Reefscapers Diary 2022

Coral Propagation – Monthly Progress

At Kuda Huraa this month, we transplanted 12 new coral frames, kindly sponsored by guests (five), the Resort (three), online orders (two), and media (two).

At Landaa, we transplanted 32 coral frames, kindly sponsored by guests (21), the Resort (eight), and online (three), using a total of 1858 coral fragments. In addition, we monitored (cleaned, repaired, photographed) 273 coral frames at various sites around Landaa Giraavaru. We also lifted four large coral frames from our Al Barakat site, and recycled them using 150 coral fragments. As part of the festivities, we recycled a Christmas tree frame and deployed it at the House Reef site along with three heart-shaped frames.

Coral Spawning (see also: our indepth reporting)

This month at Landaa, we started nightly snorkels around the full moon period (8 December). We observed spawning in five frame colonies of tenuis. Several days later, we observed spawning in 18 frame colonies of plantaginea.

At Kuda Huraa, we set our own new record this month for the greatest amount of coral spawning recorded! We witnessed 153 colonies (of eight species) spawning over three nights, across four locations.

Read our Reefscapers Diaries for further details and photographs of our ongoing coral propagation efforts and reef regeneration experiments, both in the Lab and out in the lagoon, updated each month. You may also be interested in our ongoing research and photography, studying coral spawning.

Coral Propagation – Monthly Progress

At Landaa this month, we transplanted 19 new coral frames, kindly sponsored by guests (eight), the Resort (eight), and online (three), using a total of 901 new coral fragments. In addition, we monitored 530 coral frames at various sites around Landaa Giraavaru.

At Kuda Huraa, we transplanted seven new guest coral frames, recycled (cleaned and retransplanted) two old frames, and monitored (cleaned, repaired, photographed) a total of 141 frames around the island.

Coral Spawning (see also: our indepth reporting)

This month, our Kuda Huraa team divided across two sites for 18 nights of spawning surveys around the time of the full moon. To further maximise our data collection, we also conducted morning surveys, to check for presence of gametes at unmonitored sites.

We successfully observed and documented a total of 52 coral colonies, spawning over eight nights in five locations, representing six different species: Acropora tenuis, A. plantaginea, A. humilis, A. retusa, A. secale, A. rosaria.

We collected gametes from five coral colonies of A. tenuis (from frames at the Blue hole and Water Villas sites), fertilised them, and observed successful settlement on substrate.

Gamete Monitoring

A total of nine species of wild, relocated, and local colonies (at six different sites around Kuda Huraa) were found to have gametes: Acropora monticulosa, A. gemmifera, A. humilis, A. plantaginea, A. millepora, A. tenuis, A. cf. tenuis, A. muricata, A. retusa.

Larval Development

• Acropora tenuis – larvae have continued to grow since settlement, but have not shown signs of symbiont (zooxanthellae) uptake.
• Acropora secale – due to water flow problems in our coral pool, most larvae became stressed and consequently lost their pigmentation. Microscopic analyses revealed that some of the larvae were starting to uptake symbionts. As the month progressed, the symbiont density within the larvae greatly increased (darker colouration).
• Algal removal – we trialled the addition of snails (Trochus species) to control algal growth, but this seemed to adversely affect the coral larvae. We have now resorted back to gently brushing the rubble substrate with toothbrushes, while continuing to research alternative methods.

References

• Omori, M., 2005. Success of mass culture of Acropora corals from egg to colony in open water. Coral Reefs, 24(4), pp.563-563.
• Humanes, A., Bythell, J., Beauchamp, E., Carl, M., Craggs, J., Edwards, A., Golbuu, Y., Lachs, L., Randle, J.L., Martinez, H. and Palmowski, P., 2021. A framework for selectively breeding corals for assisted evolution. bioRxiv.
• Villanueva, R.D. and Baria, M.V.B., 2013. Effects of grazing by herbivorous gastropod (Trochus niloticus) on the survivorship of cultured coral spat. Zoological Studies, 52(1), pp.1-7.
• Toh, T.C., Ng, C.S.L., Guest, J. and Chou, L.M., 2013. Grazers improve health of coral juveniles in ex situ mariculture. Aquaculture, 414, pp.288-293.

