Isla Mar assists coral restoration after boat grounding

On January 17, a FURA police boat accidently grounded at Steps Beach in the Tres Palmas Marine Reserve. There was localized damage to the coral reef. On February 11, our team and colleagues cemented roughly 100 Elkhorn coral fragments to the reef to mitigate this damage.


Vessel grounding; from the accident report.

We surveyed the reef a few days after the grounding and estimated there was about 120 Elkhorn fragments available to replant. This was enough to get approval from NOAA's Coral Reef Restoration office to approve a restoration event. So, we partnered with HJR Reefscaping and planned for a day in the water once the swell died down.





An elkhorn coral fragment; the PVC pole is 1 meter in length

On February 11, we were joined by representatives from several organizations who came out to help us with the restoration. The police dive team from FURA sent two divers to assist, Surfrider Puerto Rico's Community Manager volunteered, along with DRNA's biologist Dra. Nilda Jimenez, snorkeling volunteers from the Equipo de Respuesta a Emergencias de Arrecife (EREA). The event was filmed by Medalla Light's marketing team because we were using some of our recycled glass sand in the cement (we will share that video on our social media once it's available)! After several hours of work underwater, we planted 92 coral fragments with cement and then revisited the site the next day to secure 25 more fragments to the reef.


Although it sounds simple, and in essence it is, coral reef restoration does require some technical skill and knowledge of the surrounding coral reef environment. For example, we have to locate areas to replant the corals and these areas may not be directly at the site where the damage occurred. This is because 1) the restoration event can offer an opportunity to use the fragments in nearby areas where live coral coverage is currently low, 2) the area where the damage occurred may not provide enough suitable available habitat to replant, 3) the damaged area is not very accessible at the time of restoration (i.e. swell or surge in the water makes replanting there too difficult).


Once the chosen area is decided, our scientists have to evaluate the substrate (ground) before planting the corals. We have to ensure that we are not planting a coral next to competitive organisms like encrusting sponges or large areas of macroalgae. These organisms could quickly overgrow the coral fragment before it has a chance to secure itself over the cement. We also have to make sure we are not putting cement on top of areas with thick sediment cover because the cement itself will not stick to the substrate. This is why you may see photos and videos of us brushing the reef prior to planting (see below). The corals are never planted on top of other live coral.


Our diver brushes the substrate to clear an area for coral planting

There is a lot of preparation and planning that goes into coral reef restoration. Specifically, we cannot perform the work until we know there are at least 2-5 days of no swell forecasted for the area. If we replant the corals and then a swell comes in the next day, the fragments can become dislodged from the cement and negate any intervention we just did. Additionally, we have to have decent visibility so that we can see the reef in its entirety - both for the actual restoration process and for documenting the corals afterwards that same day. See the orthomosaic below (a series of photographs stitched together to create an "aerial" view of the restored area) which is not possible without good visibility, appropriate sunlight conditions, and limited swell or surge to the water.


An "aerial" view of the restored reef where every red number indicates a newly planted coral fragment. Photo by HJR Reefscaping

We will now continue to monitor these corals over time. The monitoring process is a very important and often underfunded or under-appreciated aspect of restoration because it allows us to understand the success of the restoration effort. In general, most coral reef restoration that we have conducted in the Tres Palmas Marine Reserve has been overall successful, which is great for promoting live coral coverage within such a delicate and important area of the west coast. After all, it was thanks to the massive Elkhorn coral populations in the reserve that prevented severe damage to the coastline in this area during Hurricane Maria and other strong natural events.


The day following the restoration, we went back out to the reef and checked on the corals to ensure that the cement had hardened and none had become dislodged. To our delight, all corals were accounted for and they are now ready to continue growing!


You can follow all of our coral restoration efforts by searching "Habitat Restoration" on this blog, or clicking on the related posts to view similar stories.