Harnessing the natural process of fragmentation to propagate large numbers of corals
Coral propagation by fragmentation is the restoration technique that we began our project with in 2012. This method is based on the asexual reproduction of corals and allows us to harness the natural process of fragmentation to propagate large numbers of corals. It enables us to produce thousands of corals without harming the wild populations.
By utilizing fragmentation, we can quickly restore coral populations using a well-established approach that has been used for years by reef restoration programs worldwide.
Today our nurseries which are distributed among several locations on the leeward side of Bonaire and Klein Bonaire can host over 23,000 corals. Each coral morphology is different and therefore there is no “one size fits all” approach. Depending on the species, corals are either hung from the branches of the trees or secured on trays.
Pop-up nurseries
We are always looking for innovative ways to scale up our restoration efforts. Nurseries that are installed temporarily next to an outplanting site, called pop-up nurseries, allow more time for corals to acclimate to the site conditions before being outplanted. Furthermore, by eliminating coral transportation between nursery and outplanting sites, these nurseries simplify logistics and reduce the stress on corals. After 2-3 years the nursery is removed and relocated to a new restoration site, leaving no trace behind.
Outplanting on the reef
Corals are selected in the nursery to be outplanted to the reef once they are “reef-ready”. This means their age, size, and overall health, makes them better-suited for survival when exposed to stressors that exist in greater abundance outside of a nursery environment. Genetically diverse corals are then tagged, taken to a selected restoration site, and outplanted back to the reef, using various methods.
Depending upon the species of coral and the environmental conditions of the reef, a variety of outplanting methods are used. Careful consideration goes into choosing an outplanting site and the method.
Corals in our nurseries
Staghorn Coral
Scientific Name: Acropora cervicornis
IUCN Status: Critically Endangered
# Genotypes in Nursery: 25
Staghorn coral used to be a major reef-building Caribbean coral species and, like elkhorn coral, is a shallow-water, branching coral that can form massive thickets. It is one of the fastest growing stony corals in the Caribbean. Thickets of staghorn provide shelter to many species of reef fish, especially juvenile fish. These corals prefer to grow in the “Staghorn Zone” from 5 – 15 meters of depth. Staghorn coral is particularly threatened by disease and bleaching in addition to reduced reproductive success due to geographic isolation, as once-massive thickets die off and only small patches remain. As a result of many threats and massive die-off, staghorn coral is at a high risk of extinction.
Elkhorn Coral
Scientific Name: Acropora palmata
IUCN Status: Critically Endangered
# Genotypes in Nursery: 25
Elkhorn coral, along with staghorn coral, was a predominant reef-building coral in the Caribbean until its rapid die-off in recent decades. It is a shallow-water, branching coral that provides an important habitat for reef-dwelling fish species, both mature and juvenile. Elkhorn coral likes to grow in depths of 0 – 5 meters, where its strong branches help break the force of wave action along the coast. In fact, sometimes colonies grow so shallow that they become exposed at low-tide. Due to a combination of disease and environmental impacts, the species has declined since the early 1980s to less than 3% of its former abundance. Without immediate action, our reefs stand to lose this species.
Lobed Star Coral
Scientific Name: Orbicella annularis
IUCN Status: Endangered
# Genotypes in Nursery: 12
Lobed star coral is one of the five major reef-building Caribbean corals, becoming more predominant as species of branching corals have collapsed in recent decades. Although they may not look like a star from afar, star corals take their name from the star-shaped pattern of their corallites. Until the mid-1990s lobed, mountainous, and boulder star corals were thought to be one species, Monstatraea annularis, that altered its form to available light conditions. Molecular analysis has since shown that these corals are indeed separate species. Lobed star coral grows from depths of 0 – 80 meters and takes the shape of several columns, or lobes, clustered together. This species has the largest average colony size of any coral species and plays an important role in protecting shorelines from surge. This species is susceptible to bleaching and is at risk of extinction due to mature coral heads dying off faster than new heads are formed.
Mountainous Star Coral
Scientific Name: Orbicella faveolata
IUCN Status: Endangered
# Genotypes in Nursery: 12
Mountainous star coral is one of the five main reef-building corals of the Caribbean. While its star-shaped polyps may look similar to those of lobed star coral, mountainous star coral can be identified due to its large, continuous shape that may be punctuated by peaks and valleys. This coral is often a deep brown with florescent green or yellow highlights. Its ideal depth range is 10 – 20 meters, but this coral can be found up to depths of 40 meters. Due to its size and encrusting nature, mountainous star coral stabilizes reefs while adding mass. The species is greatly affected by bleaching because it subsists nearly entirely off of photosynthesis rather than also capturing prey from the water. Additionally, mountainous star coral takes a long time to reach sexual maturity, 3 – 8 years, in comparison to its average life-span of 10 years. Both of these facts put it at risk of die-off.
