The first thing anyone discovers when trying to plant corals, is that it takes money and lots of hard work! This is a reminder of how important existing coral cover is. Protecting existing coral stock, and its ability to continue producing larvae, are the first and most basic steps. This protection is achieved through local management practices, responsible tourism and Marine Park regulations.
The genesis of the Coral Nurture Program has been via research into ways to speed up coral planting, which led to the testing of Coralclip®. This patented device is a small clip that enables a diver to attach a coral fragment or larval settlement unit to the reef in just a few seconds. This avoids the need for messy and laborious chemical fixatives that have long been favoured to re-attach corals to the reef. An experienced diver can plant over 100 corals using Coralclip® in a dive. A team of 8 divers can potentially plant up to 3,200 corals in a day, with a target cost of $1 per successful coral colony. This approach is not intended to replace coral on a reef-wide scale. The intended scale is multiple, geographically separate, individual locations across the Great Barrier Reef, of around one to two hectares each with ongoing coral planting when appropriate, rather than a once-off effort.
Coral planting can sometimes be done without the need for a coral nursery. On a healthy reef with reasonable coral cover, it is normal to have some broken coral. In the same way that old trees can fall in a forest and break surrounding vegetation, large colonies of fragile coral are vulnerable to damage in rough weather. Fish such as Bumphead Parrotfish can also be quite destructive when they are feeding.
Loose coral fragments (called “fragments of opportunity”) sometimes re-attach, but this is often prevented by wave action, they may fall onto another coral colony, or fall onto sand and ultimately be smothered. The easiest source of coral fragments that can be planted, is from regularly collecting these broken fragments and planting them securely in places where they have room to grow well.
There are strict permit conditions about collecting and planting these “opportunity” corals. Doing so with corals that have survived coral bleaching, where their neighbours have died, has potential to be a meaningful way of slowly, but methodically, increasing the prevalence of the corals that are already adapted to that site (survivor corals).
If a location has insufficient opportunity corals, for example due to very low live coral cover, the next step is to propagate corals in a nursery that can then be out-planted. There are a number of important considerations in coral nursery practices that need careful scientific guidance. A permit from GBRMPA is also strictly required.
During 2017 and 2018 we tested a new nursery design using cost-effective materials, readily available in Queensland. These are easy to deploy and remove and, if located correctly, are low maintenance with herbivorous fish keeping them clean. Scientific guidance is needed in deciding what to grow, but the actual nursery practices are low tech and easy to deploy and maintain if daily access is possible. This program enables small individual research coral nurseries to be deployed at tourism sites and be maintained by trained tourism crew.
Both commercial coral culture for the aquarium trade and reef restoration projects around the world, have been using coral nurseries for some time, although they are a new addition on the Great Barrier Reef. There are a number of potential pitfalls that must be avoided in nursery practice, and that therefore require rigorous scientific process. Very little knowledge still exists of what coral species grow best, where and when on the Great Barrier Reef. So, fundamental high quality science is also needed to determine what to grow and to minimise the incidence of wasted expenditure due to propagated corals dying in future bleaching events or disease outbreaks. As part of the Coral Nurture Program we have already implemented several key research steps, including the following:
Tracking Success: We developed a novel scoring metric to evaluate “success” based on coral growth and survival measurements. Scores from nursery and out-planting efforts around the world were used to evaluate which species were likely to be best to grow on our GBR nurseries. Scores can be used over time to track whether improvements in practice are required, to sustain cost-effectiveness (Suggett et al, 2018).
Developing Standard Operating Practice: A central activity of the Coral Nurture Program is adopting “Best Practice”. We are working with RRAP to ensure we have consistent regional-wide practices for reporting growth, survivorship and hence “success”. Local operators are trained in collecting this data, which then enables us to track how population and environmental variation regulate the capacity of species to grow across the GBR.
Collecting and collating the data from a coordinated program at scale enables its effectiveness to be tracked and improved.