Coral Propagation – Monthly Progress

At Landaa during October, we transplanted 33 new coral frames (using 1744 coral fragments), kindly sponsored by guests (14), and the Resort (19). In addition, we monitored (cleaned, repaired, photographed) a further 465 frames around the island.

At Kuda Huraa this month, we transplanted 9 new coral frames, sponsor by guests (3), the Resort (5) and online (1).

5000th Coral Frame!

At the start of this month, we were happy to celebrate our 5000th Coral Frame here at Landaa Giraavaru! We hosted an event on Maldives Tourism Day for staff and guests to learn more about our coral restoration project and to help build the commemorative frame… an exciting milestone in our Reefscapers coral propagation program!

Coral Spawning

This month at Kuda Huraa, we recorded spawning at the Blue Hole site (depth 3m) in Acropora secale and A. plantaginea. We collected gametes – fertilised ex-situ, and settled successfully. The development and health of the coral larvae is closely monitored and documented through routine microscopic examinations. Larval feeding began on day-5, using a krill-based food source (‘Coralific Delite’).

Gamete Monitoring

This month, in addition to our daytime gamete checks at six sites around Kuda Huraa, we conducted 16 separate night surveys to look for spawning at the House Reef and Blue Hole sites.

From our gamete checks this October, we found 48% of 142 colonies checked since July presented gametes, adding up to a total of 67 monitored Acropora colonies.

Pigmented gametes were recorded in: A. secale, A. plantaginea, A. tenuis, A. muricata.

Read our Reefscapers Diaries for further details and photographs of our ongoing coral propagation efforts and reef regeneration experiments, both in the Lab and out in the lagoon, updated each month. You may also be interested in our ongoing research and photography, studying coral spawning.

Coral Propagation – Monthly Progress

At Landaa during September, we transplanted 39 new coral frames (using 2674 coral fragments), kindly sponsored by guests (27), the Resort (10), and online (two). In addition, we monitored (cleaned, repaired, photographed) a further 628 frames around the island.

At Kuda Huraa this month, we transplanted ten new coral frames, sponsor by guests (five), the Resort (three) and online (two).

Coral Propagation – Monthly Progress

At Landaa this month, we transplanted 19 new coral frames, sponsored by guests (9), and the Resort (10).

At Kuda Huraa this month, we transplanted 5 new sponsored coral frames, retransplanted 3 existing frames, and monitored (cleaned, repaired, photographed) a total of 81 frames around the island. In addition, our apprentices and intern worked arduously to identify and remove any old frames in the Channel.

This month, we started our new Study Of Sustainable Cable Ties – research into current eco-alternatives to the standard plastic cable ties that we use to attach coral fragments onto our rebar frames.

Coral Propagation – Monthly Progress

At Landaa during July, we transplanted 36 new coral frames (24 guest-sponsored, 11 Resort-sponsored, one online order) adding a total of 2400 coral fragments onto the reef. We also monitored (cleaned, repaired, photographed) 108 coral frames at various sites around the island.

We are continuing to build our generous guest sponsorship of 50 large frames, adding a further 13 frames this month to give a total of 35 frames at Mudikaashi Reef (an area of degraded reef at the Dive Site). To ensure genetic diversity at this large new site, we have spent time harvesting coral fragments from all around Landaa Giraavaru. So far, we have repopulated this area with 3710 coral fragments, with a further 1590 fragments to go (15 remaining large frames.)

At Kuda Huraa this month, we transplanted 11 new coral frames (nine guest-sponsored, two Resort-sponsored). Additional coral work included monitoring and mapping at the House Reef, and extensive maintenance work in the Channel site by our apprentices.

Our control small-sized coral frames were monitored to estimate survival rates across the sites: 64% survival on average, but only 48% at the Channel site. Corals in the shallow areas of the House Reef and the Turtle site exhibited better health, possibly due to fewer corallivores (such as Crown of Thorns (COTs) and Drupella snails.)