Great Star Coral
Scientific Name: Montastraea cavernosa
IUCN Status: Least Concern
# Genotypes in Nursery: 12
The only species belonging to the genus Montastraea, great star coral is easily distinguished from other star corals by the large size of its individual polyps, which are often about the size of a thumb nail. Great star coral forms heads up to 2.5 meters in diameter and can live anywhere from 0 – 90 meters of depth; they are often the predominant coral species between depths of 12 – 30 meters. While they tend to grow in small mounds at shallower depths, coral heads of this species can become more plate-like at deeper depths. This coral comes in a variety of colors, such as dark brown, light brown, and white; and can even take on a red or orange florescent sheen during the day. The coral may resemble a bumpy boulder during the day, but at night the coral is often seen with its polyps extended in order to feed.
Maze Coral
Scientific Name: Meandrina meandrites
IUCN Status: Critically Endangered
# Genotypes in Nursery: 12
Maze coral is a stony coral species found primarily throughout the Caribbean Sea and Gulf of Mexico. It’s easily identifiable by its distinct, wall-like ridges called “corallites”, mini structures of calcium carbonate secreted by each polyp. M. meandrites has been observed to withstand challenging environments, namely water with high turbidity and sedimentation. Though they usually prefer depths of 8 – 30m, colonies can survive anywhere between 1-80m. Listed as Critically Endangered on the IUCN Red List, maze coral has suffered major population declines due to the widespread impact of Stony Coral Tissue Loss Disease (SCTLD). Prior to the introduction of this disease throughout the Caribbean, the species was categorized as Least Concern.
Pillar Coral
Scientific Name: Dendrogyra cylindrus
IUCN Status: Critically Endangered
# Genotypes in Nursery: 5
Pillar corals are a type of stony coral found in tropical regions throughout the western Atlantic, usually as deep as 20 meters (65 ft). True to their namesake, pillar corals build tall, vertical structures that can reach up to 3 meters high. Their unique morphology not only provides important habitat for fish and other reef creatures, but also creates a barrier to absorb the impact of storm surges before they reach shore. Their polyps sometimes feed during the day, one of the few species of hard-corals that have been observed doing so. This species is listed as Critically Endangered on the IUCN Red List, due to a number of broad and local-scale threats. Low recruitment and survival rates in juveniles, susceptibility to diseases, and damage from hurricanes and tropical storms collectively contribute to its status. Like many other Caribbean coral species, Stony Coral Tissue Loss Disease has caused localized extinction in many regions – including large-scale extinction in Florida.
Elliptical Star Coral
Scientific Name: Dichocoenia stokesii
IUCN Status: Vulnerable
# Genotypes in Nursery: 6
Elliptical star coral, also known as pineapple coral, inhabits reefs throughout the Caribbean. It prefers depths of 5-20m, but can be found up to 70m deep if enough light is available. This uniquely shaped coral has elongated, characteristically oval polyps that provide shelter for small fish and invertebrates. Though it’s heat tolerance is relatively high compared to other stony coral species, Dichocoenia stokesii is highly susceptible to Stony Coral Tissue Loss Disease (SCTLD) and other triggers of bleaching. This species is listed as vulnerable on the IUCN Red List, with recent declines in its population primarily attributed to slow growth rates and limited reproduction in the face of SCTLD.
Symmetrical Brain Coral
Scientific Name: Pseudodiploria strigosa
IUCN Status: Critically Endangered
# Genotypes in Nursery: 12
Symmetrical brain coral is a colonial type of stony coral growing at depths of up to about 40 meters (130 ft). Its namesake “brain-like” dome can reach almost 2 meters (6 ft) in diameter, acting as structural reinforcement for any reef it’s a part of. This widespread brain coral species occurs throughout the Caribbean Sea and Western Atlantic, and can sometimes be found on muddy stretches of seabed or degraded reef. P. strigosa grows very slowly, adding only about 1 centimeter (0.39 in) to its diameter per year. Unfortunately, it’s slow growth rate doesn’t bode well for natural recovery following disease events, like Stony Coral Tissue Loss Disease (SCTLD). Just like many other stony coral species, SCTLD has caused significant mortality in many populations of symmetrical brain coral. Because of SCTLD and other climate-related threats, this species is considered Critically Endangered on the IUCN Red List.
