Abstract
Understanding how coral reefs respond to disturbances is fundamental to
assessing their resistance and resilience, particularly in the context
of climate change. Due to the escalating frequency and intensity of
coral bleaching events, it is essential to evaluate spatio-temporal
responses of coral reef communities to disentangle the mechanisms
underlying ecological changes. Here, we used benthic data collected from
59 reefs in the Red Sea over five years (2014–2019), a period that
encompasses the 2015/2016 mass bleaching event. Reefs were located
within three different geographic regions with different environmental
settings: north (Duba; Al Wajh), central (Jeddah; Thuwal), and south (Al
Lith; Farasan Banks; Farasan Islands). Coral community responses were
region-specific, with communities in the south being more promptly
affected than those in the northern and central regions, with hard and
soft coral cover dropping drastically in several reefs from around
> 40% to < 5% two years after bleaching. Coral bleaching effects
were particularly evident in the decrease of cover in branching corals.
Overall, we documented a shift towards a dominance of macroalgae, turf
algae, and crustose coralline algae (CCA). Using remote sensing data, we
analyzed sea surface temperature (SST) regimes at the study sites to
infer potential drivers of changes in benthic composition. Both SST and
Degree Heating Weeks (DHW) only partially aligned with the responses of
benthic communities, highlighting the need for more accurate predictors
of coral bleaching in the Red Sea. In times of intense coastal
development along Saudi Arabia’s Red Sea coast, our study provides
crucial baseline information on developments in coral reef community
composition, as well as to guide decision-making, namely restoration
efforts.
Keywords
Coral reefs
Benthic communities
Bleaching
Community changes
Red Sea
DHW