Fish Lab & Aquaria – 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.
– Algae – stable population, mainly used for growing brine shrimp to adult size.
– Rotifers – population decreased due to less frequent fish spawning events.
– Artemia – following the decrease in moon jellyfish populations last month, we have decreased Artemia from 8g to 7g of cysts per day, sufficient for our population of fish and shrimps.
Jellyfish – Aurelia aurita
We cleaned our large display cylinder this month, and added 40 individuals from our smaller grow-out tanks.
Groupers
From 10 June, the batch containing smaller individuals is being fed once every two days, whereas the larger individuals are fed daily (usually in the mornings). We weigh the daily foods, and this month we also measured and weighed all the groupers.
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.
Our population of sea urchin continues to thrive.
Ornamental Fish & Shrimp Breeding
Clark’s anemonefish (Amphiprion clarkii) – aquarium #5 breeding pair laid 2 clutches; the couple in #3 laid 1 clutch. [Lifecycle graphic]
Blue damselfish (Pomacentrus pavo) – The two small juveniles died.
Onespot damselfish (Chrysiptera unimaculata) – Our first ever batch of larvae from 31 May died 3-4 days after hatching.
Megafauna and Marine Life
During June, 269 guests enjoyed 39 guided excursions, above and below the waves around Kuda Huraa.
At Landaa, we welcomed a total of 130 guests to our Marine Discovery Centre, and 175 guests participated in guided excursions and snorkel safaris. Megafauna sightings included hawksbill turtles (Eretmochelys imbricata), blacktip reef sharks (Carcharhinus melanopterus), spotted eagle rays (Aetobatus narinari).
World Environment Day (5 June), World Oceans Day (8 June)
This month, we commemorated both World Environment Day and World Oceans Day, collaborating with our Kuda Huraa Resort colleagues to raise awareness of conserving and protecting nature.
For World Environment Day, members from each department joined the local community of Huraa to plant new trees.
For World Oceans Day, we invited staff and guests to build a coral frame with us, and then joined a clean-up dive coordinated by the Dive Team. To finish the day, guests and staff were able to enjoy a turtle release on board the Dolphin Cruise (below).
MOBULID ECOLOGY: Planktivores of the Maldives
Our team in Kuda Huraa was blessed with many unique and exciting marine encounters during the month of June. Notably, 3 elusive Mobulid species were sighted on snorkel excursions, dolphin cruises and during drone surveys. Among pelagic stingrays (family Myliobatidae) the Mobulinae subfamily includes the planktivore taxa, which employ cephalic fins to direct planktonic organisms such as crustaceans, cnidarians, and fish fry into their filtering gill rakers. The distribution of these species is heavily influenced by the spatial-temporal zooplankton distribution. Recent increased abundance of these planktonic preys might be the reason behind these special sightings.
Reef manta rays (Mobula alfredi) are seasonally occurrent in waters next to Kuda Huraa. The 2024 manta season, however, brought exceptional sightings of individuals in our house reef, and drone surveys helped our team observe mantas visiting the east coast of our island daily and engaging in repeated feeding transects.
Short-horned pigmy devil rays (Mobula kulhii) are very rarely sighted by our marine biologists. Exceptionally, individuals were recently sighted on our house reef and in groups of up to 12 individuals in the same feeding area utilized by reef mantas, giving us a glimpse of the peaceful coexistence between these two sympatric species.
Spinetail devil rays (Mobula mobular) are also known as giant devil rays, and for good reason. During one of our dolphin cruises, 5 individuals were seen engaging in potential be courtship behaviour, as we noticed one female being continuously chased by the other 4 rays.
Manta Rays (Mobula alfredi) Maldives
Manta ray (Mobula alfredi)
Short-horned Pigmy Devil Rays (Mobula kulhii) Maldives
Short-horned pigmy devil rays (Mobula kulhii)
spinetail devil ray (Mobula mobular) Maldives
Spinetail devil ray (Mobula mobular)
spinetail devil rays (Mobula mobular) Maldives
Spinetail devil rays (Mobula mobular)
MALDIVES MONSOONS
In the Maldives there are two monsoon seasons, generally characterised as follows:
– SW Monsoon (wet season) ‘Hulhangu’ – runs from May to October (gusty winds blow from the SW, ocean current comes from the West, ocean is choppy).
– NE monsoon (dry season) ‘Iruvai’ – runs from November to April (lighter wind blows from the NE, ocean current comes from the East, ocean is generally calmer).
OCEAN CIRCULATION
It is very likely that these Mobulids made an appearance in the atoll due to the temporary increase in plankton. It is also worth noting that these sightings exclusively occurred on the outer east coast of Malé Atoll. Why do mantas and mobulas seem to pick a specific side of the islands to forage? A potential reason lies in the monsoonal-driven ocean circulation patterns which affect the distribution of these sought-after planktonic organisms. Winds are one of the main sources of energy for the motion of water masses.
