Drupella corallivorous snail Maldives

Fish Lab & Aquaria – Marine Life in the Maldives

At Kuda Huraa, we gave our sunset lounge aquaria a complete makeover, to exhibit several species of soft and stony corals, representing the diversity found in Maldivian waters.

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

– Algae – 800L have been produced this month; this is ample to feed the juvenile fish and shrimps produced in the breeding program (and to grow Artemia to adult size)
– Rotifers – population decreased to 362 individuals/mL (well within target of 300 ind./mL)
– Artemia – culture maintained at 6.5g cysts/day, to feed our growing population of fish, shrimps, and moon jellyfish (Aurelia aurita).

Jellyfish – Aurelia aurita

On 28 February, we moved 60 jellyfish from the smaller grow-out Kreisel tank to our large display cylinder.

Jellyfish Kreisel cylinder Maldives

Photo1: Our dedicated jellyfish Kreisel cylinder at Landaa Giraavaru.

Photo2: Specialised food chain, behind the scenes in our Fish Lab

Fish Lab Food chain

Groupers

Our growing groupers appear healthy and are fed daily, however we lost six individuals this month.

Seaweed Mariculture – edible sea lettuce (Ulva lactuca)

After some delays, a new batch of sea lettuce was finally received from Australia on 19 February. The batch was divided into two containers, each exposed to 24-hours of artificial light, and with air stones to keep the environment oxygenated. Once every three days, salinity is checked, and new salt water and fertiliser (F2P) is added.

In one test environment, two juvenile Clark’s clownfish feed on any microfauna, and provide natural nitrogen fertiliser (NO3, NO2, NH4).

Sea Urchins – New Project 2024

Sea urchins are herbivores found in many different marine habitats around the world, and often harvested for food (a delicacy in some cuisines). Some countries have experienced over-harvesting from the wild, causing excessive algal growth and a degraded ecosystem.

We have launched a new sea urchin echinoculture project to investigate breeding viability of the collector urchin (Tripneustes gratilla) due to its small spines making for easy handling.

On 7 February, we collected eight new sea urchins to add to our Fish Lab breeding program. We have already observed cell division (2 cell-stage) and have started experimenting with different environments to encourage development:

  • Fish Lab aquarium, 30L and 15L Kreisel tanks
  • 20L and 5L buckets, 500mL beaker, 5L bottle

Each environment was oxygenated, and when the larvae reached the pluteus stage (that includes a digestive system) we started to add microalgae as food. We refreshed the water when necessary, but observed increasing levels of mortality so we subsequently stopped the experiment after six days. Likely the high density of larvae was the cause of the mortality, so in future grow outs we plan to limit density to just five ind/L in small tanks.

Ornamental Fish & Shrimp Breeding

Dancing shrimp (Thor amboinensis) – Some individuals from the latest batch have begun settling at the bottom of the aquarium. They are still fed on algae and rotifers until we move them to another tank with lights and soft corals

Boxer shrimp (Stenopus hispidus) – On 24 February, we collected a new batch of shrimp, divided into two populations of 50-100 individuals in separate Kreisel tanks. Each tank has a different circulation system: the 15L tank has a water pump, whereas the 30L tank has an air-flow system. Water is changed daily, along with algae and rotifers as live foods.

Maldivian cardinalfish (Apogonidae family) – Males incubate eggs in the mouth before releasing the larvae. Two gestations have been observed this month, with the male presenting a bulging mouth. We hope to collect the larvae of future batches

Maldivian clownfish (Amphiprion nigripes) – popular exhibits!

Clark’s anemonefish (Amphiprion clarkii) – On 4 February, our January 23rd batch metamorphosed for the first time. Eleven individuals from the October/November batches have been moved to another grow-out tank with two youngsters. [Lifecycle graphic]

Fish Lab Shrimp breeding cycle

Megafauna and Marine Life

February was another busy month in Landaa’s Marine Discovery Centre, with many guests over the Chinese New Year, plus school students from Dharumavantha, Gan Atoll Education Centre, and Kihaadhoo. In total we welcomed 228 visitors through our doors, all eager to learn more about marine conservation.

Our Dolphin Cruise remains popular, along with our Guided Adventure Snorkels and Turtle Safaris, where we sighted abundant hawksbill turtles, plus blacktip reef sharks and spotted eagle rays.

Mimicry

The fascinating art of imitation is quite common in the natural world. Mimic species benefit from resembling model species in more than one way: some appear similar to venomous or inedible organisms, while others use mimicry to blend in with the surrounding environment.

