Corals (Montipora) thriving in shallow warm waters Maldives

Corals (Montipora) thriving in shallow warm waters (Kuda Huraa, Maldives)

Fish Lab & Aquaria – Marine Life in the Maldives

Following last month’s remodelling, all our new fish specimens have settled in well. This month, we added a second combtooth blenny (E. bicolor) to hopefully make a pair. We also found a pair of saddled toby pufferfish (C. valentini) and we have already observed mating behaviours. The female was seen with a swollen abdomen and underwent a characteristic colour change (blue tinge on the head and back), followed by spawning.

The Main Aquarium

We added a new Goniopora coral to our “goni garden” in the main tank, and performed some minor landscaping.

Plankton Production

  • Algae – consistently cycling at full volume
  • Artemia – production is keeping up with the demand of the main tank at 5g of cysts a day, with one 100L algae tub containing nauplii for grow-out
  • Rotifer – volume maintains a consistent level

Jellyfish – Aurelia aurita

All jellyfish in our main Kreisel display tank continue to thrive, with no signs of damage or shrinking. We cleaned the large cylinder tank at the end of April (quarterly clean), and all jellyfish were removed and returned to the tank with no mortalities. On 24 April, we started a new strobilation for our moon jellyfish, which is expected to start producing results around 11 May.

Zooplankton Survey Study

This month, we welcomed our first Trainee Planktologists, who conducted tows and sampling around the house reef lagoon as part of our Zooplankton Survey . Many interesting specimens were collected, including abundant barnacle nauplii, likely from the spawning activities of the barnacles under the jetty. Our trainees were very interested and enthusiastic, going on to produce media materials and starting a school project.

Junior planktologists at Landaa Giraavaru Maldives

Trainee planktologists, measuring …

Junior planktologists at Landaa Giraavaru Maldives

… collecting plankton samples …

Junior planktologists at Landaa Giraavaru Maldives

… with Helen, our marine aquarist

Megafauna and Marine Life

At Landaa this month, we welcomed a total of 58 visitors to our ever-popular Marine Discovery Immersion Tour, and a total of 255 guests enjoyed 38 accompanied marine excursions (mainly Dolphin Cruise, Guided Adventure Snorkel, and Turtle Safari).

With high Resort occupancy over Easter plus our active coral monitoring project, the whole team has been spending much more time underwater, bringing increased sightings of megafauna species. Swimming on the reef this month, we recorded many rays, green & hawksbill turtles, and sharks (especially grey reef sharks, Carcharhinus amblyrhynchos), as well as a handsome school of over ten bumphead parrotfish (Bolbometopon muricatum).

Fish lab - barnacle nauplius

Barnacle nauplius – scooped up by our  Trainee Planktologists for microscopic identification in our Fish Lab zooplankton project

Dolphin ID Maldives

Dolphin ID project – we photograph all the cetaceans we encounter, to analyse the shape of their fins for unique identification

Ornamental Shrimp Breeding

We have scaled back our fish-breeding to expand our more successful research on shrimp-breeding. Our focus is to produce replicable and consistent data for our research paper on Thor amboinensis, and to continue tracking and describing the reproductive cycle of Lysmata amboinensis.

  • Sexy shrimp (Thor amboinensis) – Our March larvae are showing consistent success for both rearing and settlement, with survival averaging 26%. A total of 293 larvae will be the final clutch that we collect for our current research paper (to be completed in May).
    On 4 April, our brooding captive-bred female’s eggs successfully hatched, producing our first batch of second-generation larvae. These F2 larvae have been reared under the same protocols as their parents, yielding higher rates of survival (68%) and growth, showing great promise for further study.
  • Boxer shrimp (Stenopus hispidus) – At the beginning of the month, we sourced a new pair with brooding eggs, that went on to hatch on 16 April. So far, they have proven to be more viable than our previous larvae, with a high number surviving to late stages. The pair has already spawned again.
  • Camel shrimp (Rhynchocinetes durbanensis) – We observed at total of eight clutches produced this month from our three breeding females, with no collection due to demands from other species.
  • Skunk cleaner shrimp (Lysmata amboinensis) – We continue to observe this species though no attempts to collect were made. We are completing our data analysis and writeup.
  • Marbled shrimp (Saron marmoratus) – Continue to grow and develop well, although there was die-off at the two-week mark.
Fish Lab - sexy shrimp larvae in egg Marine Savers Maldives

Development of larvae in Sexy shrimp eggs (T. amboinensis)

Fish Lab shrimp development R.durbanensis swimmerets

Development of swimmerets in Camel shrimp (R. durbanensis )

Fish lab Boxer shrimp larva development (Stenopus hispidus)

Boxer shrimp larva
(Stenopus hispidus)

Fish Lab sexy shrimp (T. amboinensis adult female)

Sexy shrimp (Thor amboinensis) adult female

Maldives Sea Turtle Rescue & Rehabilitation

At the close of April, we were caring for 3 Olive Ridleys (Lepidochelys olivacea), 1 Hawksbill (Eretmochelys imbricata), and zero Green sea turtles (Chelonia mydas) in our Rehabilitation Centre at Landaa.

