Monthly report updates from our Reefscapers coral biologists at Kuda Huraa and Landaa Giraavaru.

You may also be interested in:

  • previous yearbooks from 2016 – 2020 (including our extensive 2016 coral bleaching report);
  • sponsoring your very own coral frame as part of our Reefscapers coral propagation and reef regeneration projects;
  • viewing the latest photographs of your coral frame (uploaded every 6 months) – see our Coral Frame Collection.
Reefscapers coral reef propagation Maldives

Reefscapers Diary April 2021

Reefscapers coral fragments new (right) and encrusted (left)

Reefscapers coral fragments – encrusted (left); newly transplanted (right).

Coral Propagation – Monthly Progress

At Landaa during April, we monitored a total of 343 coral frames around the island, and transplanted 24 new frames (9 sponsored by guests, 15 by the Resort).

At Kuda Huraa, we transplanted 4 new coral frames, recycled 5 of our older frames, and monitored a total of 185 existing frames (mainly at the Water Villas site). We spotted (and removed) several Crown of Thorns starfish (COTs) eating our corals, and we relocated a total of 102 frames to protect them from shifting sands and increased sedimentation.

Corals at the House Reef site and the deep Blue Hole refuge (rescued Gulhi Falhu corals) are healthy and remain unaffected by  sand sedimentation and the seasonally elevated ocean temperatures.

Microfragmenting Trial – Studying Surface Area Growth Rates

During April, we started a new experiment to build on our micro-fragmenting coral propagation techniques explored in 2019-2020.

Experiments using “massive” coral species are often overlooked due to their slow growth rates, so this is an important area for us to explore, given their apparent resilience to warmer temperatures.

Read more: Micro-fragment Techniques in Coral Propagation.

Coral bleaching Maldives alerts NOAA

Bleaching Alerts – The NOAA coral bleaching alerts system categorises Maldives in “Watch” status for April-May, rising to “Warning” for June. Currently, we have not observed any coral bleaching on the natural reef or our coral frames.

Reefscapers coral fragments recovering from bleaching and starting to encrust

Coral fragments recovering from initial bleaching (due to stress) and starting to encrust

Temperature Loggers

We retrieved our temperature loggers from Kuda Huraa’s lagoon (at the Water Villas, Channel, and Sea Star sites) and plotted the data to visualise the seasonal increases in ocean temperatures. The maximum recorded temperatures peaked during the first week of April at the Water Villas site.

Ocean temperatures at 4 sites April 2021 Maldives

Ocean temperatures for the month of April 2021, at 4 different sites around the lagoon at Kuda Huraa

Coral Plates in Aquarium One (plates KH01, KH02, KH05) and Aquarium Two (plates KH03, KH04, KH06)

Our coral plates in both aquaria remain healthy, and we continue to perform weekly cleaning (Aquarium Two suffers more from algal growth). Most of the coral fragments in Aquarium One have an obvious growth direction towards the light source, so we are regularly rotating the affected plates.

  • KH01 (Acropora digitifera, millepora, Galaxea fascicularis) – continues to grow steadily. The fragments of A. millepora continue to fuse, and the Galaxea (added in November) remain healthy.
  • KH02 (Galaxea fascicularis) – healthy and growing.
  • KH03 (Acropora valida) – 4 dead fragments overgrown with algae; 2 fragments with partial bleaching.
  • KH04 (replenished December, digitifera, A. millepora) – 8 dead fragments overgrown with algae at the bottom of the pate.
  • KH05 (Galaxea fascicularis) – growing steadily, especially the upper fragments (more light).
  • HK06 (Galaxea fascicularis, new Feb-21) – continuing to grow well, with encrusted teeth.

Reefscapers Diary March 2021

Reefscapers artificial reefs Maldives house reef

Healthy coral frames photographed this month at Kuda Huraa’s House Reef site

Coral Propagation – Monthly Progress

During March at Landaa, we transplanted 14 new coral frames, and at Kuda Huraa a total of 7 new frames were located to the lagoon.
We are closely monitoring the health of our frames and currently, none of our colonies present any bleaching (as has been recorded elsewhere in the Maldives).
The frames at the Water Villas site can become buried by the shifting sands, but the seasonal thunderstorms are now pushing the sand in the opposite direction. We have now been focusing on CoralWatch monitoring, looking out for signs of bleaching (the flat frames here are an important source of coral fragments for our day-to-day reef reclamation work).

Bleaching Alerts – The global NOAA Bleaching Alerts lists the Maldives’ Baa Atoll at “Watch” status, rising to “Warning” in the upcoming weeks as ocean surface temperatures are expected to rise seasonally. Malé atoll remains in “Watch” status, with elevated temperatures expected to peak at levels lower than last year’s peak.

