The coastal aquatic environment is where garbage and plastic waste end up after being dragged downstream through sewers, canals, and river channels. 

And the coast where you farm shrimp outdoors is where nanoplastics and microplastics are mostly concentrated. 

https://journals.openedition.org/factsreports/docannexe/image/5409/img-1.jpg

As mother nature tries to push these back to the coastal shore where they came from.

https://www.youtube.com/watch?v=B-nEYsyRlYo

A polluted concoction of (1) human domestic waste, (2) toxic chemical residue runoffs, and (3) tidbits of broken-down plastics in the form of nanoplastics and microplastics mixed in the suspension of eutrophic coastal tidal surface waters