Hawaii: Environmental data from shallow-water corals allows us to look back 500,000 years
During the IODP 389 “Hawaiian Drowned Reefs” Expedition off the coast of Hawaii, scientists recovered a total of 426 meters of drill cores from the seafloor in water depths of 130 to 1,240 meters. After almost a month of intensive analysis work at the IODP Bremen core storage facility at MARUM – Center for Marine Environmental Sciences at the University of Bremen, in February 2024, the drill cores were now opened and sampled to obtain information about sea level or climate change from these extremely important high-resolution files. Geobiologist Theresa Nohl from the University of Vienna is also there. The project was led by Jody Webster (School of Geosciences, University of Sydney, Australia) and Christina Ravelo (Department of Ocean Sciences, University of California, Santa Cruz, USA).
Corals store past environmental conditions in their skeletons. By analyzing coral fossils, valuable data can be obtained about the past climate and reef conditions off the coast of Hawaii. Specifically, the international team of scientists is measuring the extent of sea level changes over the last 500,000 years. The data is intended to answer questions such as why sea level and climate change over time and how coral reefs react to abrupt changes in sea level and climate. “This analysis of the past will give us valuable information, for example, about the mechanisms of climate change”, explains Theresa Nohl.
“We have recovered a spectacular sequence of fossil coral reef deposits that will allow us to decipher in unprecedented detail how sea levels, paleoclimate and reef ecosystems have changed over the last 500,000 years, particularly during times of rapid global change.” , said Jody Webster. “We are also pleased to have recovered many fossil coral samples with distinct annual rings, which will give us, for the first time, detailed records of monthly changes in oceanographic conditions in past periods that were different from today. “Use this data to make predictions about future climate change across the Pacific,” adds Christina Ravelo.
Geobiologist Theresa Nohl from the University of Vienna is part of the land phase of the expedition as a sedimentologist. She has also spent the last few weeks at MARUM – Center for Marine Environmental Sciences at the University of Bremen, doing intensive sampling and description work. “My research question concerns the preservation of various organisms. This means I investigate the extent to which physical and chemical (microbially controlled) changes following deposition altered the reef terraces and surrounding sediments, what these changes mean for the reconstruction of ecosystem dynamics and sea level fluctuations and how these reconstructions are affected can be improved.” Samples and analyzes have been promising so far.
About the expedition
The IODP 389 Expedition scientific team is made up of 31 scientists from diverse disciplines from Australia, Austria, China, Denmark, France, Germany, Great Britain, India, Japan, Netherlands, Spain and the USA, ten of whom will be in September and October 2023 sailed aboard the multipurpose vessel MMA Valor off the coast of Hawaii to collect cores and data using a remotely controlled coring system. After the offshore phase, the entire scientific team met in February 2024 at the IODP core storage facility in Bremen, at MARUM – Center for Marine Environmental Sciences at the University of Bremen, Germany, to divide, analyze and sample the cores and evaluate the collected cores. the data begins. Scientists will continue to process the samples and data in their home laboratories over the next few years to decipher detailed information from this unique new material and associated data.
The expedition is carried out by the European Consortium for Ocean Research Drilling (ECORD) as part of the International Ocean Discovery Program (IODP). The IODP is a 21-country, publicly funded, international marine research program that explores Earth's history and dynamics as recorded in deep-sea sediments and rocks and monitors the environment beneath the seafloor. Using multiple platforms – a unique feature of IODP – scientists study the deep biosphere and ocean beneath the seafloor, environmental changes, processes and impacts, and solid Earth cycles and dynamics.
Illustration:
1: Members of the IODP Expedition 389 scientific group observe drilling cores at the IODP Bremen core storage facility at MARUM – Center for Marine Environmental Sciences at the University of Bremen. C: parker@ECORD_IODP