Healthy coral fragment growing on a Reefscapers coral frame (Sheraton Maldives)


Identifying Key Factors for Coral Survival in Reef Restoration Projects Using Deep Learning

Author(s): Gaétan Morand, Simon Dixon, Thomas Le Berre.
Journal of Aquatic Conservation: Marine and Freshwater Ecosystems
Publication date: 07 September 2022 >
The raw data files (SQL & CSV) are made available by SEANOE Sea scientific open data edition


  • Coral restoration has emerged globally as a form of life support for coral reefs, awaiting urgent mitigation of anthropogenic pressures. Yet its efficiency is difficult to assess, as sizeable transplantation programmes handle hundreds of thousands of fragments, with survival rates inherently time intensive to monitor. Owing to limited available data, the influence of most environmental and methodological factors is still unknown.
  • To address this issue, machine learning and computer vision were used to track individual colonies’ survival, in a world first. Fragments from several species of Acropora and Pocillopora were transplanted over 12 sites across two Maldivian atolls. These colonies grew on coral frames, placed between 1 and 30 m deep. Analysis of monitoring pictures provided health and growth data on 77,574 individual coral colonies to inform the influence of genus, depth, initial fragment size, and substrate on their survival.
  • Among 77,574 fragments, individual survival rate was 31% after 2 years (21% after 4 years), which is much lower than most reported results. Deeper placement was an important success factor for Acropora transplants, but not for Pocillopora. In both genera, smaller initial fragment size was key to increased survival rates. Pocillopora fragments survived better than Acropora fragments at shallow depths (≤7 m), regardless of initial fragment size. Deeper, both genera had similar survival rates, which were influenced by initial fragment size and depth with comparable importance. During the mid-2019 heat wave, previously transplanted Acropora fragments were 38% more likely to die than Pocillopora fragments.
  • Overall, the total volume of live coral steadily increased over time, by more than 3.7 × 106 cm3 per year, as the volume increase in surviving fragments more than compensated for the volume loss due to mortality. This finding supports the use of targeted coral restoration to accelerate reef recovery after mass bleaching events.

Coral Restoration Effectiveness: Multiregional Snapshots of the Long-Term Responses of Coral Assemblages to Restoration

Author(s): Margaux Y. Hein, Roger Beeden, Alastair Birtles, Naomi M. Gardiner, Thomas Le Berre, Jessica Levy, Nadine Marshall, Chad M. Scott, Lisa Terry, Bette L. Willis.
Publication date: 17 April 2020, Diversity 2020, 12(4), 153;


Coral restoration is rapidly becoming a mainstream strategic reef management response to address dramatic declines in coral cover worldwide. Restoration success can be defined as enhanced reef functions leading to improved ecosystem services, with multiple benefits at socio-ecological scales. However, there is often a mismatch between the objectives of coral restoration programs and the metrics used to assess their effectiveness. In particular, the scales of ecological benefits currently assessed are typically limited in both time and space, often being limited to short-term monitoring of the growth and survival of transplanted corals.

In this paper, we explore reef-scale responses of coral assemblages to restoration practices applied in four well-established coral restoration programs. We found that hard coral cover and structural complexity were consistently greater at restored compared to unrestored (degraded) sites. However, patterns in coral diversity, coral recruitment, and coral health among restored, unrestored, and reference sites varied across locations, highlighting differences in methodologies among restoration programs. Altogether, differences in program objectives, methodologies, and the state of nearby coral communities were key drivers of variability in the responses of coral assemblages to restoration. The framework presented here provides guidance to improve qualitative and quantitative assessments of coral restoration efforts and can be applied to further understanding of the role of restoration within resilience-based reef management.


Reefscapers at Sheraton Maldives coral reef propagation

Reefscapers Diaries

During the global coral bleaching event of 2016, we started recording detailed observations of the natural reefs and our coral frames.
These monthly diaries document our efforts to mitigate the effects of coral bleaching, and increase biodiversity of marine species.

Reefscapers at Sheraton Maldives coral reef propagation

Coral Spawning in the Maldives

Read about our pioneering research, studying coral spawning events both on the wild reef and on our propagated coral frames.
We have also transferred coral gametes to our Lab, and successfully settled coral larvae to produce coral polyps (a first in the Maldives).

Reefscapers at Sheraton Maldives coral reef propagation

Maldivian Corals Database

What are the most commonly observed species of corals in the Maldives?
Which species of corals are recommended for coral propagation and reef regeneration?
How can we differentiate between the different species of corals in the Maldives?

Reefscapers at Sheraton Maldives coral reef propagation

Propagating Coral Microfragments

Scleractinian “massive” stony corals are essential to reef ecosystems, but are neglected by global restoration research (fewer than 5% of studies). Propagation tends to focus on a small group of faster-growing coral species for ease of proliferation and rapid results.

Reefscapers at Sheraton Maldives coral reef propagation

National Turtle ID Project

We invite citizen scientists from around the Maldives to submit turtle photos to us for inclusion in our national database.
The turtle facial scutes (scales) form a unique pattern (similar to fingerprints in humans) enabling identification of individuals.

Reefscapers at Sheraton Maldives coral reef propagation

Dolphin ID Database

A dolphin can be individually identified based on the notches, scars and markings present on their dorsal fin.
We take quality photos of the dolphins we encounter, then crop/optimise the image before analysing with matching software.

Reefscapers at Sheraton Maldives coral reef propagation

Sea Turtles & Environmental Enrichment

We provide stimulating environments to encourage curiosity in our sea turtle patients, to aid with rehabilitation and recovery.
We study turtle behaviours by introducing novel ‘pool toys’ and filming individual interactions over time, for analysis.

Reefscapers at Sheraton Maldives coral reef propagation

Zooplankton Monitoring

Zooplankton feeds the world’s largest animal, the blue whale, as well as Baa Atoll’s world-famous aggregations of manta rays.
Our continuous study collects baseline data on zooplankton communities around Baa atoll, with the hope to expand nationwide.

Reefscapers at Sheraton Maldives coral reef propagation

Marine Aquaculture in our Fish Lab

At our Marine Discovery Centre at Landaa Giraavaru, we have a unique fish and aquaculture science lab.
We study breeding techniques of various marine species, including anemonefish, shrimp, and jellyfish.

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