Plastic pollution can affect the emergence patterns of loggerhead turtle hatchlings

Abstract

Coastal urbanization, plastic pollution and climate change are increasingly affecting marine turtles' nesting habitats. In addition to facing risks of mortality due to saltwater inundation or predation, their eggs and hatchlings' might also be affected by plastic debris accumulation on beaches, but no studies to date have analysed such impact. To analyse whether plastic pollution on nests' surfaces affects the embryos' and hatchlings' survival odds, we designed a field experiment in a turtle hatchery on a nesting beach of the loggerhead turtle (Caretta caretta) in Boa Vista Island (Cabo Verde). We applied three treatments with distinct plastic levels (18 nests per treatment): control (no added plastics), low density (64 plastic fragments with 24.5 g of plastic weight per nest) and high density (128 plastic fragments with 49.0 g of plastic weight per nest). Then, we tested 16 variables related to the incubation period, emergence period and hatchlings' fitness. Our results suggest that nests with high plastic density have a significantly lower probability of successful emergence. Moreover, plastics also affected the synchronized emergence of hatchlings, with more scattered and smaller emergent groups, which might increase the predation risk. Considering that turtle nesting habitats are becoming increasingly threatened, this additional threat might compromise the survival of turtle hatchlings on beaches.