Using diatom analysis in paleoecology: A case study from the du Loup Bourrou spring at the Bibracte archaeological site in France

In this work, I focused on assessing profile P2a from the du Loup Bourrou spring at the Bibracte site in France. Based on diatom analysis, I found that environmental conditions at the du Loup Bourrou spring did not change much between 1747 and 1999. There was, however, a significant decrease in species diversity, evidence of a change that must have occurred at this site, as well as a fluctuating number of species sensitive to human impact.

The next step will be to analyze profile P2a using a different method for recording the abundance of each taxonomic group––by counting the exact number of shells of each species in the samples. Another task will be to analyze the other profile, profile P1a, which was taken in the vicinity of profile P2a. It will then be possible to compare the newly calculated indices with the results presented here to determine if profile P1a confirms them.

It will also be interesting to compare the species found in both profiles and determine whether diatom communities so close to each other can differ significantly or, conversely, whether there is no large difference in species.

After both palaeoecological profiles have been assessed, it will be possible to publish the research findings in a multidisciplinary study led by archaeologist Petra Goláňová from the Department of Archaeology and Museology of Masaryk University as part of the project “Oppidum as an urban landscape: multidisciplinary approach to the study of space organization ‘intra muros.’” In an interdisciplinary study, it will be possible to compare the findings of researchers in other fields with the results of my diatom analysis and perhaps determine what changes occurred at this site within the past two centuries.

When all the findings from the diverse disciplines included in this multi-proxy study will have been analyzed together, it will be possible for archeologists to remove the stone layer from the 14th century. This way, older sediments hidden under this layer will be uncovered, and it will therefore be possible to take a new profile dated to an older period. Conducting the same multidisciplinary research on this profile will enable us to reconstruct the evolution of environmental conditions at the site deeper into the past.

Bibracte and the entire Morvan region are part of a protected area, and the results presented here may in the future contribute to managing Mont Beuvray hill. They may serve as reference points that can be used to evaluate future changes in environmental conditions and pollution levels at the site.

I would like to thank above all Markéta Fránková, Ph.D., from the Institute of Botany of the Academy of Sciences of the Czech Republic, who introduced me to diatom analysis, allowed me to engage in research work for the first time, and was always willing to answer my questions.