A species distribution model of the marine diatom Fragilariopsis kerguelensis

Fragilariopsis kerguelensis has been reported to be the main driver of the Southern Ocean silicate pump, thereby substantially affecting silicate supply in lower latitude surface water masses of the world ocean. In order to investigate the potential responses of this species to climate change, we have explored the use of species distribution modeling (SDM). These methods aim at predicting the potential distribution of a species using statistical or machine learning approaches by combining geo-referenced taxon occurrence data and layers of environmental parameters. During the last two decades, the methodology became a standard approach in biogeography as well as conservation and climate change science, though with a strong bias towards terrestrial organisms. Marine organisms are clearly underrepresented and there is little experience with the applicability of SDMs for planktonic organisms. We harvested taxon occurrence records from the GBIF network and other public resources. Environmental parameters included nutrient concentrations and oceanographic variables like sea surface temperature and salinity. The main modeling method used is maximum entropy. Results of this study will be presented to give an overview to the current availability of data records, a selection of environmental parameters, model evaluation and a projection of the model on expected environmental conditions predicted for future climate scenarios to explore potential biogeographic shifts in response to climate change. Further, a novel workflow currently under development will be presented, which will enable the integration of molecular-based taxon observation records with traditional occurrence records for distribution modeling. In summary, the resulting potential distribution maps of the models agree well with species distributions expected based on background knowledge. Our experiments clearly show that SDM methods are suitable to model the geographic distribution of pelagic diatoms, and suggest that the distribution range of the main silica carrier of the Southern Ocean might shift pole wards and substantially shrink during the upcoming decade