Survey Objectives
The survey aimed to assess the status of coral bleaching and estimate coral resilience in the Egyptian Red Sea. Specifically, it sought to:
Monitor and document current coral bleaching events and compare them with prior years (2012, 2020, 2023, and 2024).
Measure the prevalence and severity of bleaching across different coral communities.
Investigate how bleaching varies by geography, depth, and reef type.
Identify coral species and genera that are more sensitive or tolerant to thermal stress.
Study Area and Methodology
A bleaching alert was issued by the National Oceanic and Atmospheric Administration (NOAA). In response, HEPCA and the Red Sea Protectorate Authority (RSPs) activated the Bleach Watch Egypt network. Dive centers from across the southern Red Sea were engaged through standardized reporting forms, enabling rapid information gathering.
Based on initial alerts, field surveys were launched across the entire Egyptian Red Sea, including the Gulfs of Suez and Aqaba. The survey assessed bleaching across:
Two depth zones (2–5 m and 8–10 m)
Inshore and offshore reefs
Sheltered and exposed locations
A wide range of coral species and genera
Bleaching severity was scored by evaluating five points per coral colony and classifying the results into categories ranging from “Unbleached” to “Totally Dead.”
Estimating Coral Recovery
Over 280 bleached coral colonies were tagged for long-term monitoring, representing a diversity of species, depths, and reef conditions. After 45 days, researchers revisited the same colonies to measure survival and recovery outcomes.
This method helped determine:
Which coral species exhibited greater resilience
Which regions showed faster or more complete recovery
The mortality rates in different reef zones
Key Survey Outcomes
The 2024 bleaching event revealed notable trends in both bleaching severity and spatial distribution. The following key outcomes were recorded:
1. Geographical Trends
Bleaching increased progressively from north to south, with the southern sector (e.g., Wadi El Gemal) experiencing the highest prevalence of bleaching (up to 50.1% bleached and 7.7% fluorescent).
The northern sector (Hurghada) recorded the lowest bleaching level (9%, with only 1.6% fluorescent colonies).
The Gulf of Aqaba also showed relatively low levels of bleaching.
2. Severity by Depth, Exposure, and Location
Bleaching was more intense at deeper reefs (10 meters) than shallower zones (2–5 meters), marking a shift from typical patterns observed in past years.
Sheltered reefs and inshore reefs showed higher bleaching than their exposed or offshore counterparts, likely due to reduced water movement.
3. Species-Specific Susceptibility
The coral genera Acropora, Millepora, Pocillopora, and Stylophora were among the most severely affected.
In contrast, genera like Porites and Echinopora showed higher resilience, with lower bleaching prevalence.
These findings reflect species-level differences in heat stress tolerance.
4. New Developments Compared to 2023
Geographical Expansion: For the first time, notable bleaching was observed in the northern Red Sea sectors, including Hurghada and the Gulf of Aqaba.
Depth Influence: Bleaching at 10-meter depths was more severe than at shallower levels.
Tidal Stress: Exceptionally low tides in July 2024 likely intensified stress on shallow coral communities.
Sea Conditions: The summer months were marked by prolonged heatwaves and unusually calm seas, resulting in weak water circulation, which reduced the ocean’s natural cooling capacity and contributed to increased bleaching.
See Figure 4 & Figure 5 in the full report for detailed maps and data visualizations.
Implications and Conservation Priorities
Despite challenging conditions, corals in Egypt’s Red Sea continue to show higher resilience and recovery rates than most global reefs. Preliminary estimates suggest 2025 recovery rates between 75–88%, depending on species and location.
However, this resilience is under increasing pressure. The 2024 bleaching event demonstrates that even historically stable regions are not immune. Without proactive conservation, these ecosystems may not withstand continued stress.
Recommendations
To preserve the Red Sea’s exceptional reef systems, the report calls for:
Expanding marine protected areas, especially in southern regions.
Strengthening enforcement of sustainable fishing and coastal development regulations.
Enhancing scientific monitoring, including citizen-science initiatives like Bleach Watch.
Promoting global action on climate change to reduce heat stress events.
Investing in restoration and resilience strategies, especially for vulnerable species.
The Updated 2024 Bleach Watch Report is both a scientific benchmark and a call to action—reminding us that while the Red Sea corals are holding on, the window for securing their future is narrowing.
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Bleach Watch Report 2024 Update
The 2025 Bleach Watch Report, authored by Prof. Mahmoud H. Hanafy and group of scientists and researchers, presents the latest findings on coral bleaching in the Egyptian Red Sea, with a focus on the extent of the 2024 bleaching event and early recovery estimates. Amid growing global concerns over coral reef degradation, this report provides vital scientific insights
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