Among all types of wind-driven ocean currents, the most relevant to our case is the Ekman transport:
As wind blows on the surface of the ocean it drags the upper 10-100m of the water column with it. However, the Coriolis effect influences this motion, resulting in the water not travelling consistently with the direction of the wind, and leading to net transport at a 90° angle from the direction of the surface wind. In the northern hemisphere (where Kuda Huraa is located) this transport occurs at 90° to the right side of the wind direction, while in the southern hemisphere it occurs at 90° to the left (anticlockwise).
During this season’s monsoon, the main winds are blowing north-east along the coast of the Eastern side of our atoll. As a consequence, surface waters are being pushed perpendicularly away from the coast. Because of the law of mass conservation relative to the Ekman transfer, any water displaced must be replenished, therefore the movement of water directed towards the open ocean causes deep, cooler, nutrient-rich waters to rise to the surface, promoting a zooplankton bloom, which in turn attracts pelagic filter feeders such as Mobulids.
* SW monsoon – more wind & rain, but ocean currents around the Maldives are relatively weak [2012_197]
* NE monsoon (dry season) – drier weather, but strong ocean currents from Sri Lanka towards the Maldives [2012_015]
Maldives Sea Turtle Rescue & Rehabilitation
Ocean Enclosure
This month, we started repairs on our sea turtle rehabilitation enclosure out in Landaa’s lagoon. This was a large team effort over 10 days, with extra manpower from our enthusiastic Dive Team colleagues (thanks, guys!). Following multiple dive sessions, we successfully relocated the healthy coral colonies that were opportunistically growing on the netting. Some corals were transplanted onto the natural reef, some attached to “untagged” Parrot Reef frames, others were fragmented to build frames.
Following the coral rescue, we removed the netting, replaced the broken anchor rope, and installed 10 new support ropes. Next month, we plan to complete the renovations, installing new netting and sunshades, and then transferring one of our patients into the enclosure to encourage exercise and diving.
Turtle Rescue & Rehabilitation
After being rescued by our team back in January, Thiandu was successfully nursed back to health, and released on board the Dolphin Cruise on 8 June to commemorate World Oceans Day! The turtle had been found entangled in a huge ghost net, with severe damage to the front left flipper, making amputation necessary.
Following Gina’s amazing progress last month and the healing of her injuries, she was deemed fit for release at the start of this month, and returned to the ocean on 8 June to mark World Oceans Day. Gina is the latest turtle to take part in our satellite tracking programme. Within only a week, Gina had left the Maldives, heading initially towards Australia, before changing course towards Sri Lanka.
Maldivian Sea Turtle Identification Program
During June, 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.
REEFSCAPERS Coral Propagation & Reef Restoration in the Maldives
At Landaa during June, we transplanted 26 new coral frames, kindly sponsored by guests (8), the Resort (17), and online (1), adding 1400 coral fragments to the reef. We monitored (cleaned, repaired, photographed) a total of 394 established coral frames at various sites around Landaa and Voavah.
At Kuda Huraa this month, our coral experts transplanted 5 new coral frames, monitored a further 80 mature frames at various sites around the island, and removed 139 frames from the Channel for recycling (this site was worst affected by coral bleaching and subsequent mortality).
Coral Bleaching in the Maldives
The ‘summer’ hot season in the Maldives runs from January to May; the extra hours of seasonal sunshine, combined with the current elevated global sea surface temperatures (SSTs) cause increased stresses on coral reefs, leading to 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.
Despite starting the month in the lowest NOAA Coral watch level of ‘no stress’, we are still at a Degree Heating Week of 5. We have observed mass coral bleaching and mortality across all sites around Kuda Huraa. Most Acropora species have bleached, with a few noteworthy colonies resistant to bleaching, and a few further colonies starting to recover during June. Our most shallow sites (1.5m) have been devasted by near-total coral bleaching and mortality, with deeper cooler sites (3-6m) faring somewhat better (House Reef 54%, Reef Crest 29%).
During this challenging time for corals, we are collaborating with our Reefscapers team members at different projects across the Maldives. As all islands have experienced mass mortality, we are working together for support and to share knowledge. Meli and Aku (Landaa Giraavaru) spent several days at Kuda Huraa, sharing methodologies and helping with our coral frames.
At Landaa, NOAA’s coral bleaching watch guidelines have been at “Watch” status since May, so we hope to see some recovery of pale and bleached corals as water temperatures decline. In April, coral bleaching and fluorescence was observed across all sites at all depths; in May the widespread bleaching turned into mortality during June, with Acropora species being hardest hit (high mortality, low recovery rates). Bleaching has also affected Pocillopora and massive genera such as Porites. Survey results for June range from 31% mortality at our deepest site (Anchor Point), to our most affected site (Elephant) with 65% mortality and very low recovery rates.
As June has seen continued mortality of bleached corals around Kuda Huraa and the North Male Atoll, we have continued the partnership with our Dive Team colleagues to survey the bleaching of natural reefs around the atoll. At the popular ‘Lankan’ dive site (famous for its manta cleaning station) we recorded coral bleaching levels from 39% (at 20m depth) to 62% (at 10m).
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.
