This month, our Reefscapers team at Four Seasons Resort Landaa Giraavaru transplanted 38 coral frames, kindly sponsored by guests (15), online (8), and the Resort (15), adding a total of 1900 coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 431 established coral frames at various sites around the island.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

• 35 degraded frames (comprising a single corporate charitable sponsorship) were recycled, and relocated from a low-flow area (the Sea Bar) to the flourishing Elephant site.
• 50 large new frames (plus 10 Resort frames) were delivered directly from our local Fulhadhoo workshop to Voavah Private Island, to fulfil the sponsorship from a generous family group in December. Thanks to our intrepid team of volunteer divers, we harvested ~1300 coral fragments required to transplant the 12 frames so far, and out-planted them on the south side of the island at a depth of 8 metres.

• Gametogenesis – This month, we observed small white eggs in colonies of Acropora humilis (two sites), and pale pigmented gametes in colonies of both Leptoria irregularis and L. phrygia.
• Coral Spawning – Spawning was observed in two colonies of Leptoria irregularis over the February full moon period.

This month, our Reefscapers team at Four Seasons Resort Kuda Huraa transplanted 13 new coral frames, and monitored a further 91 mature frames at various sites around the island, to send out upated photos to our kind sponsors. 🙏

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Gamete Development & Coral Spawning

In preparation for the next spawning season, we have started gamete checks at two separate locations, looking for eggs in different Acropora species. We will be tracking the development of the gametes (gametogenesis) by observing the size and colour pigmentation of the eggs. In corals, the bundles will typically become a darker pink or red as they get closer to spawning. This month, we found white/pale eggs in the following three species: A. digitifera, A. hyacinthus, A. millepora.

Preparing for the Coral Bleaching Season

The ‘summer’ hot season in the Maldives runs from January to May, with March and April being particularly hot and dry. The extra hours of seasonal sunshine, combined with the current elevated global sea surface temperatures (SSTs) cause increased stresses on coral reefs (April-June), which can lead to temporary paling of the coral colonies, or even permanent coral bleaching and death.

Global climatologists are forecasting 2024 to be exceptionally hot, due to a combination of the cyclical El Niño event and the ever-increasing effects of anthropogenic climate change. Over on our Reefscapers Climate Change page, we are following developments very closely by curating the news reports from climate experts and marine scientists worldwide.

• Our teams have started to move the healthy coral frames located in shallow, warmer areas of the house reef to deeper, cooler waters. We are refining our lifting techniques using a hook, rope, and an empty oil drum as a buoy, in what is a mammoth effort, with the help of our Resort volunteer colleagues. In the coming weeks, we aim to identify as many ‘at risk’ corals as possible, to give them the best possible chances of escaping the potential coral bleaching
• We have marked a total of 225 corals (three species) across five different sites around Kuda Huraa. These colonies will be monitored over the coral bleaching season to assess the start of the paling, and the extent of any bleaching and mortality

At Landaa this month, we transplanted 37 coral frames, kindly sponsored by guests (28), and the Resort (nine), adding more than 3,000 coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 563 established coral frames at various sites around the island.

Work is continuing on the generous corporate sponsorship of 50 frames (+10 Resort-sponsored) at Voavah. With the forecasted coral bleaching event (April-June), we are harvesting coral fragments from a healthy, diverse coral garden at the deeper house reef (15-18m) and replanting the completed frames even deeper (17-22m). Many thanks to our Resort colleagues at Dive and Recreation for their invaluable assistance. We have completed 20 frames, and will finish the balance later in the year once the bleaching threat is over. This will minimise stress to both the donor colonies, and the vulnerable new fragments.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

• Coral Settlement (November 2023 Spawning) – We observed monthly declines in survivorship of our settled coral larvae, with averages of 22% for A.humilis and only 2% of A.secale recruits still alive after four months. Between “grazed” and “non-grazed” treatments, we found little difference in survivorship. It is notable that recruitment of A.secale was lower initially, so mortality of one recruit skews percentage survivorship drastically. At the end of the month, all settlement in the “grazing” tanks were moved to our outdoor open-flow tanks.
• Gametogenesis – Large white gametes were observed in Acropora humilis, and small white gametes in A.digitifera.
• Coral Spawning – We performed nightly monitoring snorkels around the full moon period, looking for signs of coral spawning, and observed coral spawning in the following species:
  • various species of Favites and Goneastria (at the House Reef)
  • Galaxea fasiculari and various Montipora species
  • Acropra secale, and possible Astreopora spp

In Situ Coral Settlement Device

Our bespoke in situ coral settlement device was successfully installed at the Blue Hole site, on the north side of Landaa Giraavaru. The water on this side of the island is shallow (<2m) except for one sand-pumped Blue Hole refuge (6-8m deep) where coral frames are growing well. (Many thanks to our Resort colleagues in Engineering).

To achieve in-situ settlement of gametes released from these frames, “tents” made from tarpaulin were placed over the frames, channelling any released gametes into an open tank at the water surface. With dispersal due to wave/wind action (reducing fertilisation rates) and high mortality for coral gametes, this tank will provide a sheltered space where gametes can fertilise and successfully form larvae, which will settle within the tent. Overall, this in situ device will allow for increased settlement success.

Frames were clustered into patches, allowing maximum coral density in minimal space. The spawning device, having been in the water since October, was moved, thoroughly cleaned, and painted blue to blend in with the lagoon. The first 7mx4m tent was assembled from tarpaulin and piping, and positioned over one cluster of frames. A pipe was installed to funnel gametes into the surface tank upon spawning.

This month, no coral colonies in the Blue Hole presented mature gametes, hence no spawning was observed. We plan to make a second tent in anticipation of spawning in April to capture maximum gametes. In the meantime, we have placed a “chiller” on the spawning device, which will pump cooler water into the tent. The hope is this cooler water will protect enclosed corals from the forecasted bleaching event.

Maldives Coral Bleaching Season

The ‘summer’ hot season in the Maldives runs from January to May, with March and April being particularly hot and dry. The extra hours of seasonal sunshine, combined with the current elevated global sea surface temperatures (SSTs) cause increased stresses on coral reefs (April-June), which can lead to temporary paling of the coral colonies, or even permanent coral bleaching and death.

Global climatologists are forecasting 2024 to be exceptionally hot, due to a combination of the cyclical El Niño event and the ever-increasing effects of anthropogenic climate change. Over on our Reefscapers Climate Change page, we are following developments very closely by curating the news reports from climate experts and marine scientists worldwide.

Bleaching: Nature vs Nurture Experiment

To determine the extent to which bleaching susceptibility depends on a colony’s genetic resistance as opposed to its environment, we halved each colony on a mature, healthy frame that has grown in shallow water (3m) and planted these halves on a frame that was placed in deeper water (12m). Over time, we will monitor bleaching for both frames to see how depth might correlate with bleaching susceptibility for genetically identical colonies.

Coral Bleaching Mitigation Measures

• Over the last year, we have been out-planting to deeper sites to minimise the damage caused by any forecasted global bleaching events. Greater depths mean cooler waters, as well as reduced UV (that exacerbates any coral heat stress)
• Frames in the shallow house reef area, created in the last 6-18 months as part of our guest Trainee Coral Biologist program, have been relocated from 2m to 10m depth
• We selected a series of healthy frames with a variety of species of large mature colonies, and relocated them from shallow (2-3m) sites down to 9-12m depth. Two weeks after being moved, these frames are healthy and exhibit no signs of relocation stress. 17 frames have been relocated so far, and we will continue over the upcoming weeks
• Monitoring pictures were taken of a series of small frames for future AI analysis, to assess bleaching and mortality

This month, our Reefscapers team at Four Seasons Resort Kuda Huraa transplanted eight new coral frames, and monitored a further 302 mature frames at various sites around the island, to send out upated photos to our kind sponsors. 🙏

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Gamete Development & Coral Spawning

During March, we continued checking for mature coral gametes and signs of coral spawning. We observed immature white eggs in various Acropora species (A.gemmifera, A.plantaginea, A.nasuta). indicating that spawning will be some weeks away.

