Four Seasons Team Diaries: September 2024

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]