Sub-Lethal Responses to Microplastic Ingestion in Invertebrates

This chapter discusses the range of sub-lethal microplastic responses reported for invertebrate species and applied the dynamic energy budget bioenergetic framework to highlight the energetic links that exist between the often-disparate responses. Microplastic ingestion can also occur incidentally, such as when gastropods ingest microplastics attached to surface of the seaweed they graze on, or when deposit-feeding annelids ingest mouthfuls of sediment that contain microplastics. The chapter uses the dynamic energy budget framework to identify mechanisms by which microplastic ingestion can generate sub-lethal responses, and we collate the experimental evidence for these potential mechanisms. The quality and amount of food an invertebrate can acquire is influenced by environmental conditions, such as season: the energy reserve acts as a buffer to dampen environmental food fluctuations, enabling organisms to survive periods where energy assimilation is insufficient to meet metabolic needs. Although the structure of digestive system varies among invertebrate taxa, digestion process is generally similar, and very much like digestion process in vertebrates.