Fish Lab & Marine Aquaria
Main Aquarium
Our new pumps are performing well, with a greater turnover of water in the main aquarium. Towards the end of April, we observed the water parameters begin to shift, with a rise in temperature and salinity (as expected, seasonally) and a small decrease in pH (important for the health of our new jellyfish, as they are very sensitive to water pH and require an optimum of 8.5).
Coral monitoring
In our main aquarium, the seasonally elevated water temperatures recently peaked at 32.3°C, causing many of the resident corals species to pale and bleach. To better control the aquarium temperature, the water in-flow was regularly reduced or closed, lowering the flow of higher temperature ocean water entering the tank. The AC in our Centre was also kept running overnight, and saline ice added directly into the tank. This process was crucial for coral survival and by the end of April it was a relief to see the colour returning to our corals again.
The Zoanthus specimens appear to have recruited extra zooxanthellae, as they are showing increased pigmentation and tentacle extension. Other species such as Stylocoeniella guentheri, Tubastraea faulkneri, Acropora and Sinularia appear to be stable. Our mini coral frames are also coping well with the higher temperatures and are healthily encrusting onto the framework.
Flying Fish
Our flying fish was moved to a glass-enclosed tank, for better observation of diurnal patterns relating to movement, feeding and activity. In the mornings, it preferred to swim at the top of the tank, until we added Artemia food, when it would start to perform 360-degree turns, resembling the feeding behaviour of a manta ray. In the afternoon it tended to stay at the bottom of the tank, swimming more slowly.
This species proved to be a very interesting addition to our Fish Lab aquarium, and we have now released it back into the ocean.
Flying fish juvenile (2.1cm) in our Fish Lab
Archive photo of an adult flying fish that had inadvertently jumped aboard our boat (before being released)
Kreisel Jellyfish Tank
We have an exciting new addition to our Centre from 29 March… a Kreisel tank for displaying jellyfish! It now sits proudly in the main floor space, all thanks to the Red-fin team – Chris’s professional installation and Toshi’s informative training.
For the past few months, we have been growing-on various species of jellyfish in our Fish Lab, to be displayed in our new tank. At first, many of the jellies acclimatised quickly to their new aquarium home and seemed to thrive. However, we suddenly started to see some casualties, as certain species were found to be more sensitive to changes in various aquatic parameters. When the health of our Sea Nettle jellyfish (Chrysaora quinquecirrha) started to deteriorate, we increased the frequency of water cycling and subsequent feeding, but this made no difference, so we released them back into the ocean. (It’s possible that micro-bubbles of air caused the jellyfish to become stressed.)
Currently, we are growing juvenile stages (ephyra and polyps) of 62 specimens of ‘Common jellyfish’ (Aurelia aurita) in our small closed-system Kreisel tank.
The first month of rearing our Aurelia jellyfish specimens was an exciting and educational process. It was remarkable to observe the anatomical developments and morphological advancements from the 0.02cm ephyrae to the 8.5cm juvenile medusae. Despite the simplicity of their function and lifestyle, being comprised of 95% water (and 5% protein) means that jellyfish are very sensitive to environmental parameters.
We expected the average bell diameter would increase over time as the jellyfish grew, but it was the rate of growth that was of particular interest. We found that sudden increases in water temperature had a negative impact on the jellyfish metabolism, slowing the rate of growth (days 6-10 and 16-20 in the graph). When the temperature went down again (optimally to 23-25°C), growth rates increased.
We can deduce that fluctuations in water temperature were not beneficial to jellyfish health, and that future tank parameters will need to be maintained within a close range to allow for optimal acclimation and reduced stress.
Based on one month’s growth data, we can predict that a steady temperature of 23°C should enable the jellyfish to grow to 10cm in diameter (population average), reaching adult status after 3 months.
Microplastics Workshop
On 2 April, members of our marine biology team attended a workshop at the Maldives National University (MNU) hosted by the Save Our Seas (SOS) foundation along with the Maldives Whale Shark Research Programme (MWSRP). The workshop was based around the ongoing research projects targeting the effects of microplastics on Whale Sharks in the Maldives. The half-day session consisted of various presentations by different researchers, along with a few interactive group sessions.
The Maldivian Whale Shark population plays an important role in ecotourism, with the South Ari marine protected area (42km2) generating $9million dollars annually from tourism. Through their planktivorous diet, the sharks play a very important role by regulating plankton populations in their ecosystem.