Humbug damselfish (Dascyllus aruanus) usually shoal among the branches of Acropora corals, and are very protective of their homes. Juvenile black snappers (Macolor niger) also exhibit a black and white colouration that might help them get accepted into the school of damselfish, escaping predation by exploiting the species’ territorial behaviour and cautious nature. A perfect use of mimicry!

Marine mimicry in fish Maldives
Marine mimicry in fish Maldives

Maldives Sea Turtle Rescue & Rehabilitation

AFAA turtle rescue & rehab Maldives

AFAA (Olive Ridley rescue sea turtle) in her recovery pool

KUNNU turtle rescue & rehab Maldives
Regular health checks for KUNNU (Olive Ridley rescue sea turtle)

Noonu’s Journey 5,871 km

After 115 days of deployment, Noonu’s satellite tag sent its final data transmission. She has travelled a total of 5,871 km, looping all the way back to us here in Baa Atoll ! We can see that Noonu was travelling in the same direction as the prevailing currents, first heading north-east towards India, and then back again towards the Maldives after the change in monsoon seasons.

See our interactive Satellite Map for further details.

NOONU's Turtle Satellite Tracking Map

Maldivian Sea Turtle Identification Program

During February, our ID project is currently on hold as we have been busy with our rescued turtle patients (eight new admissions, and two turtle release events).

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

Monthly Update Summary

At Kuda Huraa during February, we transplanted 13 new coral frames, and monitored a further 91 mature frames at various sites around the island.

At Landaa this month, we transplanted 38 coral frames, kindly sponsored by guests (15), online (eight), and the Resort (15), adding a total of 1900 coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 431 established coral frames at various sites around the island.

  • 35 degraded frames were recycled and moved from a low-flow area to the flourishing Elephant site.
  • 50 large new frames (plus 10 Resort frames) were manufactured to fulfil the generous guest sponsorship in December. With help from our Resort colleagues and volunteer divers, we were able to harvest more than 1000 coral fragments. So far, we have successfully transplanted 12 frames, located at 8m depth.
SST 1998 2016 2023-24 C3S (Copernicus Climate Change Service)

Global sea surface temperatures (1979-2024)
Highlighted: mass coral bleaching event years (1998-2016-2024)
Global temperatures for 2023-24 have been extreme

NOAA Maldives_prod_quad_composite [2024-03-17]

NOAA forecast for the Maldives, snapshot taken 24 Feb.
Each square approx represents 1 month, Feb to May/June.
Corals will be under high levels of stress from April to June.

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.

February saw the coral bleaching forecast jump from Level 1 to Level 2 in the coming weeks, for the entirety of the Maldives (NOAA’s Coral Reef Watch). This would mean higher ocean temperatures reaching the Maldives sooner than previously expected. Our teams are working hard to actively mitigate the potential damaging effects of the upcoming marine heat wave.

  • Relocation – we have already started moving healthy shallow coral frames to deeper, cooler waters. Our lifting techniques use buoys and ropes in what has been a mammoth effort with the help of our Resort volunteer colleagues. We will target the most vulnerable coral frames for relocation, to give the best possible chances of escaping the potential coral bleaching
  • Monitoring – we have marked specific coral colonies around the island to be monitored over the coral bleaching season. We will assess the start of any visible paling, and the extent of possible coral bleaching and mortality
NOAA CoralReefWatch animation 60pc (25Feb-07Jul) 2024

This animation from NOAA is a forecast made on 20 Feb for the upcoming period: 25 Feb – 07 Jul 2024.
It clearly shows the ocean heat moving from the southern hemisphere, and passing over the Maldives.
All coral reefs around the world are at great risk of elevated ocean temperatures, caused by global warming.

Peristernia snails Maldives

Are all Marine Snails Harmful to Corals?

At Marine Savers, we actively remove any corallivorous snails that we might encounter during our regular reef restoration and coral maintenance work.

This will become increasingly important during the upcoming months, as coral predators are known to strike when the corals are at their most vulnerable, such as during and following a coral bleaching event.

Many marine gastropods play an important role in the coral reef ecosystem, so we have been working to identify which corallivorous species are found on our reefs, to increase knowledge and understanding of the threats to our corals.

Some marine gastropods such as Drupella are known to eat corals, and prefer species of both Acropora and Pocillopora. This is a particular issue for our Reefscapers teams, as these 2 coral genera are favoured for coral propagation projects, being both easy to handle and giving excellent rates of growth.

Predation of the coral colonies leaves them vulnerable to disease and competition, or if left unchecked can result in total mortality of whole colonies and even large sections of reef. To increase the success of restoration projects, it is common for coral biologists to remove these snails and manage populations, to increase survivorship of the vulnerable corals.

For the graphics & write-up: many thanks to Elisha Whiting, our coral expert at Kuda Huraa. You can also slide over to our snail page on Reefscapers.

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