Fish Lab grouper grow out tanks [LG 2026.05] [1920]

Fish Lab, Aquaria, and Marine Life in the Maldives

PLANKTON PRODUCTION

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

– Microalgae (Nannochloropsis) – Overall, 40L of algae were produced throughout the month.
– Microalgae (Spirulina platensis) – Conditions have stabilised following the initial culture trials. The final ongoing trial is to determine the most suitable source of mineral salts for long-term production. Efforts have now shifted toward increasing culture volume. The month began with 1L of Spirulina culture, and ended with 5L of actively growing healthy biomass, with filaments displaying a dark blue-green colouration with characteristic bluish tones, indicating good physiological condition. In the coming weeks, we hope to start preliminary filtration and drying trials to evaluate processing methods and product quality.
– Rotifers – Rotifer cultures remained stable throughout the month, with no major changes in density or feeding routine compared to previous months. As population density was constant, food quantity per session has been kept to 2 mL of Nannochloropsis sp. microalgae, given 3 times a day.
– Brine shrimp (Artemia) – Artemia production continued daily following the same protocol as the previous month, with two separate batches being maintained. The first batch is used for feeding jellyfish, shrimps, and fish in the Marine Discovery Centre, while the second batch is allocated to corals established as part of the nursery system from last month’s spawning collection. Adjustments were made to the harvesting methodology during this period. In addition, feeding practices in the main tank were modified, shifting from Artemia cysts to live Artemia, which provides a more suitable feed for the fish. Coral feeding has been maintained at 3 g per day, while fish and jellyfish systems receive 2.5 g per day..

Jellyfish Aurelia aurita in Kreisel tank at Landaa Giraavaru Maldives

GROUPER GROW-OUT (Epinephelus fuscoguttatus)

Land Aquaculture (Tanks) – The month of May started with a size-grading of the groupers, focusing primarily on the smaller classes. Some individuals had grown significantly faster than average, making it difficult to ensure equal feeding opportunities for all groupers. A total of 20 groupers were supplied to the kitchen.

Groupers Ocean Culture (Sea Pen) – a new sea cage was constructed for the grouper sea pen culture system. On May 14th, the new cage was installed and all 99 groupers from the previous cage were successfully transferred. The new cage design incorporates a stronger mesh material and improved joining techniques between net panels to reduce the risk of fish escapes and increase overall durability. Five individuals were weighed during the transfer, with an average body weight of 625 g. May also marked the delivery of the first sea pen–reared grouper to the Main Kitchen.

Collector Sea Urchin Breeding Trial

A two-week breeding trial of collector sea urchins was conducted in collaboration with Kamille, a student intern from JCU (Australia), as part of his Aquaculture BSc. A total of 13 adult sea urchins were collected from Dhonfanu on 22 May, all of which spawned successfully in our Fish Lab. The fertilised eggs developed normally through the early larval stages, reaching the 2-arm pluteus stage (developed digestive system, feeding actively). But despite testing different culture conditions, feeding concentrations, and larval densities, all larval development stalled during the transition to the 4-arm stage. We concluded that available food sources were insufficient to support further growth, resulting in developmental arrest and eventual mortality.
This trial provided valuable information on the early development of the species and highlighted the need for more suitable microalgae strains to support larval culture. We are currently evaluating additional live-feed options for future breeding attempts, with the long-term goal of producing juvenile sea urchins.

Fish Lab sea urchin breeding trial (egg to larva)

Sea moss (green)

Sea moss (red-brown)

