Fish Lab & Aquaria – Marine Life in the Maldives

Squid night snorkel Maldives marine life

Squid, spotted on a night snorkel

We welcomed some new fish larvae this month, from around the island of Goidhoo, including Indian humbugs (Dascyllus carneus) and three-spot humbugs (Dascyllus trimaculatus). They are currently feeding on Artemia in our Fish Lab, as we hope to grow them out.

Plankton Production – Our plankton and algae cultures are used as the main food source for the residents of our Fish Lab.

– Algae800L have been produced this month to feed the juvenile fish and shrimps produced in the breeding program, and for growing brine shrimp to adult size. Populations are stable.
– Rotifers – population increased to 884 individuals/mL average, much above our average target of 300 ind/mL.
– Artemiaincreased from 7g to 7.5g of cysts a day, to accommodate our growing population of moon jellyfish (Aurelia aurita), fish and shrimps. As the amount of Artemia increased, we switched to larger flasks and 5L bottles.
– Copepods – our late March culture failed due to low temperatures inside the Fish Lab, so we collected new individuals from the dancing shrimp tank in which they were thriving. They were added to two 15L Kreisel tanks, with a heater to maintain temperatures. So far, the culture is flourishing, with visible nauplii larvae. In addition, we have also spotted unicellular ciliates (Euplotes) growing inside the tank; they can cohabit with the copepods, as an alternative live food source for fish larvae.

Jellyfish – Aurelia aurita

A further 60 jellyfish were moved from the grow-out Kreisel tank to our large cylinder display tank, which now totals 290 individuals. As some jellyfish have shown recent decreases in size, we have increased Artemia food from 350mL to 400mL per meal, to keep up with the increased demand. Brine shrimp volume will be updated as jellyfish population inside the large cylinder tank increases, and will be monitored to avoid shrinkage.

Groupers

The food source for our grow-out groupers has changed from tuna (kitchen) to reef fish (fishermen). We tried finely-cut mackerel initially, but the lengthy prep time was impractical so we switched to fusiliers and have started to see positive results. As all internal organs are now being provided, groupers are now receiving more nutrients, thus becoming healthier and improving their immune system.

Sea Urchins – New Project 2024

Sea urchins are often collected for food around the world. Some countries have over-harvested from the wild, so we launched our new echinoculture project to investigate methods of breeding the collector urchin (Tripneustes gratilla), chosen for its small spines.

One sea urchin sadly died from ‘bald patch disease’, a common condition characterised by a patch uncovered by spines (pedicellarie). Thanks to a quick diagnosis and subsequent quarantine, our remaining urchin population is doing great, and being fed regularly with carrots and various kitchen vegetables.

Ornamental Fish & Shrimp Breeding

Dancing shrimp (Thor amboinensis) – Ten individuals from our December batch were placed in the main tank close to the soft corals for shelter. Two remaining batches are growing well despite some losses, with daily water changes and tank cleaning.

Boxer shrimp (Stenopus hispidus) – Our batch from March has died, but a new batch of 400 larvae was born on 10 April. The whole batch was placed in a Fish Lab tank (with water-flow but without air-flow) but unfortunately soon died. We are developing a new rearing system (inverted pyramid) to avoid shrimp sinking down to the bottom of the tank.

Mantis shrimp (Stomatopoda) – spotted in our lagoon turtle enclosure, we brought the small new specimen back to a Fish Lab tank, with a sand and rock substrate.

Clark’s anemonefish (Amphiprion clarkii) – The overall population is still growing steadily. Two batches of eggs were produced (but not collected due to space limitations). Our January batch of juveniles is thriving together, and we have donated some individuals to a research team studying fish larvae ecology (researching techniques to determine the age of fish using environmental DNA). [Lifecycle graphic]

Fish Lab diamondback squid egg development D1-3

Fish Lab: development of diamondback squid egg (day 1-3)

Megafauna and Marine Life

At Kuda Huraa, 285 guests joined us on 41 guided excursions, with dolphin-spotting and turtle safaris being the most popular.

At Landaa, we welcomed 97 guests for a tour of our Marine Discovery Centre, plus a large corporate group who enjoyed transplanting coral frames at Voavah.
Sightings of megafauna were up, including many hawksbill turtles (Eretmochelys imbricata) encountered on our guided snorkel trips, plus regular sightings of blacktip reef sharks (Carcharhinus melanopterus), nurse sharks (Ginglymostoma cirratum) and cowtail rays (Pastinachus sephen), along with occasional encounters with grey reef sharks (Carcharhinus amblyrhyncos), pink whiprays (Himantura rai) and spotted eagle rays (Aetobatus narinari).

