28.10.16 | Congratulations! Claudia Pogoreutz of ZMT has received the highest grade “Summa cum laude” for her doctoral thesis “Coral holobiont functioning under global environmental change”.
For her experimental work, Pogoreutz spent a year at her partner institution, the King Abdullah University of Science and Technology (KAUST) in Saudi Arabia. There, she studied the effects of a widely understudied stressor on corals: dissolved organic matter. Uniquely, her work was conducted in a comprehensive ‘holobiont’ framework that investigated not only the responses of the coral, but also those of their microbial associates. The project was part of a fruitful international collaboration between the ZMT, the University of Bremen and the Coral Reef Genomics Lab at KAUST.
Dissolved organic matter (DOM), such as sugars or urea, is widely introduced into coastal waters, including coral reefs, for instance via the release of poorly or untreated wastewater and agricultural run-off via river discharge. Also organisms competing for space with corals, for instance seaweeds, are known to release large quantities of DOM onto reefs. DOM can be a cause of coral bleaching, a stress response of corals to high water temperatures and poor seawater quality.
In her PhD project Pogoreutz set out to disentangle the individual responses of the coral, the microalgae, and bacteria to this stressor. One specific aim of the project was to investigate whether DOM can affect certain biogeochemical properties in corals, for instance the nitrogen fixation pathway. Under undisturbed conditions, nitrogen fixation is a source of nutrients for the coral holobiont. Indeed, Pogoreutz and her colleagues found that changes to this pathway under the influence of DOM can severely affect coral health. This can potentially aggravate the already bleak situation for coral reefs already severely threatened by the effects of global climate change, pollution, and overfishing. Therefore, improved water quality treatment and management of seaweed populations on coral reefs will be critical in reef conservation.
