Tubastrea advancing on the Brazilian coast

When the yellow tentacles of Tubastrea began to appear on the Brazilian coastline, it immediately raised concerns among scientists. This species, which does not naturally occur in these regions, was accidentally transported along with the movement of oil platforms and ships near Rio de Janeiro in the late 1980s. Since then, Tubastrea has started to colonize reefs along the Brazilian coast.

Tubastrea is characterized by its unique ability to survive in various conditions and rapid regeneration, making its removal challenging. In response to this threat, scientists from the Institute for Systems and Computer Engineering, Technology and Science (INESC TEC) developed technology to monitor this invasive species using underwater robotics.

The scientists conducted tests in Brazil in collaboration with the Research Laboratory of the Federal University of Santa Catarina (LASUB). As explained by Nuno Cruz from INESC TEC, the results are “promising.” The experiment involved placing buoys a few hundred meters from the diving zone while divers used signal-emitting devices, allowing the operations team to monitor their location and the presence of Tubastrea. Due to the inability to use GPS or radio signals underwater, the tests relied on acoustic signals.

The researchers adapted systems used in underwater robots to track the divers and locate Tubastrea. The developed technology included a device for locating underwater objects, a set of buoys connected to GPS, and a cylinder placed on the diver’s back, emitting sound signals.

The goal was to reduce the margin of error in locating Tubastrea affecting Brazil’s marine fauna. Through triangulation, the buoys determined the relative position of the underwater object, which, in combination with GPS, provided accurate coordinates.

During the two-day test, INESC TEC supplied an acoustic signal-generating device (pinger) and three localization buoys. The cylinder worn by the diver acted as a synchronized acoustic pinger, emitting a signal every second, which was detected by the buoys. The cylinder contained an acoustic transmitter sending “pings” underwater.

An internal atomic clock ensured precise timing of signal emissions, crucial for accurate pinger localization. The buoys detected the pinger’s sound, knew the emission moment, and calculated the travel time, providing data on the pinger’s distance. This information was then transmitted via radio to the support boat, where a computer compiled the data, enabling real-time monitoring of the diver.

This technology allowed precise determination, with an error margin of less than 1 meter, of Tubastrea locations, facilitating reliable monitoring of their removal process. This enabled scientists to track the development of Tubastrea colonies and their correlation with environmental conditions such as sunlight, currents, water temperature, and acidification.

Without this technology, monitoring would have been significantly more challenging and time-consuming. Divers would have had to mark Tubastrea areas, return to the surface, take photos of the surroundings, and pass them to the GPS boat crew, resulting in a high margin of error. The new technology allows divers to focus solely on searching for and identifying Tubastrea.

An additional advantage is the automatic digital recording of all dive data, making it easier to compare results with previous dives.

Although Tubastrea is the main concern, researchers are already considering using these systems to precisely mark other coral habitats.