Environmental conditions have a strong influence on sea turtle population dynamics. Sea turtles spend most of their lives in foraging areas; however, there is a lack of information on how oceanographic and biological parameters determine habitat use and density. Here, we estimated density of green turtles Chelonia mydas and hawksbill turtles Eretmochelys imbricata in a South Atlantic foraging area (Arraial do Cabo, Brazil). We also investigated the influence of environmental variables (wind fetch, temperature, depth, and visibility) and benthic composition on the distribution of turtles. Surveyed sites were split between a colder, more wave-exposed location (western), and a warmer, more sheltered location (eastern). To ensure that these mobile and sparsely distributed species were adequately surveyed, underwater visual censuses (timed transects) were conducted. Sea turtle densities were significantly different between warm/sheltered and cold/wave-exposed locations. C. mydas were almost 10 times more frequently sighted than E. imbricata. The local distribution of E. imbricata mirrored large-scale latitudinal patterns, where this tropical species is dominant on warmer reefs (similar to habitat conditions found at the eastern location). It was not possible to assess the environmental influence on E. imbricata sightings due to their low density. C. mydas were frequently sighted in the cold/exposed sites and negatively correlated with depth. Overall, the density of E. imbricata and C. mydas suggests that Arraial do Cabo is an important feeding ground in the western Atlantic Ocean. This study highlights that visual census can produce reliable density estimates of sea turtles in foraging areas.

Biodiversity assessment is a mandatory task for sustainable and adaptive management for the next decade, and long-term ecological monitoring programs are a cornerstone for understanding changes in ecosystems. The Brazilian Long-Term Ecological Research Program (PELD) is an integrated effort model supported by public funds that finance ecological studies at 34 locations. By interviewing and compiling data from project coordinators, we assessed monitoring efforts, targeting biological groups and scientific production from nine PELD projects encompassing coastal lagoons to mesophotic reefs and oceanic islands. Reef environments and fish groups were the most often studied within the long-term projects. PELD projects covered priority areas for conservation but missed sensitive areas close to large cities, as well as underrepresenting ecosystems on the North and Northeast Brazilian coast. Long-term monitoring projects in marine and coastal environments in Brazil are recent (<5 years), not yet integrated as a network, but scientifically productive with considerable relevance for academic and human resources training. Scientific production increased exponentially with project age, despite interruption and shortage of funding during their history. From our diagnosis, we recommend some actions to fill in observed gaps, such as: enhancing projects’ collaboration and integration; focusing on priority regions for new projects; broadening the scope of monitored variables; and, maintenance of funding for existing projects.

Sea turtles spend most of their life cycle in foraging grounds. Nevertheless, given the logistical ease, bulk of studies are carried out in nesting grounds. One strategy to gather information in foraging grounds is the use of cost-effective and non-invasive techniques that allow public participation. The present study aimed to use photographic-identification to investigate the spatio-temporal distribution of Chelonia mydas and Eretmochelys imbricata. Furthermore, we describe the occurrence of fibropapillomatosis. This work was carried out at subtropical rocky reefs of the Brazilian coast in Arraial do Cabo (22°57’S, 42°01’W), within a sustainable conservation unit. The images were obtained through social media screening, citizen science and intentional capture. A total of 641 photos (between 2006 and 2021) and 19 diving forms (between November 2019 and March 2020) were obtained. All diving forms presented at least one turtle. The photo-id identified 174 individuals of C. mydas, with 45 resighted individuals. E. imbricata had 32 individuals identified, and 7 individuals resighted. The median interval between the first and last individual sighting was 1.7 years for C. mydas and 2.4 years for E. imbricata. Fibropapillomatosis was only observed in C. mydas, with a prevalence of 13.99% and regression in 2 individuals (10.00%). The results indicated Arraial do Cabo as an important development area for sea turtles with resident individuals showing fidelity for at least 6 years. As the region accumulates anthropogenic impacts, it is critical to propose significant management measures to protect sea turtles from continuous and synergistic impacts, mainly on resident individuals.

Sea turtles spend most of their life cycle in foraging grounds. Research in developmental habitats is crucial to understanding individual dynamics and to support conservation strategies. One approach to gather information in foraging grounds is the use of cost-effective and non-invasive techniques that allow public participation. The present study aimed to use photographic-identification (photo-ID) to investigate the spatio-temporal distribution of Chelonia mydas and Eretmochelys imbricata . Furthermore, we describe fibropapillomatosis occurrence. This work was carried out at subtropical rocky reefs of the Brazilian coast in Arraial do Cabo (22°57ʹS, 42°01ʹW), within a sustainable conservation unit. A total of 641 images were obtained through social media screening (n = 447), citizen science (n = 168), or intentional capture (n = 26) dated between 2006 and 2021. Additionally, 19 diving forms (between 2019 and 2021) were received from citizen scientists. All diving forms presented at least one turtle. Photo-ID identified 174 individuals of C. mydas , with 45 being resighted, while E. imbricata had 32 individuals, with 7 individuals resighted. The median interval between the first and last individual sighting was 1.7 years for C. mydas and 2.4 years for E. imbricata . Fibropapillomatosis was only observed in C. mydas , with a prevalence of 13.99% (20 of 143 individuals) and regression in 2 individuals (10.00%). Our results indicated that Arraial do Cabo is an important development area with individuals residing for at least 6 years. This study demonstrated that social media, along with photo-ID, can be useful to provide sea turtle estimates in a foraging ground using a non-invasive, low-cost method. Supplementary Information The online version contains supplementary material available at 10.1007/s00227-023-04226-z.