Let's take an example. Again, it's public education. Most people figure that goldfish are benign. There was a study at McGill many years ago—I wasn't involved with it—that showed goldfish act like little carp, little aquatic pigs, basically, rooting around in the sediment, and they can increase turbidity, reduce light transmission, and uproot plants. Visual predators like newts and salamanders and so on find their habitat inhospitable, so they leave. The goldfish do this because they're ecologically rewarded by it, because they're shiny, and when you decrease light transmission by creating turbidity, predators can't see you. They're basically engineers, and they re-engineer habitats.
I wouldn't imagine anyone who dumps their fish into a pond imagines that's going to happen. They don't have to know that that particular thing is going to happen, but they have to know that there's a cost to doing something like that.
I think the point is that most people who use the outdoors are not interested in damaging it, but I think most of them aren't aware of what they're doing.