Reformative Coral Habitats | Reef Tiles

Department: Architecture
Research Centre: Fabrication and Material Technologies Lab
Active Dates: August 2019 - July 2020

Reformative Coral Habitats | Reef Tiles
Rethinking Artificial Reef structures through a robotic 3D clay printing method.

Project Credits:
Robotic Fabrication Lab | Faculty of Architecture | The University of Hong Kong
Christian J. Lange (Team Leader)
Lidia Ratoi
Dominic Co Lim
Jason Hu

Swire Institute of Marine Science (SWIMS) | The University of Hong Kong
David M. Baker, Ph.D. (Team Leader)
Vriko Yu
Phil Thompson

The coral restoration project is a collaborative research mission between the Robotic Fabrication Lab, Faculty of Architecture, and the Swire Institute of Marine Science, both at The University of Hong Kong. The project is commissioned by the Agriculture, Fisheries and Conservation Department (AFCD) and is part of an ongoing active management measure for coral restoration in Hoi Ha Wan Marine Park in Hong Kong. Hoi Ha Wan Marine Park accounts for more than three quarters of reef building coral species in Hong Kong, and is also a home for more than 120 reef associated fishes. However, gradual deterioration by bio-erosion over the years, coupled with bleaching and mass mortality events in 2015-2016, are putting local coral community at risk. Hence, a team of marine biologists and architects has developed a series of reformative 3D printed terracotta reef-structures intended to aid coral restoration by providing structurally complex substrates at a degraded area.

Historically, artificial reefs are made from pollutants-leaching materials (e.g. plastic/concrete/metal) and now transformed into environmentally friendly materials (e.g. ceramic and terracotta). The project team from HKU uses 3D printing technology to engineer structures that can be customized for specific locations with different environmental challenges (e.g. sedimentation), thus enhancing the ecological restoration success.

The 3D printed reef tiles are designed to prevent sedimentation build up, which is one of the major threats for corals. A tailored algorithm was used to print the biomimicry patterns integrated with spaces for securing coral fragments. The production of the 128 pieces of reef tiles with a diameter of 600mm, covering roughly 40 sqm in total, was finalized in early July of 2020. They were printed through a robotic 3D clay printing method with generic terracotta clay and then fired at 1125 degrees Celsius. The design was inspired by the patterns typical to corals and integrated several performative aspects addressing the specific conditions in Hong Kong waters. The 3D printed reef tiles have been deployed in July 2020 at three selected sites within the park which include Coral Beach, Moon Island, and in a sheltered bay near the WWF marine life education center.

This pilot study aims to investigate the restoration success using mono-, mix- and polyculture of three coral species, namely AcroporaPlatygyra, and Pavona. The three selected species display different strategies, representing the historical, current, and future dominant candidates in the park – Acropora, commonly known as staghorn corals, are fast growing making them a competitive species for space; Platygyra, as known as brain corals, are adaptive to thermal stress, yet suffering from bio-erosion; and Pavona, the leaf coral, with the unique plate-like growth form are adaptive to sedimentation. The project team collected corals of opportunity, which are dislodged coral fragments that are unlikely to survive given no human intervention and given these coral fragments a second chance to thrive. The coral fragments have been outplanted in July 2020, and the experiment will be monitored for the coming year.

The researchers hope that this new method for artificial reef tiles will help to restore corals and conserve biodiversity more effectively and become a vital contribution to the ongoing global efforts to save the degraded coral reef systems in metropolises.

Completion Year:  2020

Location: Coral Beach, Moon Island, and the WWF marine life education center, Hong Kong

Built Area (m2):  ~ 40 sqm

Funding body:  AFCD

UNIVERSITY OF HONG KONG
FACULTY OF ARCHITECTURE