O uso de drones na quantificação de tartarugas marinhas na APA Costa dos Corais - AL

Abstract

Occupying one of the most important niches in their environments - marine mega herbivores - green turtles contribute to the structuring of coral reefs in the control of algae and grasslands, which compete directly with corals. This important ecological role has been threatened over the centuries, with their populations being decimated as a result of anthropic pressures. Despite effective conservation efforts, population studies for the species still need to deal with a significant lack of information. Considering that population data are highly relevant both for the establishment and management of protected areas and for the protection of species, the present study aimed to (1) map the feeding areas of sea turtles in the Costa dos Corais Environmental Protection Area (APACC) using drones; (2) evaluate the ability of the protection area's zoning categories to contemplate the distribution of the species; (3) as well as to evaluate the relationship between strandings and sightings of the species in these areas. The study was developed at APACC, in the state of Alagoas. The flyovers were divided into 136 transects, covering a total of 20% of the study area. The number of sea turtles in each photograph was determined from manual counts. The number of sightings and the total area of the transects (km²) was used to estimate the density of sea turtles. Mortality was determined by the ratio between the estimated population size and the number of stranded individuals within each sampling unit. A total of 13,538 images were obtained in the 136 transects carried out, with 182 sea turtles sighted, distributed throughout the study area, and a sighting density of 6.65 turtles/km². Four central areas of greater density were observed, in the cities of Japaratinga, São Miguel dos Milagres, Barra de Santo Antônio, and Maceió. Manual counts were carried out in each of the zoning categories with 15 green turtles being sighted in the ZPRE, 87 in the ZPRO, and 80 in the ZUMO, the latter being the one with the highest density of sea turtles of 1.19 turtles/km². The relationship between central areas of greater density and areas with a greater number of strandings demonstrated the overlapping of both. The cities of Japaratinga and São Miguel dos Milagres show the highest mortalities and considerable densities. The results presented show that the APACC zoning categories are not effective in protecting Chelonia mydas, requiring changes in the spatial patterns of the categories in order to reduce the mortality of these animals, which also proved to be high.