Pod of Spinner dolphins photographed near Kuda Huraa

Fish Lab & Marine Aquaria

Plankton Production

The month began promisingly with increasing rotifer counts, and improved algae quality. We have found that a longer wash of the rotifers is all that was required to rid the culture of ciliates (for now), however, we are still looking into purchasing options for a concentrated Nannochloropsis feed, to maintain water quality and reduce bio-fouling, while providing superior nutritional value to the rotifers.

Unfortunately, towards the end of the month, we had an unexplained crash in rotifer numbers. We have transferred the remaining rotifers in the culture into a 20l algae bucket to save them, and we will monitor closely over the coming weeks.

We have continued using the saltwater hydration method for Artemia, and we are now using day-1 Artemia for jellyfish feeds (and day-2 for main tank feeds).

We have filtered and restarted the Nannochloropsis cultures (replacing the N2 and NF2 cultures).

Our large 4000L marine aquarium display at the Marine Discovery Centre, Landaa Giraavaru (Baa Atoll, Maldives)

Large Aquarium

• The main aquarium has had several new additions over December, including a six-spot goby and cleaner wrasse, both of which have integrated well with the existing population.
• We have cleaned excess algae from the tank, and removed one of the soft coral specimens.
• We are currently exploring new options to improve circulation around the tank, preferring premium water-movement technology with readily available replacement parts.

Small Aquarium One

• Mini coral frame – five coral fragments remain healthy, but the remainder are showing some loss of tissue.

• Small Aquarium Two

• Mini coral frame – a few fragments show signs of stress or mortality, but most are encrusting over the cable ties.
• Clark’s anemonefish (Amphiprion clarkia) – laid eggs three times this month. The Blue Damselfish continues to lay eggs under the mushroom coral.

Linckia multifora sea stars

• SS1 (large specimen) – succumbed to disease and died early this month.
• SS3 (large specimen) – the arm that detached in April continues to grow well

Our Fish Lab – during December, we created five new display tanks (#11-15) with new lighting, and deep cleaned all of our tanks.

Jellyfish – Aurelia aurita

We now have 5 tanks of growing jellyfish:
(1) polyp tank #20, (2) small-jelly Kreisel, (3) a medium-jelly Kreisel, (4) a large-jelly Kreisel, (5) main display.

They are all healthy, however, growth seems to have slowed during the last month, perhaps due to our revised schedule of feeding them Artemia only once per day.

The new UV light is keeping algal growth to a minimum, and it now takes two months to exhibit visible algae on the walls of the tank. We have also designed and implemented a new vacuum drainage method, which has reduced the water change time from 24+ hours down to 12 hours.

We continue to hone our techniques and requirements to keep the jellyfish growing, with over half of the jellyfish surviving into the New Year. We still have 300,000 jellyfish in the polyp stage, and are confident that our methods will continue to produce good results.

[*] Strobilation is defined as asexual reproduction by transverse division of the body segments which develop into separate individuals.

from: Jellyfishes – Diversity, Biology