AN AUSTRALIAN GEOGRAPHIC SOCIETY-sponsored ocean expedition has found two marine species never before described in Australia – a pygmy seahorse and a coral previously thought to live only in shallow water.

Doctoral student Tom Bridge, researcher Pim Bongaerts, and a team from the University of Queensland, James Cook University and the Queensland Museum, set out to explore the unmapped depths around atolls in the Coral Sea, beyond the Great Barrier Reef.

These atolls rise up from extreme depths and are surrounded by deep oceanic water in the mesophotic zone, a region 30 to 150 metres below the surface, which scientists endearingly call the ‚twilight zone‘ because little light penetrates that far down.

Life at these depths was assumed to be minimal, given the lack of light – and therefore lack of energy for life-generating photosynthesis. However, using a remotely operated vehicle (ROV) the team found the atolls‘ mesophotic zone is home to surprisingly large and diverse reef communities.

The discovery highlights just how little is known about the mesophotic zone. „We have only been able to sample a fraction of the diversity…there is a lot more out there,“ Tom says.

The new-found pygmy seahorse (Hippocampus denise) is endemic to the Coral Triangle, the waters adjacent to Coral Sea in the Indo-West Pacific. This is the first time it has been found in Australian waters.

At 13.7mm, it is one of the world’s smallest fish species and is typically found in water shallower than 40m. The expedition team found the tiny seahorse at the unusual depth of 102m, suggesting the species has found a way to survived in the light-starved zone. ….

Source and read more:
Australian Geographic

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