NOAA bleaching alerts Maldives

2021 NOAA coral bleaching alerts for the Maldives

Reefscapers artificial reefs Maldives healthy coral frame Channel

Healthy coral frames at Kuda Huraa’s Channel site

Reefscapers artificial reefs Maldives water villas

Healthy coral frames at Kuda Huraa’s Water Villas site

Gulhi Falhu Coral Rescue

This month, our Kuda Huraa team conducted a mass coral collection at the industrialised zone in Gulhi Falhu, rescuing corals in danger of becoming smothered by the dredging and land reclamation in the area. We collected 250-300 colonies of various species of Acropora & Pocillopora colonies, to be retransplanted at various sites around Kuda Huraa.
Most of the rescued coral colonies survived the harvesting and transportation, and have started to stabilise in their new location at the Blue Hole site, which acts as a natural refuge and coral nursery thanks to the depth and good water flow.

At the House Reef, we retransplanted some of the rescued Gulhi Falhu colonies to our existing frames, and also to solid rock substrate in the area.

Reefscapers coral rescue Maldives Gulhi Falhu
Reefscapers coral rescue Maldives Gulhi Falhu

Coral Plates in Aquarium One (plates KH01, KH02, KH05) and Aquarium Two (plates KH03, KH04, KH06)

Overall, our experimental coral plates remain healthy. Cleaning is performed every 3 days to prevent the accumulation of algae on the plates and in the aquarium.

  • KH01 (Acropora digitifera, A.millepora, Galaxea fascicularis) – growing steadily; the fragments of A. millepora continue to fuse. The Galaxea fragments added in November remain healthy and are continuing to encrust and expand on the plate.
  • KH02 (Galaxea fascicularis) – making a steady recovery. Weekly rotation of the plate is performed to ensure all fragments receive enough light, and we continue to take weekly monitoring photos to monitor recovery.
  • KH03 (Acropora valida) – 2 of the 8 older fragments lost tissue and died; the 16 newer fragments are healthy, gradually calcifying and encrusting.
  • KH04 (replenished December, digitifera, A. millepora) – continuing to grow steadily and encrust on the plate; 2 fragments show tissue loss and algal growth
  • KH05 (Galaxea fascicularis) – – healthy and growing steadily; some encrusting and fusing together. We added new fragments to the lower parts of the plate.
  • HK06 (Galaxea fascicularis, new Feb-21) – all 14 fragments are encrusting on the plate. We are photographing weekly to closely monitor the encrusting process.

Reefscapers Diary February 2021

Reefscapers coral frames Valentine hearts Maldives

Reefscapers coral frames – Valentine hearts

Coral Propagation – Monthly Progress

At Landaa during February, we transplanted 33 new coral frames and sited them in the lagoon around the resort.

At Kuda Huraa this month, we transplanted 3 new sponsored frames and recycled a further 6 frames. We focused our monitoring efforts on the Channel and Water Villas sites, working to reduce the effects of the shifting lagoon sands, which have caused some mortality on the lower coral colonies. We are also on the lookout for any corallivorous COTs (crown-of-thorns starfish).

On Valentine’s Day, we transplanted two special heart-shaped frames with Pocillopora, made by Kuda Huraa’s Dive Team.

At the Channel site, with have started a mass re-transplantation project, replacing any dead coral colonies with new Pocillopora fragments, replacing missing tags and remapping the GPS co-ordinates. Any unmapped frames without tags are being relabelled with ‘RK’ recycle tags.

Reefscapers healthy coral propagation colonies

Healthy coral colonies photographed on our frames this month

Artificial Intelligence and Coral Identification

Read the full project history of our autonomous catamaran and AI coral identification project over at Reefscapers AI-4Corals.

We started training a new AI software model to detect the shape of corals on monitoring photographs. The existing model is useful for small colonies, but they start to merge with each other as they grow, making the monitoring of individual colonies impossible. Therefore, we hope that this new model will be able to measure total surface cover.

Reefscapers AI training data coral cover

AI training data – detecting total coral cover for larger colonies

Reefscapers AI data analysis coral volumes

AI data analysis – total coral volumes

Reefscapers AI species ID

Identifying coral species using AI

Bleaching Alerts

As we approach the hottest part of the year, we will be closely monitoring the NOAA’s Bleaching Alerts. Every year, this resource is consulted to allow us to prepare for the annual rise in sea surface temperature.

The latest NOAA model predicts “Watch” status in the Maldives for weeks 5-8 (from the end of February), and “Watch/Warning” during weeks 9-12. This is a marked improvement from the predictions at the same time last year, which predicted “Alert Level 2” for May 2020 (although in reality, the highest rating thankfully only averaged “Warning”).

NOAA coral bleaching alerts Maldives (2020)

2020 NOAA coral bleaching alerts Maldives

NOAA coral bleaching alerts Maldives (2021)

2021 NOAA coral bleaching alerts Maldives

Coral Plates in Aquarium One (plates KH01, KH02, KH05) and Aquarium Two (plates KH03, KH04)

Overall, the coral plates in both aquaria remain healthy. We perform weekly cleaning of algae to prevent the corals from being smothered.

