Typically in a lease termination, it would stipulate they could no longer open and operate for the public - not that they'd have to vacate the property immediately. The City would pull their operation license. It wouldn't necessarily prevent the staff from accessing grounds to care for the animals either. I'd imagine there'd be a grace period as well in which the facility can operate to care for the animals until they can find suitable homes or correct the deficiencies. Like
@MidwestFan stated, the City wouldn't have legal authority over the animals at all. Nor would they want to have city workers attempt to feed a dolphin with no training.