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Anna Koester


+49 421 218-63358


UFT, room 2170

Anna Koester
Institution: University of Bremen, Faculty 2
Other webpage(s): Web page of Anna's working group


PhD project:

Patterns and drivers of coral reef resilience at Aldabra Atoll, Seychelles

Mass coral bleaching events become an ever increasing threat to coral reefs worldwide. In the Seychelles, the 1998 mass bleaching event led to extreme mortality and the subsequent reef trajectories are documented mainly for the inner islands, harbouring the majority of Seychelles’ population. The resilience of Seychelles’ inner islands reefs has therefore also been of high interest and this has gained new momentum through the last mass bleaching in 2016 that again severely disturbed coral reefs globally and across the Seychelles. Aldabra Atoll (a strict nature reserve, special reserve, UNESCO World Heritage Site and Ramsar site) is located 1200 km south-west of the inner islands and remains relatively unimpacted by direct anthropogenic stressors such as fishing pressure, habitat destruction, pollution and nutrient enrichment. It can therefore be considered as a unique natural laboratory that allows the study of coral reefs under the exclusive influence of global stressors such as sea surface temperature rise and associated coral bleaching. Coral reef monitoring at Aldabra has a long history and continues to inform local management about reef state and the impact of disturbances. However, targeted research on the actual resilience of these reefs has not been undertaken to date and remains subject to speculation.

Coral reef resilience is a widely studied field and of high priority for coral reef conservation globally. Management for resilience aims to promote ecosystem functioning, ultimately aiming to sustain the value of coral reefs and the services they provide to humanity. The study of reef resilience has therefore seen a vast progress from early theoretical frameworks towards more applied and empirical work. The assessment of reef resilience at remote locations can provide baseline information which ultimately yields valuable implications for reef management of those areas that are subject to direct human impacts. Nevertheless, there is a need for more field data and the necessity to study a wider array of locations and environments to better understand ecosystem functioning and reef resilience processes under multiple conditions. This also calls for new assessment approaches since classic long-term reef monitoring methods (‘state’ indicators) alone are considered to be insufficient in detecting resilience levels and should therefore be complimented by methods assessing ecosystem processes (‘process’ indicators).

Within this PhD research, patterns and drivers of reef resilience at Aldabra Atoll will be studied through a combination of long term-monitoring ‘state’ indicators and additional ‘process’ indicators. This will advance the scientific understanding of reef resilience and the processes involved in absence of direct anthropogenic impacts and will enable more informed and effective management strategies to be implemented at Aldabra Atoll and ultimately elsewhere in the world.

This research is conducted in partnership with the Seychelles Islands Foundation, a public trust dedicated to protect and manage the two Seychelles World Heritage Sites Aldabra Atoll and Vallee de Mai.

Thesis committee:

Prof. Dr. Christian Wild University of Bremen
Dr. Frauke Fleischer-Dogley Seychelles Islands Foundation
Dr. Nancy Bunbury Seychelles Islands Foundation
Dr. Valentina Migani University of Bremen


GLOMAR Research Theme C