Development of artificial structures by 3D printing of biosourced materials for reef restoration

Ph.D. opportunity in Ocean and Marine environmental sciences

Scientific context

Coral reefs play a key role in the marine environment, its balance and biodiversity, providing
nursery grounds and shelter for a wide range of organisms. They also help protect coastlines from
erosion. However, their decline is now a proven fact, accelerated by global warming and ocean
acidification. Almost a quarter of these reefs have already disappeared. One strategy for restoring
damaged areas is to build and deploy artificial reefs, but several obstacles remain: (i) materials
used to date are often not environmentally friendly, (ii) they are shaped according to architectures
that do not match to the original, (iii) they poorly take in account the biological and physical
factors that aid coral larval navigation, settlement and post-settlement survival.

This PhD thesis is part of the NACRE-3D project, funded by the French National Agency of
Research, which aims to overcome these obstacles through the development of biomimetic
artificial coral reefs using 3D additive manufacturing based on sustainable, partly recycled
materials with a chemical composition close to that of coral. More specifically, NACRE-3D
explores the potential of a low-cost 3D printing technology, Binder Jetting, whose flexibility makes
it possible to manufacture both small and large structures with multi-scale porosity adapted to
di erent restoration cases. Raw materials used are CaCO3 powders recycled from oyster shells,
and binders are biosourced and with a low C-footprint. In addition, 3D structures are
functionalized with coral growth boosters using porous CaCO3 microspheres, synthesised on
demand, which are loaded with active species and used as delivery vectors.

Objectives

The goal of the thesis is to contribute to the development of artificial structures by 3D printing of
biosourced materials for reef restoration. The PhD candidate will : (i) test biomimetic, durable and
functionalized 3D structures in the marine environment using an approach combining ex situ
seeding of sexually propagated corals and in situ nursery, (ii) optimize the structures in terms of
geometric, chemical and biological characteristics using experiments and/or computational
modeling, and (iii) conduct a cost-e ectiveness analysis to assess the e icacy of the structures
compared to current restoration solutions. Structures will be produced at the CIRIMAT (Toulouse,
France) by another PhD candidate. Both PhD candidates will work in close interaction.

Scientific conditions and Financial support

Work will involve scientific diving and field and laboratory experiments in Moorea (French
Polynesia) for a long duration (~30 months). The CRIOBE station will provide laboratory and field
research facilities (experimental ecology station including ex situ larval rearing and seeding
facilities and aquaria with controlled parameters, in situ coral nurseries, diving and boat
operations, imagery and optic laboratories). The project o ers an opportunity to collaborate
across disciplines at the interface between marine biology, materials science and
processengineering through collaborations with CIRIMAT (Université Toulouse) and IRCER
(Université de Limoges). PhD grant and research will be funded by the NACRE-3D project (ANR-24-CE51-2845).

Requirements

Applicants should hold a Master degree in Marine Biological Sciences and a French diving
certification (Certificat d’Aptitude à l’Hyperbarie classe 1B or more). Experiences working on coral
reefs or marine larval ecology are preferred. Experience in computational modeling and
simulations will be an asset. Candidates should be physically fit, willing to work for long hours,
fluent in English and/or French, able to work independently in an interdisciplinary setting, and
have strong data analysis and scientific writing skills.

Supervision and Doctoral school

PhD supervisor : Maggy NUGUES (CRIOBE, Perpignan)
Co-supervisors : Sophie GUILLEMET (CIRIMAT, Toulouse) and Laetitia HEDOUIN (CRIOBE, Moorea)
Ecole Doctorale 472 PSL-EPHE, doctorat PSL, mention Océanologie biologique et Environnement marin

Duration

Position is due to start on September 1, 2025 for a period of 3 years.

Application

Interested candidates should send a motivation letter, CV with list of 3 referees, and copy of their
Certificat d’Aptitude à l’Hyperbarie (CAH) to Maggy NUGUES (maggy.nugues@univ-perp.fr). Only
short-listed candidates will be notified.

Closing Date

March 10, 2025 or until a qualified candidate is identified.