By drilling deep down into sediments on the ocean floor researchers can travel back in time.
By drilling deep down into sediments on the ocean floor researchers can travel back in time. A research team led from Uppsala University now presents new clues as to when and why a period often referred to as the ‘biogenic bloom’ came to an abrupt end. Changes in the shape of the Earth's orbit around the Sun may have played a part in the dramatic change.
Healthy ocean systems contain healthy primary producers, such as the single-celled algae diatoms and coccolithophores, which sustain all other life in the oceans through the marine food webs. Primary producers also release oxygen and regulate the climate by taking up CO2 and binding carbon into solid components that are buried in deep-sea sediments, which is an effective long-term solution for carbon removal from the atmosphere.
Most of these algae use sunlight, CO2 and inorganic nutrients to build up their body mass. However, these nutrients are quickly exhausted in the sun-lit surface waters, if not replenished by ocean mixing or renewed by river supply.
Throughout Earth’s history, paleoceanographers reconstruct changes in primary productivity by looking at algal remains buried in ocean-floor sediments. Although only a small fraction of surface water production is recorded in marine sediments, on geological time scales, changes in the accumulation of biogenic sediments (including the calcareous scales of coccolithophores and siliceous shells of diatoms) are linked to past changes in ocean productivity.
Read more at Uppsala University
Image: Karatsolis et al. studied drill cores from seafloor sediments recovered by the International Ocean Discovery Program (IODP), including IODP Expedition 356, in which sediment archives were drilled on the northwestern Australian shelf. (Credit: J. Henderiks)
