Coral restoration and monitoring with drones

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Coral reefs are exceptionally valuable in terms of the ecosystem services they deliver. They provide food, livelihoods and economic opportunity to people in more than 100 countries around the world and protect shorelines from erosion. They are a source of enjoyment for national and international tourists alike. Hosting a quarter of all known marine species, they also play a critical role in the broader coastal ecosystem. (Source)

The health of coral reefs is hence of great importance for communities and economies making use of the ecosystem services provided. Yet, coral reefs throughout the Caribbean and worldwide are suffering great damages caused by mismanagement, overexploitation, pollution and climate change. To alleviate these damages and subsequently restore full functionality of reefs, coral restauration projects are taking place all throughout the Caribbean.

In Saint Lucia for example, the CATS Programme is collaborating with CLEAR Caribbean on the development and expansion of coral nurseries in the marine protected area managed by the Soufriere Marine Management Association (SMMA), for the asexual reproduction of endangered staghorn and elkhorn coral. The project will sustainably expand existing nurseries, facilitate an outplanting programme, train community members in coral restauration and establish a sustainable financing mechanism for restauration programmes, utilising revenues from “coral restauration dive tourism”.

Other methods to propagate coral are sexual reproduction and microfragmenting. But no matter which methodology is used, all coral restauration projects have the same objectives: revive, restore and expand coral reefs to fully function as an ecosystem and provide sustainable ecosystem services to local communities.


Coral larvae floating over substrate material onto which they will attach themselves

However, measuring the success of coral restoration activities is a labour-intensive task. Indicators such as coral cover, fleshy macroalgae cover, herbivorous fish biomass and commercial fish biomass have to be evaluated. Considering that reef ecosystems often span over vast areas, the amount of time required to collect representative data is enormous. To assist with these tasks, modern technology has been developed, adopted and adapted to capture information about coral reefs that assists in the monitoring and evaluation of restoration activities. In particular drones, both airborne and submerged, have been adapted to tasks related to environmental monitoring and can nowadays deliver near-real-time information in high resolution (time and spatial) at a comparatively low cost.

To learn more about underwater drones and share experiences about environmental monitoring with aerial drones, the CATS programme participated in a workshop on the monitoring of coral reefs with drones in Bayahibe, Dominican Republic. The participants of the workshop represented various sectors, underlining that healthy reefs are a concern for everybody: governmental representatives from the Dominican Republic and Costa Rica, non-governmental organisations such as Healthy Reefs, Fundacion Grupo Punta Cana, Raising Coral Costa Rica, FunDeMar, the private sector and GIZ as development agency. The Mexican start-up company Aqua Exploracion presented their underwater drones in detail and engaged the participants in vital discussions about further improvements and features of the drones.

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These underwater drones, often referred to as Remotely Operated Vehicles (ROVs) or simplified Rovers, are not only capable of capturing high resolution pictures and videos. Equipped with different sensors, all kinds of environmental data can be collected: water quality parameters, physical and chemical parameters. Even physical samples can be collected. Software and satellite navigation allow the ROVs to move almost autonomously through a reef area, capturing images along a pre-set route and allowing the 3D-visualisation of underwater structures.


Other than capturing information and imagery, drones have been developed to actively assist in the combat against invasive species such as Crown-of-thorns starfish or lionfish, which are threatening the health of coral and native fish species, respectively. Such drones are not only capable of patrolling areas of interest. They also identify the species, inject a lethal substance or harpoon the invader. With this technology, invasive species can be controlled very effectively and with much lower risk for divers.

However, no matter how sophisticated these drones are, they cannot and are not intended to replace divers. This technology is meant to assist activities conducted by specialists, reduce the risk to divers and provide a holistic picture about the constitution of the reef at hand.

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