Project Details
Projekt
A Composite coral Approach using a Novel laser-ablation technique: Adaptation strategies in a marginal Reef [CANARY]
Applicant
Dr. Takaaki Watanabe
Subject Area
Oceanography
Geology
Geology
Term
since 2026
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 569217249
The adaptive strategy of reef-building corals (coral) in their current marginal habitats is key to their future survival. These regions can serve as environmental stepping stones for expanding corals’ habitats or even provide refugia. However, corals, in their marginal habitats, are currently sandwiched between two major stressors: increasing thermal stress in lower-latitude regions and intensifying ocean acidification in higher-latitude regions. Cape Verde is one of the corals’ marginal habitats in the Atlantic Ocean. In this region, the dominant species, Siderastrea radians forms pavement reefs. In the future, thermal stress in Cape Verde during summer will become more hostile due to anthropogenic warming combined with a weakening of the Canary Current. Besides, cold stress and ocean acidification during winter may intensify due to the intensification of Canary upwelling. Understanding how Cape Verde corals respond to these multiple stressors will provide insights into the ability of corals to survive in changing environments and/or to expand their habitat to higher-latitudes in the future. However, at present, there is no reliable record of sea surface temperature (SST) and upwelling intensity in Cape Verde covering past centuries. This project aims to understand short- and long-term changes of these two major stressors in Cape Verde and the response of the dominant coral species, Siderastrea radians, to them. I propose to reconstruct SST and Canary upwelling from past centuries up to the extremely warm years of 2023/24 using multiple coral samples from Cape Verde. I will collect 12 cores from different colonies at three sites with Siderastrea radians pavements. I will measure proxies for SST and upwelling. The Sr/Ca ratio will be analysed using a novel approach, using an ICP-OES coupled with a laser ablation system (LA-ICP-OES, installed at CAU Kiel). This method can analyse 15 cm of core per day with high spatial resolution, being enabled to obtain monthly resolved Sr/Ca records from multiple corals. The composite records can increase the signal-to-noise ratio. To evaluate non-climatic noise in Sr/Ca data, I will compare Sr/Ca with other SST-related proxies (e.g., U/Ca, B/Ca) and coral boron isotopes (δ11B). The SST-related and upwelling proxies (Ba/Ca and Cd/Ca) will be analysed using LA-ICP-MS installed at CAU Kiel. δ11B will be analysed using MC-ICP-MS coupled with a laser ablation system at Southampton University, UK. pH and carbonate chemistry in the coral calcification space are reconstructed from δ11B and B/Ca. Coral skeletal density and growth rates will be estimated from CT images and the annual cycles of Sr/Ca. Additionally, I will measure coral skeletal morphologies based on SEM imaging at CAU Kiel. By comparing coral growth responses with environmental proxy reconstructions, I will examine how Cape Verde corals adapt to multiple stressors by comparing coral growth responses with environmental proxy reconstructions.
DFG Programme
Priority Programmes
International Connection
Taiwan, United Kingdom
Cooperation Partners
Dr. Duo Chan; Professor Dr. Gavin Foster; Professor Dr. Chuan Chou Shen
