If you have a termite infestation, you might say that they're invasive to the house and it's not their natural element. However you might also say that they live there, which is equally true.

But the post is about sharks in the ocean. It is their natural habitat, they live there, but because they're sometimes inconvenient to humans, humans sometimes use the phrase "shark-infested waters", which can be damaging because it frames disrupting the ecosystem as some kind of defensive act.