Reefscapers Diary May 2023

Coral Propagation – Monthly Progress

At Kuda Huraa during May, we monitored and mapped a total of 363 existing frames, and transplanted five new frames around the island.

At Landaa this month, we transplanted 27 new coral frames, kindly sponsored by guests (nine) and the Resort (eighteen), which in total added ~1200 coral fragments onto the reef. In addition, we monitored (cleaned, repaired, photographed) a total of 487 coral frames around the island. We have also been lifting 65 buried frames out of the seabed sand along the Coral Trail, and recycling ~600 fragments.

One of our longer-term goals for 2023 is to restore the ~300 degraded coral frames at our Parrot Reef site, where some frames had been flipped by unusually strong waves. Our aim is to relocate all the frames to a more sheltered side of the reef, re-tag and re-map the frames in QGIS, recycle fragments on all frames, and monitor the site once more. This month, we started to relocate frames into neat lines at the new site, and over four days we successfully moved a total of 135 frames. Special thanks to our Dive Team colleagues, and our apprentices (Eegan and Mode) for all their hard efforts.

NOAA Bleaching Warnings for The Maldives

Throughout May, much of the Maldives has been in a “Watch” state according to NOAA’s Coral Bleaching Forecast, implying a prolonged thermal stress on all corals in the region. In addition, water temperatures are slowly rising, suggesting more stressful weeks to come due to the accumulated heat stress (measured in ‘degree heating weeks’, DHW).

High water temperature can hinder the energy production mechanism of the algae hosted in coral tissues. Therefore, coral colonies tend to expel these non-functional algae, which are also responsible for the attractive colourations of the coral itself. When this process occurs over several weeks, corals become increasingly pale and eventually reach a bleached white colouration. With no algae to provide them with food, corals can’t produce enough energy to survive for long, and risk death by starvation.

Coral Bleaching Monitoring

With the sunny warm weather throughout much of May, we observed paling and bleaching of many Acropora colonies in the shallow lagoon along the House Reef and Water Villas sites at Landaa Giraavaru. Some coral frames were moved into shaded areas under the boardwalk and villas, to encourage faster recovery, and monitoring pictures of colonies at both sites were taken for comparison over time.

At Kuda Huraa, we conducted three dives and eleven snorkels as part of our seasonal monitoring for signs of coral paling and bleaching. Out of the 300 sample coral colonies (nine species on 136 frames at five sites) we observed 43% paling, 4% bleached, 0.3% fluorescing. The Channel is currently the most impacted location (72% bleaching), and Acropora muricata the most impacted species (58% pale, 11% bleached).

Coral Relocation Project – Pyramids of Huraa

The wider Reefscapers team have been rescuing masses of corals from a large-scale reclamation project currently underway by the Maldives government at Gulhi Falhu industrial zone. Between 3 – 11 May, many of these rescued coral colonies were transported to Kuda Huraa and retransplanted onto large frames in the form of pyramids. In total, our twenty-strong team spent more than 100 working hours in-water, transplanted ~1500 coral colonies, and constructed three large pyramid structures located in our shallow house reef.

We extend a BIG THANKYOU to our colleagues at Dive, Tropic Surf, and Launch for their invaluable assistance. The pyramids have already proven to be a great success, attracting lots of attention from staff, guests, and marine life!

This is the second time Kuda Huraa has received corals from this location; the first time being in March 2022, when approximately 10,000 colonies were relocated around the island.

Although most of the corals are recovering well from the stress of their relocation, a few colonies have bleached and died (from suspected white band disease). Fragments of Acropora muricata at the base of each pyramid have started to pale, but this is consistent with our bleaching monitoring surveys of our coral frames at other sites. In addition, a few of the rescue corals have been heavily predated by a new resident bumphead parrot fish (Bolbometopon muricatum).