Maldives Coral Bleaching Season

Many of our oldest frames with the largest coral colonies can be found in the shallow waters of our House Reef at depths of only 1.5-2m. Here, the coral frames have grown quickly and flourished, but the colonies will be very vulnerable to increasing water temperatures and light levels. Last month, we started to relocate the most vulnerable frames to the deeper Reef Crest (~10m). Using ropes and buoys, we selected the lighter-weight frames, snorkelled with them to the new site, and slowly lowered them down to the depths. Thanks to a huge team effort, we successfully moved around 100 frames in this way.

For the next stage, we needed to tackle 260 large mature frames, so we designed and built a new system we’ve called ‘The Barge’, based on a design used by our teammates at Landaa. We fixed four paddleboards together with a wooden frame, and use our small ‘whaler’ boat for towing. Out on the House Reef, we raise the coral frames up onto our floating Barge platform, drive to the top of the reef crest, and then lower them back into the water. We then use the rope and buoy method to manoeuvre each frame down to their final location at 6m depth. The Barge can hold six small mature frames per trip, and so far we have successfully relocated 120 frames. This will continue into April, along with our bleaching monitoring, which will allow us to assess the success of this project.

Many thanks to all our Resort colleagues in the Recreation, Dive, and Carpentry teams for their invaluable assistance.

To streamline our methodology for the monitoring of coral bleaching, we have added a new site, adjusted the number of colonies, and selected three specific abundant species, namely Acropora muricata (branching), A.digitifera (digitate), and A.hyacinthus (plating/tabular). We selected 15 colonies at each of our five sites, plus some colonies from last year’s monitoring, totalling 391 colonies. The colonies will be monitored every two weeks, and will continue through the next several months.

This month, we also added four new temperature loggers to the existing six already situated around Kuda Huraa. To assess any variation with depth, we have placed one logger at the deep Shipwreck site (16m), and three loggers down the reef crest (3m, 5m, 10m).

At Landaa this month, we transplanted 41 coral frames, kindly sponsored by guests (29), the Resort (10), and online (2), adding more than 2000 coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 855 established coral frames at various sites around Landaa and Voavah.

A total of 20 frames (10 small, 10 medium) were sponsored by a group staying at Landaa, and built in a single day as part of an event held at Voavah. The group engaged enthusiastically with the activity, and we were delighted to see the Voavah reef looking healthy at the time of fragment collection.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Gametogenesis

This month, pigmented eggs were observed in 6 different Acropora species, followed by spawning over the April full moon period.

Coral Spawning

🗓️ New Moon (8 April) – we conducted nightly snorkel monitoring around the period of the April new moon, but no spawning was observed. As always, we recorded a full set of environmental parameters.

🗓️ Full Moon (23 April) – we performed nightly snorkels around the full moon, and observed coral spawning in 84 different colonies representing 9 species of Acropora. The following night, we observed spawning in 24 different colonies of 6 species of Acropora, plus a single colony of Goneastria spp.

Harvesting and Fertilising Coral Gametes

We placed four of our bespoke coral spawning nets over gravid (egg-carrying) colonies and successfully collected coral gametes. The gametes were removed from the collection bottles, and poured into a fat-separating jug filled with saltwater for sperm washing. Saltwater was slowly poured into the jug, allowing spoiled water to be poured away via the bottom spout, with buoyant gametes floating to the surface. Fertilisation occurred, and the ‘bowl stage’ of development was successfully observed the following morning.

Maldives Coral Bleaching Season

The ‘summer’ hot season in the Maldives runs from January to May, with March and April being particularly hot and dry. The extra hours of seasonal sunshine, combined with the current elevated global sea surface temperatures (SSTs) cause increased stresses on coral reefs (April-June), which can lead to temporary paling of the coral colonies, or even permanent coral bleaching and death.

Global climatologists are forecasting 2024 to be exceptionally hot, due to a combination of the cyclical El Niño event and the ever-increasing effects of anthropogenic climate change. Over on our Reefscapers Climate Change page, we are following developments very closely by curating the news reports from climate experts and marine scientists worldwide.

Coral Bleaching Watch

We have been tracking NOAA’s Coral Reef Watch bleaching guidelines. Baa Atoll will move into “Alert Level 1” for 5-8 weeks, meaning “severe bleaching and mortality” is expected. It is imperative we track the effects of coral bleaching on our reefs in the coming weeks.

In March, moderate paling was observed in some colonies along Landaa’s House Reef. Towards the end of April, bleaching and fluorescence has been observed at all sites across Landaa, at depths from 1m-15m. Corals of the genus Acropora are bleaching more severely than other genera (as expected), with colonies in shallow water at the Water Villas and Elephant site almost completely bleached. Bleaching has also been noted in some Pocillopora and massive genera such as Porites. Our monitoring work will provide insights into coral resilience across sites and species, useful towards future allocations of frame and species.
From 25 to 27 April, we surveyed coral recruitment at 5 wild reef sites across Baa Atoll. Bleaching of both mature and juvenile colonies was recorded at all sites and both survey depths (5m and 10m).

At Kuda Huraa this month, we transplanted 5 new coral frames, and monitored a further 90 mature frames at various sites around the island. As part of our bleaching mitigation work, we relocated a total of 130 frames (see below).

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Gamete Development & Coral Spawning

During April, our Kuda Huraa team conducted spawning monitoring of 3 sites over 7 days, totalling 25 hours in the water. Approximately 195 colonies across 8 different Acropora species were observed to spawn in April.

Looking back at our records from previous years, it is noteworthy that coral spawning seems to have occurred earlier (relative to the moon timings) than previous years. This is consistent with research that found earlier spawning times during periods of elevated water temperatures (Lin & Nozawa, 2023).

Although many colonies successfully spawned this month, there were still gravid colonies (corals with pink eggs) found in 2 species of Acropora, that are likely to spawn during the May new moon period.

CORDAP Maldives Coral Larval Restoration Training Program

The Reefscapers team had been kindly invited to join the CORDAP Maldives Coral Larval Restoration Training Program, led by Distinguished Professor Peter Harrison, and facilitated by The Maldives Coral Institute (MCI) and The Maldives Marine Research Institute (MMRI).

This month, coral restoration practitioners from around the Maldives came together to learn from Professor Harrison. The objective was to cover the biology of coral spawning, and learn how coral larvae collection and distribution can be used to repopulate damaged reef ecosystems. Our coral experts at Kuda Huraa were fortunate to represent Reefscapers throughout the workshop, and our Manager Charlie was also invited to present our spawning work and results of our paper, published last year. We were honoured to host the group on the House Reef for one night of spawning, so that gametes could be collected for fertilisation.
We are very grateful to Peter, his team and all the participants for an invaluable collaboration experience and exchange of marine knowledge. We look forward to more in the future!

BBC TV

We are proud to report that our project caught the attention of BBC TV producers, and a camera team joined us under the waves to film our work. While we are excited by the filming project, the shift we observed from healthy to bleached coral colonies was shocking, and should make for some dramatic documentary footage. This emphasised the importance of our relocation project, and we hope it increases the survival chances of some of our oldest coral colonies.

