Conventional Versus Bio-Based Microplastics—Altered Coloration of Two Freshwater Decapod Crustaceans

Plastic pollution is an escalating issue, and exposure to it can cause various negative reactions in different organisms. In response, bio-based plastics have been developed as a safer alternative for the environment, organisms, and humans. This study represents the first attempt to assess the impact of bio-based polylactic acid (PLA) and two conventional polymers: polyethylene (PE) and polystyrene (PS) on the growth, survival, and coloration of red swamp crayfish Procambarus clarkii, an invasive and aquaculture species of great economic importance and bamboo shrimp Atyopsis moluccensis, the popular species in aquarium industry. Juvenile crayfish were fed diets based on two types of commercial feed—insect meal and fish meal. The adult shrimp fed commercial crustacean food. The results showed that supply of polyethylene microplastic with food reduced the growth and coloration in P. clarkii. Polystyrene microplastic affected the carapace coloration in A. moluccensis, while no significant effect on growth was observed. Furthermore, the ingestion of bio-based PLA was associated with alterations in coloration in both crayfish and shrimp when compared to the control group. The observed changes in coloration may indicate a deterioration in body condition due to oxidative stress, potentially induced by exposure to stress factors, such as microplastic exposure. An increased abundance of Staphylococcus spp. was observed in the treatment water of crayfish-exposed groups. The addition of both bioplastic and conventional microplastics facilitates bacterial growth and resulted in an increased presence of Gram-positive bacteria. Our study provides the first evidence of coloration changes in decapods in response to microplastics, potentially linked to microorganisms that may contribute to an inflammatory response.