Marine geophysics on Ilha das Couves: initial surveys by PROMAR

Between late March and early April 2025, I participated in the first field activities of the PROMAR project – Program for Mapping Underwater Habitats in Marine Protected Areas of São Paulo, an initiative funded by FAPESP and coordinated by Prof. Dr. Luis Américo Conti (EACH-USP), which seeks to strengthen marine environmental management using high-resolution acoustic data.

Team during scientific operations in Picinguaba Bay, Ubatuba (SP).

Our starting point was the Clarimundo de Jesus Base (USP) in Ubatuba, where we participated in intensive training to operate the Edgetech 6205 system, an interferometric sonar that integrates multiphase bathymetric data and side scan sonar images. The course lasted 60 hours and included theoretical and practical classes taught by specialists from TESSEC Soluções Marítimas — representatives of the manufacturer in Brazil. It was a valuable opportunity for exchange between researchers, technicians, and students from different institutions, such as USP, UNIFESP, IPT, and Fundação Florestal.

View from the Clarimundo de Jesus Base (USP) observation deck, an essential support point for PROMAR activities in Ubatuba.

The next stage took place at sea: aboard the Santorini trawler, specially adapted for the mission, we set sail for Ilha das Couves, in the Picinguaba Bay region. This area was chosen as a pilot based on a spatial prioritization model developed by the project, which took into account ecological aspects, human uses, and operational logistics.

Sailing between Ilha das Couves and Picinguaba Bay — a stunning backdrop that marked our return to base after another productive day mapping underwater habitats.

During the field activities, one of the most enriching aspects was the interaction between team members—composed of professionals and students from different fields of knowledge, such as geology, oceanography, marine sciences, biology, and engineering. This diversity of backgrounds not only strengthened the multidisciplinary nature of the project, but also fostered the exchange of experiences and the collective construction of solutions at each stage of the expedition.

Part of the team on the daily journey between the coast and the Santorini boat — transfer carried out on a support boat for embarkation and disembarkation. For the more adventurous, there was also the option of swimming back to the beach.

Another noteworthy point was the relationship established with the local community. In particular, the participation of the boat's pilot stands out, whose experience with navigation in the region and practical knowledge of sea conditions were fundamental to the success of the campaign. His integration was such that, more than a service provider, he became a true member of the team — actively contributing to logistical and operational decisions throughout the working days.

Part of the team during acoustic data acquisition in the vessel's cabin. The diversity of backgrounds—including geology, oceanography, marine science, biology, and engineering—was essential to the success of the field activities, promoting rich exchanges and truly collaborative work.

During our days at sea, we acquired bathymetric data and acoustic images of the seabed, covering an area of more than 500 hectares. There were 114 navigation lines, totaling approximately 98 km of survey mode surveying. The strategy also included the use of an ROV for visual inspection at points of interest identified in the acoustic data. All of this was supported by software such as Qinsy, Qimera, and MOGA SeaView, which are being used to process the mosaics and refine the seabed models.

Image from the monitor during ROV operation, allowing real-time investigation of the seabed. This tool was essential for supplementing acoustic data with direct visual observations of underwater habitats.

The first images reveal a rich diversity of underwater habitats, with rhodolith beds, sandy bottoms, rocky outcrops, and complex sedimentary structures, indicating the potential of the approach to support ecosystem-based management in the state's protected areas.

Surveyors at work.

More than just data, this experience marks the beginning of a collaborative journey that brings together technology, science, and environmental conservation. PROMAR is just getting started, but it already shows how scientific knowledge can be the basis for more sustainable and effective decisions for our seas.

Santorini somewhere on the expedition.