According to a public survey, the top three threats to Whale Sharks in the Maldives are: boat strikes, unregulated tourism and marine littering. The group is aiming to understand the effects that microplastics have on Whale Sharks by analysing their faecal samples. So far, they have collected and analysed 5 samples and have found microplastic fragments present in each:
- 90% of the plastics were fibres, from both fishing nets and laundry wastewater (small fibres from clothes).
- 10% plastic fragments, consisting mainly of PETs, nylon and various polymer materials.
The plastics could be consumed by:
- trophic transfer from prey (zooplankton consume plastics and Whale Sharks then consume plankton),
- ingestion directly from seawater when filter feeding, or
- ingestion of particulate organic matter containing microplastics.
Microplastics are a rising concern in the world of ocean conservation as their effects on the marine environment are starting to become more recognised. It is thought that the effects of microplastic ingestion could range from compromised ability to capture and ingest prey and providing a pathway for the transfer of harmful chemicals, to inhabiting reproductive outcome with the production of fewer offspring.
During the interactive sessions, the question of ‘possible actions to take in order to minimise plastic pollution in the Maldives’ was posed to the workshop participants, and a variety of answers were discussed:
- Set up multiple waste disposal sites for boats to dispose of garbage (as currently, some waste is dumped directly into the ocean).
- Levy a tax on single-use plastics (straws, bags).
- Effective recycling initiatives.
- Better communication between stakeholders and government bodies, to take major action and control plastic pollution here in the Maldives (also voted as the hardest to achieve).
The SOS and MWRP will continue their work with the Whale Sharks to further understand the impacts that microplastics have on this megafauna species and will continue to bring the attention of this environmental concern to the public eye.
Thats a wrap of our very successful workshop held with marine scientists yesterday. Some great discussion, networking and very good ideas of how to tackle plastics pollution.Thanks to all the amazing participants! @giulidonati11 @AlinaMWieczorek @saveourseas @ktkit_kat @shamylio pic.twitter.com/wKrJ75Hds6
— Microplastics and Whale Sharks (@MPWhalesharks) April 3, 2019
First impressions from our marine scientist workshop held @MNUedu to identify communalities of efforts tackling plastic pollution in the Maldives and start problem framing in order to identify viable solutions. @saveourseas @AlinaMWieczorek @giulidonati11 @mwsrp @ktkit_kat pic.twitter.com/kSmSlhucx9
— Microplastics and Whale Sharks (@MPWhalesharks) April 2, 2019
Sea Turtle Conservation
Flying Turtles
This month, we re-started our ‘Flying Turtles’ project. With the hopes of keeping space available for new patients, we aim to get unreleasable patients sent to aquaria in Europe, where they would have more living space and interactions with other marine life. Sending them away to an aquarium would not only help to increase their quality of life, but they would serve as educational ambassadors and help to raise public awareness about the negative effects of marine pollution. 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.
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 April, we received 53 submissions to our national turtle ID project from around the Maldives. Close-up photographs of the turtle facial profile enable us to uniquely ID the turtles and enter them into our database as new individuals or re-sightings of existing turtles.
This month, we were able to positively identify 18 new Hawksbills (plus 3 re-sightings) and 3 new Greens (plus 2 re-sightings). Positive re-sightings enable us to keep track of many individuals, their location and even health status over the years. (Photo: Hawksbill #EI1134).
This brings our database totals of uniquely identified individuals to 1134 Hawksbills 194 Greens. A big THANK YOU to all our contributors. 🙂
Spotted a turtle? Submit your photos
Olive Ridley Sea Turtle Strandings
During April, we received more than 10 different calls for help with strandings of both Olive Ridley turtles and Hawksbill turtles. We admitted 3 new patients into our turtle Rehabilitation Centre, but sadly, a total of 5 turtles were found dead, entangled in ghost nets (discarded fishing gear, brought into Maldivian waters by the seasonal ocean currents).
In the Maldives there are two monsoon seasons:
- ‘Halhangu’ runs from May to October (wind blows from SW, ocean current comes from the West), and
- ‘Iruvai’ from November to April (wind blows from NE, ocean current comes from the East).
Ocean currents during Iruvai (above) and both seasons (right)
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.