Elkhorn sea moss

Sea grapes

AQUACULTURE – ‘SEAWEED’ AS A SUSTAINABLE FOOD

Elkhorn Sea Moss (Kappaphycus alvarezii) – 3kg of new stock was received and transferred for the first time to our sea pen adjacent to the grouper cage. With better water circulation, we expect improved biomass growth and reduced grazing pressure from polychaetes and sea slugs. Our total Kappaphycus biomass is 3.5kg, including the three previously maintained morphotypes.
Sea Grapes (Caulerpa racemosa) – we have been removing excess biomass and herbivorous organisms, and reorganising of the culture site. Additional work included excavating sections of the culture area to increase water depth and volume, reducing the exposure of the algae to direct sunlight and freshwater input during rainfall events. Following the approval of new menu items at Blu Restaurant and Café Landaa, fresh daily deliveries started on 11 May. A regular supply of 100g per day was provided to the Cold Kitchen, together with special deliveries to Blu Restaurant on Tuesdays and Café Landaa on Sundays. A total of 4.22 kg of sea grapes were supplied during May, making it the highest monthly production and delivery volume achieved since the start of the project. This increase reflects both improved culture management and growing demand.
Crunchy Hair Grass (Boodlea sp.) – total biomass reached ~700g by the end of the month. While the algae continue to grow, some epiphytic organisms remain attached to the thalli and are being monitored. The culture remains under observation to determine the optimal environmental and husbandry conditions required for sustained growth and biomass production. Kitchen trials are continuing in the resort’s restaurants, for menu items such as a seaweed-based sauce and crispy seaweed rolls.

Spirulina culture

Elkhorn seagrass

Seagrapes

Seaweed recipes

Guest Excursions

At Landaa Giraavaru, we conducted 5 guided tours of our Marine Discovery Centre for a total of 28 guests. Despite the lower numbers, tour durations were significantly longer, as guests showed increased engagement and interest during sessions. The longest tour exceeded 90 minutes, highlighting the opportunity for more in-depth discussions and educational experiences for guests.

Our guided snorkel excursions were enjoyed by 72 guests, with Turtle Safaris being the most popular. Across 5 separate Dolphin Cruises for 57 guests, we recorded sightings of 50 Spinners and an impressive 74 bottlenose dolphins.

At Kuda Huraa this month, a total of 227 guests enjoyed 33 different excursions to 5 different marine sites in the area, where we recorded 9 different megafauna species. Our Cetacean Identification Project is an ongoing study in which members of our Marine Biology team collect data about any dolphins and whales we encounter (most often, Spinner dolphins (Stenella longirostris)). We take photographs of their dorsal fins, to be analysed for identification. This is done through a software known as Darwin ID, where dorsal fin photos are traced and compared to previous uploads to find a match or a new individual. Read more about our Dolphin ID Project and enjoy some great photos from our teams!

Junior Marine Savers

During May, we conducted Junior Marine Savers for one day at Kuda Huraa. With enthusiastic young minds eager to learn more about our ocean ecosystems, it was filled with talks of turtles, dolphins, corals and how they can act to help. For the turtle specialty, the kids get to help feed our patients in the Rehabilitation Centre. With the coral specialty, they have the chance to learn about the importance of the reef before building their own coral frame. This all precedes the snorkel portion of the morning, which was full of fish, coral, sharks and smiles.

Education

During May, we conducted a fish dissection workshop for second-year apprentices from Kuda Huraa, who visited Landaa Giraavaru as part of their training program focused on plankton studies and dissection practical. The session included the dissection of four fish specimens, consisting of two reef fish and two pelagic fish species. The activity provided participants with hands-on experience in fish anatomy, allowing them to observe and compare internal organs and anatomical structures between different ecological groups. The workshop also introduced students to proper dissection techniques, specimen handling, and basic scientific procedures used in anatomical studies.

Team Updates

Our Kuda Huraa team welcomed two new interns, Conrad and Eleanor, at the beginning of the month, and we are so happy to have them! Conrad is a Coral Biology Intern, with a master’s degree from the University of Essex, and significant coral research experience. Eleanor is our new Turtle Biology Intern, with experience in animal care and research, who previously interned at the Atoll Marine Centre on Naifaru.

Marine life Maldives tropical coral reef

Maldives Sea Turtle Rescue & Rehabilitation

Turtle Updates

To commemorate World Turtle Day on 23 May, we successfully returned Ramma back to the ocean! She is a juvenile Olive Ridley turtle that was found back in January, floating on the ocean surface, extremely buoyant and unable to dive. After a course of antibiotics, Ramma did not eat for an extended period, but she slowly started to develop an appetite over time, thanks to continued treatments and encouragements from our onsite vet. During April, she overcame her buoyancy syndrome, and was soon able to dive normally again and rest on the bottom of her tank. All her wounds completely healed, and Ramma was deemed healthy for release.

