Four Seasons Team Diaries: May 2024

Be sure to read our monthly updates from Marine Savers – direct from our teams resident at
the Marine Discovery Centres at Landaa & Kuda Huraa – our long-term partnership with Four Seasons Resorts Maldives.

Landaa Giraavaru

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.

Reefscapers coral bleaching survey E14 (April-May)

Coral bleaching survey: colony E14 Bleached / Dead (April / May)

Reefscapers coral bleaching survey E44 (Mar-May)

Coral bleaching survey: colony E44 Healthy – Paling – Bleached
(March – April – May)

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%).

Reefscapers coral bleaching survey

Landaa Giraavaru: Results of our coral bleaching surveys so far (end of May). We have 4 different monitoring sites, and the effects of the seasonally elevated ocean temperatures can clearly be seen.
Most corals start off healthy (green), then start to bleach (white); some have already died (black).
Bleached corals can recover if the ocean temperatures soon return to normal (they re-uptake zooxanthellae). But they are vulnerable to predation from corallivorous species (Drupella and COTS). Dead corals quickly become overgrown with algae.

Reefscapers coral bleaching

Kuda Huraa

Acropora millepora coral bleaching Maldives

Close-up of Acropora millepora coral paling and bleaching

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.

Four Seasons Team Diaries: April 2024

Be sure to read our monthly updates from Marine Savers – direct from our teams resident at
the Marine Discovery Centres at Landaa & Kuda Huraa – our long-term partnership with Four Seasons Resorts Maldives.

Landaa Giraavaru

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.

Reefscapers coral spawning Maldives (Amelia)

Coral spawning (Acropora aspera)

Reefscapers coral spawning Maldives (Amelia)

Coral spawning (Acropora millepora)
Note the paling branches due to heat stress

Maldives Coral Bleaching Season

Reefscapers coral bleaching E14 April 5-15

Monitoring for coral bleaching: colony #E14 photographed 5 April  – 15 April 2024
From paling to fully bleached within the 10 day period

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.

Reefscapers coral bleaching - before (March)

A healthy, fluorishing Reefscapers coral frame photographed in March…

Reefscapers coral bleaching - after (April)

… but just a few weeks later in April, the coral colonies had started to pale and fluoresce due to heat stress

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).

Reefscapers coral bleaching Maldives HR32 HR90 (March-April)

Coral bleaching in our monitored colonies # HR32 (top) & HR90 (bottom)
📷 2024: March (left) – April (right)

Reefscapers coral bundling when bleached (A.hyacinthus)

Coral bundling of gametes, while bleached (Acropora hyacinthus)

Kuda Huraa

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.

Reefscapers coral spawning Maldives (April 2024)

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.

Reefscapers Maldives BBC coral film
Reefscapers Maldives BBC coral film

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 corals Maldives Reefscapers (Acropora muricata)

Bleaching in Acropora muricata 🗓️ 4 March – 29 April 🗓️ 

Bleached corals Maldives Reefscapers

Smaller coral colonies at shallow depth were the first to start bleaching

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.

Reefscapers coral spawning when bleached
Reefscapers coral spawning when bleached

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.

Reefscapers relocating vulnerable corals Maldives

Sea Snails: Are They Friend or Foe?

Corallivorous snails Maldives
Corallivorous snails Maldives
Peristernia snails Maldives

Are Marine Snails Harmful to Corals?

Our Reefscapers teams remove any corallivorous snails encountered during our regular reef restoration and coral maintenance work. (Big thanks to Elisha Whiting, Coral Biologist at Kuda Huraa, for the graphics & write-up).

This will become increasingly important during the upcoming months, as coral predators are known to strike when the corals are at their most vulnerable, such as during and following a coral bleaching event.

Many marine gastropods play an important role in the coral reef ecosystem, so we have been working to identify which corallivorous species are found on our reefs, to increase knowledge and understanding of the threats to our corals.

Some marine gastropods such as Drupella are known to eat corals, and prefer genera of both Acropora and Pocillopora. This is a particular issue for our Reefscapers teams, as these 2 coral species are favoured for coral propagation projects, being both easy to handle and giving excellent rates of growth.

