Fish Lab & Marine Aquaria

Aquarium

Our large female Humbug Damsel (Dascyllus aruanus) laid eggs on the aquarium glass. Some of the eggs were collected and examined under a microscope; the eggs had not been fertilised (no visible embryo) and it is likely there are no mature males in the tank.

Towards the end of May, our large marine aquarium showed the expected increases in salinity and temperature due to the Maldives’ seasonal high ocean temperatures (31.0°C). To control the aquarium temperature, we reduced the water flow intake and occasionally added saline ice blocks on particularly hot days to give a monthly average water temperature of 27.9°C.

Fish Lab Population

High water temperatures continue to disrupt the Clownfish breeding, with lower numbers of eggs, unfertilised eggs, delayed hatchings and no new larval development. Three new breeding pairs are currently being fed plenty of krill to encourage spawning of healthy eggs.

Plankton production has remained constant, showing good health and deep pigmentation. Artemia numbers fluctuated due to indoor cooling effects, and relocating the buckets outdoors gave greater yields. Rotifer counts remain high, averaging 893/ml.

Kreisel Jellyfish Tank

We continue to rear our Moon jellyfish (Aurelia aurita) from the ephyra stage to juvenile medusa stage and we are keenly observing the anatomical and morphological advancements from 8.5cm medusae to 15cm bells. Despite the apparent simplicity of jellyfish, being composed of 95% water (and 5% protein) they experience extreme sensitivity to environmental parameters. We are currently researching the Aurelia nervous system, with relation to pulsation and navigation/orientation mechanisms.

Overall, our Moon jellyfish continue to grow steadily, albeit with some fluctuation in growth rate. We now have 33 individuals (larger than 2cm diameter) on display in our main Kreisel display tank. These individuals appeared to acclimatise well, however, their growth rate slowed for 2 weeks (perhaps feeding was more difficult due to the larger volume of water). To attempt to improve this, smaller individuals were occasionally removed from the tank and isolated for direct feeding, before being returned to the tank.

Between 21 April to 5 May, the water in the tank became cloudy, a sign of imbalance in nutrient cycling and bacteria function. At the same time, the jellyfish displayed greater bell curvature, and a reduction to 5 pulses per minute (down from the typical 8 to 20 pulses/minute). We also observed 5 jellyfish individuals completely detach the bell from their oral arm region (and they did not recover) whilst the others became inactive and shrunk in size (by 0.4cm on average). This suggests the jellyfish were stressed and not assimilating the Artemia, despite still catching and ingesting them.

Aquarium - Humbug damsel (Dascyllus aruanus) eggs (no embryos)

Humbug damsel (Dascyllus aruanus) eggs – no embryos

Fish Lab - main aquarium water parameters

Main aquarium water parameters

Aquarium 2 - using ice containers to lower water temperature

Using ice containers to lower water temperature

Fishlab - Aurelia jellyfish growth

Aurelia jellyfish growth

Observations on Aurelia aurita care protocol

  • Tank cleaning – acclimatising to new water chemistry and physical parameters is stressful to the jellyfish. Also, direct feeding in the holding tank seems to over-stimulate and stress their oral arm receptors.
  • Average salinity was slightly high (at 36ppt), perhaps affected by the added salty food concentrates. Salinity is important for keeping the bell of the jellyfish curved, allowing for effective propulsion. Low salinity causes a flattened or inverted bell (as seen in low salinity river estuaries), whereas high salinity causes jellyfish to close up (water is drawn from the jellyfish into the surrounding water).
  • We now change 30% of the water daily (down from 100%), reduce the number of feeds, and siphon off waste, so the salinity has been gradually reduced to 33ppt.
Kreisel Jellyfish Tank at Marine Savers Maldives (1) 2×1

Sea Turtle Conservation

Flying Turtles

We continue to try to find overseas aquarium homes for our “unreleasable” turtle patients as part of our ‘Flying Turtles’ project. We aim to send 3 of our unreleasable Olive Ridley turtles (Taco, Frisbee and Chomper), that have been in our care for more than 1 year. All of them are missing at least 2 flippers, which means their ability to survive in the ocean is permanently compromised.

We are working closely with SEALIFE in the U.K. and Germany and hope to relocate Frisbee into an aquarium centre in the UK. Work has started on sample educational and awareness materials, and we are completing the import documentation for approval by Maldivian authorities.

LATEST NEWS! 2014 MV ⇄ EU 2019

Read how Peggy returned from Belgium to be released back into the wild here in the Maldives! And follow her journey on our updated interactive map, as she swims around the island and atolls enjoying her freedom once again.

Flying Turtles Team

Sea Turtle Tagging

Flipper tags are the most common method of marking and identifying sea turtles. They are made from metal or plastic and attached by piercing through the flipper skin. Here at Marine Savers, we have started using titanium tags, with a unique number (MS0000-MS0100) and a return address (in case someone encounters the turtle).

We are tagging some of the rescue turtles upon release, to learn more about their movements if they are sighted or photographed around the Maldives. We have tagged 4 Olive Ridley turtles so far (2 adult females, 2 juveniles) and have reached out to turtle research projects and nesting sites in India and Sri Lanka, in case any of our tagged turtles are sighted overseas in the future.

Maldives Sea Turtle ID Project

Photo submissions consist of close-up photographs of the turtle facial profile, which has a unique identifiable pattern in each individual (like human fingerprints).

During May, we received 16 photo submissions from the public to our ID project. We were subsequently able to identify 5 new Hawksbill turtle individuals (plus 2 confirmed resightings) and 2 new Green turtles (plus 1 resighting). Our database now totals 1154 Hawksbills, 204 Greens and 51 Olive Ridley turtles.

A big THANK YOU to all our contributors. 🙂

Spotted a turtle?  Submit your photos

Turtle ID - Green Turtle CM186 at Medhufaru, South Male Maldives
Reefscapers coral frames – Kuda Huraa water villa flower site
junior Marine Savers at Kuda Huraa

Further News & Updates

You might also be interested in our Dolphin ID Project, and our Sea Turtle Enclosure out in the lagoon at Landaa.

Looking for details of our coral propagation programme ?

Head over to our Reefscapers 2019 Diary for all the latest updates.

You can sponsor your own dedicated Coral Frame, and then see how it grows in the future by viewing the photo updates every 6 months, as part of our Coral Frame Collection.

Photos: (1) Reefscapers coral frames at Kuda Huraa water villas.
(2) Junior Marine Savers learn the importance of corals.

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