At Kuda Huraa, ‘Image-J’ analysis has been used to determine the levels of buoyancy in our patients Burrita and Seakid. Initial results analysing above-water surface areas of the carapaces suggests that over the course of the month, both turtles showed a significant improvement (reduced surface areas, as the turtles now sit lower in the water).

Our long-term turtle patient, Ari has been fussy with her food this month, and is now refusing to eat both squid and prawns. She is visibly low on energy, and has been interacting less with visiting guests. We will be giving her more swims out in the lagoon, and will introduce more environmental enrichment toys.

Meanwhile, Emma has made great progress with her diving, and is now often found on the bottom of her tank. She loves resting in her crate-cave with her head sticking out, much to the amusement of guests. Usage of her left flipper has been increasing, and she is now able to successfully hunt live crabs, so hopefully she will soon be fit for release.

Ocean pen

This month, we inspected and maintained our large turtle enclosure out in the lagoon, removing coral growth and marine organisms, and repairing several small holes that had developed in the netting.

Michelangela turtle with satellite tag Maldives

Michelangela with satellite tag

Turtle buoyancy analysis Image-J

Turtle buoyancy analysis using Image-J software

Updates on Our January Admissions

  • Xanchi – most wounds have now healed, and his fore-flipper laceration is healing well, but it is swollen and he is not yet using it. We have started a course of antibiotics that we hope will reduce the swelling; once Dr Kat gives the all-clear, Xanchi will spend a short period in our ocean enclosure prior to release.
  • Seakid – moved to a bigger tank, and he can now reach the bottom to feed, however, he still floats back to the surface. As soon as he can rest on the bottom, he should be ready for release.
  • Burrita – is making good progress with her diving and can reach the bottom of her tank for food, however, she has restricted movement in her right front flipper. She continues to have high energy levels and is a favourite with guests as she likes to splash everyone during her feeding time!
  • Michelangela – was successfully released on 4 April after 75 days of TLC at our Centre, and a healthy weight gain of 1.9kg. She was released on a Dolphin Cruise out in the open ocean, and waved on her journey by 20 enthusiastic guests. Two days earlier, Michelangela had been fitted with a satellite tag that had been secured and tested, but unfortunately the signal was lost shortly after release. She travelled 1500m to a final known location close to the island of Girifushi. We think the tag may have malfunctioned or fallen off.
Olive ridley turtle rescue EMMA Maldives

Olive ridley turtle EMMA

Olive ridley turtle rescue Maldives BURRITA

Olive ridley turtle BURRITA

Olive ridley turtle rescue SEAKID Maldives

Olive ridley turtle SEAKID

Sex Determination of Sea Turtle Hatchlings

This month, we were pleased to receive photo ID submissions for two male turtles (one green, one hawksbill), and both were found to be new additions to our database. In recent years, we have been recording sightings of fewer numbers of males, and we think this might be due to increasing global temperatures.

Unusually, the sex of most species of turtles (and some other reptiles) is determined after fertilisation. It is the temperature of the incubating eggs that establishes whether the hatchlings will be male or female (warmer sand produces more females).

  • Incubation <27.7°C, the turtle hatchlings will be male.
  • Incubation >31°C, the hatchlings will be female.
  • Variable temperatures produce a mix of both male and female hatchlings.

As the Earth experiences climate change, increased temperatures will likely result in fewer male turtle hatchlings, which could be devastating for the future survival of sea turtles.

Sea Turtle Nest Protection

  • Nest #2 (laid 27 January) – we waited for eight days after the predicted hatching date, but after no visible activity we decided to excavate on 4 April. Unfortunately, out of 81 eggs laid, only one showed significant signs of development, likely because of flooding by the high tide.
  • Nest #3 – the hatchlings emerged right on schedule on 6 April (exactly two months after laying). Afterwards, we excavated the empty nest as standard procedure, to happily discover a hatching success rate of 94% out of 96 eggs.
    – Three hatchlings were discovered alive inside the nest and were released
    – Three hatchlings were found dead in the nest
    – Six unsuccessful eggs.
    The top of the 10cm deep egg chamber was at a good depth of 72cm below the surface, and the location near tree roots would have increased water drainage.
  • Nest #4 – surprised us all by not only hatching at midday, but also after just 56 days (on 14 April). The subsequent excavation revealed two live hatchlings at the bottom of the nest, which were released to give a hatching success rate of 89% (97 hatchlings out of 109 eggs laid). The remaining eggs were either completely undeveloped, or contained underdeveloped/malformed embryos.
  • Nests #5 & #6 – expected to hatch during May, so we have deployed our remote monitoring camera, and we will soon start nightly in-person checks.
Green turtle hatchlings Maldives
Green turtle hatchlings Maldives
Green turtle hatchlings Maldives

Maldivian Sea Turtle Identification Program

During April, from the 29 new photo sets submitted by the public this month, we were able to add 6 new individuals to our national turtle database, and confirmed resightings of 9 named turtles already in our database.