  • KH01 (Acropora digitifera, A.millepora, Galaxea fascicularis) – Growing steadily. The A. millepora fragments continue to fuse; the Galaxea fascicularis (added in November) are healthy and encrusting to the plate.
  • KH02 (Galaxea fascicularis) – This plate was transplanted onto a frame in the Water Villa area, as it had been thriving in the aquarium. It did not adjust to the new environment, however, and bleached almost entirely. It was subsequently returned to Aquarium 1, and is making a steady recovery. Weekly photos are being taken to monitor the recovery of the fragments; we are assessing the relocation options.
  • KH03 (Acropora valida) – The 8 older coral fragments continue to grow and encrust steadily. One fragment shows partial death with algal growth; the 16 newer fragments are gradually calcifying and encrusting.
  • KH04 (replenished December, digitifera, A. millepora) – Continuing to grow steadily and encrust on the plate. Fragments that were planted as both bases and tips are growing equally well.
  • KH05 (Galaxea fascicularis) – Healthy overall, with the uppermost fragments growing faster than the lower shaded fragments.
  • HK06 (Galaxea fascicularis, new Feb-21) – Encrusting and healthy. Weekly photos are taken to record the encrusting period of 3 particular fragments.

Woodstock Presentation

On 24 February, Simon and Gaetan held a Zoom meeting with students and alumni of Woodstock School (India).

This session was designed to showcase the work conducted at the Marine Discovery Centre and included a tour of our facilities, some short educational videos, and a question-and-answer session.

The recorded Zoom call can be viewed here on YouTube (and embedded below).

Reefscapers Diary January 2021

Reefscapers coral fragments encrusting

Coral fragments, healthily encrusting over their cable ties …

Reefscapers coral fragments encrusting

… on a mini-frame housed in a marine aquarium (Kuda Huraa).

Coral Propagation – Monthly Progress

At Landaa during January, we transplanted 24 new coral frames and monitored a total of 397 existing frames (mainly at the Dive and Water Villas sites).

At Kuda Huraa, we transplanted 10 new coral frames and recycled 2 of our old frames with fresh coral fragments (mainly using Acropora digitifera and A. tenuis). We continue to mitigate against sand accumulation by relocating any affected frames, although we have suffered some coral mortality. We also removed 3 crown of thorns starfish (COTs) that had made their home at the Water Villas site and were feasting on our coral frames.

At the House Reef site, we have continued monitoring and mapping our frames, and we observed that frames relocated from the Blue Hole are growing very well.

Reefscapers coral frames shifting sands

Shifting sands can be a problem caused by seasonal currents, stormy weather or construction/dredging work.

Reefscapers crown of thorns starfish

Crown of thorns starfish (COTs) are deadly to corals.
Photographed on our coral frames at Kuda Huraa (January 2021)

Artificial Intelligence and Coral Identification

Read the full project history of our autonomous catamaran and AI coral identification project over at Reefscapers AI-4Corals.

We have developed an inhouse software program to visualise all the information generated by our Artificial Intelligence analysis. It will be used internally by our Coral biologists, but we also hope to expand the data that is presented online to our coral frame sponsors.

Features of our program:

  • Run Analysis – updates the database with data from any new coral frame photographs.
  • Display Results – shows ‘bounding boxes’ of the coral fragments for a specific frame, and the growth in overall coral volume on the frame.
  • Statistics – generates charts on the whole restoration program. Currently we have four options:
    1. Survival rates: Compares data for Pocillopora and Acropora in two different geographical areas (or on custom sets of frames).
    2. Mortality by zone: coral mortality over time, to identify abnormal events (bleaching, or local disturbances).
    3. Growth rates: distribution by geographical area and by genus.
    4. Volume: evolution of live and dead coral volume on the frames.
AI software data analysis coral propagation reef regeneration

Coral Plates in Aquarium One (plates KH01, KH02, KH05) and Aquarium Two (plates KH03, KH04)

All 5 coral plates in both aquaria are regularly cleaned to remove algae. There were a few mortalities, and the crabs continue to push the fragments out, but the plates remain healthy overall.

  • KH01 – (recently replenished) – fragments of Acropora millepora just beginning to fuse. The fragments of Galaxea fascicularis that were added last month remain healthy and are starting to encrust.
  • KH02 – (exclusively Galaxea fascicularis) – showing a little mortality, so we have rotated the plate several times to allow all fragments to receive more light.
  • KH03 – thoroughly cleaned of algae. The calcified areas are growing and about to fuse. The fragments of Acropora valida remain healthy and continue to grow, although they haven’t yet calcified onto the plate.
  • KH04 (replenished December) – also cleaned of algae. Only two original fragments remain (due to the loss from algal overgrowth) and of the 11 newly transplanted fragments, 4 have started to calcify onto the plate (photos, below).
  • KH05 (exclusively Galaxea fascicularis) – 1 fragment died after bleaching, but the others have now regained a healthy colouration and continue to grow (2 fragments are encrusting).
Reefscapers coral plate (KH01) A.milepora fusing (left) and encrusting (right)

Coral plate (KH01) showing fragments of Acropora millepora, fusing (left) and encrusting (right)

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