Reefscapers Diary September 2021

Coral Propagation – Monthly Progress

At Landaa during September, we used 342 individual coral fragments to transplant nine new coral frames (sponsored by guests and the resort) and a further 250 fragments were used for repairs and recycling.

Temperature Loggers

This month, we analysed the Sea Surface Temperature (SST) data from our temperature logger at Kuda Huraa’s House Reef site, and noted the following:

• The seasonal increase in SST during 2021 lasted from March-June (one month longer than we have recorded for previous years).
• Lowest SST was 27.2°C (28 January, 11:00 pm).
• Highest SST was 30.6°C (10 May, 5:00am).
• Overall, average House Reef SST (January to September 2021) is 29.1°C.
• Of all our sites, the House Reef recorded the lowest average SST during the critical May to June period, making it the preferred refuge.

At Kuda Huraa this month, a total of seven new coral frames were transplanted and deployed around Kuda Huraa. We focused our efforts on improving the frame layout in the Channel area, and relocating Water Villas frames due to seasonally shifting sands.

• Water Villas (WV) – Coral colonies remain healthy, with a little evidence of predation from corallivorous fish species. We relocated a total of 136 frames, as the seasonal water currents continue to shift sand around the island (corals on the lower bars of 10 frames suffered some mortality). This month’s new frames were sited to the North (away from the problem) using a variety of coral species (Pocillopora meandrina, Acropora austera, A. digitifera, A. gemmifera, A. hyacinthus, A. latistella, A. muricata, A. tenuis).
• House Reef (HR) – 59 frames were monitored (photographed, cleaned) and some were unburied from the shifting sands.
• Blue Hole (BH) – most coral colonies remain healthy, although drifting ocean debris tends to accumulate here, causing some mechanical damage.
• Channel (CH) – All the frames were rearranged into lines, enhancing the snorkel experience for guests, and simplifying our monitoring and mapping tasks. A total of 45 old frames were removed and brought ashore for cleaning and recycling.
• Channel – coral species list (18 species of 6 genera):
  • Acropora aspera, A. austera, A. digitifera, A. gemmifera, A. humilis, A. hyacinthus, A. latistella, A. muricata, A. secale;
  • Heliopora coerulea; Isopora palifera; Montipora foliosa, M. digitata;
  • Pocillopora damicornis, P. meandrina, P. verrucosa; Porites cylindrica, Porites rus.
• Sea Star (SS) – coral colonies are in good health; frames were fully remapped, and missing tags were noted (for future tagging and retransplanting).
• Sea Star – coral species list (11 species of two genera):
  • Acropora digitifera, A. hyacinthus, A. gemmifera, A. hemprichii, A. humilis, A. monticulosa,
  • Pocillopora damicornis, P. meandrina, P. verrucosa, P. elegans, P. eydouxi.

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

• KH01 (Galaxea fascicularis; Acropora species replenished September 2021) – suffered tissue loss in 90% of fragments (probably due to disease). The plate was removed, disinfected, and completely retransplanted with Galaxea fascicularis and Acropora fragments.
• KH02 (G. fascicularis) – healthy and adapting well to a new location within the aquarium.
• KH03 (Acropora species, replenished July 2021) – continuing to grow; the newest fragments are already well encrusted to the plate.
• KH04 (A.digitifera, A.millepora) – mainly healthy and growing (any dead fragments were removed).
• KH05 (G.fascicularis) – healthily growing and fusing. Cyanobacterial growth is removed regularly from the top of the plate.
• KH06 (G.fascicularis) – healthily growing and fusing.

Coral Experiments

Quiet this month, due to staff leave.