Reefscapers Diary August 2021

Coral Propagation – Monthly Progress

At Landaa during August, we used 1147 individual coral fragments to transplant 27 new coral frames, sponsored by guests (11) and the Resort (16), and we monitored a total of 132 sponsored frames around the island.
We have continued our frame relocation efforts, to optimise coral growth rates while ongoing work takes place around the island, and have cordoned off several areas for protection (using buoys and rebar). A total of 93 frames were retagged and remapped in QGIS, and 10 old frames were cleaned for recycling.

At Kuda Huraa this month, a total of six new coral frames and one recycled frame were transplanted and deployed around the island, mainly using fragments of Acropora and Pocillopora corals. 

• Water Villas (WV) – a total of 497 frames were monitored, and the photographs uploaded to our website for our kind sponsors to monitor the growth of their personal coral frame. Coral colonies remain healthy, and the site continues to preserve a high diversity of fish species. Loose ‘fragments of opportunity’ of Montipora foliosa were collected for later transplanting (at the Blue Hole).
• Blue Hole (BH) – most coral colonies (eight different species) present good health.
• Channel (CH) – before being photographed, frames were retransplanted with fragments of Pocillopora verrucosa, Montipora digitata and Porites cylindrica. Following extensive retagging and maintenance work, the remapping of the entire site was completed this month (600 frames). Some old frames were removed completely for recoating as recycled frames. Certain coral species are thriving (particularly Montipora digitifera, Pocillopora damicornis, Porites) and seem more resistant to algae, disease, and higher temperatures.

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

• KH01 (Galaxea fascicularis; Acropora species replenished July 2021) – fragments continue to grow and fuse. Most of the new fragments have started to encrust (any dead fragments were removed).
• KH02 (Galaxea fascicularis) – healthy and growing, especially the upper fragments closer to the light (so we rotated the plate).
• KH03 (Acropora species, replenished July 2021) – the newly introduced fragments are encrusting (any dead fragments were removed).
• KH04 ( digitifera, A. millepora) – mainly healthy and growing (any dead fragments were removed).
• KH05 (Galaxea fascicularis) – well adapted, continuing to grow and fuse. We cleaned a patch of bryozoans and cyanobacteria.
• KH06 (Galaxea fascicularis) – good health, fusing and growing.

Blue Coral Growth Experiment

Blue Coral (Heliopora coerulea) is a reef-building octocoral with high resistance to thermo-stress and bleaching (Richards et al., 2018) with warmer seawater temperatures promoting substrate colonisation (Guzman et al., 2019). In addition, species of Heliopora were one of two massive corals to affect the reef flat carbonate budget located in Huvhadoo Atoll (South Maldives) during the 2016 bleaching event (Ryan et al., 2019).

Blue coral possesses homologues of biomineralisation genes resembling that of hard corals (as Guzman) so it could be a key reef-building coral against future climatic changes. However, restoration efforts of large densities of H. coerulea should not inhibit the growth and recruitment of other coral species (Courtney et al., 2021, Artigenio et al., 2020; Guzman et al., 2019).

In order to continue expanding our coral restoration techniques, we have out-planted our first frame of Blue Coral.

On 13 August, we moved a small frame to the Al Barakat site (at 3m depth), and attached 14 coral fragments of H. coerulea. We will monitor the frame closely, and record information on health and bleaching. To track growth rates, we will take regular measurements for height, length, and width for each individual fragment.
The ecological volume is calculated using the formula: EVi = 3.14 * POWER (R,2)*H

Microfragmenting Experiment

During August, we started preliminary investigations using microfragments of Brain (honeycomb) coral, transplanted to a newly designed coral frame.

At Landaa’s Dive Site (5m depth), we harvested a healthy coral specimen of Diploastrea heliopora (taking less than 10% of the donor colony). The specimen was kept temporarily in our open-flow seawater tank, before being fragmented and super-glued onto the prototype microfragment frame. The frame consists of a flat panel with legs, for ‘wedging’ into hard substrate to ensure the frame and future coral growth becomes integrated into the reef. Each fragment was labelled (1 – 12), assessed for health and bleaching, and then photographed for surface area analysis, using FIJI by Image-J.