The survey team came across a natural mesh made of fossilised carbonate reefs that traps micro-nekton on their way to bottom of the sea, turning them into fodder for large pelagic predators like tuna and shark fish that arrive here for food.
A first-ever underwater survey of the Indian Ocean waters in the economic zone of the Maldives has revealed an “oasis of oceanic live” in the depths surrounding the atolls of the island nation. It has also shed new light on the behaviour of the Vertical Migration – the largest nightly migration on the planet.
The scientific team conducting the survey have found a series of vertical cliffs 500 metres below the surface of the ocean. The vertical cliffs have a mesh of shelving terraces that trap swarms of micro-nekton – small swimming creatures that undertake a vertical migratory journey after sunset.
The scientists call this natural trapping mesh ‘the trapping zone’.
The trapping zone is made of fossilised carbonate reefs does not allow the micro-nekton to return to their way-down-at-the-ocean-bed-homes from where they arrive – turning them into fodder for large pelagic predators, including schools of tuna and sharks, along with other well-known, large deep-water. The natural trap in which they get stuck is a feeding cafeteria for the larger animals.
As small as 2 cm and no larger than 20 cm, the micro-nekton feed on zooplankton and are part of the food chain of bigger predators like the tuna, sharks, and similar marine life as well as seabirds.
“Engaging in the vertical migration is an essential for the micro-nektons, swimming upwards to the sea surface from the deep sea at night and diving back into the deep at dawn,” said Mohamed Shimal of the Maldives Marine Research Institute.
Science to policy
While scientists have found sharks in shallow waters in the Maldives, this is the first time they were able to document “an immense diversity of sharks in the deep sea.
“We’ve observed sharks in shallower waters quite extensively in the Maldives before, but for the first time we’ve have been able to document an immense diversity of sharks in the deep sea”, explained Shafiya Naeem, Director General of the Maldives Marine Research Institute, which has partnered with Nekton on the expedition. Tiger sharks, six gill sharks, sand tiger sharks, dog fish, gulper sharks, scalloped hammerhead sharks, silky sharks and the very rare bramble shark have all been documented.
Emphasising how the scientific study is essential to draw up a policy on deep-sea fishing, the scientists from the Maldives Marine Research Institute said that this study will inform future planning on the scale of exploitation of marine food resources.
“The discovery of ‘The Trapping Zone’ and the oasis of life in the depths surrounding the Maldives provides us with critical new knowledge that further supports our conservation commitments and sustainable ocean management, and almost certainly support fisheries and tourism,” said the country’s president Ibrahim Mohamed Solih, hailing the discovery.
The Maldives Marine Research Institute has completed the underwater survey of the Maldivian oceans in partnership with Nekton Maldives. The survey has provided information on the oceanic life in the Maldivian seas. The 300 square kilometres of underwater area mapped during the project is larger than the land mass of the entire Maldives.
It also included the famous “Satho Rahaa” deep sea mountain in Huvadhoo sea – with a perimeter of 15 nautical miles and a depth of 1,500 meters.
The findings of the study will inform formulation of policies on marine conservation and climate change in the Maldives.
Image: Representative image from Wikimedia