Microplastics in the tissues of commercial semi-intensive shrimp pond-farmed Litopenaeus vannamei from the Gulf of California ecoregion

The omnipresence of microplastics (MPs) in marine and coastal environments has attracted attention owing to their effects on various organisms, including humans. We present the first study of MPs in the gastrointestinal tract (GT), gills (GI), and exoskeleton (EX) of the farmed whiteleg shrimp Litopenaeus vannamei from commercial aquaculture facilities in northwestern Mexico that have operated semi-intensively for the last two decades. We found that the number of MP items per tissue was 7.6 ± 0.6 in the GT, 6.3 ± 0.9 in the GI, and 4.3 ± 0.9 in the EX, with an average of 18.5 ± 1.2 MP items per shrimp (1.06 items/g, wet weight [ww]). MP concentrations were 261.7 ± 84.5, 13.1 ± 1.8, and 2.6 ± 0.6 items/g (ww) in the GT, GI, and EX, respectively. Microplastics ranged from 30 to 2800 μm in size (360 ± 39 μm) with fibers (∼90.8%), filament-shape (∼93.4%), and transparent (∼47.7%) being the most common ones. Polyethylene (∼54.5%) and polyamide (∼24.2%) were the most commonly identified polymers, although polyesters (∼12.1%), polystyrene (∼6.1%), and nylon (∼3.0%) were also found. The abundance of MPs in farmed L. vannamei may be related to their feeding habits and the availability of MP sources in aquaculture facilities.