Drone Mapping in the Caribbean: Estimating the Abundance of Sargassum Seaweed from the Air

The Challenge

Dr. Baldwin explained that increases in sargassum are linked to a continuously warming planet. In recent years, influxes have not only increased in quantity but also in terms of frequency, now occurring up to eight months out of the year, oftentimes with critical marine life such as sea turtles and dolphins entrapped. With piles of beached sargassum up to 3 meters high, these rotting masses pose a health hazard to the coastal marine ecosystem ( like seagrasses, coral reefs and mangroves) and beach visitors alike. However, as she explained, if the sargassum could be harvested while still fresh, it could become part of the $13 billion global commercial seaweed market, thereby helping to offset the losses in tourism and fishery revenues, critical to livelihoods in the Caribbean. To inform clean-up operations and attract business entrepreneurs to take up the challenge of valorizing sargassum, it would be critical to be able to accurately measure and monitor the amount of raw material available.

Recognizing the time sensitivity of removal operations, Dr. Baldwin set out to create a surveying and estimation workflow that could be applied by teams working with her across the Caribbean. As an already-certified Part 107 pilot, drone technology seemed a natural fit.

The Solution

Dr. Baldwin utilizes DroneDeploy solutions developed for construction and agriculture as her conservation tools of choice. The Plant Health Variability Index is leveraged to quickly map and quantify the abundance of beached sargassum, and in a DroneDeploy first, is employed to map offshore mats of sargassum still floating in the ocean. Dr. Baldwin has also been able to map coral reefs up to a kilometer offshore with true-to-scale results. “We're able to detect the location of coral heads and even map the three-dimensional reef rugosity to show underwater features such as crevices or reef slope,” Dr. Baldwin stated.

From here, Live Map is used both on and offshore to ‘ground-truth’ mapping features, like identifying sea turtle nests or critical fishing areas. The tool is also leveraged to annotate the communities’ space-use patterns and knowledge of impacts to coastal infrastructure, with potential mitigation measures written directly on the aerial maps.

Compared to scientific surveying methods, this process presents a radical improvement in time, cost, and resources. “Previously, our team had to walk kilometers of shoreline, gather field samples, and manually process the data,” Dr. Baldwin explained, “this project is really exciting because accurate data collection is now easier, faster, and far more cost-effective than ever before!”

The Results

While traditional, physically-intensive beach field surveys may take up to three hours to conduct, a drone beach survey takes just 20 minutes and can cover 4 times the survey area. Additionally, panoramas, landscape photos, and video surveys provide supplementary information on the condition of beach monitoring. When integrated with drone mapping results, annotated field observations using DroneDeploy’s Construction Progress Report template documents findings, which is an added value for site-level planning and regional management applications. Moreover, cloud-based processing and centralized data storage allows drone teams around the Caribbean to work collaboratively with minimal resources to capture, store, and easily share information with various stakeholders around the world.

Since 2016, Dr. Baldwin has trained over 400 people across seven Caribbean islands in drone operations and mapping surveys. Throughout the course of the SargAdapt Project, the CERMES internal drone team has grown to four full-time individuals, plus rotational student volunteers. During year two, Dr. Baldwin will create a User’s Guide for the sargassum Drone Monitoring Protocol and train five drone teams (comprising 50 people) across the Eastern Caribbean in its use.