It's no secret that the world's coral reefs are dying off at an alarming rate. In order to encourage the growth of the coral that remains, scientists from the University of Hong Kong have developed what are known as "reef tiles."
The idea behind the tiles is that they be placed in interlocked groups on the ocean floor, providing a reef-like structure upon which coral will grow. Users can both "seed" the tiles with coral fragments, and wait for coral polyps to naturally colonize the tiles as the organisms are carried past on ocean currents.
Measuring 60 cm (23.6 in) across, the tiles are robotically 3D-printed out of conventional terracotta clay, which is then kiln-fired at a temperature of 1,125 ºC (2,057 ºF).
According to the scientists, clay is much more eco-friendly than concrete or steel, which have previously been used in other groups' reef-building projects. Not only does the production of the latter two substances produce greenhouse gas emissions, but the materials themselves can also leach toxic substances into the ocean water.
In a pilot project, 128 of the clay tiles were seeded with three types of native coral, then deposited in three sites within Hong Kong's Hoi Ha Wan Marine Park. The park is currently home to over three quarters of the reef-building corals in Hong Kong waters, although a combination of habitat destruction and coral bleaching has led to a reduction in coral numbers over recent years.
The tiles will be monitored over the next year and a half, to see if they can help restore the reefs.
Source: University of Hong Kong
