Visiting mesophotic coral reefs

May 1 to 16 is Science Odyssey, a celebration of all things science! OWLconnected is recognizing this two-week event with lots of science content, as well as with an amazing contest, presented by our friends at the Natural Sciences and Engineering Research Council of Canada (NSERC). Details are at the end of this post—be sure to enter!

To continue our odyssey, we're diving deep into the ocean to see some spectacular sights!

Hidden reefs

When you think of coral reefs, what do you picture? Schools of tiny, rainbow patterned fish. Eels and crabs peeking out between the growth. Tentacles of anenomes and octopus waiting to clutch their next meals.

And above all, you probably think of brightness. And not just bright colours. Coral reefs are found in tropical shallow areas where sunlight is regular and can easily reach them. They are warm, full of life, and full of light.

But not all corals exist in shallow water. There is a whole other class known as mesophotic coral reefs that are found between 30 to 150 metres (100 to 490 feet) under the surface. No less majestic, these deeper sea corals are starting to become better known thanks to the efforts of groups like Australia's Schmidt Ocean Institute (SOI). They recently shared some exquisite photos from a trip to the mesophotic corals at Ashmore Reef Marine Park.

Let's check them out now!

Rare beauty

'Mesophotic' means low light. But despite being dimly light, these reefs are almost as bright and full of life as their shallow water cousins. See for yourself!

Peek-a-boo! (Schmidt Ocean Institute)

The team found several sea snakes at the reefs, much to their surprise! (Schmidt Ocean Institute)

This hand coral is full of vibrant colours, despite its low lit surroundings. (Schmidt Ocean Institute)

Beautiful, right? For an even better look, listening to the researcher explain their dive in this video. (At around the 2:00 mark, you'll also start to see some awesome footage of sea snakes, fish, sponges, and corals!)

A challenging place to get to

So why are we only going to places like Ashmore now?

Mesophotic coral reefs aren't in total darkness like the truly deep sea areas that we've written about here and here. (And did a video about here!) But they do get significantly less light than shallow reefs receive. And they are also at a depth where the pressure starts getting extremely dangerous for humans.

This is why they have been so poorly explored by people. As explained on the NOAA (National Oceanic and Atmospheric Administration) website, much of the world's mesophotic coral reefs are too deep for conventional scuba gear, but also too shallow for a lot of deep-diving tech like submersibles and remote vehicles. (Often these vehicles are just so expensive to operate, that people tend to save using them on much deeper parts of the ocean.)

But the recent expeditions by SOI where carried out using their newest submersible probe: ROV SuBastian. This state-of-the-art vehicle is loaded with sensors, navigation tools, and everything needed to observe depths of up to 4,500 metres (14,760 feet). Thankfully, they choose to bring ROV SuBastian a little closer to the surface and share these incredible photos of mesophotic coral reef life with us!

Take an animated tour of this super cool vehicle in the video below.