Underwater Quick-Hardening Vegetable Oil-Based Biodegradable Putty for Sustainable Coral Reef Restoration and Rehabilitation

Coral reefs are threatened by climate change and the effects of human activity on the marine environment. Researchers are attempting to rescue this fragile ecosystem through coral restoration actions, and a common step in these procedures is transplanting the new coral colonies into coral reefs. To do that, commercial concrete or epoxy resins, also called putty, are utilized, highlighting different concerns about their mechanical and hardening performances and their impact and fate once released into the environment. Hence, this study presents a new biodegradable epoxidized soybean oil acrylate (ESOA)/zein-based coral putty capable of quick hardening underwater as an ecofriendly alternative for transplantation of new coral colonies in the reef. Coral putty is composed of two components, containing one a radical initiator and the other a radical accelerator. Once the two components are mixed, coral putty becomes hard underwater in 20–25 min, showing a hardening timescale much faster than other commercial products. The coral putty is biocompatible when applied to the coral Stylophora pistillata in aquaria and Acropora tenuis corals are out-planted on the reef in the Maldives, demonstrating how this new class of vegetable-oil-based materials can be a more sustainable alternative to epoxy resins commonly used in coral restoration procedures.