Abstract

The invention of plastic based on synthetic polymers changed our lives forever; being one of the most versatile materials ever produced. However, its wide use has resulted in 9.5 million tons of discarded plastic waste entering the ocean each year, making plastics the most prevalent form of marine pollution today. Over time, plastics break down into microplastics, or are released directly from other products in which they are important components, such as personal care products (e.g. facial cleansers and toothpaste). These microplastic particles of 300-5000 μm in size are now present in marine sediments and the water column where they can be ingested by marine organisms, and passed up the food chain. This trophic transfer is an indirect, yet potentially major, route of microplastic ingestion by top predators, including humans. This study was carried out on four species of marine mollusc exhibiting four different feeding strategies: (1) a carnivore (Melongena corona bispinosa); (2) a herbivore (Pseudosuccinea columella); (3) a filter feeder (Ischadium recouvum); and (4) two species considered to be both detritivorous and herbivorous (Nassarius vibex). Microplastics were analyzed using a non-destructive method that involved sampling the individuals' feces. Sampling took place primarily in the Yucatan Peninsula, Mexico, ten individuals of each species were sampled. Microplastics were extracted from the feces samples by degradation of the organic matter, followed by re-suspension of the sample and examination under a stereomicroscope and using a scanning electron microscope. Microplastics were present in all mollusc feces samples and included fragments, fibres and sheets. The filter feeders and carnivorous molluscs were found to have significantly higher abundance of microplastics in their feces than the herbivores and detritivores.

PDF Preview