Fish Lab, Aquaria, and Marine Life in the Maldives

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

– Algae – populations remain steady at 9mL per day. 600L of algal culture were produced this month, to feed the juvenile fish and for growing our brine shrimp to adult size.
– Rotifers – population is stable, with a concentration of ~300 individuals/mL on average.
– Artemia – following last month’s increase, the culture remains at 6g of cysts per day.

The July jellyfish batch continue to thrive and grow in the 80L Kreisel tank. From this batch, 110 individuals were relocated to the large display cylinder tank. We feed each tank with Artemia twice per day (550ml for the Kreisel, 200ml for the cylinder tank).

Groupers

This month, we received 205 brown-marbled grouper fingerlings (Epinephelus fuscoguttatus) into our grow-out project. Our initial dry food feeding attempts were abandoned (they ignored floating foods) so we switched to finely-minced fusilier baitfish. Feeding was scheduled 3 times per day for the first 3 weeks, then reduced to twice daily. Currently, they are consuming 2 portions of 100g, per day. We have lost ~30% of the fingerlings due to a water circulation issue, and instances of cannibalism.
Our existing adult grouper population is healthy, with zero casualties this month. To encourage growth, we have increased food from 300g to 350g per day.

Sea Urchins

On 16 October, we artificially induced spawning in 4 of our urchins, by following the standard technique of injecting potassium chloride (KCl) solution into the soft tissue between the mouth and the shell. After a dose of 1mL KCl, 1 individual started spawning as female within 20 seconds of the injection. The 3 remaining inviduals did not show signs of spawning, so dosage was increased to 2mL, which induced a second urchin to spawn. The remaining 2 individuals later shed spines and died. Interestingly, our KCl concentration (at 0.24mol/L) is lower than recommended in scientific articles. We now have 5 sea urchin specimens in our Fish Lab.

• Clark’s anemonefish (Amphiprion clarkii) – breeding pairs in tanks #3 and #5 have been producing eggs weekly. Ten of the largest individuals from our January batch (tank #33) were moved to tank #16 which includes large individuals of the same batch, to encourage further growth. [Lifecycle graphic]
• Boxer Shrimp (Stenopus hispidus) – The female carried two batches of eggs under her belly but no larvae were collected.
• Dancing Shrimp (Thor amboinensis): Every individual from the September batch had reached settlement stage by 25 October. Two pregnant females were isolated in a Kreisel tank to collect the hatching larvae. Over 2 days (October 7-8th) we transferred ~600 individuals into a cubic tank, with circulating aerated water. For feeding, 2L of algae and 1L of rotifers are provided daily.
• Imperial Shrimp (Periclimenes imperator) – On 23 October, one pregnant female was accidentally found on some live corals while monitoring for coral genotyping. Back in our Fish Lab, the shrimp was acclimated in a small Kreisel tank so the larvae could be collected. The ~300 larvae hatched on 25 October, and were divided across 3 small Kreisel tanks.
  Imperial shrimps have a very specific ecology; they are commensal species that live on the backs of some species of nudibranchs and sea cucumbers, specifically feeding on the faeces of their host. Because of this unique lifestyle, the female was released back onto the reef.
• Molluscs – This month, 3 common spider conch (Lambis lambis) were added to different aquaria: 1 in the main tank, and 2 in the yellow boxfish tank. Spider conch can be useful in tank-cleaning, as they eat algae found in sandy substrates.

At Landaa this month, we held 14 tours of our Marine Discovery Centre, totalling 44 guests from 10 different countries. We conducted 12 dolphin cruises for a total of 114 guests; we only sighted 40 cetaceans, but an exciting encounter with a large reef manta ray was a huge bonus! Snorkel excursions were enjoyed by 147 guests (12 Guided Adventure Snorkels, 12 Turtle Safaris, 3 Night Snorkels, 3 Parrot Reef Snorkels).

At Kuda Huraa, 223 guests joined us on 31 excursions to 6 different local marine sites. We also successfully trained six new local apprentices in a comprehensive range of marine biology topics.
In recent months, the Marine Discovery Center has undergone several upgrades, including the addition of a new stainless steel table for turtle procedures, installation of ‘Reef Breeders’ lights, and freshly painted turtle tanks. Looking to the future, our goal is to create an even more enriching experience for our visitors while providing valuable educational tools that promote marine conservation. We believe that by enhancing our facilities, we can inspire a deeper appreciation for marine ecosystems and the important work we do here at the center.

Maldives National University: Career Guidance Day – Paths in Marine Science

On 15 October, members of our Reefscapers teams from both Landaa Giraavaru and Kuda Huraa attended Maldives National University, to give a lecture to Male’ A-level students on marine conservation. Our talk focused on our marine conservation work, and was well-received by the ~200 students in attendance, with many remaining after the talk to ask questions and share their thoughts.

This lecture will form the first of a series designed to increase the awareness of marine conservation and biology amongst school students in the Male’ area, in the hope they will be encouraged to consider a marine-related career. This first event was designed to inspire the students and to share information about opportunities and potential career paths.
We shared information about the Four Seasons apprenticeship program as well as the Reefscapers internships and potential future employment opportunities. Dr Riyaz, Dean of the department of fisheries and ocean sciences, discussed the marine science courses offered by the university and the students were also presented with a video showcasing university facilities.