The term marine debris applies to the litter in the marine created by humans that intentionally or unintentionally has been discharged in a lake, ocean, sea or water-body. Though the landlocked countries (a country or nation entirely blocked by land) are blocked by the land from all the sides they used to contribute to the marine debris. The fact can be prove with the indirect involvement in Marine debris, as in this case the trash is indirectly created in a city hundreds of miles away from the sea.
If want a direct answer it would be the decrease in mice, but if you want to get technical the decrease in grain spills caused mice to leave so that would be the indirect cause
