Four Seasons Team Diaries: August 2024

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.