Project title: Recruitment-enhancing living materials for artificial and natural coral reefs

Project lead: Dr. Joan Anne Kleypas

Co-applicants: Dr. Daniel Wangpraseurt, Dr. Linda Wegley Kelly

Countries involved: Costa Rica, USA

Takes place: Costa Rica, USA

Supporting institutions: Raising Coral Costa Rica, University of California, Scripps Institution of Oceanography

Total budget: USD $984,067

Duration: 36 months

Project overview

In coral reef restoration projects, artificial reefs or substrates are often deployed to provide a suitable area for corals to settle and grow. But these artificial places are also available to other organisms that can use the space and outcompete corals, requiring extensive manual cleaning by practitioners to ensure the growth and survival of the corals. As such, using off-the-shelf settlement substrates can easily compromise the success of coral restoration actions. Therefore, it is urgent to develop substrates that facilitate coral growth but not the growth of other organisms. As of today, numerous studies have shown that the presence of species of crustose coralline algae (CCA) and their associated bacterial biofilms facilitate the highest settlement rates and recruitment densities for coral larvae. That is why this project aims to engineer substrates made from biopolymers containing CCA-enriched bacteria and their excreted compounds, to enhance coral settlement and reduce early-stage mortality. The team has previously been working on early prototypes under laboratory conditions, but now the researchers will take a step further towards developing a final product and test it in Costa Rica.

Specific objectives

1. Optimize the cultivation of beneficial microorganisms and harvesting of their metabolites.
2. Produce and test living coating powered by microorganisms.
3. Transfer the knowledge to networks of coral restoration practitioners in Costa Rica and the eastern tropical Pacific region.

How the objectives will be met

• Beneficial microorganisms & metabolites

• Collect seawater to sample and identify beneficial microorganisms associated with corals.
• Create a simple, optimized workflow for cultivating beneficial microbes.
  

• Manufacture the living coatings

• Test 5 types of bioinks for their capability to favor the encapsulation and growth of beneficial microbial communities.
• Identify the optimal coating solutions and synthesize them in larger volumes for field deployment.
  

• Field trials

• Test in situ the coating effectiveness on three substrate types, including reef stars, ceramic disks, and terracotta tiles.
• Optimize and test UV procedures in the field.
• Quantify the density and describe the distribution of new recruits on coated substrates versus uncoated controls (biweekly for the first 3 months; then, every month).
  

• Knowledge transfer

• Organize webinars, seminars, and hands-on training sessions for local stakeholders, including coral restoration practitioners and marine park officials.

Impact of the project

The successful completion of this project will result in the development of a bioink that can be applied as a coating to enhance coral recruitment success. Researchers anticipate that this method will increase larval recruitment directly in the field, therefore bypassing other restoration steps that often require a coral nursery phase.

The project will also build local and regional capacity by organizing multiple training sessions for practitioners and university students. These will cover CCA collection, cultivation, biopolymer application, and larval recruitment monitoring, and will include at least three local trainings and one regional workshop.

Major highlights

• Lab testing of 5 types of bioinks
• A thin layer of bioink is estimated to cost $2.5 per square meter
• The bioink will be applied using low-cost methods such as paint brushing and spraying of the material onto a set of restoration substrates
• Under laboratory conditions, the prototype bioinks experienced a 4-fold increase in recruitment compared to the controls.