Boom and bust of keystone structure on coral reefs

• Published in: Coral reefs 2019-08, Vol.38 (4), p.625-635
• Main Authors: Wilson, Shaun K., Robinson, James P. W., Chong-Seng, Karen, Robinson, Jan, Graham, Nicholas A. J.
• Format: Article
• Language: English
• Subjects: Abundance; Biodiversity; Biomedical and Life Sciences; Colonies; Coral bleaching; Coral reefs; Corals; Economic conditions; Extreme heat; Feeders; Fish; Freshwater & Marine Ecology; Habitats; Heat stress; Heat tolerance; Heat waves; Life Sciences; Oceanography; Polls & surveys; Recovery; Reef fish; Reef fishes; Surveys; Variation
• ISSN: 0722-4028; 1432-0975
• DOI: 10.1007/s00338-019-01818-4

Repeated bouts of coral bleaching threaten the long-term persistence of coral reefs and associated communities. Here, we document the short- and long-term impacts of heatwave events on coral and fish assemblages, based on regular surveys of 18 reefs of the granitic islands of Seychelles over 23 yr. Extreme heat events in 1998 and 2016 led to bleaching-associated declines in coral cover, whilst between these years there was an interim period of coral recovery on some reefs. Coral decline and recovery were primarily due to changes in the cover of branching coral, particularly those from the families Acroporidae and Pocilloporidae. Surveys during the 2016 bleaching found that 95% of the 468 Acropora and Pocillopora colonies observed were either bleached or recently dead. The extent of bleaching and subsequent mortality were best explained by a priori assessments of community susceptibility to heat stress. One year later (2017), coral cover had fallen by 70% and average coverage across the 18 reefs was at 6%, similar to levels recorded in 2005, 7 yr after the 1998 bleaching. Decline in coral following the 2016 bleaching coincided with reduced abundance of fish