Our current database now has uniquely identified totals of:
1411 Hawksbills, 305 Greens and 97 Olive Ridleys (from 5500+ separate sightings, across 17 different atolls of the Maldives).

Submissions consist of close-up photographs of the turtle facial profile, enabling us to outline the unique pattern of scales (scutes) that act like a human fingerprint.

Spotted a turtle?  Share your photos

Turtle ID Maldives - unique facial scales
Turtle ID safari wild hawksbills (Milkshake, Onchao)

Photo shows ‘Milkshake’ EI1357 (left) interacting with ‘Onchao’ EI1248 (at Makunudhoo Reef, photographed on Turtle Safari)

REEFSCAPERS Coral Propagation & Reef Restoration in the Maldives

Reefscapers coral spawning monitoring

Observing coral spawning on our Reefscapers artificial reefs

Monthly Progress

At Landaa during March, we transplanted 38 new coral frames, kindly sponsored by guests (23), the Resort (12), and online orders (3), using a total of ~2100 new coral fragments. In addition, we monitored (cleaned, repaired, photographed) a total of 600 coral frames at various sites around Landaa Giraavaru. We have also lifted a total of 78 buried frames out of the sand at various sites, and repopulated with new fragments where necessary.

To celebrate Earth Day (22 April) the Resort sponsored a commemorative coral frame, which was built by guests and staff. A big thank you to everyone who came to participate and support the event. 🙏

At Kuda Huraa, we transplanted 7 new guest coral frames, kindly sponsored by guests (2), the Resort (2), and online orders (3). We also monitored (and mapped) a total of 182 existing frames (mainly at the House Reef site). In addition, we relocated 108 frames at the Water Villas site to provide the coral with shading and reduce stresses over the warmest period of the year.

Reefscapers checking for coral spawning Maldives

Monitoring for signs of coral spawning on our Reefsapers coral frames.
Outside our Marine Discovery Centre, Landaa.

Reefscapers healthy corals Maldives

Healthy corals thriving in shallow waters

Coral Bleaching Study

Here in the Maldives, we are currently in the high ocean temperature season (March to May), so our team is actively monitoring for signs of coral stress, paling and coral bleaching. Our bi-weekly surveys of five sites around Kuda Huraa are monitoring 300 coral colonies (135 coral frames, nine coral species).

This month, we conducted 20 hours of bleaching monitoring (two dives and nine snorkels), and our results so far show 17% colonies are paling and 1% are bleached, with the shallow Water Villas site currently most impacted by the warmer ocean temperatures.

Addu Coral Festival

Members of our team attended the 2023 ‘Coral Festival’ on S. Hithadhoo from 27-30 April (organised by the Maldives Coral Institute). Our Reefscapers stall was visited by global government representatives, NGOs, charities, international conservationists, and many interested members of the public from nearby local islands. It was an ideal platform to showcase the full range of our work to fellow marine biologists and passionate conservationists.

On the second evening, our 2023 coral spawning documentary (embedded below) was screened, alongside videos from the Manta Trust and the recent Nekton deep sea expedition. Throughout, our team attended various lectures, including:

  • keynote presentations by prominent coral scientists Prof Callum Roberts and Prof Madeline Van Oppen
  • workshops on artificial intelligence in ocean science
  • panel discussions on coral restoration and conservation

Monitoring for Coral Gametes and Observing the April Mass Coral Spawning Event

Over several nights at Landaa, we observed multi-specific spawning in 100+ coral colonies (from 8 different species) at various times after sunset, and we successfully collected gametes for ex-situ fertilisation and settlement.

At Kuda Huraa, we conducted 22 hours of coral monitoring across three sites around the island (thanks to our colleagues at Tropicsurf for their valuable assistance 🙏 ). We observed spawning in 130+ coral colonies, and collected data on 139 colonies (9 species).

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.

Junior Marine Savers activities

Further News & Updates

You might also be interested in:
– our ongoing Dolphin ID Project, our specialised Sea Turtle Lagoon Enclosure, and our Zooplankton Monitoring Project.

Looking for details of our Reefscapers coral propagation and reef restoration program ? Then head over to our Reefscapers Diaries for all the latest updates.

You can sponsor your own frame and see photographs (updated every 6 months) in our Coral Frame Collection.

Junior Marine Savers activities: (1) Reefscapers corals, (2) turtle care.

Junior Marine Savers children turtle care Maldives