Fish give ‘fins up’ to 3D-printed coral reefs

3D-printed artificial corals could help the animals that live in coral reefs withstand or recover from bleaching caused by warmer water temperatures, finds a new study.

Warmer water temperatures are leading to a rise in weather events such as bleaching and storms, which can be disastrous to coral reef systems and the animals that live in them. In order to keep the right animals on a reef after an emergency, scientists are exploring how 3D-printed coral models can be used to replace or supplement coral reef systems during recovery.

Key to the success of this approach is knowing that the 3D-printed material used won’t harm coral or negatively affect fish behaviour.

“If the fish on a reef won’t use the 3D-printed coral models as a habitat in the wild, it could place them at greater risk for predation by other larger species,” said University of Delaware (UD) associate professor Danielle Dixson. “If coral larvae won’t settle on 3D-printed materials, they can’t help to rebuild the reef.”

Together with her UD alumnus Emily Ruhl, she has shown that 3D-printed objects do not impact the behaviour of coral-associated damselfish or the survival of a settling stony coral. What’s more, their study demonstrated that fish showed no preference between materials used to 3D-print artificial corals, opening the door to using environmentally friendly materials, such as biodegradable cornstarch instead of plastic

Ruhl said she was surprised that the fish behaved the same near artificial coral even with a natural coral skeleton present.

“I thought the natural skeleton would elicit more docile (that is, accepting) behaviour compared to 3D-printed objects,” said Ruhl. “But then we realised the small reef fish didn’t care if the habitat was artificial or calcium carbonate, they just wanted protection.”

The researchers’ lab experiments also revealed that mustard hill coral larvae settled at much higher rates on 3D-printed surfaces compared to having no settlement surface at all, which could occur if a reef were flattened in a storm.

Dixon called 3D-printed habitats a way of providing reef organisms a “structural starter kit” that can become part of the landscape as fish and coral build their homes around the artificial coral. “And since the materials we selected are biodegradable, the artificial coral would naturally degrade over time as the live coral overgrows it.”

Image credit: wembley via Unsplash

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