User blog comment:Unownshipper/Flora and Fauna of Rapture/@comment-188.30.28.114-20131020195226/@comment-1500935-20131020202128

We can hear bird chirps in Tenenbaum's recordings in Arcadia and Famer's Market (probably recorded in Arcadia) so that may be a hint there were birds living in there. It could also be recordings used to make the place more charming, but you can't hear any in BioShock.

Also concerning sealife, I'm surprised no one mentioned starfishes. Minerva's Den starts with one right on Sigma's face, and I'm pretty sure we see some during sea floor walks.