Predation of the coral colonies leaves them vulnerable to disease and competition, or if left unchecked can result in total mortality of whole colonies and even large sections of reef. To increase the success of restoration projects, it is common for coral biologists to remove these snails and manage populations, to increase survivorship of the vulnerable corals.

Peristernia nasatula = Friend

Commonly mistaken for: Coralliophila costularis (below) as it also has a purple aperture and red operculum. There is no published literature that identifies this species as corallivorous. Although they can be found around Drupella, they do not leave behind feeding scars

Coralliophila costularis
(formerly: Coralliophila retusa)

  • Prey Preferences: Acropora (also found around Montipora digitata)
  • Location: on the substrate around the base of Acropora colonies (particularly branching species)
  • Key features: distinctive wavy edge on the outer lip, dark purple aperture, and red operculum

Coralliophila costularis

Coralliophila erosa
(formerly: Coralliophila abbreviate)

  • Prey Preferences: Acropora
  • Location: around the base of Acropora colonies (particularly branching and digitate species). Very well camouflaged
  • Key Features: distinctive diamond shape, white/ light purple aperture, and yellow operculum

Coralliophila erosa

Coralliophila monodonta
(sessile species of Coralliophila)

  • Prey Preferences: Pocillopora
  • Location: on branches of Pocillopora colonies
  • Key Features: rounded shape, variety of aperture and operculum colours (pink-purple). Well-camouflaged inside the colony and covered in algae

Coralliophila monodonta

Coralliophila violacea
(sessile species of Coralliophila)

  • Prey Preferences: Massive Porites
  • Location: in the crevices of massive Porites boulders
  • Key Features: rounded shape, purple aperture, and dark operculum

Coralliophila violacea

Drupella corallivorous snail Maldives

Four Seasons Team Diaries: March 2024

Be sure to read our monthly updates from Marine Savers – direct from our teams resident at
the Marine Discovery Centres at Landaa & Kuda Huraa – our long-term partnership with Four Seasons Resorts Maldives.

Reefscapers coral frame relocation mitigation "barge"

Landaa Giraavaru

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
Reefscapers coral propagation Maldives closeup
Reefscapers coral details

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.

Reefscapers coral propagation healthy Maldives
Reefscapers coral spawning Maldives

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.

We have been tracking NOAA’s Coral Reef Watch bleaching guidelines, and over the next few weeks, the Maldives will reach “Alert Level 2”, indicating severe bleaching and significant mortality. So far, we have recorded moderate paling for some colonies along Landaa’s House Reef. We are continuing to track bleaching and will be monitoring the situation closely over the coming months.

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

NOAA’s coral bleaching forecast for Maldives as at 31 Mar.
Predicting Alert #1 (April) rising to Alert #2 (May-June).
(Right) Multi-year plot of ‘degree heating weeks’. Note that temperatures in the Maldives have now hit the coral bleaching threshold this year (black line).

Kuda Huraa

Reefscapers coral frame relocation airlift bags

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.

Reefscapers coral frame relocation airlift bags

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).

Reefscapers coral frame relocation airlift bags

Four Seasons Team Diaries: February 2024

Be sure to read our monthly updates from Marine Savers – direct from our teams resident at
the Marine Discovery Centres at Landaa & Kuda Huraa – our collaboration with Four Seasons Resorts Maldives.

Landaa Giraavaru

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.
Reefscapers healthy corals Maldives

Healthy corals

Reefscapers large coral frames for Voavah

Large coral frames for Voavah

Reefscapers large coral frames for Voavah

Team effort for Voavah

Reefscapers old degraded frame for recycling

Old degraded frame for recycling

Kuda Huraa

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.

February saw the coral bleaching forecast jump from Level 1 to Level 2 in the coming weeks, for the entirety of the Maldives (NOAA’s Coral Reef Watch). This would mean higher ocean temperatures reaching the Maldives sooner than previously expected. Our teams are working hard to actively mitigate the potential damaging effects of the upcoming marine heat wave.

  • 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
Reefscapers coral maintenance
Reefscapers coral maintenance
Reefscapers coral reefs Maldives
SST 1998 2016 2023-24 C3S (Copernicus Climate Change Service)
NOAA Maldives_prod_quad_composite [2024-03-17]