Fish Lab & Marine Aquaria

Fish Lab clownfish breeding Maldives

Clownfish Breeding

  • Clark’s clownfish (Amphiprion clarkii) – we have had good success with our hatchlings, and now have 49 healthy juveniles in our display tank.
  • Maldivian clownfish (Amphiprion nigripes) – several egg batches but no hatchlings this month. We have 12 juveniles ready for release onto the natural reef.
  • Common clownfish (Amphirion oscellaris) – several egg batches but no hatchlings this month. Our 3 juveniles continue to grow.

We continue to maintain levels of Artemia to feed our Clownfish juveniles and inhabitants of the main aquarium. Rotifer production has been reduced, and we have performed deep cleaning on the equipment. During the global lock-down, we have been reviewing all of our operations and have implemented various changes to scale back and lower running costs:

  • the water pump rate for our tanks has been reduced from 38mᶟ/hr to 20mᶟ/hr;
  • breeding tanks #1-20 have been emptied, and our Clownfish rehoused in tanks #21-35;
  • various marine specimens have been relocated to the large aquarium;
  • we have drained our interactive touch tank and released the marine inhabitants;
  • the sand filter back-wash procedure is now performed every other day;
  • we are cross-training extra staff to keep things running smoothly.
Fish Lab clownfish breeding tanks Maldives
Fish Lab clownfish breeding juveniles Maldives

Small Aquarium One

Increased water temperatures have increased the growth of algae and caused bleaching in the mini-frame Acropora coral fragments; 17 fragments have encrusted, 1 fragment is bleached, 7 fragments are dead. We have also transplanted a new mini coral frame (KH06) with Galaxea fascicularis coral fragments, which is doing well so far.

Small Aquarium Two

The mini coral frame has 19 fragments; most are now encrusting, but 12 are bleaching and 7 are paling.

The Clark’s anemonefish (Amphiprion clarkia) breeding pair have laid 3 egg clutches this month, and we continue to study egg development under the microscope.

One new addition is a partially-bleached colony of Acropora microphthalma that we rescued from the lagoon. We will monitor this colony and hopefully follow its recovery process. The coral also came with some hitch-hikers… three furry coral crabs! [photo]

Aquarium-2 Acropora microphthalma and furry coral crab

Moon Jellyfish (Aurelia aurita)

Sadly, our Moon jellyfish have all fallen victim to the increased water temperatures and reduced water flow this month. We had previously seen that jellyfish are very sensitive to adverse environmental changes.

Our jelly fish polyps, however, have shown a marked improvement. We relocated the Kreisel tank into the Fish Lab to provide better air temperatures, and have increased the feed to 500ml of S-Presso enriched artemia (day 2). This has improved the number and condition of the polyps, with a healthy orange hue and widespread attachment.

Large Aquarium

The reduced water flow (to lower running costs) has affected our large marine aquarium. The resulting lower oxygen levels and seasonally warmer water temperatures have combined to prove fatal to many of our marine inhabitants. We have replaced some of the lost herbivores, but the resultant algal overgrowth will take some time to restabilise.

  • Zebra dart goby (Ptereleotris zebra) – reach a size of 12cm. They are fast active fish, that stay close to their hiding spot for if they feel threatened by larger individuals.
  • Yellow tail basslet (Pseudanthias evansi) – schooling fish usually found in the upper edge of drop-offs. They feed near the surface, away from the reef and are easily overlooked due to their size and colour.
  • Clark’s anemonefish (Amphiprion clarkii) – added from our breeding stock. It took a few days for the pair to become comfortable in their anemone.

The mini-frame coral fragments have started to grow and encrust, although there are signs of bleaching due to the warmer waters (monthly average of 31°C). To reduce the tank temperature, we have started experimenting with the introduction of ice during the morning (the air conditioning cools in the evening).

The following specimens have been relocated to our large aquarium:

  • Banded Coral Shrimp – where it might provide a ‘cleaning station’ to the fish inhabitants.
  • Juvenile Rock Lobster – very healthy and continuing to grow at a good rate (2 moults in April).
Aquarium marine Maldives

Linckia multifora sea stars

  • SS1 (large specimen) – some of the arms have decreased in length, while others have increased (the total size of all arms, however, remains the same).
  • SS3 (large specimen) – average increase in arm length of 1.2mm (one arm has decreased in length). Interestingly this month, the sea star has self-amputated; autotomy is a form of asexual reproduction where the arm can grow into a new individual.
  • SS4 (automised arm) – thought to be hiding somewhere in the tank.

