Fish Lab & Marine Aquaria

Main Aquarium

The wrasse family is probably the most diverse among the reef fish species, and they undergo major colour-change during maturation. It is thought that being coloured differently from the adults gives them a greater chance of survival, and the various patterns and bright colours distract predators and helps them to escape.

Our juvenile Queen wrasse (Coris formosa) was just 6cm long back in May 2017 (6cm juvenile), but has now grown to 15cm and is undergoing metamorphosis to become an adult female. Wrasses are “sequential protogynous hermaphrodites”, meaning they can change sexes if required.

Aquarium-2 Clark's anemonefish in bubble-tip anemone

Clark’s clownfish in bubble-tip anemone (Aquarium-2)

juvenile Queen wrasse (Coris formosa)

Aquarium - regenerating starfish (Linckia laevigata)

Aquarium Two

Recent additions include a wild anemone (Entacmea quadricolor), two mantis shrimp and some corals (small specimens of Favites and a small fragment of Warrior coral (Goniopora). We also received four Clark’s clownfish from the Fish Lab at Landaa, and we have observed our original larger Clownfish seemingly protecting the smaller ones from the Humbugs.

Aquarium One

Recent additions include a Six-spot goby, two mantis shrimps, one peacock mantis and four extra Maldivian clownfish. Our regenerating starfish (Linckia laevigata) is growing well, with the longest arm growing 6mm in just 19 days, and the remaining arms slowly catching up in size to the original arm (click image to enlarge).

Seahorses

One of our small male seahorses gave birth for the first time, and we moved 40 of the tiny hatchlings to a newly constructed specialised tank. However, the larvae were very weak and died after several days. Our new dedicated ‘kreisel tank’ is expected to arrive soon, which we hope will enable better results. (Photo credit: Simon).

Fish lab – seahorse hatchlings [LG 2018.11] (2)

Fish lab – seahorse hatchlings [LG 2018.11] (1)

Clownfish Breeding

We have changed the diet of our Clownfish breeding pairs, and this seems to have restarted their laying behaviour. We have been feeding them 3 times daily with Mysis (a kind of zooplankton) freshly collected from Voavah reef and frozen a few months ago back in our Fish Lab. After more than one month without producing eggs, two of our breeding pairs of Maldivian Clownfish have started laying again. One of our Clark’s Clownfish breeding pairs produced more than 400 larvae, and we are expecting half of these to metamorphosise into juveniles.

We recently observed natural recruitment of anemones inside our turtle recovery pools, so we have released 20 lab-raised Clownfish to populate them. If this is a success, we might be able to use this new environment to grow on our Clownfish and also produce new anemones.

As reported last month, some of our juvenile Maldivian clownfish seem to be developing a new pattern of half-bar stripes and three spots. And now our Clark’s clowfish are also showing some pattern variations. These can be seen in nature between different Clownfish species, but as our parent-fish appear to be pure-bred, maybe the hybridisation occurred some generations ago.
To follow these heredity varieties, we have started recording the proportion of each pattern per generation. We have also isolated a future breeding pair of half-barred three-spotted Clownfish and hope to breed an original “Made in Landaa” Clownfish! (Photo credit: Simon).

Fish Lab – Maldivian clownfish with unusual markings Marine Savers Maldives (2)

Maldivian clownfish – unusual markings

Fish Lab - Clark's clownfish with unusual markings Marine Savers Maldives (4)

Clark’s clownfish – unusual markings

Maldivian Sea Turtle Conservation

Turtle Nests at Landaa Giraavaru

Our two Green turtle nests (laid in September) were expected to hatch during November. However, unusually high tides on 27 November caused waves to flood both nests, and this was followed by heavy rain the following day. Therefore, on 29 November, we decided to give nature a helping hand by excavating the nests of the wet compacted sand.

Nest #1 (V200) sadly did not have any survivors (4 dead hatchlings, 28 under-developed, 28 unfertilised eggs, 16 empty shells, 2 yolkless eggs).

Nest #2 (V210) was much better, with 29 live hatchlings (plus 1 dead hatchling, 7 under-developed, 54 unfertilised eggs, 45 empty shells, 1 yolkless egg). The live babies were released into the open ocean after night fall.

Nest #3 (V200) is higher up the beach and had escaped the waves. We are monitoring for activity, as it is expected to hatch in December.

Maldivian Sea Turtle Identification Programme

During November, we received over 40 submissions to the Turtle ID project, from various atolls around the Maldives and from both fellow marine biologists and members of the public. This enabled us to identify 6 new Green turtle individuals (plus 7 re-sightings) along with 5 new Hawksbills (and 4 re-sightings).

Close-up photographs of both sides of a turtle’s facial profile enable us to uniquely identify a turtle individual, as the pattern of facial scales (scutes) is unique to each animal. We enter the photos and all relevant details into our database, and either match with previous sightings or create new individual entries.

Most sightings this month have come from South Malé atoll, allowing us to expand our knowledge of Green turtle populations in this region. The majority of the turtles in our database are Hawksbills (1914 individuals) with only 342 Greens, so we hope to better understand the dynamics and distribution of the Green Sea turtle population in the Maldives.

This month has also been the first in which we have started to transfer data into our new pattern-recognition software, ‘i s’. This programme has been designed to recognise the facial patterns of turtles through a complex algorithm. Once we transfer all the existing turtles into the programme over the coming months, it will then allow us to compare new submissions to the current ones by simply adding them into the software. This will make the identification process faster and more efficient.