Coral Propagation – Monthly Progress

At Landaa during June, we transplanted 33 new coral frames (17 guest-sponsored, 14 Resort-sponsored, two online orders) using almost 2000 coral fragments. We also monitored (cleaned, repaired, photographed) around 200 existing coral frames at various sites around the island.
We are continuing to build the generous guest sponsorship of 50 large frames. This month, we completed a further nine frames, giving a total of 22 frames out-planted to Mudikaashi Reef (Dive Site). To ensure genetic diversity at the site, we have spent time harvesting more than 2200 coral fragments from all around the island.

At Kuda Huraa this month, we transplanted eight new coral frames (five guest-sponsored, one Resort-sponsored, two online orders) using 500 coral fragments. In addition, we monitored the House Reef site (removing Drupella snails), retransplanted the complete Turtle site, replaced some predated Water Villas corals, and relocated 30 frames buried by the seasonally shifting sands.

Spawning Monitoring

During June at Kuda Huraa, coral eggs were observed in two coral species on frames in the Water Villas and the Blue Hole.

• Acropora latistella – pigmented (orange) eggs found: 8 March, 26 May.
• Acropora digitifera – pigmented (pink) eggs found: 23 May, 26 May, 6 June.
• Acropora digitifera – spawning: 7 May (around new moon); 2 June; 12 June.

We recently analysed our spawning data (2021-2022):

• Gametes observed in 17 different coral species.
• Spawning events recorded in four species (A. secale, A. plantaginea, A. tenuis, Montipora digitata).
• Temperature/tide profiles were charted alongside spawning events, to aid the prediction of future spawning events.

Coral Settlement Update

Our Acropora millepora and Acropora digitifera polyps from March/April 2022 are growing nicely. Regular maintenance includes removing any competition (algae) and keeping the tanks clean.

Tracking Gametogenesis

During June, we observed immature oocytes in A. squarrosa and A. plantaginea. As we near the second coral spawning season here in the Maldives (October/November), it is important we track gametogenesis. Understanding the reproductive biology at a local and regional scale is crucial to uncover how populations maintain fecundity.
Research shows that thermal stress reduces reproductive output of coral species, which in turn could hinder their ability to recover after disturbance. It is crucial we understand the reproductive biology of Acropora species in the Maldives, to better understand life history traits.

Maldives Marine Research Symposium (MMRS)

Our proposals have been accepted by the MMRS, for presentation at their symposium in August. We have been creating infographics and slides to detail our research findings on gametogenesis, embryogenesis, and coral spawning of both wild and frame colonies. This will also include a statistical review of our dataset to identify any similarities or differences between locations on spawning synchronicity.

• Oral presentation: “Methodology for the use of coral larvae settlement ex-situ, for upscaling restoration of the declining Acropora species”.
• Poster presentation: “Observational insight into coral spawning patterns on two Maldivian Reef Ecosystems”.

Six Month A.I. Analysis

To assess growth rates and mortality since last year’s annual review, we reanalysed our coral frame photographs using our bespoke AI software. The volume (in litres) of Acropora and Pocillopora coral species have both increased as follows:

• Acropora volume was 4000L (2021 Q4), now increased to 6000L (2022 Q2)
• Pocillopora volume was at 10,000L (2021 Q4) and is now over 15,000L (2022 Q2)
• Volumes of dead corals appear to have remained steady

Coral Propagation – Monthly Progress

At Landaa during May, we transplanted 14 new coral frames using a total of 542 coral fragments. In addition, we have been busy monitoring (cleaning, repairing, photographing) a total of 846 coral frames across all sites around the island. This month, we also relocated the last of our 300 Moon frames to the Elephant site; we arranged them neatly and mapped their QGIS coordinates.

At Kuda Huraa this month, we transplanted 15 new coral frames using a total of 1153 coral fragments. We spent time repairing some Gulhifalhu rescue colonies that were damaged in a storm brought in by the south-west monsoon (some coral colonies detached from frames and sustained damage). Also this month, we removed 100 Drupella snails from several corals colonies at the House reef, and monitored for predation by fish and Crown of Thorns starfish (COTs).

