Patterns and Pace of Polar Bioerosion

• Applicant: Dr. Max Wisshak
• Subject Area: Palaeontology
• Term: from 2017 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 387793556

In the understanding of biosedimentary processes, research on bioerosion is gaining momentum, acknowledging the important role of this process in carbonate (re)cycling, and the significant impact of the present global change (ocean acidification, ocean warming, eutrophication) on this process. In the marine realm, investigations in bioerosion of tropical coral reefs are far advanced, and research on temperate settings has caught up to some degree. Studies about bioerosion of polar carbonates, in contrast, are anecdotal and merely descriptive - despite prominent centres of cold-water carbonate production being situated in the polar biogeographic realm. This very gap in research is the subject of the present proposal. The project comprises a set of five closely interlinked objectives that are ultimately directed towards a better understanding of the qualitative and quantitative role of bioerosion in polar carbonate factories and depositional environments. These objectives are (i) to elucidate the ichnodiversity of polar microbioerosion, macrobioerosion, grazing, and attachment etching, as reflected in the various bioerosion traces found in polar skeletal carbonates, (ii) to study the bathymetrical distribution pattern of these bioerosion traces as a function of the photic zonation, (iii) to study the ecophysiological tolerance limits of key bioeroders in respect to seasonality and temperature by studying the latitudinal limits in the occurrence of their bioerosion traces, (iv) to draw a comparison of the above aspects, both between polar bioerosion in different sites in the Arctic, as well as between the Arctic and Antarctica, and (v) to calculate rates of polar bioerosion for concluding a latitudinal transect of carbonate cycling experiments - undertaken by the applicant in recent years - spanning the tropics, warm-temperate, cold-temperate, and now also polar waters.The proposed study will primarily be based on experimental substrates from settlement platforms that were deployed in the Svalbard Archipelago and recovered after 10 years of exposure during M. S. MERIAN cruises MSM 2 and 55, respectively, and on samples of marine epibenthic calcifiers that were sampled during these cruises. For a more comprehensive picture on polar bioerosion, the proposed project extends the analysis from the Svalbard settings to comparable material from the Canadian Arctic, and to carbonates sampled in the polar Southern Ocean around Antarctica. This will, for the first time, allow a characterisation and direct comparison of bioerosion traces and trace assemblages between the polar regions of both hemispheres, and help us to gain a better understanding of the role of bioerosion in the dynamics of carbonate (re)cycling in polar carbonate factories.

• DFG Programme: Research Grants
• International Connection: Canada, Italy, New Zealand
• Co-Investigators: Dr. Lydia Beuck; Professor Dr. André Freiwald
• Cooperation Partners: Dr. Evan Edinger; Professor Dr. Jochen Halfar; Professor Dr. Marco Taviani; Professorin Dr. Di Tracey