The Evolution and Biogeochemical Impacts of Bioturbation
with Lidya Tarhan, Assistant Professor of Earth & Planetary Sciences, Yale University.
Bioturbation—sediment mixing and ventilation by burrowing animals—shapes seafloor ecology, sediment properties and global marine biogeochemical cycling. Well-mixed sediments have long been assumed to appear at the Ediacaran-Cambrian boundary. However, field-based stratigraphic analyses indicate that sediment mixing in shallow marine environments lagged significantly behind other early Paleozoic advances in benthic ecology, and that the development of bioturbation was a protracted process. An equally critical question is when and how in Earth’s history bioturbators began to substantially influence marine biogeochemistry. Recent modeling work has suggested that even limited early Paleozoic bioturbation could have driven productivity crises and ocean-wide deoxygenation—in striking contrast to macroevolutionary and macroecological predictions. In order to move forward this debate, I will present new diagenetic modeling data exploring quantitative relationships between bioturbation and global nutrient cycling—focusing on phosphorus, the ultimate limiting nutrient on geological timescales. This approach indicates, in contrast to previous studies, that bioturbation does not uniformly or unidirectionally mediate increased phosphorus burial. Bioturbation does, however, appear to have enhanced the sensitivity of carbon and oxygen cycling to environmental perturbations.
The Earth Science Colloquium Series is sponsored by Lamont-Doherty Earth Observatory and Columbia University Department of Earth and Environmental Sciences (DEES). This series provides a lively forum for discussing a wide variety of topics within the earth sciences and related fields. Colloquia are attended by the full range of scientific and technical staff at LDEO. Colloquium attendance is required of all pre-orals DEES graduate students. The Colloquium Series supports the Lamont Seminar Diversity Initiative.
Zoom link will be provided the day of the seminar.