In situ observations of coral bleaching in the central Saudi Arabian Red Sea during the 2015/2016 global coral bleaching event

Abstract

Coral bleaching continues to be one of the most devastating and immediate impacts of climate change on coral reef ecosystems worldwide. In 2015, a major bleaching event was declared as the “3rd global coral bleaching event” by the United States National Oceanic and Atmospheric Administration, impacting a large number of reefs in every major ocean. The Red Sea was no exception, and we present herein in situ observations of the status of coral reefs in the central Saudi Arabian Red Sea from September 2015, following extended periods of high temperatures reaching upwards of 32.5°C in our study area. We examined eleven reefs using line-intercept transects at three different depths, including all reefs that were surveyed during a previous bleaching event in 2010. Bleaching was most prevalent on inshore reefs (55.6% ± 14.6% of live coral cover exhibited bleaching) and on shallower transects (41% ± 10.2% of live corals surveyed at 5m depth) within reefs. Similar taxonomic groups (e.g., Agariciidae) were affected in 2015 and in 2010. Most interestingly, Acropora and Porites had similar bleaching rates (~30% each) and similar relative coral cover (~7% each) across all reefs in 2015. Coral genera with the highest levels of bleaching (>60%) were also among the rarest (<1% of coral cover) in 2015. While this bodes well for the relative retention of coral cover, it may ultimately lead to decreased species richness, often considered an important component of a healthy coral reef. The resultant long-term changes in these coral reef communities remain to be seen.

Long‐Term Impacts of the 1997–1998 Bleaching Event on the Growth and Resilience of Massive Porites Corals From the Central Red Sea

“…Yet again the corals in this study showed no evidence of reduced growth or trace element disruption during that year, with only a minor disruption of some trace elements in 2009. Similarly, in 2015/2016 when bleaching was also reported in the region (Monroe et al, 2018), the site-specific DHWs were 0.1°C weeks while the Coral Reef Watch station suggests >10°C weeks. Alternatively, it could have been a combination of the strength and duration of the 1997-2001 ENSO event that caused the noticeable disruption in calcification and trace element incorporation that was not replicated during the milder 2010 La Niña event.…”

“…Given that widespread bleaching and mortality is likely to occur at around eight DHWs (G. Liu et al, 2013), this created a thermally stressful environment for shallow-water corals, which periodically experienced temperatures that were > 1°C above the MMM (Figure 2). In addition to the episodic El Niño related events, the Red Sea's average SST is increasing at a faster rate than most tropical regions, with models forecasting a 2 to 3°C SST rise in the central Red Sea by the end of the 21st century (Cantin et al, 2010;Monroe et al, 2018;Stocker et al, 2013). In addition to the episodic El Niño related events, the Red Sea's average SST is increasing at a faster rate than most tropical regions, with models forecasting a 2 to 3°C SST rise in the central Red Sea by the end of the 21st century (Cantin et al, 2010;Monroe et al, 2018;Stocker et al, 2013).…”

“…In the Red Sea, coral communities were severely affected by /1998El Niño (DeVantier et al, 2000, which until the recent 2015/2016 El Niño was the most intense stress event in the region (Monroe et al, 2018). In the Red Sea, coral communities were severely affected by /1998El Niño (DeVantier et al, 2000, which until the recent 2015/2016 El Niño was the most intense stress event in the region (Monroe et al, 2018).…”

Marine heatwaves reveal coral reef zones susceptible to bleaching in the Red Sea

“…Most recently, a strong event occurred during the 2015 El Niño (Figure S9), which could be the same as the one that caused bleaching in the nearby Al Lith region (Figure ). Although details have yet to be published, bleaching has been reported near Farasan (Monroe et al, ). We have also observed MHWs of high intensity over the northern NRS, and some bleaching was confirmed at Ras Qisbah (eastern northernmost coast) in 2006 (Bruckner & Dempsey, ).…”

Environmental latitudinal gradients and host‐specificity shape Symbiodiniaceae distribution in Red Sea Porites corals

“…Besides their role as fundamental reef builders, Porites corals are also among the most resistant corals to increasing water temperatures (LaJeunesse et al, ). During both the 2010 and the 2016 bleaching events, Porites was among the least‐affected coral genera in the Red Sea, with less than 40% of the resident population showing signs of bleaching (Furby, Bouwmeester, & Berumen, ; Monroe et al, ).…”