Green Sea Turtle Nests

We have had two new Green Turtle nests at Landaa Giraavaru, bringing the total for 2018 so far to six nests!

• Nest #1 laid 21 January (all 110 eggs had to be relocated higher up the beach). To check on the eggs, we carefully dug into the nest twice (on day 53 and day 63). Two eggs from the top of the nest were checked, but no developing embryo could be seen. We have scheduled the excavation of the whole nest, and will open all the eggs to look for any signs of development (and to try and determine the reason it failed to hatch).
• Nest #2 laid 5 February close to shrubbery (number of eggs unknown). On 28 March (day 50) we covered the site with a cage to contain any hatchlings that might emerge.
• Nest #3 laid 15 February at the water’s edge, so we relocated all 111 eggs (2 broken) to a higher, drier location (alongside nest #1).
• Nest #4 laid 27 February, again close to shrubbery (number of eggs unknown).
• Nest #5 laid 11 March in front of Villa 222.
• Nest #6 laid 24 March near Villas 204-205. The tracks in the sand on the left side show the green turtle coming up the beach; eggs were laid and covered (groove in between the tracks); the track on the right shows the return to the sea.

Maldivian Sea Turtle Identification Programme

Tourists and resident marine biologists from up and down the Maldives have been sending us their underwater photographs of wild sea turtles. A big THANK YOU to everyone for their help! 🙂

During March, we received over 80 submissions to the turtle ID programme, mainly through our Turtle ID Facebook Group. After software analysis of the facial scales, we were able to positively identify 44 new individual turtles (38 Hawksbills and 6 Greens) and add a further 10 good quality re-sightings of known turtles in our database.

Wild Hawksbill turtle ‘Hana’ (EI0447)

Turtle Photo-morph Project

We continue to record the growth of the hatchlings from the moment they are accepted to our Centre until their release into the wild. Twice weekly, close-up photographs of the sides of the head and the carapace are taken, in order to record the evolution or transformation of the scales and scutes during growth and assess how they change over time.

We have a custom-built stand for a DSLR camera, and when used with a plexiglass sheet and measuring tape, we can place the turtle in the same exact position and distance each time, to give accurate size and scale measurements.

At the end of the data collection period (15 to 18 months), we will upload all the photographs for an individual turtle into “Photomorph” software, which blends one picture into the next to create an animated video revealing how the turtle scales and scutes evolve with time. This will also reveal the stage at which the scales have reached maturity and no longer appear to change, thus enabling an individual identifier from the facial recognition software.

‘Ethan’ (EI042) – latest project photo

Fish Lab Population

Throughout March, we focused on the production of Maldivian (Blackfoot) Clownfish (Amphiprion nigripes), with breeding pairs 22 and 23 producing good batches of larvae. We transferred the newly metamorphosed larvae on day 19 to the small fish tank, making the first good batch of the year. We have already collected 20 juveniles and a further 30+ larvae are ready to change into small fish. We also collected 22 Clark’s Clownfish (Amphiprion clarkii) juveniles this month.

The larvae survival rate has increased since we have started enriching the rotifers with microalgae and S-presso. Changing 70% of the water volume per day is also important, as well as feeding enriched food to the breeding pairs (less food giving rise to unhatched eggs). We have been studying the quality of our larvae under the microscope at Day 0 and Day 1. The colouration of the yolk sac and lipid globule indicates good nutrition of the breeding pair. As a future experiment, it would be interesting to locate some breeding pairs into the lagoon (under a cage) for a period, before returning them to the Fish Lab and studying the resultant larvae (would they be better quality?)

Micrographs of 1-day old Clownfish larvae

Children’s educational activities

Clownfish Release

On 22 February, we released 7 anemones with 10 clownfish at the house reef, placed under a protective coral frame cage for a month. Under the cage, the fish and the anemones were doing well – we did not lose any fish and the anemones stayed in place. However, as soon as we removed the cage, we lost track of both the anemones and the fish in just 5 days.

For future experiments, we could select different locations, perhaps close to wild anemones, or at sites that we’ve used previously with some success. We could also keep the cage in position for a longer duration, to see if this helps to keep them anchored in the area.

Watching spinner dolphins on safari is always an exhilarating experience!