Avaliação da ingestão de plástico por tartarugas marinhas no litoral do estado de Alagoas, Brasil

Abstract

Plastic in the oceans is a growing problem for the health of marine ecosystems. Regarding the impacts of plastic pollution, ingestion by marine organisms is probably the most serious and poses a major threat to sea turtle conservation. Plastic ingestion by turtles has increased over the past few years and has been reported for all species. Knowing the type of material and the original use of the debris ingested by turtles, as well as identifying the main variables that contribute to the input of plastics in coastal marine environments is crucial to try to prevent their entry into the environments and, consequently, minimize the impacts on marine biota. Therefore, the aim of this study was to analyze the plastic intake in sea turtles in the state of Alagoas and to classify the items found as to the type of material and original use. The presence of plastic on the state's beaches and the degree of beaches’ urbanization was also evaluated. Data from night light satellite images were used as proxy for urbanization of 15 sampled beaches along the Alagoas coast. Among the municipalities analyzed, Maceió presented beaches with the highest average light intensity. In the same way, 15 beaches were studied regarding plastic pollution in February and March 2020. The anthropogenic debris found was categorized according to the type of material (e.g., rigid plastic, flexible plastic, rubber, nylon, and rope) and classified according to the original use (e.g., plastic bags, fishing and food items). Plastic was the most commonly found material, with flexible plastic being the most present, accounting for 40.6%, followed by rigid plastic (19.5%) and Styrofoam (13.8%). To evaluate the ingestion of plastic, the entire digestive tract of the turtles was analyzed and all the material found was classified in the same way as the materials found on the beaches. We analyzed 227 sea turtles of the species Chelonia mydas found stranded dead along the coast of the state of Alagoas from May 2018 to March 2020. Altogether, 31.2% of the sampled turtles ingested plastic, with an average of 6.05 items per individual. Plastic was the main material ingested, with flexible plastic being the most present (64.6%), followed by nylon (24.1%). Only one third (30.3%) of the ingested items could be identified in relation to their original use, whereas mostly (69.6%) were unidentifiable fragments. The results here reveal the need for more effective actions focusing at the reduction and/or prohibition of plastic on the coast of Alagoas, thus preventing this pollutant from causing greater damage to sea turtle populations in the area, as well as all the local marine biota.