Response of marine diatom communities to Late Quaternary abrupt climate changes

The high temporal resolution of the marine microfossil record makes it possible to explore how microbial communities responded to abrupt climate changes in the past. We analysed changes in species richness and total abundance of marine diatoms in sedimentary records from the Mauritanian upwelling system and the Panama Basin spanning the last 100 000 years. The analysis shows instances of community change and recovery linked to episodes of rapid, sub-millennial scale climate change (e.g. Heinrich events). The probability of sampling a given species during the perturbation increased with the mean abundance of the species in the database, indicating that (i) dominant species were persistent through long periods of time and (ii) rare species, with low population densities, accounted for much of the variability in species richness. To the extent that contemporaneous climate change falls within the range of climate variability analysed here, our results point to important changes in the structure of marine diatom communities, yet these changes will be reversible. These results highlight the importance of integrating fossil data and ecological theories to understand the effect of climate change on the ecological and biogeochemical functioning of marine ecosystems.