Looks like you have some issues with spaces, etc, in this (see the leading space, a space preceding but not following a comma, ...). Please proofread before issuing pull requests. 

Also, it looks like you have two pull requests here. You can just update one by continuing to make commits to it. I'll close the other PR in favor of this one. 

Instead of ``Occupants of the surgeonfish...``, I suggest ``Members of the surgeonfish microbiome...``

Instead of ``Unlike the human microbiome, surgeonfish are a natural population, ...``, I suggest ``The surgeonfish microbiome, unlike the human microbiome, generally has not...```