UK scientific expertise supports first high-resolution fossil coral record of environmental data off Hawai’i

Andrew McIntyre (University of Leicester) loading a core into the high-resolution core imager. Credit: parker@ECORD_IODP

For the first time, an international research team has succeeded in obtaining a high-resolution continuous record of environmental data from shallow-water corals off the coast of Hawai’i (USA) by coring fossil coral reefs. 

These cores were obtained during an International Ocean Discovery Program (IODP) expedition involving a UK scientist from the University of St Andrews, and scientific operators from the University of Leicester and the British Geological Survey. The cores have now been opened, analysed and sampled by the scientific team, following almost a month of intensive work in Germany during February 2024. 

The IODP Expedition 389 “Hawaiian Drowned Reefs” aimed to recover a record of past climate and reef conditions off the coast of Hawai’i. 

During the offshore phase of the expedition a total of 426 metres of cores were recovered from below the seabed at water depths from 130 to 1240 metres. Corals store past environmental conditions in their skeletons. Researchers will use cutting-edge methods in their laboratories to extract information about sea level or climate changes from these tremendously important high-resolution archives. Looking back in Earth’s history will provide valuable insight into the mechanisms that cause climate change, including abrupt events, and into the impact of these changes on reef growth and health. 

IODP Expedition 389 was led by Co-Chief Scientists Professor Jody Webster (School of Geosciences, the University of Sydney, Australia) and Professor Christina Ravelo (Ocean Sciences Department at the University of California, Santa Cruz, USA). The Science Party includes 31 scientists of different disciplines from Australia, Austria, China, Denmark, France, Germany, United Kingdom, India, Japan, the Netherlands, Spain and the USA, ten of whom sailed onboard the multipurpose vessel MMA Valour in September and October 2023 off the coast of Hawai’i, to collect the cores and data using a remotely operated coring system. 

Tim van Peer (University of Leicester) determining the core’s colours. Credit: parker@ECORD_IODP

Expedition Project Manager Dr Hannah Grant, from the British Geological Survey, said: "We are so pleased that we have recovered unique fossilised coral reef material. This expedition is the culmination of many years of planning by the co-chiefs and the scientific community to carefully select the best locations to obtain records of past changes to inform and test important climate change theories.”

After the offshore phase, the whole Science Party met at the IODP Bremen Core Repository, at the MARUM – Center for Marine Environmental Sciences at the University of Bremen, Germany, in February 2024 to split, analyse and sample the cores and begin to interpret the data collected. The scientists will continue to work on samples and data over the next years in their home laboratories in depth to decipher detailed information from this unique new material and associated data.

Dr Marisa Rydzy and Dr Andrew McIntyre, IODP Research Associates from the School of Geography, Geology and the Environment at the University of Leicester, travelled to Bremen to operate the physical properties equipment, just like they did during the expedition’s offshore phase. To support the laboratory work, IODP Research Fellow Tim van Peer and IODP Research Assistant Walid Naciri joined their Leicester colleagues in Bremen.

Dr Rydzy, the Petrophysics Staff Scientist, said: “We are excited to have participated in this expedition. The physical properties measured offshore and onshore will greatly help to reconstruct the reefs’ history and help the scientists get a better understanding of the links between reef growth, sea level, water chemistry, and volcanic activity.”

One of these scientists is Dr Nicola Allison (University of St Andrews), who participated in the expedition as an inorganic geochemist. She added: “The fossilised reefs encode a record of past sea level and seawater temperature. We can detect annual growth bands in the fossilised corals and see how their growth responded to past environmental change. This will help us to predict how modern climate change and rising sea level will impact today’s reefs.”

Prof. Webster and Prof. Ravelo added: “These fossil coral reef deposits enable us to decipher in unprecedented detail, how sea level, past climates, and the reef ecosystem have changed over the past 500,000 years, particularly during periods of rapid global change.”

The expedition is conducted by the European Consortium for Ocean Research Drilling (ECORD) as part of the International Ocean Discovery Program (IODP). IODP is a publicly-funded international marine research program supported by 21 countries, which explores Earth's history and dynamics recorded in seafloor sediments and rocks, and monitors sub-seafloor environments. Through multiple platforms – a feature unique to IODP – scientists sample the deep biosphere and sub-seafloor ocean, environmental change, processes and effects, and solid Earth cycles and dynamics.

The ECORD Science Operator has extensive experience working in sensitive ecosystems such as coral reefs, following seagoing expeditions to the Great Barrier Reef (Australia, 2010) and Tahiti (2005).