References
• Boström-Einarsson, L. & Rivera-Posada, J. (2016). Controlling COTs using household vinegar. Coral Reefs 35, 223–228
• Dumas, P., Gereva, S., Moutardier, G., Ham, J., Kaku, R. (2015). Lime juice for COTs outbreaks in Vanuatu. SPC Fisheries Newsletter. 146, 47–52.
• Great Barrier Reef Marine Park Authority (2017). COTs control guidelines. GBRMPA, Townsville.
• Moutardier G, Gereva S, Mills SC, Adjeroud M, Beldade R, Ham J. (2015). Lime Juice and Vinegar to Control COTs. PLoS ONE 10(9): e0137605.
• NOAA Satellite and Information Service. Coral Reef Watch, updated 26 May 22.

We conducted our coral watch assessment during the first week of May. Mature coral colonies are well settled, exhibit good health, and have survived the seasonal temperature peaks. We will continue to monitor the stressed colonies at shallow sites (Water Villas, Turtle) to assess their health and recovery in the coming weeks.

Rescue Coral Health Monitoring

We continue to monitor our Gulhifalhu rescue corals:

• 10% Healthy: no dead or decaying areas since introduction.
• 18% Pale: discolouration due to temperature stress (can transition to bleaching).
• 41% Bleached or fluorescing: due to the loss of symbionts; >20% alive.
• 6% Predated: predation caused decay or death (<80%); caused by Drupella, fish, algae or sand smothering.
• 25% Dead: >80% of total surface.

Kuda Huraa Temperature Profiles

The temperature profiles in our coral propagation sites follow similar patterns to the official NOAA bleaching alerts.

• 22 March to 10 May – average temperatures above 31°C were regularly recorded.
• 26 March – highest recorded temperature of 34.7°C.
• 7 April – highest recorded temperature of 35.5°C.
• 26-27 April – peak coral bleaching period (from field observations across all sites).

Spawning Monitoring

Since October 2021 at Kuda Huraa, we have recorded gametes in 11 coral species, and witnessed spawning events in four different species (A. secale, A. plantaginea, A. tenuis, Montipora digitata).

During May, eggs were observed in three species on coral frames at the Water Villas. Interestingly, frames of A. digitifera that were relocated from the Water Villas to the Starfish site in January did not show signs of spawning. We also did not find any eggs in the Gulhifalhu rescue colonies.

Measuring April Spawned Colonies

This month, we measured the 52 colonies that spawned in April.  Increasing our knowledge on corals and their reproductive biology is important for assessing connectivity of regional coral populations. We hope to determine when corals mature by measuring the spawning colonies (ecological volume using callipers to measure height-length-width).

Coral Settlement Update

In our lab, the settled coral polyps continue to grow well, especially the Acropora plantaginea fertilised and settled in November 2021.

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

• KH01 (Galaxea fascicularis; Acropora species) – removed for cleaning.
• KH02 (Galaxea fascicularis) – good health.
• KH03 (Acropora species) – removed for cleaning.
• KH04 (Acropora species, mushroom coral) – the fragments continue to be healthy.
• KH05 (Galaxea fascicularis) – the fragments continue to be healthy.
• KH06 (Galaxea fascicularis) – the fragments are healthy, fusing and growing.

Coral Propagation – Monthly Progress

At Landaa during April, we added a total of 3300 coral fragments to the reef, transplanted onto 47 new coral frames (sponsored by guests [36], the Resort [8], online [3]). We also monitored 434 coral frames around Landaa Giraavaru, cleaning and repairing them where necessary, and sending out updated photographs to our valued sponsors.

Raft Building and Frame Relocation

During April, we initially relocated 40 frames from our ‘Moon’ site to the ‘Elephant’ site, and then built a custom raft to help transport a further 176 of the larger and heavier coral frames.

