Effects of water temperature over benthic diatom communities: insights from thermal springs

ABSTRACT

Background

Thermal springs provide extreme ecological conditions for aquatic communities owing to their high water temperature and particular water chemistry. The thermal springs and their connected watercourses provide a thermal laboratory by offering a wide range of temperatures within short spatial distances. To date, the information on how the biodiversity of these springs is related to water temperature or chemistry is limited.

Aims

We studied the effects of water temperature on diatom community diversity and structure with the objective to supply a baseline for the conservation of thermal springs.

Methods

We sampled 31 sites of 16 thermal springs across a temperature gradient between 18.5 and 63.0°C in the north-western Iberian Peninsula and related diatom richness and structure to water temperature.

Results

A total of 124 diatom species were identified in springs with water temperature between 18.5 and 42.4°C. Community diversity decreased with increasing temperature and the highest species richness was found at temperatures ≤ 25°C. Three diatom assemblages were defined, discriminated by temperature ranges (≤25°C, 25–35°C and ≥35°C).

Conclusions

Water temperature was found to be an important driver of diatom community composition in the thermal systems studied. Temperature affects diatom distribution decreasing diversity with the increase in global water temperature.

KEYWORDS:

• Biodiversity
• eukaryotic algae
• Iberian Peninsula
• rivers
• temperature preferences

Acknowledgements

This article is included in the project “Study of diatom communities from hot springs and river areas of influence in the prediction of climate change impacts” funded by Xunta de Galicia (I2C Posdoctoral Fellow granted to the first author). We thank the Department of Biology and Geobiotec Research Centre from the University of Aveiro and MARE – Marine and Environmental Sciences Centre at University of Coimbra (Portugal) for the use of their facilities; and the Foundation of Science and Technology, Portugal for the strategic projects granted to Geobiotec (UID/GEO/04035/2019) and MARE (UID/MAR/04292/2019). We thank the reviewers and specially the editor Laszlo Nagy for their comments, Catarina Moreirinha, Fatima-Vaz Pinto, Lorena Gonzalez-Paz for their contributions and especially Ana González, Claudio Padilla for their help with the field work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

Cristina Delgado´s contract was funded by goverment of Xunta de Gallicia (Spain) awarded two posdoctoral grants (I2C A and B; Posdoctoral Fellow) and her proyects: “Study of diatom communities from thermal springs in the prediction of climate change” and “Diatom ecology as indicator of changes in freshwater and marine ecosystems”.

Notes on contributors

Cristina Delgado

Cristina Delgado is a postdoctoral researcher and the main interest is focused on diatom ecology and taxonomy in European freshwater and marine ecosystems.

Maria J. Feio

Maria J. Feio is an ecologist with special interest in rivers, aquatic communities and ecosystem functioning, and ecological assessment.

Isabel Pardo

Isabel Pardo is professor of ecology. Her research is focused on the ecology of rivers, particularly on the biotic and abiotic controls acting on river and stream communities.

Salomé F.P. Almeida

Salomé F.P. Almeida is a lecturer in biology with a main research interest in diversity, ecology, taxonomy and toxicology of freshwater diatoms and their use for water quality assessment including a genomic approach (eDNA) more recently.