Never mind chaos theory's flapping butterfly: one carelessly disposed of plastic item inland, could end up in the gut of an albatross chick on a remote inland thousands of kilometres away. That object could be one of many plastic fragments and particles that will fill this bird's belly thus starving the animal to death.
Hundreds of seemingly insignificant nurdles are swallowed by other animals such as fish, leaching toxins into their bodies.
What can anyone do about any of this? We can all learn to be responsible. We can tell others about it. We can share articles and images with our friends and family to help them understand no piece of plastic is insignificant. It means life or death for the animal that eats it. That animal could indirectly be us. As the dominant species on this planet we have the capacity and therefore the responsibility for our collective actions.