Project Details
Projekt
Heterotrophy and coral resilience during marine heat waves – from organism responses to its skeletal signature (HeROeS)
Applicant
Dr. Marlene Wall
Subject Area
Oceanography
Term
since 2026
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 569255476
Coral reefs are among the most species-rich ecosystems on our planet and are a hotspot of marine biodiversity, teeming with life. However, this ecosystem is disappearing at an alarming rate. This has led to the search for places that can offer protection from certain factors of global change, so-called climate refugia, such as the upwelling-influenced reefs studied here. It is known that upwelling of deep, cold water can mitigate warming during heat waves and protect corals from bleaching. It is less well known whether the transport of nutrient- and particle-rich water also provides energy subsidies for corals, which recharge their energy reserves through heterotrophic nutrition. Although these energy subsidies represent a seasonally recurring oceanographic feature, they may play an even more important role during heat stress. In the first phase, the project focused on the reduction of heat stress and its role in reef resistance in a changing ocean in the future. It was clearly shown that IW-exposed reefs contribute to reef presistence. Furthermore, it was found that IWs also provided protection during previous bleaching events. The project proposed here will again use the Andaman Sea, with its internal waves (IWs) exposed reefs, as a natural laboratory. In addition, the project takes advantage of a comprehensive assessment of the physiological characteristics of corals during the severe heat wave of 2010 from which the skeletons are still remaining. However, this project will focus on the previously neglected aspect of enhanced nutrition through IWs and their contribution to coral resilience. The aim of the project is to determine whether heterotrophic energy acquisition during heat stress events can contribute to coral resilience and is manifested in the geological records of corals by distinct spikes in the skeletal δ13C signal. Such spikes were found in a parallel study (IndOC-E) in the same regions in a 25-year coral record from a reef exposed to IWs. Therefore, it was hypothesized that this reflects the use of energy subsidies by corals during heatwave events. Based on a multifactorial experimental design, the project aims to verify the δ13C signal and to decipher the relative contribution of reduced energy from the loss of symbionts and energy gain from increased food intake to this signal. In particular, it will be determined whether an increased heterotrophic energy uptake capacity is associated with coral origin and locations with known energy subsidies from IWs. To achieve this goal, past bleaching scenarios will be simulated experimentally and investigated using samples collected during the 2010 bleaching event. Together, these investigations will provide insights into how bleaching and food supply are manifested in the coral skeleton δ13C signal.
DFG Programme
Priority Programmes
International Connection
Thailand
Co-Investigators
Privatdozent Dr. Jacek Raddatz; Professor Dr. Claudio Richter
Cooperation Partner
Dr. Lalita Putchim