Eagle ray Maldives marine life

A majestic eagle ray, spotted off the house reef at Kuda Huraa

Maldives Sea Turtle Rescue & Rehabilitation

turtle heads - our inpatients

Turtle Rescue & Rehabilitation

Sadly, we are currently at carrying-capacity at both of our turtle rescue centres. The almost weekly sightings of injured and entangled sea turtles floating on the ocean surface has thankfully come to an end, but most our resident patients have severe and long-lasting injuries.

Oekaashi is an adult female Olive Ridley turtle that was admitted to our turtle rescue centre after suffering from a severe blunt-force trauma to the front of her carapace, perhaps from a boat strike. We are pleased to see that the crack in her carapace is slowy healing.

Gina arived in very poor health, suffering from various injuries and requiring a flipper amputation. Thanks to some intensive treatments and non-stop care from our resident turtle veterinarian, her wounds are slowly and steadily healing.

Thari is suffering from a common ailment in rescued turtles, “bouyancy syndrome” – meaning she is unable to dive below the water surface for any length of time. She cannot be released back into the ocean in this state, so we are experimenting with weights attached to her carapace, to aid diving (photos below).

Read more turtle stories by clicking on the collage above, or scroll down to the photo ‘corkboard’ of individual turtles.

THARI turtle rescue & rehab Maldives
THARI turtle rehabilitation Maldives

Maldivian Sea Turtle Identification Program

During April, our ID project is currently on hold as we have been busy with record numbers of rescued turtle patients, and are currently at full capacity.

Spotted a turtle?  Share your photos

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.

Turtle ID Maldives - unique facial scales

REEFSCAPERS Coral Propagation & Reef Restoration in the Maldives

Reefscapers relocating vulnerable corals Maldives

Monthly Update Summary

At Kuda Huraa this month, we transplanted 5 new coral frames, and monitored a further 90 mature frames at various sites around the island. As part of our bleaching mitigation work, we relocated a total of 130 frames.

At Landaa this month, we transplanted 41 coral frames, kindly sponsored by guests (29), the Resort (10), and online (2), adding more than 2000 coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 855 established coral frames at various sites around Landaa and Voavah.

A total of 20 frames (10 small, 10 medium) were sponsored by a group staying at Landaa, and built in a single day as part of an event held at Voavah. The group engaged enthusiastically with the activity, and we were delighted to see the Voavah reef looking healthy at the time of fragment collection.

Reefscapers relocating vulnerable corals Maldives

Preparing for the Coral Bleaching Season

The ‘summer’ hot season in the Maldives runs from January to May, with March and April being particularly hot and dry. The extra hours of seasonal sunshine, combined with the current elevated global sea surface temperatures (SSTs) cause increased stresses on coral reefs (April-June), which can lead to temporary paling of the coral colonies, or even permanent coral bleaching and death.
Global climatologists are forecasting 2024 to be exceptionally hot, due to a combination of the cyclical El Niño event and the ever-increasing effects of anthropogenic climate change. Over on our Reefscapers
Climate Change page, we are following developments very closely by curating the news reports from climate experts and marine scientists worldwide.

We have been tracking NOAA’s Coral Reef Watch bleaching forecast, and the Maldives will soon move into “Alert Level 1” meaning “severe bleaching and mortality” is expected.
In March, we observed moderate paling in some colonies along Landaa’s natural House Reef, as the corals started to lose their characteristic colour. Towards the end of April, bleaching and fluorescence (caused by heat stress) has been observed at all sites across Landaa, at depths from 1m-15m.

Bleached corals Maldives Reefscapers

Corals bleaching and fluorescing under heat stress

Bleached corals Maldives Reefscapers

Acropora digitifera colony, before/after bleaching
Photographed: 🗓️ 4 March / 29 April 🗓️

At Kuda Huraa, we have continued our ambitious project of relocating 260 established frames to deeper, cooler waters. We moved 120 frames in March, and have moved a further 115 frames this month, mainly using our floating barge. Given the large work load, we were pleased to be ably assisted by Reefscapers founders Thomas & Marie, who joined Aku from Landaa to help with the relocation efforts.

Our project has even caught the attention of BBC TV producers! A documentary camera crew joined us under the waves to film our work, (photos below) which should make for some dramatic documentary footage. Coming soon, to a TV screen near you! 📺 

Reefscapers Maldives BBC coral film

Working on our bleaching Reefscapers coral frames …

Reefscapers Maldives BBC coral film

… under the watchful gaze of a BBC film crew

Coral Spawning

This month, our Reefscapers coral teams scheduled nightly snorkels around the periods of both the New Moon (8 April) and Full Moon (23 April). We looked for coral colonies with pigmented mature gametes, indicating imminent spawning. Our patience and perseverence paid off, and we were able to successfully observe and document spawning events in over 100 coral colonies (across 10 different species).

See our extensive spawning research (button below) and our Reefscapers News for further details and photographs.

Reefscapers coral spawning Maldives (April 2024)

Healthy corals spawning

Reefscapers coral spawning when bleached

Bleached corals spawning

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