New designs to give coral settlers a headstart for restoration
Coral restoration that takes advantage of the corals own natural reproduction (Sexual Coral Restoration), is not limited in the number of coral larvae. During one spawning event scientists and restoration practitioners may be able to collect millions of coral gametes and fertilize them by up to almost 100%, depending on location and species. However today, the absolute number of corals available for restoration efforts is mainly limited by the survival of coral settlers in their fragile early life stages, as well as by the time needed to transplant the bred corals onto the reef.
“One of the ways SECORE is aiming to reduce the costs of restoration is by designing substrates for corals to settle on that do not need to be manually attached to the reef, but rather can be sown, similar to how a farmer would sow seeds in a field,” explains Aric Bickel, SECORE’s Project and Workshop Manager. “We call these settlement substrates ‘seeding units’. The seeding unit needs to be attractive for coral larvae to settle on, as well as giving them shelter to enhance the otherwise very low natural survival rate of coral settlers in the wild.”
Photos: left) Pilot test study on large-scale restoration techniques conditioning settlement substrates in Mexico; mid) young outplant of the endangered elkhorn coral colony on Curaçao; right) mature elkhorn coral of the first raised cohort, 7 years old, Curaçao (all Paul Selvaggio/SECORE International).
In a pilot study, the first generation seeding units, nicknamed tetrapods, have shown the potential of the sowing concept to support the upscaling of coral restoration. After several years of trials with the tetrapods and other substrates, SECORE started a project in 2017 to create a second generation of seeding units. Together with long-term partner The California Academy of Sciences, SECORE reached out to the Autodesk Foundation to enlist their support for engineering and design expertise that could support the creation of a suite of new seeding unit prototypes. The challenge for this group was to take all the lessons learned about shape, surface texture, microhabitat, and material, and incorporate them into a set of designs that eventually could be produced on a large scale.
Photo: top) Inspecting new coral settlement prototypes; on the right Aric Bickel, SECORE's Workshop and Project Manager (California Academy of Sciences); mid) Different stages of the substrate production. The new prototypes are 3D printed (Andrew Meyer and Andrew Jeffery of Boston Ceramic) bottom) The 2nd generation of SECORE seeding units. (Reef Patrol / Valerie Chamberland/Vincent Lavigne)
One focus was to find a material and surface texture that would help to reduce the competition towards corals on the seeding units. The difficulty here was to find the balance between a texture that is attractive enough for corals to settle on, yet smooth enough to hamper growth of fouling organisms such as turf algae on the seeding units. The microhabitat is also critical to the success of these units; there need to be sheltered spaces that protect corals from predators and grazing. Additionally, the seeding units had to have a shape, which enables them to self-attach to the reef by getting locked in little crevices and holes. Finally, the substrates must be able to be manufactured at large scale at low price.
7 prototypes with different shapes and surfaces were developed with the help of Emerging Objects, a design firm spun out of the University of California, Berkeley. After the development phase, SECORE decided to have all of the new prototypes 3D printed in time for 2018 field trials. “3D printing does not require molds, which significantly reduces the cost of prototyping a small number and does not restrict the shapes or surface structures we could experiment with”, explains Bickel. The seeding units are being manufactured by Emerging Object themselves and Boston Ceramics, a U.S. based company that specializes in 3D printing in ceramics.
Photos: Close-ups of the 2nd generation of SECORE seeding units. (Andrew Meyer and Andrew Jeffery of Boston Ceramic)
Through the Global Coral Restoration Project, SECORE and partners have set their sights on developing methods to implement large scale coral restoration, including the goal of outplanting 1 million seeding units by 2021 ('California Academy of Sciences and SECORE International aim to revolutionize coral reef restoration with one million pieces of concrete'). “Keeping this goal in mind, Boston Ceramics is one of the few companies we are aware of in the world that can potentially meet our expected needs for these units through 3D printing”, Bickel says.
At the moment, the prototypes are being shipped to SECORE's field locations in Curaçao, the Bahamas, Mexico, and Guam for field testing throughout 2018. The first ones will be tested during the Diploria spawning on Curaçao this June—which starts right now!
Photo: School of surgeon fish on a relatively healthy Caribbena reef at East Point, Curaçao (Paul Selvaggio/SECORE International)
Carin Jantzen, Aric Bickel