Ingestion of marine debris by juvenile sea turtles in coastal Florida habitats

Abstract

Digestive tracts from 51 sea turtle carcasses that washed ashore on the east and west coasts of Florida were examined for the presence of anthropogenic debris. Debris was found in 24 of 43 green turtles (Chelonia mydas), 0 of 7 Kemp's ridleys (Lepidochelys kempi), and 1 of 1 loggerhead (Caretta caretta). Ingested debris included plastic, monofilament line, fish hooks, rubber, aluminium foil, and tar. For green turtles, ingestion of debris was not significantly affected by location of stranding, season, or body size. Debris ingestion was significantly affected by sex of the turtle. Frequency of occurrence of debris was significantly higher in females, but differences in the mass or volume of ingested debris were not significantly different between the sexes. Although frequency of occurrence of debris was high in green turtles (56%), the mass and volume of the debris were small—mean 0.52% of wet mass of gut contents and mean 0.72% of the volume of gut contents, respectively. However, small quantities of debris can kill sea turtles; the death of at least two turtles in this study resulted from debris ingestion. The debris in the two turtles represented 4.6% and 5.8% of wet mass and 3.2% and 9.8% of volume of the gut contents, respectively. In both turtles, the debris represented inflated percentages because the turtles had not been feeding normally prior to death because the debris affected gut function. Sublethal effects of debris ingestion (e.g. absorption of toxins) has an unknown—but potentially great—negative effect on the demography of sea turtles.