Diatoms can be found in all aquatic habitats around the world. Among them, there are cosmopolitan species but most diatom species have very precise preferences for ecological conditions, related to a specific habitat. The species composition of diatoms in oligotrophic environments is less known than in aquatic environments affected by human impacts. Springs are still poorly understood ecosystems that may be a refuge for rare and endangered diatom species – especially connected with bryophytes in spring habitats (Cantonati et al., 2020, 2022).

A spring located in Dwerniczek, studied in the years 2011-2023 (Bieszczady Mountains, Poland), is affected by human impact. In previous studies of spring habitats located in the Bieszczady National Park, a number of species recorded on bryophytes was higher than on surface sediments (Żelazna-Wieczorek & Mostowik, 2017; Żelazna-Wieczorek & Knysak, 2019). There is an opposite tendency in Dwerniczek. This negative impact on the bryophytes and epibryon diatom assemblages could be caused by human impact. Moreover, due to anthropogenic transformation, the epilithic microhabitat was lost.

Bryophytes can provide microhabitats for many species of microscopic algae. Moreover, it is considered that different bryophytes can create very specific microhabitats for certain diatom species (Chen et al., 2012). Species of diatoms associated with mosses (epibryon) in spring habitats often have a “Highly Threatened” status according to Red Lists for Germany (Hofmann et al., 2018). Examples of such taxa found in the Western Bieszczady Mountains include, among others: Cymbopleura austriaca (Grun.) Krammer, Eunotia kruegeri Lange-Bert. and Psammothidium altaicum (Poretzky) Bukht.

References

Cantonati, M., Angeli, N., Bertuzzi, E., Spitale, D., & Lange-Bertalot, H. (2012) Diatoms in springs of the Alps: spring types, environmental determinants, and substratum. Freshwater science, 31(2), 499–524.

Cantonati, M., Hofmann, G., Spitale, D., Werum, M., & Lange-Bertalot, H. (2022) Diatom Red Lists: Important tools to assess and preserve biodiversity and habitats in the face of direct impacts and environmental change. Biodiversity and Conservation, 31(2), 453–477.

Cantonati, M., Segadelli, S., Spitale, D., Gabrieli, J., Gerecke, R., Angeli, N., … & Wehr, J. D. (2020) Geological and hydrochemical prerequisites of unexpectedly high biodiversity in spring ecosystems at the landscape level. Science of the Total Environment, 740: 140157. https://doi.org/10.1016/j.scitotenv.2020.140157

Chen, X., Bu, Z., Yang, X., & Wang, S. (2012) Epiphytic diatoms and their relation to moisture and moss composition in two montane mires, Northeast China. Fundamental and Applied Limnology-Archiv furHydrobiologie, 181(3), 197–206.

Hofmann G, Lange-Bertalot H, Werum M, Klee R (2018) Rote Liste und Gesamtartenliste der limnischen Kieselalgen (Bacillariophyta) Deutschlands. In Metzing, D., Hofbauer, N., Ludwig, G. & Matzke-Hajek, G. (Eds.): Rote Liste der gefährdeten Tiere, Pflanzen und Pilze Deutschlands. Band 7: Pflanzen. – Bonn (Bundesamt für Naturschutz). – Naturschutz und Biologische Vielfalt 70 (7): 601–708.

Żelazna-Wieczorek J., Knysak P. (2017) Okrzemki (Bacillariophyta) źródła na Przełęczy Goprowskiej (Bieszczadzki Park Narodowy) w ocenie wpływu ruchu turystycznego. Roczniki Bieszczadzkie, 25, 321–338.

Żelazna-Wieczorek J., Mostowik K. (2019) Różnorodność gatunkowa okrzemek Bieszczadzkiego Parku Narodowego: okrzemki źródła Elizy na Połoninie Wetlińskiej. Roczniki Bieszczadzkie, 27, 345–360.