Approaching microbial bioerosion.

The participation of microorganisms in construction and destruction of sedimentary structures is widely recognized, and so is the importance of studying such geological processes in modern systems, where the conditions, participating forces, and the results can be observed and recorded. This information is important for understanding and interpreting corresponding processes if their effects were preserved as part of the fossil record. The present contribution refers to topics discussed during the 9th International Bioerosion Workshop in Rome on Oct. 23–27, 2017, dedicated to the evaluation of microbial traces as paleoecological and paleobathymetric indicators. The paper reviews the habitats, methods of collection, and preparation of samples, followed by observation of extracted microbial euendoliths. This approach is complemented by producing images of three-dimensional display of inhabited microborings in their original positions using resin-casting and double embedding of the microbially invaded substrates. This contribution stresses the value of recognizing the microboring organisms' identities as a key aspect of the interpretation of their traces. It discusses different and complementary ways of how to achieve such parallel assessments. It reports on the importance of photo-documentation and morphometric evaluation of microbial populations, while avoiding possible artefacts caused by the methods used. The study also briefly summarizes the distribution patterns of microboring organisms and their boring and etching traces along depth profiles. Problems arising in the naming of complex traces and the relation to biological nomenclature are discussed. [ABSTRACT FROM AUTHOR]