Coral reef restoration is a popular subject at the moment with many projects sprouting all over the world. One of them caught our attention. In Indonesia, a coastal community of 26 young locals took the matter into their own hands and decided to fix their own damaged reef where they grew up, swam, and fished as young kids. Throughout their lifetimes, they have seen the local coral colonies slowly disappear, while the fish have gotten smaller, and some species have completely disappeared. Suddenly, there were no more Napoleon wrasses, large sharks left the area and giant clams were distant memories.

To the untrained eye, this place seems abundant with marine life. That’s the problem of so-called shifting baselines. The eye gets used to it, and if you haven’t seen what it looked like before, you won’t be able to notice the changes. But for people that grew up here, the change in marine life is striking.

Coral reefs around the world are in great danger. We already lost more than 50% of them, and the list of their threats keeps on growing. Their survival is greatly jeopardised, but a group of villagers on Nusa Penida, a small touristic island southeast of Bali, together with a local NGO called Ocean Gardener decided to start fixing up their reef which got damaged by large tourist pontoon moorings and boat anchoring.

To turn around the fate of their coral reef, the village first decided to revoke the pontoon license. It was then moved to another location, while fixed moorings were installed for diving boats. This was followed by the formation of a ‘Kelompok’, an association of villagers, and a coral lover group named Nuansa Pulau to educate and protect their reef. Led by their charismatic elder Pak Nyoman Karya, and together with different associations, including Ocean Gardener, they started to plant thousands of corals on their reef as part of their coral restoration project.

Nusa Penida is located right in the middle of the Lombok Strait, a deep trench that separates the islands of Bali and Lombok. Here, the Wallace line, a faunal boundary line, separates Asia from Australia. In 1859, Alfred Russel Wallace found out that this passage that is over 250m deep stops Asian animals to migrate east.

However, this special place is not only magical in regards to terrestrial fauna. The coral reef fauna of the Lombok Strait is one of the most diverse and richest in the world. This stretch is 60km long and 20km wide and channels waters from the Indonesian Throughflow into the area.Here, a large volume of warm, rich surface water from the Pacific Ocean flows into the cool, mineral-rich waters of the Indian Ocean. And just in the middle of all of this lays the magnificent group of the three islands Nusa Penida (the big one), Nusa Lembongan (the medium one), and Nusa Ceningan (the small one).

This small group of islands is known by divers all over the world as one of the best place to admire the great Mola alexandini, the sunfish, as well as manta rays which hover over some shallow cleaning stations at the bottom of the cliff in South Nusa Penida, and are suspected to have a breeding and nursery ground just south off the islands.

The north coast of Nusa Penida is a coral nerd heaven. Snorkelling the shallow waters just around the reef edge and observing the astonishing number of different coral species is mesmerising. The strait is also home to an endemic species of coral called Euphyllia balinensis that only very few privileged people have seen.

The Lombok Strait is a strong tidal mixing hotspot, and the northern coastlines of these islands have an invaluable mix of scleractinian corals. These hard corals have proven to be very resilient to climate change and tourism-induced pressure as healthy large table Acropora colonies and other corals still dominate the shallow water of Nusa Penida. This very special location is a genetic source flow for corals in the rest of the area and is of enormous importance for the future of coral reefs in this particular place of the world. 

They started off by setting up a nursery ; a step that is vital before any subsequent coral reef restoration project using coral fragments can be started. It was decided to create a rope nursery in the shallow, warmer water of the lagoon. These fragments of corals adapted to the slightly higher than average temperatures in the lagoon and were then intended to be planted in the shallow outer reef with slightly deeper, and cooler waters.

Then, restoration began: The first step was to plant out the very shallow branching corals that normally can be found on the reef’s front part to stabilise the top of the reef slope. The community group used foundation corals which were mainly branching-type hard corals from the genus Acropora, Hydnophora, Pocillopora. The coral fragments were attached to the cotton ropes that were suspended between stakes. Corals then grow in three dimensions until they reach the substrate and anchor into it, stabilising it at the same time.

Once the foundation branching corals are growing nicely, reaching the substrate, and stabilising it, the second phase can begin. Other coral species with slower growth or different growth shapes are added. In the meantime, the rope technique was modified – the group learned that by using bamboo pieces instead, they could grow a much broader diversity of corals. During the third phase, after the high energy shallow water outer reef is properly colonised and stabilised, the lower coral field is colonised.

During all this time, maintenance is critical, and every week, a group of four divers patrols the area, removing coral-eating parasites such as Crown of Thorn starfish and drupella snails that are especially abundant in disturbed reef areas as they are attracted by the smell of stressed corals. They remove any algae, sponges and soft corals that tend to overgrow the hard corals. They also tighten up ropes, replace damaged corals and do anything that increases coral survival, growth, and health.