Leicester scientists voyage to Hawai’ian fossil coral reefs to find window into the past and future

University of Leicester scientists are joining a unique expedition off the coast of Hawai’i to collect samples of fossilised coral reef from the seabed, to gain insight into half a million years’ worth of environmental change.

A look back at environmental change throughout geologic history can tell us a lot about the future – especially when it comes to globally and societally important topics such as sea level, climate change and coral reef ecosystem health. An international scientific research expedition, carried out on behalf of the International Ocean Discovery Program (IODP), aims to recover a record of past climate and reef conditions off the coast of Hawai’i (USA). The two-month research expedition will leave the port of Honolulu at the end of August.

Coral reefs are very sensitive to sea level and other changes in environmental conditions. As fossils they provide a record of past conditions over hundreds, thousands and millions of years of Earth’s history. There is, however, a discontinuity in the global record over the past 500,000 years, especially during periods of major and abrupt climate instability. IODP Expedition 389 “Hawai’ian Drowned Reefs” focusses on this missing link and is led by Co-Chiefs scientists Professor Christina Ravelo (Ocean Sciences Department at the University of California, Santa Cruz, USA) and Professor Jody Webster (School of Geosciences, the University of Sydney, Australia).  

Joining them on the expedition are Dr Marisa Rydzy and Dr Andrew McIntyre, International Ocean Discovery Program Research Associates from the School of Geography, Geology and the Environment at the University of Leicester. They will also provide scientific support to the expedition.

Dr Marisa Rydzy said: “I am very much looking forward to our next Mission Specific Platform (MSP) expedition. The University of Leicester has taken part in all MSPs to date. We provide staff, equipment, and our expertise in physical rock properties. The goal of the MSPs is to take rock samples from the sea bed and below. In this expedition, these rock samples will be fossil corals. We will measure various physical properties of these corals, such as their bulk density, right here onboard the vessel.”

Professor Sarah Davies, lead of the IODP group at Leicester and Head of the College of Science and Engineering at the University of Leicester, said: “These expeditions are years in the planning by the scientific community. We are absolutely delighted that the University of Leicester and partners the British Geological Survey, MARUM, and the University of Montpellier are working together as the implementing organisations to facilitate new scientific discoveries.” 

Professor Christina Ravelo said: “The Hawai‘i fossil reefs are storytellers of the past climate and ocean changes and of the reef ecosystem responses to those changes. These stories can be unlocked through careful study of the fossils that we hope to recover.”  

Professor Jody Webster said: “We hope that information recorded in the fossil reefs will help scientists make improved predictions about the rate and magnitude of sea-level rise, what impact global warming and cooling has on short-term climate phenomena like droughts, floods and marine heat waves, and how coral reef ecosystems respond to these changes.”

The expedition aims to recover cores from water depths between 134 and 1,155 meters at a maximum of twenty locations. Even though this will be the first time that a seafloor coring system will be deployed in this area, the anticipated sites are well studied. 

The scientific objectives of the expedition aim to address questions on four main topics: 

• To measure the extent of sea level change over the past half a million years
• To investigate why sea level and climate changes through time
• To investigate how coral reefs respond to abrupt sea level and climate changes, and
• To improve scientific knowledge of the growth and subsidence of Hawai’i over time.

The planning phase of the expedition includes intensive environmental observations and a comprehensive risk assessment.

In order to recover the material that scientists will use for their analyses in the coming years, a seafloor corer will be deployed off the multipurpose vessel MMA VALOUR during the expedition. The seafloor corer will be provided and operated by a renowned geotechnical industry specialist, to be lowered to the ocean floor to recover up to maximum 110-meter-long cores beneath the seabed.

29 scientists from Australia, Austria, China, Denmark, France, Germany, India, Japan, the Netherlands, Great Britain and the USA will participate in the expedition. Ten of them will sail onboard the MMA VALOUR, leaving Honolulu port on August 31. The offshore phase of the expedition will end on October 31. All science party members will meet for the onshore phase at the IODP Bremen Core Repository, located at MARUM – Center for Marine Environmental Sciences at the University of Bremen (Germany) to split, analyze and sample the cores and interpret the data collected in February 2024. 

The cores will be archived and made accessible for further scientific research for the scientific community after a one year-moratorium period following the onshore phase of the expedition. All expedition data will be open access and resulting outcomes published.

The expedition is conducted by the European Consortium for Ocean Research Drilling (ECORD) as part of 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 great experience working in sensitive ecosystems such as coral reefs, following seagoing expeditions to the Great Barrier Reef (Australia, 2010) and Tahiti (2005).