Maldives Coral Bleaching Season

April saw the inevitable start of coral bleaching around Kuda Huraa. From our observations, the first corals to start paling were species of Acropora (across our shallow 1-2m sites: Channel, Turtle, Water Villas).

• On 7 April, we recorded pale colonies of 5 different Acopora species (at the Turtle site) that surprisingly turned fully bleached overnight.
• Pocillopora colonies also started paling at the Water Villas, but are showing a higher resistance than Acropora at all other sites.
• Our temperature logger data recorded consistent temperatures of 29-30°C at a depth of ~10m from March into April. Despite these elevated temperatures, we have not yet observed bleaching of colonies below 4m.

Bleached Coral Spawning

When corals bleach, they lose the microscopic algae that are the main energy source for coral polyps. If corals are bleached but were able to produce mature gametes, they can either preserve energy and reabsorb the gametes, or use their limited reserves to spawn. Of the 195 colonies that spawned this month, 56% of these (n=110) were either partially or fully bleached. Only three of these bleached colonies spawned alongside healthy colonies, the remainder spawned at the end of the month.

Interestingly, colonies of Acropora muricata were seen to spawn underdeveloped egg bundles (white, and smaller than is typical for the species). We will continue to monitor the health of these bleached colonies to see if spawning hinders the ability to recover.

Bleaching Mitigation Efforts

During April, our team continued the ambitious project of moving 260 of our most established frames to deeper, cooler waters. After moving 120 frames in March, the team continued into April. A total of 115 frames were moved with the barge this month, and 15 frames were moved with the pully-system to deeper locations on the House Reef. As bleaching had already started at the beginning of the month, some of our frames had to be moved while paling and fluorescing. Big thanks to Reefscapers founders Thomas & Marie, who joined Aku from Landaa to lend extra experienced hands to our relocation efforts.

Our team continued with the ongoing bleaching monitoring at 5 different sites around Kuda Huraa. It will be particularly interesting to see if the relocated frames will start to recover over the next few months.

At Landaa this month, we transplanted 20 new coral frames, kindly sponsored by guests (5), the Resort (14), and online (1), adding almost 900 coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 315 established coral frames at various sites around Landaa and Voavah.

A total of 20 frames (10 small, 10 medium) were sponsored by a group staying at Landaa, and built in a single day as part of an event held at Voavah. The group engaged enthusiastically with the activity, and we were delighted to see the Voavah reef looking healthy at the time of fragment collection.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Research Paper Submission

This month, research documenting the relationship between environmental factors (sea temperature, precipitation, wind speed and tide depth) and spawning patterns of Acropora corals at Landaa Giraavaru and Sheraton resorts was submitted for review.

Maldives Coral Bleaching Season

The ‘summer’ hot season in the Maldives runs from January to May, with March and April being particularly hot and dry. The extra hours of seasonal sunshine, combined with the current elevated global sea surface temperatures (SSTs) cause increased stresses on coral reefs (April-June), which can lead to temporary paling of the coral colonies, or even permanent coral bleaching and death.

Global climatologists are forecasting 2024 to be exceptionally hot, due to a combination of the cyclical El Niño event and the ever-increasing effects of anthropogenic climate change. Over on our Reefscapers Climate Change page, we are following developments very closely by curating the news reports from climate experts and marine scientists worldwide.

Coral Bleaching Watch

Over the last few months we have been tracking NOAA’s coral bleaching watch guidelines. After two months of Baa Atoll being in the “Warning” and “Alert 1” status levels, with the turn of the monsoon we are now at the “Watch” status level. As such, we hope to see some recovery of bleached/pale corals as water temperatures decline.

🗓️ In March, moderate paling was observed in some colonies along Landaa’s House Reef.

🗓️ In April, bleaching and fluorescence was observed at all sites across Landaa from 1m-15m.

🗓️ During May, more widespread bleaching and mortality was observed across all sites around the island, both on the natural reef and our Reefscapers coral frames. As expected, corals of the genus Acropora are bleaching more severely, with colonies in shallow water at the Water Villas and Elephant site being the most affected. Bleaching has also been noted in some Pocillopora and even some massive genera such as Porites.

Photos below – single colony of coral (3 species), shown: ║ Healthy ║ Bleaching ║ Dead ║

Bleaching Monitoring

Following NOAA’s modelled predictions on mass bleaching for this season in the Maldives, we have established a monitoring protocol to assess the impact, extent, and recovery of potential bleaching across our restoration sites at Landaa Giraavaru. This monitoring project should provide an insight into restored coral resilience across sites and species, information that could prove useful towards future frame and species allocation.

We are analysing data percentages of Healthy (codes 4 to 6 on coral health chart scale), Bleached (codes 1 to 3), and Dead colonies at each site. At present, an average of 64% of colonies across the monitored sites have bleached, plus an average of 20% are dead.

🪸 Our Water Villas site has seen a gradual bleaching progression since February, whereas our House Reef site started bleaching in late April; currently, both  sites are similarly affected.
🪸 Anchor Point, our deepest site, presents more resilience than the other sites, although the newer frames are more severely impacted. It’s noteworthy that a few coral colonies at this site (alone) have started to show signs of recovery.
🪸 The Elephant site has been severely affected by bleaching since March, and presents the highest rate of mortality (34%).

At Kuda Huraa this month, we transplanted 6 new coral frames, and monitored a further 80 mature frames at various sites around the island.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Maldives Coral Bleaching Season

Coral Bleaching

May saw continued bleaching and mortality of corals around Kuda Huraa and the North Malé Atoll. To gain more information on the impact of bleaching in the surrounding areas, we partnered with the Kuda Huraa Dive teams to assess the health of nearby reefs at popular dive sites. So far, we have assessed two sites that were found to be 32% and 40% bleached. With the continued support of Dive, we will aim to survey more sites next month.

On the House Reef, bleaching has reached natural corals at ~14m depth (in the genus Pachyseris), and surprisingly, paling was observed in Mycedium at a depth of ~22m. The deepest occurrence of corals bleaching on our frames is at ~15m (Acropora muricata). This highlights the reach of these high temperatures on the House Reef, and how depth does not always guarantee safety for corals.

As the high temperatures in April continued into May, the shallow corals that bleached last month sadly began to die and become dominated by algae. Over the course of the month, the NOAA coral watch for Maldives dropped from ‘Alert Level 1’ down two levels to ‘Watch’. We hope this marks the end of the high temperatures for Kuda Huraa, and that we may start to see signs of recovery in June.

Coral Monitoring

The team continued with the ongoing bleaching monitoring of 391 colonies on our Reefscapers frames, over 3 species, at 5 different sites around Kuda Huraa. Out of the 5 sites, the Water Villas and Channel are the most shallow, and were the first to bleach in April and have been very badly affected since. This month, we calculated mortality rates to be 93% (Water Villas) and 99% (Channel).

The coral bleaching montage images show Before (5 March), During (30 April), and After (27 May) for the three species we monitor. These colonies are located on frames by the Seastar at 1.5m deep. We will continue to monitor the bleaching, to see if any of the colonies are able to recover.

Ongoing Bleaching Monitoring

During extreme heat waves, not only corals are affected; anemones also experience the loss of endosymbionts (zooxanthellae). As we conduct the bleaching surveys every two weeks, we are also observing changes in sea anemones. Over the course of one month, one anemone at the Channel site went from healthy (15 April), to pale (28 April), to completely bleached (13 May).

Clownfish and anemones may be the most iconic symbiosis example at a macroscopic level, but a lot is going on at a microscopic level too. The clownfish will swim constantly between the tentacles of the anemone, allowing the movement of prey, nutrients, oxygen, and water flow; but their microbes are also strongly related, both metabolically coupled and functionally related.

