New research reveals Aldabra’s’ coral reef resilience and recovery capacity |13 October 2020

Aerial view of the Aldabra atoll (Photo credit: © FotoNatura, courtesy of SIF)

As the world’s oceans warm due to a changing climate, research on how coral reef ecosystems recover from coral bleaching events is critical to identifying solutions for their conservation.

Research on the impacts of the most recent bleaching event to Aldabra Atoll’s coral reefs, led by University of Bremen PhD student and former Seychelles Islands Foundation (SIF) marine research assistant, Anna Koester, has been published in scientific reports.

The paper, ‘Early trajectories of benthic coral reef communities following the 2015/16 coral bleaching event at remote Aldabra Atoll, Seychelles’ co-authored by SIF’s consulting director of research and conservation, Dr Nancy Bunbury, presents several key findings. Coral mortality following the 2015/2016 bleaching event was not only substantially lower in Aldabra’s lagoon than on its seaward reefs, but lagoonal reefs also recovered their pre-bleaching coral cover and community composition within only four years after bleaching.

The research indicates that high daily temperature fluctuations inside Aldabra’s lagoon probably enhances the coral’s tolerance to heat stress in these sheltered waters. Hard coral recovery also occurred on seaward reefs at five-metre depth, but this varied with location, with westward reefs recovering faster than eastward reefs, thought to be due to higher wind and wave exposure on the east of the atoll.

Speaking about the implications of her research, Anna Koester said “the results of our research show that rapid reef recovery is possible, and highlight that reducing local stressors to coral reefs can enhance their resilience against climate change.”

She added that “the study also underlines the urgency to drastically reduce greenhouse gas emissions, as time periods between bleaching events are projected to become too short for recovery, even for highly protected and more resilient areas like Aldabra”.

Commenting on the publication, SIF chief executive Dr Frauke Flesicher-Dogley said: “It is my firm belief that this specific research on Aldabra’s coral reefs is of crucial value for not only the atoll and Seychelles, but at a global level. As we all well know, coral reefs are hugely impacted by climate change and only by understanding what makes our reefs resilient can we adapt our management practices and policies fully. Aldabra’s reefs serve as a benchmark since direct human impacts are extremely limited and therefore recovery rates are expected to be at their ‘best’ and can be used to calibrate the resilience and recovery of other reefs that provide for the daily livelihood of the many coastal communities around the world.”

With severe bleaching events expected to occur annually on 90% of the world’s coral reefs by 2055, such research and long-term commitment to monitoring these valuable ecosystems is critical. Through the annual Aldabra reef monitoring programme, which started in 2013, SIF is in a position to supply science of global significance to contribute to the world’s adaptation to a new climate reality.

The paper is available open access at: https://www.nature.com/articles/s41598-020-74077-x  

Contributed by SIF