Turtle rescue and veterinarian treatments Maldives RAMMA

Turtle beach release RAMMA [LG 2026.05] [800]

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REEFSCAPERS Coral Propagation & Reef Restoration in the Maldives

Reefscapers coral frames at Voavah Maldives

To see the progress of your own frame, please visit our Reefscapers Four Seasons monitoring page where we upload new photos every 6 months or so.

At Kuda Huraa this month, we transplanted 6 new frames, kindly sponsored by guests and the Resort, and our team monitored (cleaned, repaired, photographed) a total of 114 existing coral frames at all sites around the island. We completed maintenance and monitoring across all four restoration sites around the island.

At Landaa Giraavaru during May, we transplanted 22 new coral frame orders kindly sponsored by guests, the Resort, and online, adding ~875 newly propagated coral fragments to the reef. We also monitored 60 existing frames, lower than target due mainly to some periods of stormy weather.
We are excited to welcome the new Four Seasons Apprentices to our marine centre, along with colleagues on rotation from other departments. The Apprentices have been a huge help with recycling frames on the shallow House Reef, and making any new frames ordered online.

Reefscapers coral planting apprentices Maldives

Four Seasons apprentices with reefscapers Team [LG KMi] [800]

Marine life Maldives tropical coral reef [LG 2026.05] (2) [800]

Voavah Frames

The Coral Team and Apprentices spent a lot of time at Voavah this month, on both in-water and out-of-water projects. We recycled 20 large frames in the water over two days, with the help of scuba divers and free divers. On land, we constructed 37 large frames across multiple days with around 10 team members helping each day. We harvest 4,000 coral fragments by scuba and free diving to complete the task! 25 frames were constructed on the first day, and 12 on the following day.

Staff Reef Update

Staff Reef received 6 frames this month, making a total of 14 frames at the Landaa Reef Garden (10 Staff Reef Frames, 2 Staff Transfer Frames, 2 Special Frames – Earth Day and Apprentice Frame). The newly placed frames were planted to the left side of the Wedding Pavilion as more light is available. The existing frames that had been placed underneath the Wedding Pavilion were relocated closer to the seawall as they were covered by macroalgae. The corals on the older frames are mostly growing well, with fragments calcifying around the cable ties to the bar, and some are even fusing with other fragments! All the frames were scrubbed and new fragments were attached to replace any dead ones.

Coral Bleaching

As seasonal sea surface temperatures remained at levels detrimental to coral health, bleaching at our shallow-water sites continued to intensify. In response, much of our effort was directed toward mitigating these impacts and closely monitoring the progression of bleaching across our restoration sites. To help reduce stress on corals at Kuda Huraa’s Blue Hole Site, we installed several shading structures to minimise UV radiation exposure. Our shallow-water sites remain the most affected, but bleaching was also recorded at depths greater than 6m (indicating the widespread extent of thermal stress) and at the wild reefs of several local snorkelling sites.

Corals paling due to elevated sea temperatures

Bleached white coral v healthy coral

Reefscapers coral bleaching Maldives reef

Coral bleaching & fluorescing due to heat stress

Reefscapers coral fluorescence [LG 2026.05] [800]

Coral fluorescence - beautiful but stressed

Coral Spawning

May Full Moon period – at Landaa we observed 51 coral colonies spawning. We had already conducted a gamete-check dive, and found pigmented eggs (mature and readying to spawn) in several Acropora species. Scuba diving checks were conducted for Acropora spawning as most of the House Reef’s corals are deeper than 5m. We later switched to freediving to observe shallow spawning in massive growth forms (Astreopora, Montipora, Goniastrea, Galaxea, Cyphastrea).
At Kuda Huraa we recorded spawning in species of Acropora and Galaxea, clocking up 24 night dives across both the full moon and new moon periods. Spawning activity was documented on six nights in total, including some coral species which exhibited split spawning across two or more nights.

Our Coral Spawning Research

Four Seasons Team Diaries at Reefscapers

Be sure to read our complete Team Four Seasons Diaries over on our Reefscapers website, and then browse our Global Research pages where we curate the latest marine science research (open access) alongside news on how the oceans are being changed by climate change.

Further News & Updates

You might also be interested in our specialised Sea Turtle Lagoon Enclosure, and our Dolphin Diaries & ID Project.

Looking for details of our Reefscapers coral propagation and reef restoration program ? Then head over to our Four Seasons Team Diaries at Reefscapers.

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

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