So what is the effect of the bleached anemone on their clownfish? It can have consequences on clownfish behaviour and physiology, changing foraging patterns, and increasing the risk of predation (more visually conspicuous in a white host.) Bleached anemones can recover, and we will continue monitoring over the next few months.

Stormy Season

May brings the start of the wet season in the Maldives, and this year the El Niño event has amplified regional weather patterns, resulting big storms and rough seas across the whole country and wider Indian Ocean region. Following the storms, we observed that some of our coral frames had been flipped, and  several of our larger bespoke structures had been moved or suffered collapse. Fortunately, no major damage has been done, and we will be working to correct the damage during June, with the arrival of calmer weather.

At Landaa this month, we transplanted 26 new coral frames, kindly sponsored by guests (8), the Resort (17), and online (1), adding 1400 coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 394 established coral frames at various sites around Landaa and Voavah.

A total of 20 frames (10 small, 10 medium) were sponsored by a group staying at Landaa, and built in a single day as part of an event held at Voavah. The group engaged enthusiastically with the activity, and we were delighted to see the Voavah reef looking healthy at the time of fragment collection.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Maldives Coral Bleaching Season

Over on our Reefscapers Climate Change page, we are curating the latest global news & research from climate experts and marine scientists worldwide.

Coral Bleaching Watch

We have started to see some recovery of bleached/pale corals as water temperatures decline. Recovery, and re-uptake of zooxanthellae in some colonies has been observed, but most remain fully bleached or dead. Corals of the genus Acropora are bleaching more severely and dying more than other genera as expected, with colonies in shallow water at the Water Villas and Elephant site being the most affected. Bleaching has also been noted in some Pocillopora and massive genera such as Porites, a clear indication of proloned elevated temperatures. Despite our efforts to collect corals from healthy resilient colonies and plant frames in deeper water, we have noted mortality of our most recently planted Reefscapers frames.

Bleaching Monitoring

We are continuing to collect data and take photographs of 100 selected colonies at each of our sites (except 62 at Elephant), with regular monitoring of these colonies since April.

This stacked bar chart shows monthly progression of bleaching (%) following MMRI’s categories for each of the four selected sites since February 2024. For the month of June, an average of 14% of colonies across the monitored sites have been recorded as ‘severely’ or ‘fully’ bleached, and an average of 45% of the colonies monitored are dead, indicating an increase of 25% mortality since May.

We have observed an average of 25% of colonies have recovered across sites since last month, with 40% remaining unchanged, and 35% experiencing a decline in health. At present, the highest recovery (36% since May) has been observed at our deepest site, Anchor Point, with also the lowest mortality levels (31%). House Reef and Water Villas sites have similar rates of recovery (27-31%) and mortality (45-46%). Elephant is our most affected site, with 65% of mortality and only 6% recovery as of June.

The stacked bar chart shows rates of bleaching recovery, no change, and decline towards bleaching/mortality across sites from May to late June 2024.

At Kuda Huraa this month, we transplanted 5 new coral frames, monitored a further 80 mature frames at various sites around the island, and relocated a total of 139 frames from the Channel.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Maldives Coral Bleaching Season

Coral Bleaching

June saw continued mortality of bleached corals around Kuda Huraa and the wider North Malé Atoll. Despite starting the month in the lowest NOAA Coral watch level of ‘no stress’, we are still at a Degree Heating Week of 5. The majority of Acropora spp. colonies across Kuda Huraa have bleached, however, at each site there have been some resistant coral colonies that are showing no signs of paling, fluorescing or bleaching. Although we have seen high mortality rates, some partially-bleached corals of Acropora spp are starting to show signs of recovery at the end of June.

Wild reefs – we have continued our collaboration with our Dive Team colleagues, to assess the bleaching of local dive spots. At dive site ‘Lankan’, famous for its manta cleaning station, we recorded bleached corals at 10m deep (62%), at 15m (53%), and at 20m (39%).

Ongoing Bleaching Monitoring

We continued with our ongoing bleaching monitoring of the 391 colonies on our Reefscapers frames, over 3 species, at 5 different sites around Kuda Huraa.

All corals selected for the bleaching monitoring study were healthy at the start of March. We have been tracking the health of each colony every two weeks, and have unfortunately seen mass mortality and bleaching across all sites. The highest mortality rates have been at shallow sites (<1.5m deep). We have recorded 100% mortality (n=76) at The Channel, and 95% mortality at both the Water Villas (n=57) and Seastar (n=124). The sites with the lowest rates of mortality are at the Shallow House Reef (54%, n=40) and Reef Crest (29%, n=13), where the depth of frames range from 3-6m.

All of the colonies that were 100% bleached earlier in the study have died, and only three sites still have healthy colonies. There is one healthy colony remaining at the Seastar, the Shallow House Reef has 2 colonies, and the Reef Crest has 3. Slight recovery has been observed at the Shallow House Reef and Reef Crest across all three species, and we hope this will continue over the next few months.

The Channel was once our main coral propagation site, as corals thrived here in the shallow waters with strong water currents. But site has evolved over recent years, with reduced water-flow resulting in overgrowth of algae and domination by wild Montipora digitata. Due to the bleaching event this year, we now have hundreds of dead and empty frames which we are removing for recycling (see photos, below).

Team Collaborations

During this difficult time for corals, Reefscapers have collaborated and supported each other from different projects across the Maldives. As all of the Reefscapers locations have experienced mass mortality, we are working together to share knowledge and ensure the future of our conservation efforts. Earlier in the month, Sofia and Kathryn (from Kuda Huraa) spent a day at Sheraton Maldives with project manager, Katelyn. Together, they worked to manage the aftermath of the bleaching event, including frame maintenance, moving and re-mapping frames, and removing dead colonies.

Later in the month, we were joined at Kuda Huraa by Meli and Aku, our Reefscapers counterparts from Landaa Giraavaru. It was a great opportunity to compare notes on research and methodologies, and we greatly appreciated their help with coral work and maintenance of our marine aquaria.

At Landaa this month, we transplanted 28 new coral frames, kindly sponsored by guests (13), the Resort (11), and online (4), adding 1380 coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 286 established coral frames at various sites around Landaa and Voavah.

A total of 20 frames (10 small, 10 medium) were sponsored by a group staying at Landaa, and built in a single day as part of an event held at Voavah. The group engaged enthusiastically with the activity, and we were delighted to see the Voavah reef looking healthy at the time of fragment collection.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Maldives Coral Bleaching Season

Bleaching Experiment: Nature vs Nurture

To determine the extent to which bleaching susceptibility depends on a colony’s genetic resistance as opposed to its environment, we halved each colony on a mature, healthy frame that has grown in shallow water (3m) and planted these halves on a deep water frame (12m). Over time, we will monitor bleaching for both frames and see to what extent depth correlates with bleaching susceptibility for genetically identical colonies. [PHOTOS, below]

Anga Faru: Reef Restoration Project

Anga Faru is located to the east of Dhonfanu Island, and lies between popular dive sites Dhonfan thila and Dhigu thila. Anga Faru was designated as a protected area in 2009 and is recognized as an important nursery site for grey reef sharks. Anecdotal evidence suggests that although Anga Faru was previously considered to have high coral coverage and biodiversity, in recent years the reef has been severely affected by coral bleaching. As a result, the reef is now considered to be highly degraded by local users.

On 27 July, our Reefscapers team conducted a survey of Anga Faru (at the request of Baa Atoll Biosphere Reserve and Baa Atoll Council) to assess the reef for its suitability as a site for a coral restoration project. In this survey, we aimed to assess the overall live coral cover across the reef, as well as the suitability of the substrate for the placement of coral frames. The findings of this survey have been passed back to the Biosphere Reserve team, who will use this as part of their application for a new coral restoration project at the site.

