REEFSCAPERS Coral Propagation & Reef Restoration in the Maldives

Monthly Progress

During October, we transplanted 27 new sponsored coral frames around both resorts, using ~2,000 harvested coral fragments for our transplanting and maintenance work.

Coral Spawning Event, October 2021

An initial sign that coral colonies are ready to spawn is the presence of gametes within the coral tissue, that look like tiny white eggs initially, which then grow in size and develop colouration (pink/orange).
On 19 October at Landaa Giraavru, we first spotted eggs within various Acropora species of corals.
26 October – A synchronised spawning event took place at 19:57, involving many coral species, and lasting 20 to 30 minutes. The gamete bundles float to the surface and we were able to collect them using custom-made egg collection devices.

On 27 October at Kuda Huraa, we observed coral spawning occurring from 20:00 to 20:15 (Maldives time, GMT+5). We successfully harvested some eggs, and placed them into our aquarium for observation, along with a dead coral skeleton as a settlement substrate. Some eggs became attached by 20:45 (30 mins after spawning) but we did not see coral larvae.
From our notes, we observed this spawning event occurred:
– 1.5 hours before the lowest tide (which was at 21:42);
– Seven days after the full moon (which was on 20 October);
– One day later than in Landaa Giraavaru (Baa Atoll).

Coral Spawning Workshop

This month, we took part in the second series of a two-day online coral larvae workshop in partnership with CSIRO, the MMRI and MUI (among others) to further understand and identify coral spawning events across the Maldives. This informative workshop detailed the use of coral larvae in reef restoration, to upscale future efforts. It is evident that sexual propagation will result in higher genetic diversity amongst species in comparison to asexual propagation. Moreover, corals are extremely fecund, meaning a large number of juvenile corals could be produced if mortality at early life stages of fertilisation and settlement are reduced. This technique could enhance coral propagation programs here in the Maldives, if the asexual technique is coupled with sexual broadcast spawning and rearing.

At Marine Savers, we have transplanted and grown many different species of corals over the years which are large enough to produce mature spawning colonies. Our large database allows us to pinpoint transplantation dates, identify age of maturity, track mature colonies, and record coral spawning across multiple years. This data can be used to ensure genetic diversity, as we can confirm gamete collections from different frames based on these dates.

To expand our knowledge of coral spawning around Landaa Giraavaru, we reviewed the data from our previously documented spawning events (2013 – 2020). It is incredibly difficult to predict when coral might spawn, therefore it is important to take note of tidal cycles, lunar cycles, and water temperatures from previous years, to be utilised as indicators for predicting spawning this year.

Sea Turtle Rescue & Conservation

Sea Turtle Rehabilitation

At the close of October, we were caring for 3 Olive Ridley turtles (Lepidochelys olivacea) and 1 Hawksbill (Eretmochelys imbricata) in our Rehabilitation Centre at Landaa. At Kuda Huraa, our turtle patients include 2 rescued Olive Ridleys, plus our rehabilitating juveniles: 4 Green turtles (Chelonia mydas) and 2 Hawksbills.

Flying Turtles

During October, we finalised details with our overseas partners to send our unreleasable Olive Ridley patient, ‘April’ to a new permanent aquarium home, with departure planned for 19 November. Ale, our turtle expert and Marine Discovery Centre Manager, will be accompanying April on her journey, along with staff from the aquarium.