Coral Growth Results 2025

Over the past year, our team has been carefully monitoring coral growth at the Swahili Nurseries to better understand which coral species grow best at different depths. We are happy to share the results of our latest analysis, based on measurements taken in March and November.

In March, we measured 9 depth gradients holding a total of 360 coral fragments. Unfortunately, one gradient holding 40 corals was lost in June due to rough ocean conditions. In November, we re-measured the 280 remaining corals, allowing us to analyse growth over a 7-month period across 8 species of Acropora and 5 depth levels.

Our results clearly show that different coral species thrive at different depths, highlighting the importance of species-specific placement in reef restoration.

• Acropora tenuis showed an average growth rate of 554%, with the fastest growth occurring at the deeper end of the gradient, especially between 7 and 9 m, and peaking at 9 m.

• Acropora muricata grew by an average of 390%, performing best at mid-range depths, with the highest growth rates at 6 and 7 m.

• Acropora verrucosa stood out with an exceptional average growth rate of 1600%. This species was healthy at all depths but showed its strongest growth in shallower water, reaching  a remarkable 2300% at 5 m and 1700% at 6 m.

• Acropora valida achieved an average growth rate of 736% and performed best at mid-range depths, with peak growth at 7 m (1266%) and 8 m (872%).

• Acropora anthocercis had an average growth rate of 487%, growing best around 6 meters. While generally healthy, it showed reduced performance at 5 m.

• Acropora humilis grew by an average of 374%, with the strongest growth at 7 m (645%) and 8 m (498%), again highlighting the importance of mid-depth placement.

• Acropora tenera showed steady and healthy growth across all depths, with an average increase of 371%, and peak growth at 6 and 7 m of about 540%.

• Acropora carduus performed best at greater depths, with an average growth rate of 613% and 1206% growth at 9 m, indicating a strong preference for deeper conditions.

These findings help us make better, science-based decisions for our coral reef restoration work. By placing each coral species at the depth where it performs best, we can increase survival rates, maximize coral growth and build more resilient reefs. This data will directly guide our future outplanting strategies onto artificial reef structures and degraded reef areas in the Diani-Chale National Marine Reserve.

We are proud of our Reef Ranger Swabrina for the consistent monitoring, careful measurements, and detailed analysis. Monitoring like this turns coral restoration from trial-and-error into a knowledge-driven process, giving our reefs the best possible chance to recover.