Site Survey: The reef consists of a ring of shallow top reef (1-3m depth) with a central lagoon and has a small sandbank on its southern side. The outside of the reef slopes down to a depth of 20-30m on all sides before leveling off. Visual assessment and video transects were used to approximate live coral coverage across the site. Species diversity was estimated using direct observations to family level (eg. Acropora). Suitability of locations within the site for restoration were based on visual assessments of live coral coverage, reef slope angle, degree of sedimentation and reef rugosity. In total, 3 areas around Anga Faru were assessed:

Site 1: The north side of the island presented a sparse top reef (1.5m depth) with stable substrate consisting of rubble, <5% coral cover consisting of Pocillopora spp. and encrusting/massive genera including Cyphastrea, Montipora, Porites and Astreopora. Some healthy Acropora was found 7m down a steep reef slope, but coverage of this family was sparse. The north reef also showed relatively high levels of sedimentation, with prominent sand coverage on all but the steepest slopes. The reef slope was noted to be approximately 90 degrees between 1.5 and 16 metres, with some broad shelves located between 5 and 8 metres sloping approximately 45-50 degrees. Below 16m depth, the substrate became sand sparsely interspersed with boulders.

Photos, from left: the shallow top reef showed coral coverage less than 5%, several broad sloping shelves were located between 5 and 8 metres deep. At 15-17 metres the reef slope leveled off, the steep higher reef slope showed high levels of sedimentation. 

Site 2: The south-east side of the island presented a top reef with 10-15% coral cover, dominated by Pocillopora spp. and encrusting/massive genera. The substrate was stable and consisted of rubble and larger boulders with a higher rugosity on both the top reef and reef slopes than site 1. The top reef was slightly deeper at between 2 and 3 metres, with a shallower reef slope of approximately 45 degrees descending to below 25 metres depth.

Photos, below. The south-east side of Anga Faru showed higher species diversity, reef rugosity and overall coral coverage than site 1. Healthy coral recruits were also noted, indicating good environmental conditions for coral growth at this site.

Site 3: The south-west side of the reef presented a top reef with stable substrate and 15-20% coral cover, dominated by Pocillopora spp. and encrusting/massive genera. The overall topography of the reef was broadly similar to site 2 with a top reef of 2-3m and a slope angle of approximately 45 degrees, leveling off and becoming sand substrate between 15 and 20 metres. Coral cover increased towards the centre of the south side, with a good diversity of Leptoria, Platygyra, Goniastrea, Montipora, Porites and some larger healthy Acropora below 3m. At both sites 2 and 3, higher numbers of the coral predator Culcita schmideliana (spiny cushion star) were noted.

Photos, below. Larger colonies of living Acropora corals were found below 3 metres but were more concentrated at the bottom of the reef slope, between 12 and 15 metres. The higher reef slope (right) consisted of stable rubble and boulders with similar numbers of recruits as site 2.

Secondary Site Report: In addition to Anga Faru, surveys were carried out at three additional sites to assess their suitability as donor sites: Gaaviligili, Bodhu Gaafaru, Olhugiri.
1) Gaaviligili (south-western edge of Baa Atoll) – large healthy colonies of Heliopora coerulea. This site anecdotally has high coverage of healthy coral on the west side, including a large area of Montipora foliosa, but due to strong currents it was not possible to fully assess the site.
2) Bodhu Gaafaru – shallow reef flat with similar topography to Anga Faru. The reef here was highly degraded, with <5% live coral cover. The site had many recently dead table corals, likely casualties of the 2024 mass coral bleaching event, and was considered unsuitable as a donor site.
3) Olhugiri Reef – protected area, with restrictions on access to protect the fragile mangrove habitat of the island. The reef was degraded, with few colonies of healthy Acropora and Pocillopora but higher coverage of massive coral species. Olhugiri reef has potential as a small-scale donor site.

Recommendations:
– The top reef of both sites surveyed on the south side of Anga Faru (sites 2 and 3) are suggested as suitable locations for conducting coral restoration through the coral frame method.
– None of the donor sites can be recommended as donor reefs at this stage, and further surveys are required to identify suitable sites. However, Gaaviligili reef merits further examination before it’s exclusion as a donor reef due to the anecdotal reports of high coral cover at this site.

At Kuda Huraa this month, we transplanted 5 new coral frames. To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Maldives Coral Bleaching Season

Coral Bleaching

Following coral bleaching events, numbers of corallivorous species can increase rapidly as they devour any sick coral colonies. This month, we removed the following coral-eating species from the reef and from our frames: 2 crown-of-thorns starfish, 8 cushion starfish, 300+ corallivorous snails.

Coral bleaching continued in corals around Kuda Huraa during July. The coral mortality rate has slowed, and we are seeing increased recovery in natural colonies and on coral frames around the island. This includes recovery in a few purple Acropora humilis colonies (at Seastar and Water Villas sites), surprising as these two sites have some of the highest mortality rates, and A. humilis was one of the species hit hardest by bleaching. We have also observed soft corals regain symbionts and healthy colouration this month.

At Landaa this month, we transplanted 27 new coral frames, kindly sponsored by guests (15), the Resort (12), and online (0), adding 1185 new coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 467 established coral frames at various sites around Landaa and Voavah.

Some of the coral frames close to Blu are still showing significant levels of mortality caused by bleaching, despite being located at greater depths.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Recycling and Maintenance following this year’s Mass Coral Bleaching Event

This month, we started a huge team effort to recycle coral frames on the House Reef. Frames at all sites around Landaa have suffered considerable mortality, but the decision was made to focus recycling efforts on one site at a time to improve overall productivity. The House Reef and Jetty area was considered the highest priority as they are visited most frequently by guests for snorkelling and diving activities.

We started with shallow frames (<2m); dead coral was removed using a hammer and a chisel, and new coral fragments were attached. We cleaned a total of 49 frames, and fully re-transplanted 38 of these using ~1,250 coral fragments. Of the living corals, we noted higher survival rates of Pocillopora than Acropora at shallow depths (<2m), hence we re-transplanted newly cleared frames with Pocillopora. Corals for re-transplantation were harvested from healthy frames near Villa 200 (due to upcoming construction work).

Spawning Device Reconstruction

Following the storms in mid-August, the ropes anchoring our spawning device broke, causing some damage to the tent. The spawning device was re-anchored, and next month we plan to fix the central opening so the pipe that will funnel gametes into the device is secure. Following the bleaching event, many corals within and outside the tent have died and are now overgrown by algae; some are beginning to recover well.

Predation

This month, we noted an outbreak of corallivorous Drupella snails on the corals at the House Reef site, and have been opportunistically removing any snails we encounter (600+ and counting). We have also spotted numerous cushion stars on the reef along with some signs of predation on smaller coral colonies. With juvenile wild colonies of Acropora growing well, we plan to remove cushion stars to prevent predation and aid natural reef recovery following the bleaching event.

Massive Corals Spawning Database

Following the spawning of non-Acropora corals that we documented back in March, a database has been created to monitor spawning of massive corals. For future reference and research, each colony that spawned has been GPS-mapped and given a unique physical tag (eg: LGM001). A total of 79 colonies from 8 different genus were recorded spawning (identification to species level is ongoing).