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

• KH01 (Galaxea fascicularis; Acropora species) – more new Acropora fragments were added.
• KH02 (Galaxea fascicularis) – the fragments continue to thrive. The plate was rotated two times this month.
• KH03 (Acropora species) – more new Acropora fragments were added.
• KH04 (Acropora species, mushroom coral) – the fragments continue to be healthy.
• KH05 (Galaxea fascicularis) – the fragments continue to be healthy.
• KH06 (Galaxea fascicularis) – the fragments are healthy, fusing and growing.

Coral Propagation – Monthly Progress

At Landaa during March, we used almost 2000 coral fragments to transplant a total of 31 new coral frames (18 guest-sponsored, 11 Resort-sponsored, plus two online orders). In addition, we monitored (cleaned, repaired, photographed) more than 400 coral frames at various sites around Landaa Giraavaru.
We also received a most generous donation that will enable us to make 54 new medium/large frames over the coming months, that will add an impressive 5600 coral fragments onto the reef.

At Kuda Huraa during March, we transplanted nine new coral frames, and recycled two existing frames, using a total of 411 coral fragments from nine different species (mainly Acropora, plus Montipora foliosa).

During the last week of March, we helped with the major rescue of thousands of coral colonies from the large industrial development project at Gulhi Falhu (by the Maldives government). The colonies were divided up as follows:

• transplanted to our existing frames on the House Reef,
• wedged into suitable locations directly onto the natural reef,
• stockpiled on the reef for future transplantation.

• Water Villas (WV) – After the mass frame relocation in January, the 148 remaining frames are recovering and generally healthy overall. We performed some repairs, and the site is now fully mapped, tagged and monitored.
• Sea Star (SS) – The 249 frames recently relocated here exhibit good health, but fish predation continues to be a minor threat. Monitoring, retransplanting, and remapping activities were continued, and all the frames are now fully mapped and monitored. Some frames were retransplanted with ‘fragments of opportunity’ (broken pieces that fall from recently relocated frames).
• House Reef (HR) – the new Gulhi Falhu coral colonies will provide a massive boost in genetic diversity to our reef ecosystem around the island. Within minutes of replenishing an old frame with fresh corals, dozens of fish would arrive… a miraculous sight to behold!
• Channel (CH) – further retransplanting and monitoring; Montipora digitata and Porites cylindrica seem less healthy at this site, perhaps due to the seasonally slow water current (causing increased temperatures and some breakouts of algae). The colonies that survived the last yearly bleaching event will continue to be monitored during the following months.
• Blue Hole (BH) – coral health continues to be exceptionally good. Three additional flat frames were placed here this month and transplanted with some of the new Gulhi Falhu coral colonies. We will monitor these closely for health and possible spawning events.

Coral Spawning Monitoring

At Kuda Huraa this month, coral eggs were recorded in 28 frames (initially transplanted between January 2018 and December 2019) located at the Water villas (0.5m depth) and Starfish (1.5m depth) sites. Egg presence was recorded in six Acropora species (no eggs in Acropora humilis):

• Acropora millepora: many colonies with white eggs.
• Acropora digitifera: many colonies with eggs, which started pigmenting during late March.
• Acropora nasuta: all colonies found with eggs, that started pigmenting during late March.
• Acropora tenuis: a few colonies with immature pale eggs.
• Acropora gemmifera: a few colonies with immature pale eggs.
• Acropora monticulosa: one colony with pigmented eggs.

Coral Spawning Diary

• 8 March onwards – egg maturity was observed in some colonies.
• 18 March – full moon.
• 16-22 March – we carried out night surveys. Monitored colonies were revisited to follow egg development, and on each visit we took photos and recorded: date, time, species, tag number. None of our monitored colonies spawned.
• 18-22 March (around 20:00-22:00h MV time) – we observed ‘coral slick’ (pinkish eggs) floating on the ocean surface at two locations around the island (the sunrise and northern parts) probably from Montipora digitata.
• For more indepth reporting and photos, please see our dedicated report on Spawning Research 2022.

