Contaminação por microplástico em ovos não eclodidos de tartaruga-de-pente Eretmochelys imbricata em praias urbanas de Fortaleza/CE

Abstract

Sea turtles, such as Eretmochelys imbricata, face severe threats from microplastic (MP) pollution—synthetic particles smaller than 5 mm—that can be transferred from the mother to the eggs. This study investigated the presence of MPs in unhatched E. imbricata eggs on urban beaches in Fortaleza, focusing on quantifying and classifying pollutants by size, color, and material type, as well as comparing their presence in embryonated and non-embryonated eggs. A total of 48 eggs were collected within 72 hours after nest hatching, from 24 nests on Futuro and Sabiaguaba beaches, between January and June 2024, under SISBio license number 53083-12 issued by ICMBio. Two eggs per nest were randomly selected, cleaned, and stored at -10°C. After thawing, the eggs were weighed, measured, and subjected to chemical digestion with 10% potassium hydroxide (KOH) to remove organic material, being heated at 60°C for 24 hours. Negative controls were conducted to monitor external and reagent contamination. After digestion, the samples were vacuum-filtered using 0.45 μm membrane filters and dried for 48 hours. MPs were identified, quantified, and classified by size, color, and type (e.g., blue, red, transparent; fragments, fibers, films, spheres) using a stereoscopic magnifier. The average egg weight was 30.19 ± 3.21 g (ranging from 20.6 to 36.0 g), and the mean diameter was 37.28 ± 1.33 mm (ranging from 34.1 to 40.5 mm), with low standard deviation, indicating little variation in egg dimensions. A total of 125 MPs were identified, with filaments being predominant and blue as the most common color. MPs were found in eggs from 21 nests. Statistical analysis showed no significant correlation between MP quantity and egg weight (CS: 7.214, p > 0.2837) or between the presence of an embryo and the quantity or size of MPs (MW: 310, p = 0.7809). Non-embryonated eggs had an average of 0.8042 particles, while embryonated eggs had 0.7645, with no significant statistical difference between groups (T-test Welch = 0.60493, p = 0.7986). The study confirmed the presence of MPs in the eggs, with a predominance of blue filaments, and suggested that variations in size, color, and MP type indicate different incorporation mechanisms. Larger fragments were more prevalent in non-embryonated eggs, suggesting a stronger toxic effect on embryonic development. Future research should investigate the origin and toxic effects of these materials, tracing their impacts on the reproductive health of sea turtles and contributing to the conservation of this threatened species.