At Kuda Huraa this month, we transplanted 8 new coral frames, and 100+ existing frames were monitored (cleaned, repaired, photographed). To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

We continued with maintenance work across our sites after the beaching event, and our team worked hard to successfully clear and repopulate the frames in the Channel and Blue Hole sites. We have noticed an increase in coral predation during and after the bleaching event, a common phenomenon following  reef bleaching events. Predation from fish, Crown of Thorns starfish (CoTs), cushion stars and marine gastropods (Drupella spp. & Coralliophila spp.) are impacting the recovery of those coral colonies that have managed to survive. We have been focusing our efforts on the removal of these species, and since the bleaching began in April we have removed ~1200 corallivorous gastropods, 11 CoTs, 81 cushion stars.

Coral Bleaching

The average sea temperatures around the Maldives continued to fall in August, with NOAA’s Bleaching Alert falling to ‘No Stress’, and the ‘Degree Heating Weeks’ dropping to zero . This was reflected in the continued recovery of the corals around Kuda Huraa. Algal symbionts have returned, restoring the colour in coral colonies on frames and naturally occurring on the reef.

From our observations, the only coral colonies still bleached are located deep on the House Reef, as we suspect these were some of the most recent colonies to bleach. All natural corals that bleached have now either recovered or died.

• Acropora gemmifera seems to be the most resilient species across all sites, with a few colonies remarkably remaining unbleached throughout.
• At the Blue Hole, natural colonies of Acropora millepora, A. tenuis and A. latistella that had bleached have now bounced back in shallow waters (~ 1m depth), but these species have not been so successful in other shallow sites.
• Colonies of Acropora muricata were the first to show signs of bleaching back in early March, and although many colonies have died, this is the only Acropora species to have survived in the shallows (~1.5m) at the Turtle and Seastar.

From March until the end of this month, we have been tracking the health of each survey colony every two weeks. August was the last month of the monitoring, as we are no longer seeing any major changes in coral health due to bleaching. Unfortunately, we have seen mass mortality and bleaching across all sites, but some colonies have been resilient.

At Landaa this month, we transplanted 58 new coral frames, kindly sponsored by guests (45), the Resort (14), and online (0), adding 4992 new coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 571 established coral frames at various sites around Landaa and Voavah. We have been continuing our mass recycling efforts, following the coral bleaching event earlier in the year. We prioritised the House Reef and Jetty sites (frequently visited by snorkelling guests) by removing dead corals from 30 frames, fully retransplanting 18 frames, and opportunistically removing 730 Drupella around Landaa (and Voavah).

To see the progress of your own frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Coral Spawning

The full moon was on 18 September, so we planned our nightly snorkels around this period. We successfully observed spawning in a single Montipora colony on 2 consecutive nights [photos, above].

Coral Settlement

We are planning to outplant our settled Acropora secale (from November 2023) onto the reef. We have started to make concrete moulds (“coral cookies”) to hold the coral settlement plugs for cementing on the reef.

Spawning Device Reconstruction and Film Crew Visit

This month, a film crew visited our Landaa team to film our spawning device. Prior to the visit, new ropes were used to securely anchor the spawning device following detachment due to heavy storms in August. The central opening of the tent was fixed by securing a new sheet of plastic tarpaulin and reattaching the pipe to the floating spawning device at the water’s surface. (Unfortunately, we are currently unable to run the chiller as a power supply cable snapped during the storms.)

Voavah Project

This month, the remaining 40 large frames were built at the Four Seasons private island of Voavah, kindly sponsored by guests (50) and the resort (10). We had already built 20 of these frames back in March, sited at depths of 17-22m in the hope that deeper water would better protect them from the anticipated  mass coral bleaching event. As it turned out, 30-60% coral mortality was documented for these coral frames – a good result, considering the widespread mortality of 80-95% of Acropora colonies at some of our sites.

This month, the remaining 40 large frames were built. Coral was collected from a thriving patch of wild Acropora in a south-side bay, and the frames were located in groups of 10 on the south-west side at depths of 2-8m. Ten of the March frames were moved from deeper water (17m) to a shallower site (9m) as a snorkelling feature.

Completion of this project would not have been possible without the help of our Dive and Recreation resort colleagues, and all of the first and second-year  Four Seasons apprentices. Thank you to everyone for enthusiastically supporting our project! [photos below]

At Kuda Huraa during September, our coral experts transplanted 8 new coral frames. We monitored and retransplanted more than 20 existing frames, including four large Xmas frames and one large coral pyramid, totalling 51 man-hours of diving.
Following the damage caused by the global mass coral bleaching event earlier this year, we continue our extensive maintenance work around the island. Additional predation by fish and snails, and competition from sponges and algae, became increasingly damaging post-bleaching (from June of this year). We actively seek and remove known corallivores that eat the living corals (this month: 1 crown-of-thorns starfish, 2 cushion starfish, 373 corallivorous snails).

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Coral Maintenance: The Pyramids

The three pyramids and tree frames at Kuda Huraa suffered some of the highest mortality rates after the bleaching event. All colonies of both Acropora clathrata and A. monticulosa colonies were sadly lost, and these are the only known colonies on the House Reef. Only Acropora muricata and one large plating A. cytherea survived on the pyramids. We have therefore dedicated more than 50 man-hours (13 dives with 2-4 divers) to clearing the dead colonies and repopulating these frames. Our goal is for the three pyramids to be a showpiece of the coral diversity around Kuda Hura. This will not only serve as a beautiful feature for guests diving and snorkelling, but also create a hub for spawning monitoring and fragment collection in the future. While clearing the Acropora muricata from the base of the structures, we have observed predation by Coralliophila erosa and Drupella snails, as well as different sponge species smothering and killing corals.
Repairs were also conducted this month on the rope nursery where the deeper location (~10m) appears to have protected many colonies from the bleaching. New buoys were attached to lift the structure, and large heavy corals were relocated to the pyramids.

Coral Maintenance Challenges

After the Channel site was cleared and repopulated last month, the site was unfortunately impacted by a high level of sand movement in the area. Stormy conditions caused sedimentation damage to the youngest  fragments. The storms have also brought trash onto the house reef, with a high number of plastic woven sheets and bags getting stuck to and smothering corals on frames. 

Analysis of our Temperature Logger Data – Sea Surface Temperature (SST) Coral Bleaching Threshold = 30.9°C
The photograph below shows our temperature logger in situ, attached to a Reefscapers coral frame in the lagoon at Kuda Huraa. The first line graph shows the average daily temperature for three depths during our study period. The second chart adds an overlay of the NOAA Coral Bleaching Alert Levels, with annotations to mark the key moments during the 2024 coral bleaching event. [CLICK to enlarge]

At Landaa this month, we transplanted 19 new coral frames, kindly sponsored by guests (7), the Resort (11), and online (0), adding 700+ new coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 873 established coral frames at various sites around Landaa and Voavah.

When recycling frames, dead corals are removed and new fragments attached in their place. This month, a total of 57 frames were recycled (14 small, 1 medium, 14 large and 11 heart) on the House Reef, Jetty, and Voavah frame sites, adding ~2,200 new coral fragments to the reef.

To see the progress of your own frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Coral Settlement

During November last year, gametes from 2 colonies of Acropora secale were collected and successfully settled ex situ. Following a year of growth in our Fish Lab, 10 coral recruits were fitted into concrete moulds (“coral cookies”) to hold the coral settlement plugs for cementing on the reef.
On 30 October, 5 of these recruits were out- planted onto the reef by cementing onto stable substrate on the House Reef. Recruits were planted at depths ranging from 2m-5m. Monitoring pictures were taken so that growth in situ can be monitored over time.

