Recent and sub-recent microborings from the upwelling area off Mauritania (West Africa) and their implications for palaeoecology

Late Quaternary dead molluscan shells off Mauritania (West Africa) from the intertidal zone to 220–300 m water depth were studied for microborings. The study gives preliminary data on microborings in upwelling areas and their implications for the fossil record. In total 18 ichnotaxa are described. They are considered to be produced by cyanobacteria, green algae, red algae, fungi and foraminifera. The ichnotaxonomic composition shows minor differences relative to tropical/subtropical areas of investigation. No ichnotaxa are believed to be specific to upwelling areas. Bathymetrical distribution patterns revealed different depth ranges for individual ichnotaxa. Relative to areas with similar latitude but not influenced by upwelling, the absolute depth of the photic zone is shallower. The majority of ichnotaxa observed are already known from the fossil record (tropical and subtropical study areas) and should also be expected from ancient upwelling areas.