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Extinction debt of Galápagos foundational coral associates: ENSO-related cold-water bleaching triggers community biodiversity loss and turnover
  • Olivia Rhoades,
  • Margarita Brandt,
  • Jon Witman
Olivia Rhoades
The University of British Columbia Institute for the Oceans and Fisheries

Corresponding Author:[email protected]

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Margarita Brandt
Universidad San Francisco de Quito Colegio de Ciencias Biológicas y Ambientales
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Jon Witman
Brown University
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During a cold La Niña period (August 2007-January 2008) in the central Galápagos archipelago, 70% of Pocillopora finger corals were bleached across three long-term monitoring sites, affording an opportunity to examine the impact of El Niño Southern Oscillation-related temperature anomalies on the persistence of these corals and their associated community of fish and mobile macroinvertebrates. Using a time series empirical approach, we tagged and tracked the fate of 96 coral heads and their associates. When surveyed in July 2008, live (recovered) and dead corals supported similar levels of randomized observed species richness and Chao 1 estimated species richness. Whereas richness on the surviving live corals remained fairly stable, Chao 1 estimated richness on dead corals underwent a nearly 50% increase between July and January 2009, thereafter declining to 50% of originally surveyed richness by February 2010. This nonlinear change in species richness was largely due to influx and decline in opportunistic generalists including pencil urchin bioeroders, gastropod snails, and hermit crabs that colonized dead corals and fed on sessile invertebrates and algae that had initially recruited to dead and undefended coral substrate. Thus, dead corals retained high overall species richness until live corals had recovered; after which richness declined as dead corals eroded and disappeared (July 2011). Live corals attracted a less speciose but stable assemblage of mutualistic xanthid crabs and fishes that increased in abundance over time with the recovery and growth of live coral tissue. Overall, three physical features of the finger coral habitats (coral vital status, total surface area, and maximum branch length) predicted the number of species associated with each colony. The delayed diversity loss of associated species following La Niña disturbance to a foundation species represents a local extinction debt of 32-49-month duration. A better understanding of the scale of extinction debt in foundational marine ecosystems is needed to quantify the breadth of impacts of climate oscillations on biodiversity and ecosystem functioning.
29 Nov 2022Submitted to Marine Ecology
05 Dec 2022Submission Checks Completed
05 Dec 2022Assigned to Editor
09 Dec 2022Reviewer(s) Assigned
26 Mar 2023Review(s) Completed, Editorial Evaluation Pending
04 Apr 2023Editorial Decision: Revise Major
29 May 20231st Revision Received
30 May 2023Assigned to Editor
30 May 2023Submission Checks Completed
31 May 2023Reviewer(s) Assigned
04 Jun 2023Review(s) Completed, Editorial Evaluation Pending
04 Jun 2023Editorial Decision: Revise Minor
23 Jun 20232nd Revision Received
23 Jun 2023Assigned to Editor
23 Jun 2023Submission Checks Completed
02 Jul 2023Review(s) Completed, Editorial Evaluation Pending
03 Jul 2023Editorial Decision: Accept