Is that citation in the lead needed, and why isn't it used anywhere else in the article?
Moved to Definitions, where now used.
"In Press (X): XX." What is this supposed to signify? The article seems to have been published long ago.
Fixed.
"intertidal invertebrates" This could be explained.
Done.
", keystone predator can be even less" Predators?
Yes.
The quote after " the jaguar is a charismatic big cat" could be attributed in text.
Done.
Like you explain the results of eliminating wolves, could this be stated for the sea otter also? Now the section about the otter does not mention that humans have a hand in the lack of sea otters where urchins are abundant.
Rewritten.
On this note, I think it could be made clearer that humans are often the cause of disrupting the balance between keystone species and their prey.
Said so.
"it has been criticized for oversimplifying complex ecological systems." Only stated in intro, this should be covered in more detail in the article body, perhaps under history. Then it doesn't need a citation in the intro either.
Moved to 'Limitations' section and expanded.
You should add that wolves were reintroduced to Yellowstone (as you mention in an image caption), and that this is how it is known what effect they had.
Done.
"Yellowstone's apex predator, the wolf" to "The wolf, Yellowstone's apex predator"? The other section titles have the keystone species' name first.
Done.
I think you could explain in the sea star section that Paine made his discoveries by removing sea stars from an area to see what would happen (at least that's how I remember it).
Done.
"the parrotfish on the Great Barrier Reef is the sole species" Parrot fish are a group of species, is any particular species meant, or is it the group as a whole?
The group.
It should probably be noted who has criticised the concept, especially since all the criticism is sourced to one article.