🗓️ Coral Spawning around the full moon of 17 October

We scheduled our nightly snorkels around this period to check for signs of coral spawning. We successfully observed coral spawning in 3 colonies of Acropora plantaginea, 11 colonies of Galaxia, and 1 colony of Acropora plantaginea, and recorded inferred spawning in 2 colonies of A.secale and 2 colonies of A.plantaginea via loss of gametes.
Interestingly, Galaxia corals are known to spawn either male or female; if spawning female, then bundles of mature eggs (pink/red in colour) are released. If spawning male, then bundles containing immature eggs and sperm (white in colour) are released. This month, we observed the release of both male and female gametes on separate days. [photos below]

🗓️ Coral Spawning around the new moon of 1 November

Again, we scheduled our nightly snorkels around this period, and successfully observed spawning in 4 colonies of Acropra loripes, and 3 colonies of Acropora (A.rosaria, A.plantaginea, A.gemmifera).

New Project on Genotyping: Tracking Resilient Coral Genetics

The global coral bleaching event earlier this year resulted in high mortality of branching corals in the Maldives (and worldwide). For successful coral propagation, we use fragments from resilient, surviving corals to re-populate the reef in the hope that this increased heat-tolerance will fare better under future periods of heat stress.

Some of our coral propagation sites suffered higher coral mortality than others, due to differences in characteristics such as depth and water flow. Surviving colonies at sites with higher overall mortality (“stress sites” of shallow water with limited flow) are more resilient than surviving colonies at other sites with lower mortality (“safe sites” of varying depth and good flow). By repopulating safe site frames with corals from stress sites, we plan to track the origin and specific placement of fragments to compare longterm survivorship.
To increase genetic diversity, we select fragments from colonies that are located far apart, and treat these as distinct genotypes.

Syntax: Recording Genotype Code of Colony from “Stress Site”

Coral coding will be structured as follows: frame number, frame face, face, bar, coral species.
– Face: face#1 displays the frame number tag; faces count in a clockwise direction.
– Bar: counts from top to bottom.
– Position: coral colony location; each bar contains 10 positions, numbered 0 to 9 (right to left).

For example: LG1000F1B3P2AAS = frame number (1000), frame face (1), bar (3), position (2), species (AAS = Acropora aspera).

‘BX’ = all bars, ‘PX’ = all positions; eg: transplanting fragments from LG1000 to all bars & positions of F1 on LG2000 = LG1000F1B3P2AAS – LG2000F1BXPX

At Kuda Huraa this month, our coral experts transplanted 5 new coral frames. We monitored and retransplanted more than 80 existing frames and repaired 3 of our large coral pyramids. During monitoring, we actively seek and remove known corallivores that eat the living corals (this month: 9 crown-of-thorns starfish, 4 cushion starfish, 787 corallivorous snails).
This month, we also conducted 27 hours of underwater monitoring over 13 days, looking for signs of coral spawning.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Old Coral Frames

Since June, we have cleared, stacked and moved over 300 old frames from ‘The Channel’ (sunrise beach site). Over two days this month, we combined removing frames over land on a golf buggy with our barge method over water. We removed a further 293 empty frames, finally clearing the site. As the Channel was the main site for frames since the early days of our artificial reef project, many of the frames were over 10 years old. We therefore sorted through and disposed of irreparable frames, only moving those that could be recycled to the House Reef. Despite removing many frames from this location, there are still around 100 frames in this site. Thank you to the Dive, Purchasing, Engineering and Recreation departments for assisting us, and helping to organise a dhoni to move a large number of frames in such a short space of time.

Coral Maintenance at The Pyramids & Water Villas

Our three coral pyramids suffered some of the highest mortality rates after the bleaching event. We have continued to clear and re-populate the second and third pyramids, by harvesting fragments of different species from around the House Reef and from natural colonies at the Blue Hole. By collecting fragments from both coral frames and naturally occurring colonies, we aim to maximise the number of genotypes on the pyramids. We have continued to clear the Acropora muricata from the base of each structure, removing parts covered in algae and sponges, and re-attaching the healthy fragments. Once the base of each pyramid was repopulated, the remaining fragments were then taken and used to repopulate the Moon and Yin-Yang in the Water Villas.

While finishing the pyramids, we also worked to clear, re-populate and monitor the coral frames at the Water Villas. A shallow frame site with high temperatures, the Water Villas had a high rate of mortality due to coral bleaching. The site has also had an increase in invasive Montipora digitata coverage, Drupella spp. predation, and macroalgal blooms. These impacts have limited coral growth at this site, and altered the morphology of some colonies. We have completed 75% of the frames, and will work to complete the maintenance of this site by the end of November.

Genotype Experiment

In the aftermath of the bleaching event, we are working hard to repopulate frames with healthy, thriving corals from similar depths and conditions. This will then increase the likelihood that the frame will grow and thrive in the future, even in high temperatures. In addition to this, we will be conducting field tests on coral colonies of interest, using a method to track the genotype of each coral designed by our founder, Thomas Le Berre. Around the resort, we experienced up to 90% mortality in the shallow sites during the bleaching event. However, natural colonies of different species had a higher recovery rate. We will therefore look into these resilient natural colonies, and trial them on frames at other shallow sites around the resort.

We will focus on 3 shallow locations (1.5 – 2m) around the resort (see map below) that suffered the highest mortality rates. Although these frames will be at similar depths, the success of different coral species could vary due to the specific environmental conditions at each location. Each site will have 4 frames, 2 small frames from each of the other 2 locations. We will continue to develop and
document these frames over the next month.

Coral Spawning

The October full moon initiated the start of the second spawning period of the year for Kuda Huraa. Throughout the month, we had started to find pigmented eggs in colonies of Acropora secale and A. plantaginea (these same species were observed to spawn last October). We started our underwater spawning monitoring around the full moon period, and successfully recorded coral spawning in 36 colonies of A. secale and 8 colonies of A. plantaginea. Interestingly, unlike October 2023, we did not observe mature eggs or spawning in any colonies of A. tenuis.

We observed some gravid colonies (corals with maturing pink eggs) of Acropora secale and A. plantaginea, so we predict they will spawn around the November new moon period. White eggs were also found in some colonies (A. austera, A. humilis) in the Deep House Reef area; we will continue to track these gamete developments in November. [Photos below: pigmented eggs in Acropora secale]

Corallivores

In October, we removed a record number of corallivorous snails from around the island by optimising spawning night dives. As Drupella snails are nocturnal, they leave the reef crevices to feed at night, making them easier to find. As well as removing 551 Drupella, we also removed 201 Coralliophila violacea from both massive Porites species, and Porites cylindrica. We have also continued removing corallivorous echinoderms; the cushion star (Culcita schmideliana) and Crown-of-Thorns starfish [CoTS]  (Acanthaster planci).
We have observed a decrease in the size of the corallivores; CoTS are typically ~30cm, and cushion stars are ~19cm in diameter. This month we found a CoT only 10.5cm, and two cushion stars under 13cm. It is unclear if this is a result of us removing larger adult individuals over the year, or if this is due to the reproductive cycle. Little is known about the specific life cycles of these species in the Maldives, which is why observations like these can help fill knowledge gaps in the future.

At Landaa this month, we (again!) transplanted 19 new coral frames, kindly sponsored by guests (7), the Resort (10), and online (2), adding ~1000 new coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 359 established coral frames at various sites around Landaa and Voavah. We actively remove any corallivorous species encountered during our maintenance work, which this month included 245 Drupella snails, 5 Monodonta snails, and 6 cushion stars.

Seabar Frames: we relocated 35 medium-sized frames from the Seabar/ Elephant site that had suffered 100% mortality following this year’s coral bleaching event. We moved these frames to the entrance of the seawall, where high water flow and plentiful recruitment of wild corals suggests this site will be good for our newly transplanted fragments. So far, 12 old frames have been fully recycled, with completion of this project being a priority for next month before the sponsors’ return to Landaa in January.

