[Coral-List] New publication - Heat stress destabilizes symbiotic nutrient cycling in corals - "corals bleach before they pale"

Chris Voolstra chris.voolstra at gmail.com
Mon Feb 1 08:11:22 UTC 2021


Dear friends and colleagues, 

We are excited to share with you our latest publication where we show that heat stress impedes symbiotic nutrient cycling in corals with implications for our understanding of coral bleaching: https://www.pnas.org/content/118/5/e2022653118 <https://www.pnas.org/content/118/5/e2022653118>

In a nutshell, we set out to characterize the effects of heat stress on the coral-algal symbiosis long before any visual signs of bleaching become evident. We could show that increased metabolic energy demands during heat stress shift the coral host metabolism towards the enhanced catabolism of amino acids. The resulting release of ammonium stimulates agal symbiont growth and promotes their retention of photosynthates. Together these processes form a ‘passive' feedback loop that destabilizes symbiotic nutrient cycling and presumably leads to the collapse of photosynthate translocation between the algae and coral host. 

While we are still away from understanding what eventually causes algal symbiont expulsion during heat stress, we believe this publication bears implications for our understanding of coral bleaching. For instance, our findings suggest the observed mortality of corals after bleaching may not be the direct consequence of the loss of algal symbionts per se but more fundamentally reflect the starvation of the coral host due to the collapse of symbiotic nutrient cycling before algal symbionts are actually lost. Thus, we find the tagline “corals bleach before they pale” fitting!

Needless to say that this work builds on the great work of so many others. We think it nicely integrates many independent observations made over the years into a common model that e.g. explains the notion of selfish symbionts or how water nutrient levels affect bleaching susceptibility in reef sites.

We hope you enjoy the open access read and look forward to your feedback!

All the best,
Chris & Nils

Prof. Dr. Christian R Voolstra
Professor of Genetics of Adaptation in Aquatic Systems
Department of Biology, M1035
University of Konstanz
Germany

Fon +49 (0)7531 88 3860
Web reefgenomics.org <http://reefgenomics.org/> / SymPortal.org <http://symportal.org/> / scholar.google.com/citations?user=wg421oQAAAAJ&hl=en <http://scholar.google.com/citations?user=wg421oQAAAAJ&hl=en>
Twitter @reefgenomics


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