REEFSCAPERS Coral Propagation Program

Coral Reef Transplanting

The NOAA bleaching heat stress projections for Maldives are categorised as “Warning” for April, rising to “Alert level 1” in May. 

At Kuda Huraa during April, 416 frames were monitored around the island, involving cleaning, repairing and photographing each one. We also re-positioned all 500 frames at the Water Villas site, to give extra shade under the boardwalks to reduce the sunlight intensity during the upcoming period of elevated ocean temperatures.

At Landaa, we transplanted just 4 new coral frames this month, due to the seasonally elevated ocean temperatures (newly transplanted frames are particularly at risk of bleaching).

Check out our 2020 Diary for further details.

Reefscapers ocean temperatures house reef Maldives

Average ocean temperatures on our House Reef, March-April 2020

Our Reef-Monitoring AI Catamaran

After more than a year of work on our artificial intelligence project, we have now reached a major goal … our program has successfully analysed several complete frames!

The software was able to automatically identify the correct coral species, which was recorded along with the size of the colony. We now plan to analyse the whole database, which could take up to a month of PC processing time!

Read our in-depth development journal at Reefscapers for the full story, along with more photos and video.

Coral Reproduction Spawning Experiment

Yaniu Rauf, our Four Seasons Apprentice, graduated this month. He was in charge of our Coral Reproduction Project, and presented his experimental work to a panel of judges.

Continued monitoring revealed the coral colonies had recovered from bleaching, helped by actively feeding them with rotifers as an alternative food source.

Being unable to photosynthesise during bleaching, the polyps survived and reincorporated zooxanthellae inside their tissues.

Sea Turtle Conservation

At the close of April, our turtle rehabilitation centre at Kuda Huraa was home to: 1 Green turtle (Chelonia mydas), 5 Hawksbills (Eretmochelys imbricata) and 7 Olive Ridley turtles (Lepidochelys olivacea).

At Landaa, we closed the month with 7 Olive Ridley turtle residents.

  • Asha – was soon able to dive down and feed from the bottom of her recovery  pool.
  • Chomper – our long-term patient showed great improvements out in our lagoon enclosure.
  • Macau – all of her wounds healed quickly, and she was released directly from the sea turtle enclosure.
  • Aisha – soon able to dive and rest/feed from the bottom. She was released to mark the 50th anniversary of Earth Day (22 April).

Sea Turtle Enclosure

Two of our turtles (Chomper and Macau) showed great improvements whilst rehabilitating in our sea turtle enclosure out in the lagoon at Landaa, and were released directly from the enclosure’s platform. The extra freedom and space offered by the net was a great help in improving their swimming skills, regaining the ability to dive, overcoming buoyancy syndrome and being able to rest on the bottom of the netting.

Read more about the setup, use and maintenance of our unique rehabilitation enclosure.

Maldivian Sea Turtle Identification Program

Turtle photographs are kindly sent to us from members of the public, fellow marine biologists and dive centres stationed at other resorts around 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.

During April, we received 10 photo submissions from the public, taken at various sites around the Maldives … a big thank you to everyone! 🙂

Our current database now contains 4700+ recorded sightings, from which we have confirmed the unique identification profiles for the following numbers of individual sea turtles in the Maldives: 1258 Hawksbills, 217 Greens and 95 Olive Ridleys.

Spotted a turtle?  Share your photos

Turtle identification Maldives (CM214)

Green turtle #CM214, from our ID database of Maldivian turtles

Reefscapers coral frames – Kuda Huraa water villa flower site

Further News & Updates

You might also be interested in our Dolphin ID Project, and our Sea Turtle Enclosure out in the lagoon at Landaa.

Looking for details of our coral propagation programme ?

Head over to our Reefscapers 2020 Diary for all the latest updates.

You can sponsor your own dedicated Coral Frame, and then see how it grows in the future by viewing the photo updates every 6 months, as part of our Coral Frame Collection.

Photos: (1) Reefscapers coral frames at Kuda Huraa water villas.
(2) Junior Marine Savers learn the importance of corals.

junior Marine Savers at Kuda Huraa

Our Unreleasable Turtle Residents

Our Current Turtle Patients

Our Turtle Hatchling Patients

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