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

• KH01 (Galaxea fascicularis; Acropora species) – new fragments were added to replace several mortalities.
• KH02 (G. fascicularis) – fragments continue to thrive. The largest fragments were removed to make a mini frame that was located at the Water Villas.
• KH03 (Acropora species) – many fragments were lost this month, so the plate will be retransplanted.
• KH04 (Acropora species, mushroom coral) – fragments continue to be healthy. The small mushroom corals have been removed by the resident crabs.
• KH05 (G.fascicularis) – fragments present steady health. The plate continues to accumulate cyanobacteria, which is regularly removed.
• KH06 (G.fascicularis) – fragments continue to be healthy and keep on fusing and growing.

Coral Propagation – Monthly Progress

At Kuda Huraa during February, we transplanted eight new coral frames plus one recycled frame, using a total of 448 coral fragments (from eight different coral species).

• Water Villas (WV) – After the mass frame relocation carried out during January, the 148 remaining frames are either healthy or recovering well from the sand damage. During February, we monitored (repaired, photographed) 39 frames at this site.
  Immature white eggs were spotted in some coral colonies (Acropora hyacinthus, A. digitifera), and we are monitoring for a possible spawning event in the coming weeks.
• Sea Star (SS) – The 249 frames recently relocated next to the Starfish are in good health, but fish predation continues to be a threat. Monitoring, re-transplanting and remapping activities will be resumed.
• House Reef (HR) – This month’s nine new coral frames were deployed at this site; we also removed several Crown of Thorns starfish (COTs).
• Channel (CH) & Blue Hole (BH) – some repair work and monitoring.

At Landaa during February, we transplanted a total of 2250 harvested coral fragments on 41 new coral frames (including a very generous guest donation for 16 frames).

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

• KH01 (Galaxea fascicularis; Acropora species) – some paling and mortality, due to water flow issues.
• KH02 (G. fascicularis) – the fragments continue to thrive. The plate was rotated twice this month.
• KH03 (Acropora species) – some paling and mortality, due to water flow issues.
• KH04 (Acropora species, mushroom coral) – the fragments continue to be healthy, although the small mushroom corals have been moved again by the resident crabs.
• KH05 (G.fascicularis) – fragments continue to be healthy. We regularly clean accumulating cyanobacteria (and small sponges).
• KH06 (G.fascicularis) – fragments continue to be healthy.

Coral Propagation – Monthly Progress

At Landaa during January, we transplanted 20 new coral frames (11 Resort-sponsored, nine guest-sponsored) and monitored (cleaned, repaired, photographed) 266 existing frames. We used 1164 individual coral fragments for our new frames, plus 2130 fragments for repairs and recycling work, totalling 3294 fragments for the month.

• Yin Yang site – we relocated all 31 frames to the Moon site, repairing and retransplanting as we went along.
• Moon site – retagged, repaired and recycled 37 old frames.
• Bissie’s Reef on the Coral Trail – repaired and recycled all 15 coral frames (at 10-12m depth).

Coral Spawning Database

Our new coral spawning database was created and shared among the team, to document our observations of gametes throughout the year. We will use standardised methods to collect observational information, including consistent categorisation of egg colouration (white, pale, pigmented).
We have also started work on a research paper and plan to submit for publication later in the year (after the March/April spawning event).

During January at Landaa, we observed white eggs in three species of both wild and frame colonies (A. nasuta, A. digitifera, A. millepora) and one frame colony with pigmented A. valida eggs.

• 22 January – white eggs in Acropora digitifera on a Water Villas frame at Kuda Huraa.
• 27 January – white eggs in Acropora nasuta (frame KH2444) and A. digitifera (KH2555), Kuda Huraa.

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

• KH01 (Galaxea fascicularis; Acropora species) – since September, the fragments continue to grow. New fragments were added due to removal by resident crabs.
• KH02 (G. fascicularis) – most fragments are healthy and growing. The plate was rotated twice this month.
• KH03 (Acropora species, replenished Oct-Dec 2021) – fragments continue to grow apically, and are encrusting well.
• KH04 (Acropora species, mushroom coral; replenished Oct-Nov 2021) – overall healthy, with increased growth.
• KH05 (G.fascicularis) – steady health; cyanobacterial growth is regularly removed.
• KH06 (G.fascicularis) – healthy, fusing and growing.