To see the progress of your own frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Coral Settlement

🗓️ November 2023 – gametes from 2 colonies of Acropora secale were collected and successfully settled ex situ. Following a year of growth in our Fish Lab, 10 coral recruits were fitted into concrete moulds (“coral cookies”) to hold the coral settlement plugs for cementing on the reef.
🗓️ 30 October 2024 – 5 of these recruits were out- planted onto the reef by cementing onto stable substrate on the House Reef. Recruits were planted at depths ranging from 2m-5m. Monitoring pictures were taken so that growth in situ can be monitored over time. A steel “cage” was placed over one of the recruits to reduce predation from larger fish.
🗓️ This month – we recorded predation in 4 of 5 recruits, with the only surviving recruit being was under the cage. So we now plan to plant the remaining settlement plugs under this cage. We observed paling in the surviving recruit two weeks post-out-planting, but it is now recovering.

🗓️ Coral Spawning around the full moon of 15 November

Early this month, we noted varying stages of gamete development in several Acropora species. Nightly snorkels were scheduled around the 15 November full moon, looking for bundling of mature coral gametes. On nights where multiple genera needed to be observed, one freediver collected data on the House Reef, while two SCUBA divers collected data at our Dive Site.
During this period, we initially observed spawning in various colonies of Montipora and Goniastrea, later followed by colonies of Acropora and Galaxea. We also deduced spawning via loss of gametes in species of Acropora.

At Kuda Huraa this month, our coral experts transplanted 9 new coral frames. During monitoring, we actively seek and remove known corallivores that eat the living corals (this month: 7 crown-of-thorns starfish, 5 cushion starfish, 589 corallivorous snails). This month, we also conducted 27 hours of underwater monitoring over 13 days, looking for signs of coral spawning.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Coral Maintenance

In a massive team effort, we used a local dhoni (traditional Maldivian boat) to load and transport a total of 150 coral frames from the Channel site, which was devastated by this year’s mass global coral bleaching event. These frames will now be recycled and used for other projects.
Over the course of the month, we continued to clear and repopulate coral frames in the Water Villas and House Reef. During October, we pruned large quantities of excess branching Acropora from the healthy pyramid bars, and used these fragments to help repopulate the Water Villas frames. Initially, many fragments started to pale and bleach in their new environment (not unexpected) so we are closely monitoring their acclimatisation. We have also harvested Monitpora foliosa from the Blue Hole site, and used these fragments to help repopulate the Water Villa frames.

Coral Spawning

After October’s coral spawning event, many Acropora colonies clearly had pigmented eggs remaining, so we scheduled our spawning monitoring around the 15th November full moon period. We successfully observed spawning over several days in various species of Acropora on the House Reef. In addition, our gamete checks revealed white eggs in various Acropora colonies, indicating a possible upcoming spawning event in December (later than previous years).

Resilient Corals: Genotype Experiment

This month we began creating frames with tracked genotypes. The aim is to repopulate frames with resilient corals following this year’s coral bleaching event. We will be repopulating these frames with at least two genotypes of a species, tracking both donor frames and new frame locations. On the House Reef, we will be moving these corals to the bottom of the reef crest to preserve them from high temperatures.

In addition to preserving resilient corals, we are also testing wild Acropora colonies from our Blue Hole site that survived the bleaching in depths as shallow as just 0.5m. We have tagged these natural colonies of Acropora vermiculata to create replica frames at the Water Villas, Channel and in the shallows of the House Reef. We selected Acropora vermiculata, as we have many large colonies that recovered well after the bleaching event.

At Landaa this month, we transplanted 20 new coral frames, kindly sponsored by guests (8), the Resort (12), and online (0), adding ~900 new coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 388 established coral frames at various sites around Landaa and Voavah. We actively remove any corallivorous species encountered during our maintenance work, which this month included 245 Drupella snails, 5 Monodonta snails, and 6 cushion stars.

Seabar Frames: we relocated 35 medium-sized frames from the Seabar/ Elephant site that had suffered 100% mortality following this year’s coral bleaching event. This month, we completed our recycling work here, before the sponsors’ return to the Resort next month.

To see the progress of your own frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Coral Settlement

🗓️ November 2023: coral gametes were collected and successfully settled ex situ. Following a year of growth, 10 recruits were fitted into concrete moulds.
🗓️ October 2024: 5 coral recruits were out-planted onto the reef, one under a steel “cage” (recruits outside the cage were soon predated).
🗓️ This month: the remaining 5 recruits were out-planted under a steel “cage” for protection, and they are growing well so far.

Coral Spawning around the Full Moon

Around the full moon period (15 December) we surveyed for signs of coral spawning in massive and encrusting genera. We successfully recorded spawning in colonies of Montipora peltiformis, Galaxea fascicularis, and Astreopora species.

At Kuda Huraa this month, our coral experts transplanted 10 new coral frames. During monitoring, we actively seek and remove known corallivores that eat the living corals (this month: 6 crown-of-thorns starfish, 2 cushion starfish, 347 corallivorous snails). This month, we also conducted 20 hours of underwater monitoring over 5 days, looking for signs of coral spawning.

To see the progress of your frame, please visit our dedicated Four Seasons monitoring page where we upload new photos every 6 months or so.

Coral Propagation Training Programme

This month, we hosted Sharnietha (Marine Biologist at Club Med Kani) for a 5-day training session. Our coral propagation training programme was hands-on and very comprehensive, covering topics such as: fragmentation techniques, frame building, how to take good monitoring pictures, genotype tracking, data collection & entry, QGIS overview, in-water maintenance, diagnosing & troubleshooting past problems.

Coral Maintenance

The Channel – With the reopening of the Channel site to guests during the festive season, this month we focused our efforts into repopulating frames in this area. The conditions at this site are not conducive to the survival of Acropora species, therefore we transplanted Porites cylindrica and Pocillopora meandrina fragments as they grow well here (despite the low flow of water, and increased sand movement). We have been monitoring how these fragments adjust to their new environment throughout the month, and so far they have been responding well. We will continue to monitor their progress into the new year.

Water Villas – We are pleased to report that the Montipora foliosa fragments from last month appear to be adapting well to their new environment! Due to this success, we have continued repopulating frames at this site with Montipora foliosa and also Pocillopora verrucosa. We have noticed the emergence of a few juvenile Acropora colonies, and some transplanted fragments of Acropora muricata are slowly regaining their symbionts. This suggests that conditions at this site might be improving, and therefore we will continue monitoring fragment survival in the coming months.

Coral Spawning

Mid-month, we conducted gamete checks on species which have previously spawned in the Maldives during December. Several colonies of Acropora tenuis were found with highly pigmented eggs, suggesting that these colonies might spawn during the December full moon. We conducted spawning checks around this period, but no spawning was observed (or inferred by missing eggs). These colonies remain gravid, so it’s possible they may spawn in the coming weeks.

Resilient Corals: Genotype Experiment

🗓️ During November, we transplanted coral fragments from resilient natural colonies of Acropora vermiculata onto our frames at various sites.
🗓️ This month, we identified wild colonies of Pocillopora verrucosa and Pocillopora eydouxi on the reef flat behind the Blue Hole which had survived the bleaching event. As these wild colonies are found relatively far apart, we can assume these corals are of different genotypes from one another. We labeled the colonies and collected fragments to transplant onto frames (at the same sites), so we can monitor their progress in challenging conditions.

In addition to challenging these resilient corals, we want to ensure that we protect them too. To do this, we are following the same method as described, but outplanting frames at sites with conditions ideal for coral growth. This will hopefully ensure that we preserve these genotypes during more severe bleaching events that are almost certain to occur in the future. This work to both challenge and protect resilient corals will continue into the new year.