Microplastics exposure affects the feeding behavior of the whiteleg shrimp Litopenaeus vannamei by impairing the appetite, olfaction and digestion

The ubiquitous presence of plastic products has led to widespread accumulation of microplastics (MPs) in the environment. Since MPs have been detected in nearly all aquaculture sites and natural habitats of the whiteleg shrimp Litopenaeus vannamei, their impacts on this species are of significant concern. However, the effects of MPs on shrimp, particularly on their feeding patterns, remain poorly understood. Therefore, this study investigated the potential effects of MPs on the feeding performance of L. vannamei. Our results indicated that MPs exposure significantly reduced feed intake, with shrimp exposed to micro-MPs and nano-MPs showing a 24.92 % and 28.48 % reduction in specific feed intake compared to the control, respectively. To elucidate the underlying affecting mechanisms, the olfactory response to feed attractants, the ion transporter activities, inflammatory status, lipopolysaccharide content, neuropeptide Y levels, digestive enzymatic activities, and gut microbial composition were also examined. We observed a delayed behavioral response of the shrimp to feed attractants, suggesting olfactory dysfunction. Our 16S rRNA sequencing indicated that MPs disrupted gut microbial homeostasis, leading to significant increases in gram-negative bacteria abundance to over 99.00 % in MP-exposed groups. This dysbiosis would influence appetite through the microbiota-gut-brain axis. Additionally, significant increases in digestive enzyme activities and oxidative damage were detected in the digestive system. In conclusion, this study demonstrated that exposure to environmentally relevant levels of MPs substantially impaired the feeding performance of L. vannamei by disrupting appetite regulation, olfaction and digestion.